My last car, a Mk2 Mondeo suffered a broken spring. An independant garage only changed the one. I personally always thought both should be changed so I'll probably get them done shortly.
As someone has stated, you don't know what the effect might be under a heavy braking, steering scenario.
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My last car a Mk2 Mondeo suffered a broken spring.
A broken spring is rather a different kettle of parrots - however, most people only notice at MOT time. If you wanted to be sure that you'd got both springs (or dampers) the same, you would have to measure them - manufacturing tolerances mean that a random "pair" of springs are likely to vary somewhat anyway.
An independant garage only changed the one.
Yup.
I personally always thought both should be changed so I'll probably get them done shortly.
:) I wonder how long one would run a broken spring, or "old" damper, with a new one, before thinking that any subsequent replacement would have to be a "pair"?
As someone has stated you don't know what the effect might be under a heavy braking steering scenario.
'Course not. Could easily, and I'm sure someone'll be along in a minute to say "IT WILL", flip the car. ;)
Edited by FotheringtonThomas on 30/07/2008 at 22:41
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FT: for bimbling about in town at low speeds in the dry, a tired old jalopy with a random assortment of new and part-worn springs and shock absorbers will usually be perfectly all right. On the road or at any speed or on bumpy bits or in the wet, it won't. You're wrong, very.
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You are making certain assumptions which are "wrong very". Never mind, ICBA. Continue to take advice from the spotty oik at (your unquestioned fitting firm) and don't worry about it.
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You are making certain assumptions
And those are?
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There's no need to change springs in pairs
It makes a lot of sense to change shocks in pairs.
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There's no need to change either in pairs, unless you want your car's handling to be at least symmetrical and close to design performance. Personally I regard that as a matter of some importance.
Springs get tired as well as shock absorbers. All you have to do to understand this is remember the way an old car goes down with its belly close to the road like a Basset hound on heat. Do you really want it to lean over sideways as if it was trying to scratch its ear on the ground? If so, just get it a new spring on one side or better still two on the same side. One assumes of course that if it is virtually new these replacements won't be needed.
I am shocked by you people. I can only conclude that you are super-mimsers and handling never comes into it for you even in the emergencies that you never have of course.
I am shaking my head sadly.
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Springs, dampers, and braking components should always be changed in axle pairs.
MOT standards should be maintained 365 days a year, not just the day of the test.
Springs lose tension and sag with age, its the combination of the spring and damper that keeps the tyre on the road to aid handling and braking.
If they are leaking they are not going to get any better and are not doing the job correctly.
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I can only assume that FT has never taken a pair of springs off a car to replace them without them having been broken!
If he had he would notice that the unsprung height of a worn spring is lower than that of an unused one.
Please explain how this is not wear ?
Will it affect the handling of a car? Yes! How can it not ?
And no I dont work for any fastfit concern I work for myself; and have turned jobs away before now rather than fit items I dont consider correct. (I have refused to swap 1 spring before now on a corsa!) Why? Because it was of a different design to the one on the car (modified design apparantly).
In this instance fast fits are offering better advice than FT !
Simple logic says if its been used it has to have suffered in some way (measurable or not)
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I can only assume that FT has never taken a pair of springs off a car to replace them without them having been broken! the unsprung height of a worn spring is lower than that of an unused one. Please explain how this is not wear ?
That isn't wear, it's deformation. The same applies to torsion bars, which, were I to be similarly insulting, I should say you've never even heard of.
Simple logic says if its been used it has to have suffered in some way (measurable or not)
So - and please be exact here - if the "wear" on a component is not measurable, then how is the PFD thing "worn"?
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erm, springs dont break unannounced?
Erm deformation isnt wear?
erm torsion bars never wear out?
need i go on?
Do you not consider safety on the road to be good practice?
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Erm,
Simple logic says if its been used it has to have suffered in some way (measurable or not)
So - and please be exact here - if the "wear" on a component is not measurable, then how is the PFD thing "worn"?
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To be exact
measurable or not (by the average man at home) would be a better phrase.
A used shock absorber is not new, therefore its worn to some extent! After 10 miles, negligble. After 10k miles detectable? likely? After 50k miles definitely noticeable! At what point is it ok to keep using? Difficult to answer, so proper advice is to ALWAYS replace in pairs!
