Rear Wheels Locking

[feb 47]

Hi,

One of my rear wheels is locking under heavy braking (usually the nearside one if braking on a straight line, but on right hand uphill bends it's the offside one). I did a search, how can I tell whether it's a sticky caliper or a duff compensator?

Makes for interesting over-steer if you are expecting it but need to get it fixed soon before it catches me out!

 

Thanks

[ashlee205gti 1]

Drums or discs? My 1.6 did this, stripped the drums down, bit of copper grease on where the shoes contact the backing plate and bobs your uncle.

[feb 47]

Forgot to say it's a 1.9, so discs

[ashlee205gti 1]

Hmmm....foreign territory, Ive not long had my 1.9 so i havent had chance to rip it apart

[Rob_the_Sparky 9]

On bends the unloaded wheel will tend to lock-up even if everything is OK (not that you should be braking hard mid bend anyway).

 

Not sure of the reason on the straight but can tell you that mine does it as well and AFAIK it is brake compensators. Having said that it doesn't do anything scary under braking when locked up it just sounds/looks impressive but passes an MOT no problem at all.

 

Rob

[mbayley77 0]

Jack the car up on the back.

With the hand brake off, spin each wheel independantly. If all ok pull the hand brake up a notch and repeat until one of the wheels locks or both lock. If just one locks then it is probable that one of the calipers is working better than the other, or possibly the pot in the caliper that locks first could be further wound out which would mean adjusint or freeing up the offending caliper.

I had something similar in my 309 and it needed the pots winding out on one side. Now i have the same problem on my 205 as you describe but just havnt looked into at the moment.

Oh and i dont have any compensators in my system.

[Col 0]

that method might not work if say one of the handbrake cables was on its way out.

[feb 47]

On bends the unloaded wheel will tend to lock-up even if everything is OK (not that you should be braking hard mid bend anyway).

 

Rob

true, this happened at the new big roundabout between L. Earley and Foster Wheeler where there is anti-slippery surface on the tarmac.

 

Not sure of the reason on the straight but can tell you that mine does it as well and AFAIK it is brake compensators. Having said that it doesn't do anything scary under braking when locked up it just sounds/looks impressive but passes an MOT no problem at all.

it was a bit scary and at the same time enjoying having the tail going out on a straight, haven't noticed it before though. will try to get it checked on a MOT place.

Thanks.

[Anthony 1,003]

Almost certainly a failed brake compensator - quite common on 1.9's

[Big_Jimbob 0]

Yep, id say brake compensator, cause mine failed its mot on this, as soon as i fitted the new one it stopped locking up and passed the mot.

 

hope this helps

 

jim

[mbayley77 0]

Can anyone help with why mine might be locking without any compensators in the system whatsoever? I have twin wilwood master cylinders with single lines to the front and to the rear. Any reason why it would lock one wheel on this set up?

 

Cheers

[feb 47]

Thanks guys, just ordered a new brake compensator, the guy said there is one at each side, is there a way of testing them to find out which is the faulty one?

They are costly at £37+vat each!

[veloce200 3]

Thanks guys, just ordered a new brake compensator, the guy said there is one at each side, is there a way of testing them to find out which is the faulty one?

They are costly at £37+vat each!

not sure. it's still a good idea to take the pads out clean the carriers, wind the pistons in (with proper tool) a fraction, refit with copper grease and test. Sometimes a pad partly siezes in the carrier or the piston can get tight. rears do little work and pads wear slowly so they get more neglected than fronts.

[feb 47]

Hi guys, i replaced the rear pads, wind the pistons and refitted with copper grease as suggested, it has slightly improved but under heavy braking the rears still lock.

I am using standard brakes with M1144 pads all round.

What else could be causing this as i dont trust the car anymore

Are the fronts too weak or is the problem with the rears?

 

Many thanks,

[hengti 2]

Think it's just (another!) quirk of the car.

 

They're very light at the back which is why it's relatively easy to lock up the rear brakes. You just have to drive round it.

 

Besides, trail braking's fun!

[feb 47]

Think it's just (another!) quirk of the car.

 

They're very light at the back which is why it's relatively easy to lock up the rear brakes. You just have to drive round it.

 

Besides, trail braking's fun!

I am not sure about this as in a couple of occasions in the past i have managed to lock the fronts on more slippery surfaces.

Not that i brake that hard every time but it would be useful to know how other people's cars behave under heavy braking with normal brakes.

it is "interesting" when you expect it to get the tail out when braking from 80 but you would want the car to behave itself better in a case of emergency.

Edited February 5, 2006 by feb

[hengti 2]

Agree it's not best for safety on the road

 

You could try switching the rear pads back to std - I guess the mintex pads aren't helping at the back

[Simes 248 2 Cars]

When my compensator failed it didn't allow any fluid through to the caliper.

[feb 47]

When my compensator failed it didn't allow any fluid through to the caliper.

I forgot to mention i changed the nearside compensator.

Usually when the compensator fails you have no brakes at all which is in line with what you say Simes.

[feb 47]

Would new (reconditioned to be precise) rear calipers cure this problem, as I don't want to pay £65 per side (exchenge from GSF) to find out

As said, it only happens when braking really hard

[Anthony 1,003]

Have you swapped the compensators as suggested? In 95% of cases that is the problem, especially if you're only locking up one rear wheel.

[pacey205 2]

When my rear compensator went the rear passenger wheel used to lock up way before the fronts. Suddenly did on the entry to a roundabout off the M1 with all my worldy belongings in the car on the way back from uni. Took me a little by surprise as I suddenly entered the roundabout sideways lol.

 

Swapped for another compensator and had no more problems. Theyre normally a bastard to get off though and as theyre right under the tank you cant get a blowtorch on it to heat it up. I used a chef's blowtorch (really small one) and a shield to heat them up to aid removal.

 

Michael

Edited February 9, 2006 by pacey205

[feb 47]

Have you swapped the compensators as suggested? In 95% of cases that is the problem, especially if you're only locking up one rear wheel.

Hi Anthony,

i have only changed one of them, going to do the other one as well.

Can't tell which wheel is locking, the car turns left (tail goes right and me facing the kerb!)...

will let you know how it goes. could it be a blocked brake pipe at the front, causing reduced pressure upfront?

thanks,

Edited February 9, 2006 by feb

[hengti 2]

You can find out which wheel's locking by finding some gravel/loose ground and locking up on it - then just get out and see which side has left a mark

 

Unless you're getting lock up with anything other than v heavy braking, I still think you're worrying about something which is normal

 

The car hasn't got ABS - you're going to be able to lock the wheels if you try hard enough - and, due to weight transfer, it's going to be the rears that lock!

That said, you can probably do things to improve it - but it's still going to happen if you brake hard enough ...

[Anthony 1,003]

Front wheels should always lock before the rears in my experience. Anything else is dangerous on the road frankly