Technical Bleeding rear brakes

[Bougainvillea Rosso]

Hello all,

I'm tearing my hair out trying to get the air out of the rear circuit on the 4x4. I've got too much travel on the pedal and clamping the rear flexi makes the pedal firm: logic dictates that air in the rear system must be the problem. I've bled both rears 4 times now all told and am exhausting the Western world's supply of brake fluid. Does anyone have any bright ideas how I might be able to shift it? Might there be another problem I'm not seeing?

Ta

 

[purple haze]

I guess your doing the back offside first..

I had the same prob once and took the nipple off completely which seemed to work when bleeding. Bit messy though.

 

[Bougainvillea Rosso]

I may not have been scrupulous in the order of bleeding after I first bled both circuits (I'm pretty sure the fronts are fine). Do you find that makes a big difference? I wondered about getting a third person to tap the lines...

P.S. That's 'tap' as in knock gently!

 

[Giacosa]

Hello all,

I'm tearing my hair out trying to get the air out of the rear circuit on the 4x4. I've got too much travel on the pedal and clamping the rear flexi makes the pedal firm: logic dictates that air in the rear system must be the problem. I've bled both rears 4 times now all told and am exhausting the Western world's supply of brake fluid. Does anyone have any bright ideas how I might be able to shift it? Might there be another problem I'm not seeing?

Ta

The servo is adjustable which can take a lot of travel out of the pedal. Stuartl had a similar problem with his 4x4 and he sorted it out this way. Admittedly it won't help get air out of the system but you shouldn't have to bleed it 4 times to do that.

 

[Bougainvillea Rosso]

The servo is adjustable which can take a lot of travel out of the pedal. Stuartl had a similar problem with his 4x4 and he sorted it out this way.

Thanks. Yes, I've seen the thread but my insinct is that it's air - particularly as clamping the flexi firms up the pedal. The pedal hasn't always had this amount of travel and presumably the servo wouldn't have adjusted itself?

 

[Bougainvillea Rosso]

Just seen your edit. I know, it's weird. I've bled pandas quite a few times now and have never had this problem before. Having replaced the shoes, I wondered if that was all OK with the setup but I can't see any problems there either. I've driven it round quite a bit to bed everything in too.

 

[purple haze]

Usually the farthest from the resiviour first then work backwards to the nearest.

 

[firstcar-Y10]

More likely the adjusters on the new rear shoes that's causing the long pedal, just a long push before the rear shoes make contact with the drum and start to bite. Rear drums off and lever the shoes out as far as you can on the stupid never work properly friction adjusters so the drums only just push back on, should take up a lot of slack on the pedal.

 

[Bougainvillea Rosso]

More likely the adjusters on the new rear shoes that's causing the long pedal, just a long push before the rear shoes make contact with the drum and start to bite. Rear drums off and lever the shoes out as far as you can on the stupid never work properly friction adjusters so the drums only just push back on, should take up a lot of slack on the pedal.

I did tap those out with a mallet but that's a good call. I'll have a go at levering them. Just a big screwdriver?

 

[firstcar-Y10]

I did tap those out with a mallet but that's a good call. I'll have a go at levering them. Just a big screwdriver?

Yep, the rear drum should only just go back on, if the brakes feel like they're just binding slightly all the better, they'll free off far more effectively than they'll ever adjust themselves back up. If there's a lip on the edge of the braking surface you may have to file it back slightly (without scoring the area the shoe contacts) to allow the drum back on with the adjusters out far enough.

 

[Liquid Knight]

I had a similar problem with my Fantasia (and dreading the brakes on the racer), I changed the compensator valve, rebuilt the master cylinder, and bled the system through at least five times before I realised I was using the wrong brake fluid and it was passing through the seals. Pandas need either 3 dot or the thicker 4 dot stuff otherwise the master cylinder won't work properly. You'll have some brake pressure but the pedal will then drop to the floor. If that is the issue at least the lower viscosity stuff has cleaned your lines through.