Is that exact enough?
Would you please be exact in your reply as to whether safety on the road, and advice given about it, is a good idea or not?
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To be exact (...) Is that exact enough?
Yes, that's fine.
Would you please be exact in your reply as to whether safety on the road and advice given about it is a good idea or not?
Safety on the roads is in most cases paramount, of course. However, making unneccessary replacements to conform to some fallacious ideal is not.
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Springs of all descriptions 'deform' under the weight of a vehicle because they suffer over time from fatigue. They become softer and less 'springy', so the same force applied to them deforms them more when they are old than when they are new. Obviously this isn't 'wear' in exactly the same sense as wear in sliding or rotating parts or in (for example FT) shock absorbers, but it doesn't seem unreasonable to call it 'wear' because it is in fact a deterioration of performance over time as a result of use.
I really can't understand why you are arguing about this. You have pointed out that the MoT test passes cars whose handling in particular may be well down on their design specifications. That may have been new information to some people, although others including me have commented on it in the past. But why the insistence that a car with lopsided handling is acceptable just because it isn't illegal? Seems barmy even by BR standards.
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While the MOT inspection method appears to be simplistic and lax, there is a subtle reason why it's actually quite safe.
So, although dampers may have worn, and while there may be a discernible difference felt by the driver when new ones are fitted, dampers can remain safe.
Here's the logic, or subtelty (sorry, there's a formula!).
Zeta=C/(2*sqrt(K*M))
Zeta is the damping ratio
C is the damping constant (units of Newton seconds per metre)
M is the mass (kg)
K is the spring stiffness (Newtons per metre)
sqrt(...) stands for - take the squre root of the value in the brackets
Now, bouncing on the car, and making sure that it doesn't continue to bounce excessivley makes sure that the damping ratio is above a reasonable threshold - typically, about 0.2.
But, this is using the sprung mass of the car as the vibrating mass, i.e. M, on the denominator is large.
The effective damping ratio when considered for the much lighter unsprung mass is much higher - hence, the shock absorber is being more effective in controlling the wheel than might be imagined.
I'm not going to get dragged into the one or two dampers debate, except to say that I can't get too excited by either point of view.
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I feel you are being a tiny bit mischievous here NC, but only a tiny bit because after all we all have to mimse most of the time and handling is seldom a real issue for most drivers.
However: when I got it my VW 411, a car with quite sophisticated, safe and comfortable suspension, was slightly tail-happy on wet bumpy corners, indeed on any bend under heavyish braking, and I noticed that on certain ripply back-road bends the offside rear wheel in particular could bounce more or less uncontrolled between the spring and the elasticity of the tyre over the ripples for several seconds at a time. Although the MoT didn't fail them, I changed all four dampers using inserts for the front struts (and a bit of a pig of a job it was). It made, believe me, a very considerable difference, as it has every time I have changed dampers in a car. It improved not just the handling but the ride.
As FT (reading between the lines) and you, along with the MoT, point out though, it may not matter much because people mimse anyway and some of the wheels on most cars have partially functioning shock absorbers.
There was an old man who supposed
That the street door was partially closed;
But some very large rats
Ate his coats and his hats
While that futile old gentleman dozed. (Edward Lear)
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I feel you are being a tiny bit mischievous here NC, ...
Not really Lud, turning round the logic described in my post, one conclusion that can be drawn is when the MOT says dampers should be changed, then, they REALLY should be changed. Like many of the MOT requirements a fail really does indicate that something isn't safe.
The obvious exception is the beastly emissions rule - a purely political requirement which doesn't affect safety at all.
Yes, handling may benefit from being replaced before they reach MOT failure point, but deterioration from the as new standard does not automatically make the car unsafe.
In summary, I think the MOT is a very sensible way to make sure that dampers which are truly unsafe are no longer used on the road.
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Sorry if i disagree that you think the test on springs and shocks is safe nc.
By the time they are bad enough to fail the mot (unless visibly leaking) the car is probably dangerous!
I would have thought with your experience that you would never advise anybody to drive with 2 different condition components on the suspension!
There is a difference between a competent mechanic assessing the condition of components on his/her own car before deciding to replace 1 or both but to advise people who are not competent mechanics, not to change both, is potentially dangerous.
IMO of course !
