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If they look OK they probably are.
10.9 is a high tensile strength bolt class, (ultimate tensile strength of 1000 N/mm² or so), so its unlikely that you stretched them. If you did they would probably be distorted in the thread area and would be difficult to run in. You could check this by running a nut down the clean thread by hand, if you have a nut that fits. Should go down with finger pressure
I don't generally use a torque wrench but caliper bolts are, for me, a borderline case where I might.
Part of the reason I dont generally use a torque wrench is because torque specs are usually for "dry" fastners, and I really dont like using dry fastners.
IIRC the last time I used a torque wrench on (lubricated) caliper bolts I ended up going by feel anyway, backing off the specified torque by about 50%. This is actually in line with some recommendations for lubricated fastner torque reduction, but these vary wildly. For example
www.engineeringtoolbox.com/torque-lubrication-effe...m
LubricantTorque Reduction
(%) Graphite 50 - 55 White Grease 35 - 45 SAE 30 oil 35 - 45 SAE 40 oil 30 - 40 No lube 0
I cant remember how I lubricated those particular bolts. I generally use chassis grease and polythene sheet, which you wont find tabulated, but for a bolt that might get quite hot like a caliper bolt, I might have used antiseize, (ditto), perhaps with PTFE thread tape (double-ditto).
Of course you could avoid all this angst by just torquing dry, as is (probably) specified, but then you (or your heirs) will likely have trouble getting the bolt out later, (as you did) and could conceivably damage it (though you probably didn't).
Anyway, havnt had any calipers fall off.
Edited by edlithgow on 28/06/2024 at 03:55
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You can reuse the slide pin bolts provided the thread and head is in good condition. These are not a stretch bolt.
Under no circumstances lubricate the thread! Put a spot of locking compound on the thread and nip up tight - do not overtighten. Typical torque is around 25 ft. lb.
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You can reuse the slide pin bolts provided the thread and head is in good condition. These are not a stretch bolt.
Under no circumstances lubricate the thread! Put a spot of locking compound on the thread and nip up tight - do not overtighten. Typical torque is around 25 ft. lb.
Well, "a spot of locking compound" would be a lubricant, so that's at least one circumstance where you've QED'd yourself.
I'd think you could assume, however, that if Kia specify a torque AND specify a locking compound, they've allowed for that.
I'd also think the OP is talking about the caliper securing bolts rather than the slider pins, but you never know.
Slider pins I use (rubber compatible) silicone grease and a PTFE tape wrap, which I extend over the threaded portion.
I've never had a car that specified a locking compound on them, but if I did I suppose I might have to reluctantly consider trying to find some.
In Taiwan
I last did this for an oil pump drive sprocket, where I was a lot more convinced it was necessary, (though I dont recall it being specified) and it was a PITA
Probably a dilemma I'll never have to face though
Edited by edlithgow on 28/06/2024 at 10:40
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Looking at the chart that came with the Caterham when I built it and checking with what is on line now the dry torque for a 10.9 spec10mm bolt is 40-45 lb ft dry with HD spring washers, no need for thread lock.
As for putting PTFE tape on threads that is not what its for, its for sealing unions on pipes. Sliding pins should only have a smear of the correct lubricant.
Follow the advice in previous posts at your peril.
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Looking at the chart that came with the Caterham when I built it and checking with what is on line now the dry torque for a 10.9 spec10mm bolt is 40-45 lb ft dry with HD spring washers, no need for thread lock.
As for putting PTFE tape on threads that is not what its for, its for sealing unions on pipes. Sliding pins should only have a smear of the correct lubricant.
Follow the advice in previous posts at your peril.
Sure. Its what they call an improvisation, and wasn't "advice", merely information.
In this case its an improvisation that works rather well.
Sorry about that.
I did at one point have some concern that the tape on the sliding pins might break down under extreme brake heat and release fluoric acid, which is unusually nasty stuff, but then I found that some of the "correct lubricant" has PTFE in it, so that should be OK.
If it was good enough for a Volvo branded lubricant (before they were Chinese, already) its probably good enough for me.
What "peril" did you have in mind?
Edited by edlithgow on 29/06/2024 at 01:10
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What "peril" did you have in mind?
Thought that would have been obvious.
Use of products not intended for the purpose you propose could have disastrous consequences. Braking is a serious matter and one not to be "bodged".
OK the correct lubricant has PTFE in it but not in tape form.
Anyone reading the advice given by Edlithgow should simply ignore it, to do otherwise is just plain daft.
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What "peril" did you have in mind?
Thought that would have been obvious.
Use of products not intended for the purpose you propose could have disastrous consequences. Braking is a serious matter and one not to be "bodged".
OK the correct lubricant has PTFE in it but not in tape form.
Anyone reading the advice given by Edlithgow should simply ignore it, to do otherwise is just plain daft.
Nothing in mind at all then. Encouraging.
Bit more explanation of my rationale in this case.
