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Braking with a TC auto gearbox - John Boy

My small car with a torque convertor auto gearbox needed new front discs and pads a lot sooner than I expected. I've wondered if that's because I use the brakes to slow the car when I'm going downhill, rather than putting the car into a lower gear and using engine braking. I'm reluctant to use the latter because I don't understand the long term consequences for the gearbox of doing it. It's the first automatic car I've owned and would appreciate some advice.

Braking with a TC auto gearbox - elekie&a/c doctor

Always use the brakes.A lot cheaper than replacing the gearbox.

Braking with a TC auto gearbox - gordonbennet

I'm not qualified to give an engineering answer, but common sense to me thinks you could buy between 20 and 50 sets of front discs and pads for the cost of one TC box.

Braking with a TC auto gearbox - daveyjp
I suggest you take a couple of automatic lessons from someone who knows how to drive one properly.

It will be well worth it to get to know how to control an automatic car, using lock up should be part of this training as it can be very useful in ensuring you continue to drive the car and it doesn't start to drive you.

Edited by daveyjp on 24/11/2015 at 20:04

Braking with a TC auto gearbox - coopshere
Each hill will have its own set of circumstances and each auto box has its own characteristics.

If the hill means you will be using the brakes a lot then the best method will be to brake down to the speed at which you can safely negotiate the hill then select, assuming you have a manual function, the correct gear to be able to maintain that speed during descent. This method is the same for manual gearboxes too. It will mean you have better control and stability for your car. Providing you dont change to a gear that is too low for the speed you are travelling there will be no undue wear on the gearbox.

Prolonged heavy breaking can cause brake fade and if the brake fluid is old, meaning it may have moisture contamination, it could cause boiling of the fluid which could mean loss of any braking.
Braking with a TC auto gearbox - Avant

I'm going to show my age now. I learned to drive in the 1960s when it was quite possible for brakes to fade or fail, and I was taught to engage a low gear when going down a reasonably steep hill.

I still do, and that includes holding a low 'gear' when driving an automatic. As long as that low ratio isn't stupidly low (for examle, one wouldn't normally engage first), I can't see why this should cause excessive wear on the transmission.

Braking with a TC auto gearbox - gordonbennet

I think there's a difference Avant, car brakes have never been more effective and now with the internet we have never had such a cheap supply of quality friction parts, also a complete novice can swap a set of pads and discs in an hour or two they are in effect the sacrificial part of the system.

There's a world of difference when you talk about robust proper 4x4 transmissions designed to engine brake the vehicle in off road and heavy towing conditions, and lorry transmissions which are designed, and always have been, to use auxilliary braking on top of natural engine braking, using maximum safe engine revs in the lowest possible gear, for full retard and continuous use.

Cars are not designed to be used like this, no reasonable person would expect it and i'd be extremely surprised if the designers of modern car boxes have factored such use in.

Braking with a TC auto gearbox - xtrailman

I've always used engine braking and never had a transmission fail.

There's a reason why some descents have signs saying select low gear now. Autos don't always select the correct gear so i would use the manual option in those circumstances.

Braking with a TC auto gearbox - RT

I've always used engine braking and never had a transmission fail.

There's a reason why some descents have signs saying select low gear now. Autos don't always select the correct gear so i would use the manual option in those circumstances.

+1

Driven properly, it doesn't even increase brake brake wear - I've just sold a 2 tonne SUV at 55,000 miles with original front/rear pads under 50% worn.

The economy mode on my new Touareg "coasts" when lifting off the throttle - it slows down much less than a conventional car so needs mor braking to come to a stop.

Braking with a TC auto gearbox - jeffreyburkholderRoom

While the car is idling in D and stopped, the automatic transmission is sort of in a 'ready-and-waiting' mode, with the torque converter partially engaged.

Braking with a TC auto gearbox - RT

While the car is idling in D and stopped, the automatic transmission is sort of in a 'ready-and-waiting' mode, with the torque converter partially engaged.

Depends on the car - many modern ones have an "automatic neutral select" feature when stationary with footbrake applied.

Braking with a TC auto gearbox - madf

I drive an auto Jazz . My front pads appear to be 75% unworn after 16,000 miles. I don't drive slowly - but I don't rush up to lights/stops/queues and brake at the last minute. (which many drivers appear to do.....and then crash in snow!)

Braking with a TC auto gearbox - John F

My small car with a torque convertor auto gearbox needed new front discs and pads a lot sooner than I expected.

Really? Who said so? Did you believe them? Was it a case of "better change these, squire, as they won't last till the next service..."?