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>>that you would never advise anybody to drive with 2 different condition components on the suspension!
I haven't said that, or anything like it in this thread.
>>There is a difference between ...
I fully agree.
Edited by Number_Cruncher on 31/07/2008 at 18:18
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But both you and FT are being a bit obtuse when you insist that because deteriorated dampers aren't regarded as unsafe or deemed illegal, there's no difference between changing them one at a time and changing them in pairs. I can drive almost anything and have driven plenty of thoroughly sloppy, still road-legal cars. But you can't use such jalopies properly because they are rubbish, so I find them depressing to drive.
Even if you are a person who doesn't notice this sort of thing - I find it hard to believe that either of you is one - or doesn't care because he or she is an extremely slow, cautious mimser, it is either a false economy or foolish arrogance to change dampers or springs at either end of any car singly, except perhaps under pressure of extreme poverty. Emergencies can arise on the road without warning in which the behaviour of car, as well as driver, can make the difference between, er, one outcome and another. As any fule kno, or ought to.
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But both you and FT are being a bit obtuse when you insist that because deteriorated dampers aren't regarded as unsafe or deemed illegal there's no difference between changing them one at a time and changing them in pairs.
I don't think I said that, did I? I don't think NC did, either.
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Oh stop it FT. You didn't say specifically that there was no difference, no. But the burden of your message is that the difference doesn't matter.
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Oh stop it FT. You didn't say specifically that there was no difference no
Thanks.
But the burden of your message is that the difference doesn't matter.
Very ofthen it doesn't - in the case of some components, it makes no difference at all. I stand by that.
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You have mentioned dampers, springs and brake discs. You are in fact wrong about all of those. In the case of discs, they are so cheap that it seems foolish to risk asymmetric behaviour (perhaps as a result of differing heat dispersal under very heavy braking) by having one thin one and one thick one on the same axle.
Perhaps in a car with rear drums it might be OK to change just one of those. As for calipers, to change one is perfectly all right if it is defective or damaged and the other is still working properly. That's because in the case of a caliper, wear makes little difference to performance until the point of catastrophic failure is reached.
I'm tired of this.
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In the case of discs they are so cheap that it seems foolish to risk asymmetric behaviour (perhaps as a result of differing heat dispersal under very heavy braking) by having one thin one and one thick one on the same axle.
If one's wafer thin, I agree - however, they would then be U/S. However, for normal wear,
this won't be the case. Tell me that there will be a noticable difference in use between a brand-new disc and one that's worn, but within limits - the new one having new pads, the old one having (say) 1/2 the material remaining - both "bedded in". Hm? Bet you won't.
Perhaps in a car with rear drums it might be OK to change just one of those.
Hm. If there *were* to be a braking difference, then on the back is exactly where you do *not* want it. I can't easily reconcile your point of view that "things must be changed in pairs" with your latter, diametrically opposite, statement.
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But when around 75% of the brakes performance comes from the front brakes perhaps you might enlighten me why the rear brakes would have more concerns than the front?
I am also sure an mot tester would be able to determine a difference in braking ability of different component front brakes (especially that of different pad materials as you describe) on an mot brake testing machine. Are you saying comprehensively that it is ok to change brake pads on one wheel only? I honestly cannot believe you are suggesting that !
In all of this arguing over items of car safety I think you are confusing the difference of yourself analysing a component on your own car to be fit for use or not, compared to advising a person who is obviously not so mechanically able to determine the same.
As such it is wrong to advise them to do anything other than change both sides of suspension and steering and braking components should any need changing. To advise otherwise is poor advice at best!
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around 75% of the brakes performance comes from the front brakes perhaps you might enlighten me why the rear brakes would have more concerns than the front?
Think about less-than-ideal conditions - slippery roads. It's the same reason as "why you should fit newer tyres on the back". Once the back end comes around, it's almost certain that you've had it.
I am also sure an mot tester would be able to determine a difference in braking ability of different component front brakes
Really? Why? I should love to know, given that nothing's excessively worn, but all are bedded in, as I described.
(especially that of different pad materials as you describe)
I certainly did *not* describe nor advocate using different pad materials. If different friction materials were used, I would agree that there could well be a difference.
on an mot brake testing machine. Are you saying comprehensively that it is ok to change brake pads on one wheel only? I honestly cannot believe you are suggesting that !