 

[Bougainvillea Rosso]

I'm using Dot 4 so should be OK. Well I've levered the shoes out and it doesn't seem to have made much difference. This is really frustrating.

 

[VmanC]

Why were you bleeding the brakes in the first place, have you done other work on it?

 

[Bougainvillea Rosso]

Yes, I've put new discs and pads on the front and new shoes on the back. It's been on SORN whilst I've been renewing the front suspension and my garage had told me that there was overtravel on the brake pedal that would need sorting out before the MOT. I wonder if there is another issue causing excess travel? I initially wondered about the master cylinder but the pedal feels pretty firm once it bites so that doesn't seem to be a likely cause. Everything points to the problem being the rear brakes.

 

[panda1408]

Have you changed the shoe return springs? We had a similar problem on my Dads original Fiat 500, the previous owner fitted new brake shoes just before we picked it up, which left it with pretty much no brakes. We tried everything, changed the master cylinder, bled several times, in the end it was the new return springs that were too short, which meant the shoes were being pulled back too far and therefore lots of pedal travel. With the correct length springs the brakes are perfect.

 

[Bougainvillea Rosso]

Have you changed the shoe return springs? We had a similar problem on my Dads original Fiat 500, the previous owner fitted new brake shoes just before we picked it up, which left it with pretty much no brakes. We tried everything, changed the master cylinder, bled several times, in the end it was the new return springs that were too short, which meant the shoes were being pulled back too far and therefore lots of pedal travel. With the correct length springs the brakes are perfect.

Yes I did put a new kit on. It's interesting that you say that as it had crossed my mind. I've noticed that there are two fitting kits which seem to use a different system to hold the shoes down, one using a spring clip: http://www.ebay.co.uk/itm/Brake-Sho...Parts_SM&fits=Model:Panda&hash=item2578bd8a63 and the other springs and a plate: http://www.ebay.co.uk/itm/MINTEX-br...Parts_SM&fits=Model:Panda&hash=item56529960fd. These are both listed for use with the pre ratchet type shoes so presumed there would be no difference. I used the springs from a kit with the springs and plates. Visually, the springs look the same but maybe they are not... Has anyone used the second type before? Maybe that's the problem. Something else to check anyway!

 

[VmanC]

Also check that the springs are attached in the right place, if you have connected them in a wrong hole it could be stretching the spring too far.

 

[firecolour]

I had a lot of trouble with the rear brakes on firecolour. One was binding when I bought her (an MOT advisory) and I only got 5 miles down the road from the seller before I had to stop and disconnect that rear brake.

During the refurb, I couldn't get any fluid to the rear brakes whilst bleeding, despite the fact they worked, of sorts. I changed the compensator valve (a pig of a job in itself) but then it bled and worked perfectly.

What method are you using to bleed the system? I used an "automatic" system, ie a bottle full of fresh fluid pressurised from the spare tyre (let down to 5-10psi first!). If plenty of fresh clear fluid is running out of the nipple, I don't think it's air. As firstcar says, it might be the shoe adjustment. If it's got the little auto tensioners on, check they are not seized. It's common on many cars for back brakes to sieze (esp the VW Golf) due to lack of use. A hefty push on the pedal once a week makes sure it's kept freed up. The adjusters needed overnighting in diesel and a good workout in the vice before they freed up on firecolour.

Good luck!

 

[Bougainvillea Rosso]

Cheers. I think you may have had the later shoes with the ratchet adjusters? These are the old school ones. Thanks for the tips. I read your thread hunting around for ideas! I agree, I don't think it's air. I'm of for a few days holiday soon so it will have to wait till I get back now. I'll get there in the end but I'm glad I have another fully functioning Panda!

 

[Bougainvillea Rosso]

Thought I'd just add a footnote to this post in case it helps anyone. The end of the story is a bit embarrassing. The pedal travel issue was finally sorted by adjusting the handbrake up further so it holds the car on three clicks rather than five. A bit of a schoolboy error that I didn't try that myself but you live and learn (as I discover quite frequently!)