As noted earlier, this is not really advice, just information. I have no reason to care whether anyone else does the same thing.
Slider pins are an unusual lubrication situation, in that there isn't much movement,so there is no "hydrodynamic" separation, but the pressures are potentially quite high, and there is potentially metal to metal contact. This is probably why at least some of the "proper" lubricants have solids in them, like PTFE or ceramics, to better maintain separation under lateral pressure, and probably why a lot of people use antiseize, though they probably shouldn't, since it isn't primarily designed as a lubricant, and, more importantly, it isn't rubber compatible
You can't buy any of these "proper lubricants" in Taiwan. I bought some silicone grease in a motorcycle shop in Rinko, Japan, descibed to me as Brakku Grizu, or sounds to that effect, by the biker yoof san behind the counter.
Smartphone translation of the tube labelling came up with something involving lubricating the neck rings of fishing Cormorants (?). Honest. I kid you not.
They dont make AI like they used to? Or perhaps that's actually what it was for?
It seemed fairly low viscosity, and I dont believe it had any solids in it.
It occurred to me that if I greased AND PTFE wrapped the slider pins I would get the advantages of a solid reinforced lubricant, only possibly more so, since the PTFE would fully enclose the pin and couldnt be squeezed aside like fine particles suspended in grease could, so thats what I did, leaving a slight gap between the spiral wraps to retain some extra grease.
I expected it would probably eventually wear and perhaps "bunch up", perhaps becoming less effective, but didn't think that would cause an actual problem, since its very thin.
Taking both sides apart some years later it was, AFAICT, pretty much unchanged, so I renewed it in the same way, though by now I'd got some pricy Bendix Ceralube stuff in Australia which in theory should have been superior, and which I never used.
No issues in use whatsoever, and my (originally quite corroded) brakes remained in smooth operation until the cops got the car.
So I'm convinced.
I'm not too bothered if no one else is, since I'm not selling anything.
Actual technical reasons why it might be a bad thing to do would be of interest.
"Because I've never heard of it / its not in the handbook" jive, OTOH is only of mild sociological interest.
Edited by edlithgow on 29/06/2024 at 17:12
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It probably isnt in my handbook either though.
Cant be sure because its in Chinese, and the pages are stuck together.
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Stumbled across a picture of my (evidently controversially) PTFE tape wrapped slider pin removed after 4 years. The PTFE tape spirals, in silicon grease, are just visible.
Since this was remarkably intact it tended to confirm that this was an OK thing to do, so I renewed it and did it on the other side too.
forumosauploads-12829.kxcdn.com/original/3X/b/f/bf...g
I have to say though, that, currently back in The Yook and doing some plumbing work on my flat, I bought some PTFE tape at BnQ, and it seems fairly nasty.
Its thicker than the Taiwan stuff, requiring to be cut rather than snapped, and has two distinct laminations, with a clear and an opaque layer, which can delaminate messily in use.
If that was all I could get here I wouldn't be so keen on using it on car brakes, but fortunately I no longer have car brakes, so it isn't a problem.
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As for putting PTFE tape on threads - that is not what its for, its for sealing unions on pipes. Sliding pins should only have a smear of the correct lubricant..
Agreed, Skidpan, it's not 'what it's for', but any thread will cut through PTFE tape under all but the smallest torque, so it will 'seal' the thread rather than lubricating it. Many commercial products can be used satisfactorily for various purposes other than those listed 'on the tin'. For example, Brasso can be used to polish off marks on CDs, but the makers don't suggest that. I'm quite sure some people have a range of specific metal polishes, while only two or three varieties are really necessary ?
Of course this argument only applies to people with some experience of car-DiY or other forms of engineering. Shouting down other such people ill becomes you, sir !
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Of course this argument only applies to people with some experience of car-DiY or other forms of engineering. Shouting down other such people ill becomes you, sir !
As you know I have far more experience of car "DIY" than most on here having built 2 Caterhams from kits and raced them. Experience tells me to use a product intended for the purpose. Its not like it costs a fortune does it?
As for PTFE tape (or string) plumbers use it generously on the threads and if you did that on automotive applications you would never be able to correctly torque a bolt.
As for using the correct product I remember a few years ago when a chap building a Westfield decided that he would use ordinary silicone sealant on his sump (the later 2 piece type) instead of the more expensive product specified by Ford. After a short time the hot oil had turned said product to Gorilla snot which blocked the oil pickup. A brand new crate engine wrecked for the sake of a few pounds.
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<< .... a chap building a Westfield decided that he would use ordinary silicone sealant on his sump (the later 2 piece type) instead of the more expensive product specified by Ford. After a short time the hot oil had turned said product to Gorilla snot which blocked the oil pickup. A brand new crate engine wrecked for the sake of a few pounds. >>
Yes, I can understand the difficulty here - there are all kinds of silicone sealants and it would need some advanced physico-chemical knowledge to substitute a suitable one for the Ford stuff. But I suspect the reason may be less to do with 'a few pounds' than the hassle of getting the proper one and quite likely the presence on the shelf of something similar - or maybe in Ed's case being able to get it at all ?