It won't affect braking performance (once bedded in, same materials, etc.), but it would most likely mean, however, that the part-worn pad would have to be changed at some time before the renewed one.
In all of this arguing over items of car safety I think you are confusing the difference of yourself analysing a component on your own car to be fit for use or not compared to advising a person who is obviously not so mechanically able to determine the same.
I'm not giving blanket advice.
As such it is wrong to advise them to do anything other than change both sides of suspension and steering and braking components should any need changing.
Their Technical Consultant can do that. However, a quick fitting Technical Consultant will always seek to make money where possible, and may not actually *be* very technical. Hence the "replace everything as a pair" stuff.
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"Think about less-than-ideal conditions - slippery roads. It's the same reason as "why you should fit newer tyres on the back". Once the back end comes around, it's almost certain that you've had it."
I was trying to leave this thread alone. You can only bang your head against a wall so often before you realise it hurts! But that statement you made just proves you are talking out the back of your head ! (politely!).
I retract my comment about you being competent to assess the condition of your own components if that is your considered comment!
THe only time and I mean ONLY time rear brakes will EVER cause a problem is when they are too strong in relation to the front brakes (ie the fronts not working correctly) or when the suspension is in such poor condition it upsets the balance of the car under heavy braking ! Even with badly out of balance rear brakes a car will still pull up in line (excluding very heavy big cars). This is even more true with abs systems fitted!
It is quite possible (try it by clamping the rear flexis sometime if you get the chance off road somewhere) to drive without any rear brakes and not actually notice much difference in braking effort. To state that the use of unpaired rear brakes is worse than the fornt is nothing but dangerous comments to anybody unaware that may be reading this!
"It won't affect braking performance (once bedded in, same materials, etc.), but it would most likely mean, however, that the part-worn pad would have to be changed at some time before the renewed one."
Again, complete tosh! You are assuming that the caliper will give equal pressures when 1 is nearly "home" and 1 is "hallf way out". Very, very unlikely. Also, as any brake manufacturer will tell you the effect of heat on pads of different thicknesses can cause uneven braking effort/reaction!
I am also very suirprised that NC did not pick this up too and comment on it.
A brake testing machine will show this different reaction (to an experienced operator) quite easily. A lot of motorsport guys will spend time bedding pads and discs in before race/rally time so that if needed to be changed and used during competition they will be ready for use immediately and they will spend a lot of time on a brake machine to ensure the brakes work evenly!
To even consider driving on unmatched brakes (front or rear) is just dangerous; to advise anybody to do it is unbelievable!
Edited by yorkiebar on 01/08/2008 at 17:56
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Apologies for all the quoting below; needed to maintain context.
THe only time and I mean ONLY time rear brakes will EVER cause a problem is when they are too strong in relation to the front brakes (ie the fronts not working correctly) or when the suspension is in such poor condition it upsets the balance of the car under heavy braking ! Even with badly out of balance rear brakes a car will still pull up in line (excluding very heavy big cars).
That isn't at all true, given a low-friction surface.
It is quite possible (try it by clamping the rear flexis sometime
No, thank you. That is quite unacceptable and dangerous. I very much hope that you do not do any maintenance for anyone which involves you doing this.
if you get the chance off road somewhere) to drive without any rear brakes and not actually notice much difference in braking effort.
Perhaps, but that was not the point. The point was having "out of balance" rear brakes. Read again, if in doubt.
To state that the use of unpaired rear brakes is worse than the fornt is nothing but dangerous comments to anybody unaware that may be reading this!
Given the circumstances I suggested, though, it is true.
"It won't affect braking performance (once bedded in same materials etc.) but it would most likely mean however that the part-worn pad would have to be changed at some time before the renewed one." Again complete tosh! You are assuming that the caliper will give equal pressures when 1 is nearly "home" and 1 is "hallf way out". Very very unlikely.
I do not believe that you know much about hydraulics. The piston is only a ram. The "pressure" will be the same. If you do not believe this, I shall be particularly interested to hear your reasoning - in fact, if you only answer one point in this post, please answer this one.
A brake testing machine will show this different reaction (to an experienced operator) quite easily.
It's a machine. It gives a reading with a blinkin' great dial, or a set of numbers. It doesn't need "an experienced operator".
