Brake compensator.

Morning.

What does the above do? It's the little piston thing attached to the rear axle.

Mine has rattled when I go over bumps since I've had the car (I think it's that, the rubbers seem shot)

Haynes says take it to VW to adjust because it needs brake fluid pressure gauges?

What gives?

Peter.

What I've been told it does is when you brake and the rear end starts to lift, the compensator (if working) increases the braking on the rear to keep the car level.. don't know too much about fixing/servicing it though, I'm going to VW during my lunch so might ask them about it!

Don't mention brakes to me!  :evil:  If you've read my posts on here, you'll know I've had nothing but trouble with my brakes, and I'm sure this valve is part of the problem. The thing is, without knowing how it's suppose to operate (I know what it's supposed to do) it's hard to tell whether its working properly or not!

As far as I know there's no adjustments that you can do to them, replacement is the only option I think. You can buy replacements from gsf for about ?56, but they're a pain to fit because the rear beam inhibits access to it properly, and good luck getting the brake pipe nuts undone (mine were all seized)

Mike

That compensating valve .
Its job is to stop the rear wheeels locking under heavy braking so it shuts the fluid supply and transfers the effort to the front . There is a plate and spring on the valve attatched to the rear beam axle , the more weight in the rear of the car the longer the valve stays open . Some - most MK1's don't have one . I stripped and cleaned mine during my rebuild not much in it just a piston , springs and a few seals , GSF have replacements for ?65.00 last time i looked ….

Chudd……………

Edit …Pete your rattle maybe the spring on the plate ? If the rear of the car is empty its under no tension and could rattle . Mouted on rubber at one end and nylon pully at the other these could be worn .

didn't I read a post that if you bleed the brakes, because of this 'great' compensator thing… you HAVE to have the car on the ground or you'll ALWAYS get air in the system??

Not if you use a Gunsons Easy bleed , the pressure pushes the air out . Although the good book does say "bleed with the compensator valve plate pushed to the rear of the car" , all this does is open the valve fully so it will not make much difference when using your Easy bleed …

God look at the time ! Better get back to work like the rest of you on here today  Chudd out……..

PhillTMK1GTI said

didn't I read a post that if you bleed the brakes, because of this 'great' compensator thing… you HAVE to have the car on the ground or you'll ALWAYS get air in the system??

You'll have to have the compensator valve open, which is easiest to achieve by lowering the car (with the rear wheels off) on to blocks/axle-stands under the bottom of the rear shocks. You can disconnect the spring between the valve and the axle-beam, but this could be trickier than it looks (seized parts, etc).

If you've done it wrong, the symptom that you'll have is that the brake pedal feels firm under pumping, but sinks slowly when kept under pressure. This is exactly the symtom of a dead master cylinder, but if you've just bled the rear brakes, don't panic - your MC is probably fine, but you need to bleed the rears again!

PS: It is a "great" item to have on your car (big-block engined cars only) - In my youth :wink:, I came up to a roundabout in my 1.3 CL (no valve) at a bit of a fast lick, with 4 people in the car, and unexpectedly had to brake heavily for a guy who had shot into the roundabout at speed - I jammed on, the rear of the car lifted, the rear wheels both locked up, and we ended up at about 45 degrees to the Give Way line. We stopped to clean our underwear, and then continued on our way  

Ah I see..  I've replaced the front and got new rear friction parts, going to replace the brake fluid to so it's good to know the best way before hand  :wink: might get some WD40 and/or grease on it in case I need to replace it at some point

Thanks guys.

Mine is adjusted so the spring is actually loose when the car's empty.

Think that's wrong for a start.

To adjust it you slide it in the groove left and right, kind of like an alternator adjuster.

Gonna have another look and maybe a fiddle. I imagine the rubbers worn.

Thing is I will be able to adjust but I won't know if it's working or not will I?

Hmmm.

Peter.

Try some braking tests - you should not be able to lock the back wheels with the car unloaded.

Check whose behind you first  8O

Glad Tallpete has raised this issue.
My brakes passed the MOT okay but I was concerned about having to grab the steering wheel towards me to bring my baby to a stop!
We changed the regulator but as has previously been advised Haynes Manual says you should go to a VW garage to get it set up properly.
It made no difference at all.
Has anyone set one up before or does anyone have access to pucker VW Workshop Manuals to get the gen?

Thought I would revive this one as my car has just failed its MOT on a leaky compensator, plus the rear brake pipe fittings were "excessively corroded".