I have had autos for 30yrs and expect front pads to last 50,000m and discs to last 100,000m.

My records show our current small auto Ford Focus, bought from a dealer at 29,100m with new discs and pads (presumably to make it feel new) got new pads at 82,600. It has now done 110,000 and the discs, regularly serviced by myself, hammering and carborunding off the rust, still have plenty of wear left, as do the pads.

I admit to a dislike of braking and drive accordingly as pad wear = burnt fuel, but the auto is always in either D or N, however steep the hill, as 'riding and gliding' does wonders for the fuel consumption and pads are cheap.

Braking with a TC auto gearbox - hillman

“I'm going to show my age now. I learned to drive in the 1960s when it was quite possible for brakes to fade or fail, and I was taught to engage a low gear when going down a reasonably steep hill.” Avant

“I've always used engine braking and never had a transmission fail.

There's a reason why some descents have signs saying select low gear now. Autos don't always select the correct gear so i would use the manual option in those circumstances”. Xtrailman

“I have had autos for 30yrs and expect front pads to last 50,000m and discs to last 100,000m.” JohnF

I was taught to use the gears to hold a steady speed when going downhill. Now that I’ve a TC automatic I still use the technique. One of the BRs in a previous thread said that the gear chosen to hold the car down the hill is the same as that going up the same hill. I don’t quite do that, going up Blaze Hill near Bollington, Cheshire, I use 2nd gear, but going down I use 1st.

The car is now 9 years old and has done just over 100,000 miles I used the dealer for servicing for the first three years and then went to an indi. My indi serviceman has the ultimate say in how my car is serviced and he has changed the pads and discs at least once. He’s changed the transmission fluid twice and I asked the dealer to change it at 17,000 miles. My indi serviceman says that the dealer ‘might’ have changed it but there’s no evidence of that. It’s true that brakes are not as prone to ‘fade’ as the once were but now, with the new version of braking system the discs wear too, which was not the case with the original asbestos shoes.

Braking with a TC auto gearbox - John F

Now that I’ve a TC automatic ...The car is now 9 years old and has done just over 100,000 miles I used the dealer for servicing for the first three years and then went to an indi. ..... He’s changed the transmission fluid twice and I asked the dealer to change it at 17,000 miles. My indi serviceman says that the dealer ‘might’ have changed it .....

Yet another example of needless service expense. The Scion (I assume that's what it is) USA forum suggests that auto is sealed for life. Some say change at 100,000 or 60,000 hard driving. In the benign conditions of the UK I'd add 20% to those figures.

Braking with a TC auto gearbox - RT

"sealed for life" is a misnomer - they simply mean "no scheduled maintenance"

Braking with a TC auto gearbox - John F

"sealed for life" is a misnomer - they simply mean "no scheduled maintenance"

Fair comment. i.e. if it works, don't mend it! I wonder how many tiny dust/grit particles are now circulating in his overserviced box?

Braking with a TC auto gearbox - gordonbennet

Fair comment. i.e. if it works, don't mend it! I wonder how many tiny dust/grit particles are now circulating in his overserviced box?

Normal service resumed, i just agreed with you on another thread, still reckon half your posts are tongue in cheek, this being one.

Braking with a TC auto gearbox - John F

......half your posts are tongue in cheek, this being one.

Not entirely. I have seen many examples on various forums of problems from sometimes incompetent overservicing although in this case I appreciate that there are inbuilt filters in most autos these days.

However, time and again cheap belts are incorrectly fitted, failing within the next 30,000m; discs and pads changed when barely half worn so the pistons never travel far, inviting early caliper failure; the wrong oil put into gearboxes ( e.g. the old LT77 fluid being needlessly changed and erroneously filled with EP80); spark plugs changed needlessly early, a small proportion cackhandedly resulting in stripped thread and pricey helicoil; fresh coolant loaded with corrosive oxygen; and as for the waste of time, money and pollution of unnecessary 365day low mileage oil changes.....

IIWDMI

Braking with a TC auto gearbox - John Boy

Thanks for the replies to this topic.

No one appears to know for sure if using the low ratios to slow down contributes fundamentally to wear in the gearbox. On balance, therefore, I think I shall carry on doing what I do - engage low ratios to go down dangerous hills, but use the brakes the rest of the time. I don't race up to lights and brake at the last minute or anything like that. Most of my driving is in a hilly town and I'm aware of having to keep slowing the car downhill to remain within the speed limit.

I too was taught to drive, using the gears to slow down, but I changed strategy when I had my previous (manual) car. That was because a friend, doing mainly short trips, insisted on using the gears in that way and ended up with braking issues - lack of use caused the brake discs to corrode.