A lot of motorsport guys will spend time bedding pads and discs in before race/rally time so that if needed to be changed and used during competition they will be ready for use immediately and they will spend a lot of time on a brake machine to ensure the brakes work evenly!
This would surely be more to ensure they worked at good efficiency straight away, rather than to ensure they were matched (which would need rather complicated measurement).
To even consider driving on unmatched brakes (front or rear) is just dangerous;
Unmatched in "braking effort", and I agree.
to advise anybody to do it is unbelievable!
I have not advised anyone to drive with brakes unmatched in "braking effort". Quite the opposite, as in my reply to which you allude above (back brakes).
Edited by FotheringtonThomas on 01/08/2008 at 18:21
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This is my last post on this thread.
It is beginning to hurt ! FT.
You are at best mis informed and at worst dangerous with the advice and comments you persist with!
To answer your comments.
1 THe only time and I mean ONLY time rear brakes will EVER cause a problemis when they are too strong in relation to the front brakes (ie the fronts not working correctly) or when the suspension is in such poor condition it upsets the balance of the car under heavy braking ! Even with badly out of balance rear brakes a car will still pull up in line (excluding very heavy big cars).
That isn't at all true, given a low-friction surface.
This is true! YOU are wrong!
2 >> It is quite possible (try it by clamping the rear flexis sometime
No, thank you. That is quite unacceptable and dangerous. I very much hope that you do not do any maintenance for anyone which involves you doing this.
Oh please ! Its a recomendation to try OFF ROAD if you have a chance; so that you might comprehend the subject!
3 >> if you get the chance off road somewhere) to drive without any rear brakes and notactually notice much difference in braking effort.
Perhaps, but that was not the point. The point was having "out of balance" rear brakes. Read again, if in doubt.
It is VERY relevant to what you stated (point 1). Read again if you dont understand what you said!
4 >> To state that the use of unpaired rear brakes is worse than the fornt is nothing butdangerous comments to anybody unaware that may be reading this!
Given the circumstances I suggested, though, it is true.
Unbelievable reply. I just cant comment !
5 I do not believe that you know much about hydraulics. The piston is only a ram. The "pressure" will be the same. If you do not believe this, I shall be particularly interested to hear your reasoning - in fact, if you only answer one point in this post, please answer this one.
Okay, technically you are correct! However, in the real world there are other factors in operation, including the surfaces the caliper piston works on. Whilst the preesure may be the same; the effect is not necessarily so!
6 It's a machine. It gives a reading with a blinkin' great dial, or a set of numbers. It doesn't need "an experienced operator".
Just shows your lack of understanding of the "machine" !
7 This would surely be more to ensure they worked at good efficiency straight away, rather than to ensure they were matched (which would need rather complicated measurement).
No its to ensure the brakes are even in performance. Not all bedded in pads/discs would be used ! Only those that are acceptable!
8 >> To even consider driving on unmatched brakes (front or rear) is just dangerous;
Unmatched in "braking effort", and I agree.
to advise anybody to do it is unbelievable!
I have not advised anyone to drive with brakes unmatched in "braking effort". Quite the opposite, as in my reply to which you allude above (back brakes).
Again unbelievable reply. You have clearly alluded to drive with mismatched pads/dsics. eg a skimmed disc 1 side and half worn pads versus new on the other side.
Your advice is DANGEROUS !
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To answer your comments. 1 THe only time and I mean ONLY time rear brakes will EVER cause a problem is when they are too strong in relation to the front brakes (ie the fronts not working correctly) or when the suspension is in such poor condition it upsets the balance of the car under heavy braking ! Even with badly out of balance rear brakes a car will still pull up in line (excluding very heavy big cars). That isn't at all true given a low-friction surface. This is true! YOU are wrong!
OK, well try this then. Note, it really *is* dangerous advice, so take appropriate safety
precautions, and make sure no-one else is likely to get hurt.
Wait until there's a bit of snow, and find a road where the surface has been packed down and is slippery (or find a skid pan).
Get a nice new Vise-grip or similar, with pristine jaws. Use it to cramp up one rear brake flexible hose. Make sure it's nice and tight, and can't fall off. This to disable one rear brake.