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RE "you would never be able to correctly torque a bolt." as I said, I dont generally worry about correctly torquing bolts, and hence I dont very often use a torque wrench.
Snugging bolts up by feel is just fine for the vast majority of bolts on a car, and has never, ever been a problem.
Where you want to actually control the tension on a bolt lubricated by grease, oil, antiseize, PTFE, etc or my wheel nut (though I've never torqued a wheel nut) favorite, grease and polythene sheet, and you only have the dry specs, you can do this using the "turn of the nut" method, either assuming it was correctly torqued when you took it off and tightening it the same number of turns, or by first torquing it dry and then tightening it the same number of turns when lubricated.
Where it gets tricky is where you've got gaskets or washers that crush (or I suppose stretch bolts, though I've managed to avoid them) where, strictly speaking, you can't re torque without using a new gasket/washer/bolt.
Thankfully, such cases have been rare on my sort of cars
Come to think on't, as I understand it, stretch bolts normally specify a torque-then-angle, so perhaps one could get away with torquing dry, noting/marking the angular position, then re-installing lubed to the same angular position, then applying the final angle.
I don't know this for a fact, though, and it is obviously not advice. I suppose it would depend on whether the bolt is already compromised when the initial torque is applied, before the final angle, which I don't offhand know.
I've never had to deal with stretch bolts and hope to keep it that way.
Edited by edlithgow on 30/06/2024 at 03:02
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Seems likely my speculation above on stretch bolt torquing is correct.
Didn't, from a quick look, see an explicit statement to that effect, of course, but sources refer to the initial torquing as a "low, base torque", suggesting its probably the subsequent angle(s) that take a stretch bolt into the plastic deformation, no-reuse range.
For example
www.felpro.com/technical/tecblogs/tta-vs-tty-bolts...l
That source seems to imply also that lubrication isnt (much of?) an issue with TTA and TTY bolts, since they are essentially using a variant of the turn-of-the-nut method.
If this is true one might expect them to no longer spec torque dry, though I don't know if that is actually the case.
Edited by edlithgow on 01/07/2024 at 03:46
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Snugging bolts up by feel is just fine for the vast majority of bolts on a car, and has never, ever been a problem.........
......for you, I presume.
An experienced mechanic who has practised with a torque wrench might get within 10% of the recommended torque 'by feel', but for the occasional amateur it is unwise. Many learn the hard way after incurring the hassle and expense of helicoiling the holes for their spark or sump plugs after stripping the thread. Also, it is wise to retorque wheel bolts after a tyre change to check they have not been overtightened (personally I err on the low side by around 10%) because the inability to change a wheel by the roadside after a puncture would mean the expense and hassle of a rescue.
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The "Snugging bolts up by feel is just fine for the vast majority of bolts on a car," is a general statement, so in that context your presumption would be incorrect.
"has never, ever been a problem" is, of course, a personal statement. I make no claim to proximity to the recommended torque (how would I know?), simply that any deviations from it havn't caused me grief.
Re not being able to change ones wheels, I remember having to steal a scaffolding pole off a building site to remove wheels after naively (it was a long time ago) putting my first car in for a "free safety check".
Having got them loose, I put them back on again. Still no necessity to use a torque wrench on them.
And those were greased wheel studs. Not supposed to do THAT if you use a torque wrench
Come to think on't I'm fairly sure people were generally supposed to grease their wheel studs in those distant dark days.(I remember it being mentioned on The Archers, surely the epitome of recieved opinion), but then probably very few used a torque wrench.
Life was cheap, and short.
I do remember being narrowly missed by a loose Morris 1000 wheel, but that was due to front suspension failure, which they went in for.
Latterly I greased wheel studs and put polythene sheet on them before running the nuts down (polythene comes off like a thread-formed shed snake skin) so the nuts could probably still be removed after over-torqueing,
Edited by edlithgow on 08/10/2024 at 21:52
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Re the "correct lubricant", that can be a bit mysterious.
IIRC the Daihatsu Charade manual specified red rubber grease, which isn't very specific, since there are a variety of products matching that description on sale in Japan
Other cars may be more precisely specified, but OTOH there are certainly cars and motorcycles here in Taiwan (Toyota Zace, for example) for which no technical information at all is readily available.
Since no specialist brake lubricants are available here (or used?) either, this probably doesn't matter locally.
By chance I just stumbled on what seems to be a pretty extensive resource on brake lubricants. Since it acknowledges some inconsistencies/uncertainties it seems fairly plausible so 4WIW I'm linking it here.
bobistheoilguy.com/forums/threads/my-study-of-comp.../
Edited by edlithgow on 10/07/2024 at 07:14
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