Reading between the lines in the replies here, I can see that the controls available on TC gearboxes can vary in complexity. Mine are the most basic, so I think I'll be giving those lessons a miss!

I'm afraid I can feel a bit dismissive when people claim that they're getting very long mileages out of discs and pads. Perhaps they are, but the results can't really be compared with others unless the vehicles concerned are doing exactly the same trips.

Some of the answers have drifted into what to do when you're waiting at traffic lights. I wanted to ask about that in a separate topic, so I've started it here:

www.honestjohn.co.uk/forum/post/index.htm?t=112033

Braking with a TC auto gearbox - John F

I'm afraid I can feel a bit dismissive when people claim that they're getting very long mileages out of discs and pads. Perhaps they are, but the results can't really be compared with others unless the vehicles concerned are doing exactly the same trips.

It's nothing to do with identical trips. It's to do with two other things - driving style and how much you wear them before you throw them away!

Braking with a TC auto gearbox - gordonbennet

I can't comment on disc/pad wear on cars, i don't use gear braking unless the road is seriously steep, but i too don't rush up to junctions and brake at the last minute, however i have a regular place i buy MIntex discs and pads from at stupid prices so any wear i dislike they get replaced...ie new discs and pads all round on the Subaru Outback £134 all in, not worth messing about with.

Lorries on the other hand, still designed with retarders of some description, even if its a basic exhaust brake, i use appropriate gears and maxiumum assisted engine braking all the time (even though modern trainers wrongly teach new drivers brakes to slow gears to go) and i only use the brakes to actually come to a stop, obviously like anyone else i'll get caught out and have to use the brakes hard now and again.

My lorry has done well over 400k kms now, pad depths are available on the on screen menu.

Steering axle has 80% life left of its second set of pads, mid lift axle still 50% left of originals, drive axle 60% life left of its second set, all original discs.

I drive it about 60% of its mileage, if it was solely mine reckon with a bit of luck it might still be on the originals all round.

Sister lorries same age almost same mileage within 20ks either way are on their 3rd and 4th sets of drive and steer axles pads, with new discs often going on with the 3rd pad set, one driver in particular actually turned the auxilliary braking off cos he didn't like the lurching he felt as it engaged in the lower gears, worrying in that he couldn't select how and when to use it, he's as old as me too.

Way you drive makes a massive difference.

Edited by gordonbennet on 27/11/2015 at 15:41

Braking with a TC auto gearbox - HandCart

If you're not supposed to use the '2' and '1' positions of a TC auto box when descending steep hills, what are they there for?

Braking with a TC auto gearbox - hillman

"If you're not supposed to use the '2' and '1' positions of a TC auto box when descending steep hills, what are they there for?" Good question, HandCart

I don't think my having the car serviced at 6 monthly intervals is "unnecessary servicng". I'm not familiar with most of the acronyms that the BRS use, but I do understand TLC. That never fails to extend the life of machinery.

I just looked at the Service and Warranties handbook and it says that the transmission fluid should be replaced every 36 months or 30,00 miles. I don't support the extended service intervals that makers quote. I regard that as aimed at fleet managers who run their cars and when they come up for service - sell them on.

Braking with a TC auto gearbox - Sofa Spud

The idea of automatics is to provide a car where the driver doesn't need to change gear. I don't drive automatics very often, but when I do I go by the guideline 'leave it in 'drive' unless there's a good reason not to'. That's what automatics are designed for! I might put an auto into neutral, with handbrake when stopped in traffic for any length of time, or put it in a lower gear to descend a long, steep hill, but that's about all. I've never been stuck in snow or mud in an auto, but I believe it's advisable (very advisable!) to make sure an automatic is locked in a gear - 1st or reverse, normally, before attempting to spin the wheels out of a slippery rut!

Edited by Sofa Spud on 28/11/2015 at 19:55

Braking with a TC auto gearbox - madf

I just looked at the Service and Warranties handbook and it says that the transmission fluid should be replaced every 36 months or 30,00 mile

In reality, you cannot drain most auto gearboxes of oil like a manual. Most only lose approx 1/3rd of the contents on a simple drain. So changes every 30k miles replace all the oil every 90k miles.

For a full drain, you need to remoive the pan and filters etc..

Hence the every 30k drain and refill interval..The sealed for life boxes usually only last for 100k miels - go figure..

It is not a co-incidence most Japanese makers have much better relaibility figures than other makers. Their service requirements are far more rigorous.. like gearbox oil (manual) every 40k miles or so.