Now, drive at about 20MPH - not too fast! - on the slippery surface. Jam on the brakes. When the back end comes around, recover control. Demonstration over.
Remove the Vise-grip. If you went too fast and were hospitalised, don't forget to remove the Vise-grip when you get out, if you are able.
During your further driving (if your car was repairable), note that your rear hose could have been damaged by the clamping action of the Vise-grip, and could have been rendered liable to failure.
If the flexible hose does fail when you are braking, simply recover control, and renew the flexible hose if your car was repairable, and/or when you are out of hospital, if you are able.
(this post was supposed to be both humerous and instructive, BTW)
Edited by FotheringtonThomas on 02/08/2008 at 11:01
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I was really really trying to ignore this post but FT you are getting under my skin with your lack of understanding and subsequent poor advice.
For your information I have (in a rally off road) ripped a rear brake hose and SAFELY (if rallying can ever be safe) finished the stage to efect a repair.
Did I actually have any problems braking? Er no! Er why? Probably because the front brakes do most of the work ! The rear cant overtake the front if the fronts are working correctly (another good reason to ensure matched components are used on both sides!)
You may now say what you want, because I am not replying further.
I think its safe to say that anybody still reading this thread will have seen sufficient comments on both sides to at least be aware there may be a problem with mismatched components. Only a few (yourself included) seem to ignore this !
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>>The rear cant overtake the front if the fronts are working correctly
Sorry YB, but, that's not right, it's perfectly possible.
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Look guys, can't you just agree to disagree on this one and put this thread to bed?
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(this post was supposed to be both humerous and instructive BTW)
Even the humorous side of FT on suspension can pall quite quickly. As for the instructive side, the less said the better.
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Settle it with a custard pie fight, video it and post it here.
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Yeah yorkie. You try to eplain these things to people but they think they can make a more cunningly meticulous analysis than you can, and then give people dodgy advice on the strength of it.
One can only hope something, not too lethal of course, will happen to wise these tiresome people up. But there's no justice so it probably won't. And anyway given the line they have been taking it's highly unlikely that they would ever put two and two together in this context to make four.
Damn idiots if you ask me, but they probably think the same about us.
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I have just thought of an example which may be helpful, since we're talking about braking components.
You have bought a new car. It has done 0 miles. You have one disc skimmed to to make it 1/2 worn. You have the pads on that side taken down to 1/2 worn, as well. What difference in performance will you notice?
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None whatsoever.
Rubbish. If you brake several times extremely heavily from very high speed you may well notice a difference. But only a complete halfwit would try it. Of course there are some of those around.
Shut up, both of you. You are being tiresome to put it mildly.
Edited by Lud on 31/07/2008 at 23:37
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Hang on a minute..
No. Shut up.
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>>If you brake several times extremely heavily from very high speed you may well notice a difference.
I don't think it's going be such a great difference - if any at all. The pads are going to heat up in a similar way, and the material will fade similarly. It isn't as though FT has suggested the comparison between a new pad, and a pad on the verge of being dangerous - there's still plenty of meat on both pad and disc.
To set the record straight. In actual practice, I wouldn't mix brakes or suspension components, and I always replace them in pairs, and still less would I recommend it as good practice.
This discussion is similar to the MOT standards thread in that the dividing line between a car being safe and not safe isn't obvious. The MOT is usually a good start in defining the boundary.
In some ways, many people are arguing that everything reasonably possible should be done to promote safety. That's the common prevailing view which pervades all we do in the UK at the moment, and has led to the dominance of the 'elf & safety culture.
I think that the balance has swung too far, and that reasonable (like the MOT's requirements, for example) are being replaced by a more extreme view. It's an extreme view which I can't really go along with, because while it's likely that most on here, enthusiasts, will have no trouble with more rigorous standards, but, really, that's preaching to the choir. I'm much more worried about the cars which avoid the MOT already, a number which would only grow if the MOT were to become more rigorous and costly. Do we really want an almost Japanese MOT inspection system?
>>Shut up, both of you.
Why? - I don't *think* I'm breaking the site's rules.
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Why? - I don't *think* I'm breaking the site's rules.
Is that the only reason why you might want someone to shut up, NC? As far as I'm concerned you can break the rules any time. My rudeness is purely personal, although I don't really want to offend you or even FT any more than you have offended me.