Can't believe these things are so expensive - ?56+VAT from GSF  8O . Have to say the Campaign ownership experience is beginning to sour a bit after all the fuel problems and having to shell out on the new warm up reg recently as well… now this :roll:

Anyway, back to the subject at hand - who has actually replaced one of these suckers? Haynes is worse that useless for this - just says take it to a VW dealer. My Haynes resto book has a bit more info but suggests there are mechanical and hydraulic versions and that again any adjustments should be made at a dealer or place with a rolling road. If I just get the GSF one, will it require any adjustment or can it just be swapped straight in?

PLEASE tell me you don't need to remove the rear axle beam to do this. If this is the case then I think I may well just give up on the golf for now and resign myself to it being off the road for a while until I get all the bits I need.

Any tips for replacing the flexi- brake lines as well? If the car is up on a drive on ramp is it necessary to have the wheels off the car to do the flexi brake lines? Only reason I ask is it makes my life 10 times easier if I can do the brakes without removing the wheels as my garage is extremely narrow.

Cheers,

Chris

Bad luck Chris, you really will get a break soon.

Stick a second hand compensator on there, it'll do the trick. Wonder if they come apart?

You don't have to take off the rear beam to get them off! It's just mounted on a bracket under the car and connected to the brake lines. I would imagine all the connectors are corroded up nicely by now!

Talked to people about setting the compensator and the bodge way of doing it is just fit it so the spring is tight when the car is unloaded.

My car just failed on corroded brake pipes, front ones. Got them replaced with copper piping which seems to be the standard now.

Apparently they changed the rules so that any corrosion on them will mean failure.

On another subject, how is that new warm up reg going? My car is chugging like a good un when cold.

Peter.

tallpete said

Apparently they changed the rules so that any corrosion on them will mean failure.

ANY corrosion? even the slightest bit?  

Looks like I might be replacing some!

Hi Pete - thanks for the words of encouragement  :wink: . Don't get me wrong I love driving the car, and I know any 20+ year old car is going to need work, but its just always the expensive things that seem to break on mine for some reason, also at the time wehn I am completely strapped for cash  :roll:

To be honest where the braking system is concerned I will probably go for new parts. The MOT testers notes indicated the car should not be driven until this is fixed as technically its leaking brake fluid, although only tiny amounts 8O. I know I am complaining about the cost, but the peace of mind will probably be worth it.

The new warm up reg, replacement coil, dizzy cap and HT leads all seem to be running a treat and car has been A1 since they were replaced.

I am wondering if now might not be a good time to overhaul the brake system and stick some copper pipes and braided lines on there and generally dismantle, clean and paint everything so I know its A1. Problem is I know I will get myself into the situation that Chudd found himself in - start off intending to just replace one dodgy fuel pipe and end up doing a partial resto on the car!!!!!

I do have a list of things that I have been putting off for a while including replacing the inlet / exhaust manifold gaskets, draining the cooling system and fitting some new hoses, investigating some electrical "funnyness", rebuild spare DX head and swap with existing TSR one, fit head unit and speakers I have had knocking around for over 6 months - the list goes on!!!!

With the braking system though the connectors all look pretty corroded, so it may just be easier to put a new set of copper pipes on there with new connectors whilst doing the compensator valve and the flexi lines. I just know its gonna cost a few quid though and I am still technically out of work so its not the best time financially.

Whats the going rate for a copper brake pipe kit with fittings - I am guessing something like automec is what most folks go for?

Thanks for the tip on adjusting the compensator btw.

Cheers,

Chris

Ok, done some checking… this is what the MOT website says about the corrosion of Hydraulic systems

c. excessively chafed, corroded or damaged

Note: Chafing, corrosion of, or damage to, a rigid brake pipe so that its wall thickness is reduced by 1/3 (eg approximately 0.25mm for typical hydraulic brake pipe) is a reason for rejection

Hi Chrisb
knowing you, you'll get all that done at the weekend!!
TC

Hi Terry - touched by your faith in me mate, but I suspect the cost of the items just to get it through an MOT may mean its going to have to hide away in the garage for the next few months.

Sadly it might mean I won't be able to bring it to the meet in August, so I might be looking to scrounge a lift off someone  :wink:

Cheers,

Chris

In reality I don't think the compensator does too much. This is esp. true on cars with uprated (harder) suspension that are less liable to 'dive' on heavy breaking. They most commonly fail the MOT for being seized (through lack of use), but you can free them off with WD40 and tapping back and to …..
You can remove the compensator completely and bridge the unions which is fine for the MOT. If it's there it has to be working.
Cheers,
Mark

Hi Chris,

Keep at it! I had to change my rear compensator, it was about the only brake component I didn?t change when I was restoring the car. And of course a year or two later it started weeping. It?s a pretty straightforward bolt off old, bolt new back on but as mentioned any existing brake pipe connectors will probably be corroded solid to their pipes and twist off. If you are already replacing the pipes this won?t be the heart break it could have been. I just put the compensator and spring back to their original positions.