Drum Brake Advice, Poor Effort

[Malc 45]

I am not getting a great effort from my rear brakes, current set up on 1.9 split system. Front 206 GTI 180 calipers, drilled and grooved discs, rear set up 309 1.1 drum brakes, new drums, shoes and cylinders, rear compensators removed and running a 24mm master cylinder from 406. Brakes just been bleed again and all air well out. Also made sure the rears were adjusted correctly. Car passed mot last week but advised the rear brakes are only giving about half the effort they should, when the peddle is held down I can still turn the wheel, surely they should lock, any thoughts?

[Miles 331 1 Cars]

I know the 1.1's etc have the compensator's built into the slave cylinders , Why not use GTi drums as these are more upto the job

[Malc 45]

Miles would the compensators in the wheel cylinders possibly be giving poor braking, if I switched the wheel cylinders to non comp this would give a better brake surely. Am I right in thinking the GTI set up is only a slightly wider drum/pad with non comp cylinders?

[dcc 855]

Do you have any inline compensators?

[dcc 855]

Ah ignore just saw in the post. I have a similar set up but with inline 1.9 compensators and gti rear drums, works spot on. So i assume that your component mix doesnt work well together as intended.

[Malc 45]

Nah not at all, I thought removing the inline comps and fitting the wheel cylinders with built in comps would work, obviously not, think I will switch the wheel cylinders back to non comp ones

[RossD 44]

Be careful here! The tester may be saying he expects higher effort as they could be comparing to modern, ABS equipped cars which will control the rear bias using the ABS system. These cars will give a higher initial bite to the rear compared to simple pressure limiting valve that is used on the 205 slave cylinders.

 

From memory, 205 / 309 base model drums with the compensators built into the slaves will pull around 70kgf on the MOT rollers. Enough for a pass, but you will be able to turn the wheels with the brakes on if you have large enough biceps - I certainly can turn the rear wheels on my 205 with full brake force applied with some effort.

 

I know the same is also true on the 1.9 GTi with rear discs, mine had its MOT recently and pulled ~75 - 80kgf - This is all they are designed to do with the standard pressure limiting valves (Compensators).

 

As it passed the MOT, I wouldn't be too worried.

Edited July 21, 2014 by RossD

[johnnyboy666 195 1 Cars]

Sorry to hijack but, I have just had a similar issue, but with NO rear brake effort at all! its a 1.8 diesel, so I assume will have the base model slave cylinders, and I cant see any inline compensator.

Any ideas what could be going on here?

Would I be able to change to gti drums without adding a compensator, or would that leave me with my arse trying to overtake me?

 

Cheers

 

P.s handbrake effort is perfect, so pads/drums are presumably fine

Edited July 21, 2014 by johnnyboy666

[welshpug 1,646]

I'd try new cylinders, they're cheap.

 

if you wanted to fit a gti setup you'd need backplates drums shoes and cylinders, and a compensator, drums are pretty good without a limiting valve.

[johnnyboy666 195 1 Cars]

I've got a complete gti setup 'in stock' but I cant. Really be arsed replumbing too much, so ive ordered some new cylinders (you're right, they are cheap) and we'll see where that gets us

[Malc 45]

Be careful here! The tester may be saying he expects higher effort as they could be comparing to modern, ABS equipped cars which will control the rear bias using the ABS system. These cars will give a higher initial bite to the rear compared to simple pressure limiting valve that is used on the 205 slave cylinders.

 

From memory, 205 / 309 base model drums with the compensators built into the slaves will pull around 70kgf on the MOT rollers. Enough for a pass, but you will be able to turn the wheels with the brakes on if you have large enough biceps - I certainly can turn the rear wheels on my 205 with full brake force applied with some effort.

 

I know the same is also true on the 1.9 GTi with rear discs, mine had its MOT recently and pulled ~75 - 80kgf - This is all they are designed to do with the standard pressure limiting valves (Compensators).

 

As it passed the MOT, I wouldn't be too worried.

Thanks mate, you have answered my question. All I wanted to know was how good are 205 rear brakes, with driving modern motors I was expecting my rear brakes too lock but the again not, as I don't want switching ends on track!! Honestly my brakes are great, soft pedel, but stops on a dime, just wanted some some real feedback, thanks again.

[RossD 44]

No worries. MOT testers don't see so many 'older' cars like the 205 these days and so base their observations on more modern cars without actually thinking about the potential differences between the 205 and new cars (i.e weight and an electronically controlled ABS system!)