Anyone can see it isn't going to make 'such a big difference' in a lot of cases. But if you advise people (or collude in advising people) that MoT standards are all that is needed to ensure that their car has safe suspension, you aren't really doing them a favour and may be signing their death warrant. Apart from the moderate cases of asymmetry that you describe, there might be other cases, within legal parameters, where the asymmetry is more extreme. Do you really care about the risk you may, just possibly, be encouraging people to take?
I don't know about FT, but I note that in your own case you adopt sensible policies. Isn't it a bit carp of you to mislead others in the way you have been doing? Not everyone reads or understands every word or takes it in. Basically you and FT are trying to kill people, whether you realise it or not. I feel as annoyed with you as people do with me when I say it's all right to exceed the speed limit. But if I'm a suspension mimser and goody-goody, you are suspension psychopaths. So there.
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Show me where I've advised anyone that they should only change one damper, one brake pad, or one disc.
MOT standards, while not being perfect are, at least, sensible.
Also, remember that anyone considering only fitting one side begins from a situation of asymmetry.
>>Basically you and FT are trying to kill people
No, you really have got the wrong end of the stick - I haven't advised anything that's unsafe. Please re-read what I have written, and not what you think is between the lines.
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>>>>Basically you and FT are trying to kill people
Although it was done in a spirit of rhetorical hyperbole, I slightly wish I hadn't written that. It is an ill-natured thing to say. And you made it clear that you yourself change the things that ought to be changed in pairs in pairs.
However, FT had advised people that changing them singly would be just as good, which I insist is poor advice at best, and conceivably actually dangerous. By coming in with your equation showing that partially functioning dampers are, er, partially functioning, you seemed to be giving credence to that view. As I said, not everyone reads every word or takes it in.
AS for FT, I don't seem to be alone in suspecting him of enjoying a nice wind-up. I don't really have anything against that (annoying though it can be if you are the slow-in-the-uptake victim), and FT says he never ever washes his car, so he can't be all bad.
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However FT had advised people that changing them singly would be just as good which I insist is poor advice at best and conceivably actually dangerous.
Although your reason for saying that seems to be "because one should" or "because many of the motoring population are generally imbeciles", or similar - rather than for any real technical reason.
Never mind.
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>> Never mind.
Carphound (loud and prolonged raspberry).
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Said it would go to penalties ! Anyone counting ?
;-)
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I know we dont always see eye to eye NC but that answer is absoloute tosh!
Calipers dont stick when pads are half worn etc?
Pads dont get affected by heat when they are different thickneses?
Discs dont get affected by heat in their use too?
Oh please!
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Calipers dont stick when pads are half worn etc?
The calliper sticks when the calliper sticks! What's that got to do with the pads?
Pads dont get affected by heat when they are different thickneses?
No. I wouldn't expect my brakes to be any better/worse when hot or cold. Would you? The pads are designed for heavy usage and will not be affected by heating. If they did, all new pads would be destroyed before they had a chance to bed in, as the points of contact is in localised areas during that time.
When I had a stuck calliper, meaning only one pad was moving on one front wheel, I didn't notice anything unusual about the breaking, as the 'free' pad just ended up doing all the work. The only symptom was a scraping noise whilst braking and a settlement of rust on the unused side.
Discs dont get affected by heat in their use too?
To affect the braking enough for you to notice there would have to have been considerable heat passed through the discs to change the metallurgy of the steel/iron. By which point your discs would be warped so badly the car would be un-driveable.
The surface area of a disk compared to it's thickness is large enough to allow any temperature difference to be unnoticable if they are different, or at least irrelevant.
Edited by mfarrow on 01/08/2008 at 19:39
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All pads and discs are designed to operate at high themperature.
The more resistance to fade (the higher temperature they can stand).
Different brands will work better at different temperatures.
The same brand (half worn) WILL operate different to new same brand. If in doubt discuss with brake pad material manufacturers. Until you do its just your opinion !
Brake discs are similar.
A half worn disc will operate at a different temperature to a new one, which will affect the pad, which will affect its performance. Possibly not by a lot, but why take the risk is the point trying to be made !
a a rough guide it is estimated on an average car, stopping from 60 to 0 mph in a sudden fashion generates enough heat to boil approx 1 ltr of water (from cold)! heat has no effect? That heat has to be dissipated for the brakes to keep working! Uneven thickness of metal in the 2 discs, you tell me what happens ?
Edited by yorkiebar on 01/08/2008 at 21:22
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Don't waste your breath yorkiebar. All the arguments about heat dispersal and suspension control and so on have been rehearsed, and it seems unlikely that they have really not been understood. Even if they have though, it doesn't matter. Either people are being annoying on purpose or they are invincibly ignorant.
I wouldn't have to numb myself with native gin to drink with you though. We could drink something that tasted good and talk about something interesting.
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As Yorkiebar says, there are plenty of road-legal cars whose virtually non-existent suspension control makes them dangerous, especially in clumsy hands, but anyway.
It has also been pointed out in previous threads that the 'bounce test' on each corner used in the MoT doesn't really work well, especially with large cars, because resistance in the suspension joints and bushes has a weak damping effect that may mask the presence of totally shot non-leaky dampers.
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All gone a bit quiet hasn't it? I was enjoying that. Would probably have gone to penalties mind.
;-)
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We used to own a renault 19, I noticed one day driving along a dual carriageway that there was a knocking noise coming from the back. The car did seem to wander a bit at 70mph but other than that all seemed to be in order.
When we got home I checked in the boot to see what was making the noise, I was expecting to find something loose that was rolling around. I was quite surprised to see the end of the shock absorber poking right through into the boot!
Turns out that there was a large metal cup on the top of the shock that had completely rusted away. The other side was also in a very poor state.
Effectively the car was being driven with only one shock absorber.
While we didn't perform any emergency stops in that time the only noticeable effect on the handling was the slight wander at speed. And no, the car didn't flip, burst into flames or suffer any other sort of disaster!
This same car also suffered a broken spring, this wasn't noticed until the MOT. I will confess my sin of only replacing the one spring. 3 months later the spring on the other side broke in exactly the same place. Note that it was the first 3-4 inches of the coil that broke, hence no noticeable effect on the car.
Since owning that car I vowed we would never own another french made car. That car had all sorts of problems in the time that we owned, most of which I put down to poor quality build and materials.
Edited by moonshine {P} on 31/07/2008 at 18:54
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Saved this one for another post to stop the above one being too long.
A couple of years back I replaced the shocks on the supra as one of them was leaking. I replaced them as a pair and bear in mind that the supra has gas shocks they were hard to find and expensive!
When removed I compared the old shocks with the new by pressing them down by hand. The old shocks could very easily and quickly be pushed all the way down with very little effort. The news took considerably more effort to do so and the shocks compressed much more slowly.
However, the key thing is that after fitting the new shocks the only difference in handling that I could pick up on was that there seemed to be a bit less roll on a tight corner - but it's so subjective I couldn't say for sure.
Is anyone aware of an accident that was caused by worn shocks? I wonder if on modern cars they are not as critical as we are led to believe?
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I think you should all go to the pub or open a bottle of something good from the Rhone valley.
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Fino I think...
Do you mean pale dry sherry Mm? Not at all sure that would do the trick.
Cane spirit, ogogoro, gongo, chang'aa or poteen still warm from the, er, still might just make one numb enough, or if one was lucky dead enough, to drink for half an hour with certain elements without having an apoplexy...
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Nothing legal numbs the senses quite so well as a home distilled caiperinia on the edge of the Rio favellas at sundown. In fact, nothing has ever numbed my senses so much as the favellas actually.
Had my '74 Ford Landau refurbed to showroom condition by a favella mechanic / coachbuilder once. He charged $800 to turn a wreck into a cool cruiser.
He fitted new shock absorbers BTW. I'm sure it was a pair.
;-)
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i cant believe i share the roads with idiots who know so little about the handling of there car
you should ALWAYS change shockers in pairs
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The penalties have finished !
extra time was over long ago.
Im now so knackered with banging my head against the brick wall I dont care who won the "discussion".
Just keep away from me on the road if you share opposite point of view to mine!
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you should ALWAYS change shockers in pairs
I agree, but try telling that to garages who generally insist on only changing the faulty one that has failed under warranty.
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I drove a MK 2 cortina with original shocks when it has 124k on the clock. I learnt to drive on it and I dare say that I learnt to match the push on the go pedal to the performance.
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