Braking Issue

[Eddie.]

Okay, this might be an easy fix, but I thought I would ask on here while it's on my mind.

I fitted new braided lines the other day, to the front brakes, and bled the system with an Easybleed kit.

All seemed to be fine on the driveway, but the other night, I took the car round the block, for a very quick test drive.

The brake pedal has a lot of travel when you first press it, to the point where it doesn't engage the brakes, so nothing happens. I then pump the brakes, and they engage as they should, but only on the second attempt at pushing the pedal.

It did this everytime I went to brake.

Is it just a case of rebleeding the system, or could it be something else?

The passenger side disc is also binding/rubbing a bit, don't know if that is linked?

Cheers.

[Jeroen]

If its binding you need to rebuiold the calipers anyway, but it appears you have loss of pressure. Might be that the brake master is up for a rebuild as well.

[nas80]

Either air in the system or the master is knackered.

Last time this happened to me turned out it was the master

[nas80]

Also make sure your wheel bearings are not loose. It might be knocking the pads

[Eddie.]

Nice one, where's best to buy rebuild kits for everything?

How hard is it to do?

[nas80]

Well the hardest bit is getting them out.

Rebuild kits should be available at the dealer. You will probably need snap ring pliers.

[Jeroen]

Hmmmm we don't have a how-to on rebuilding calipers and master cylinders? About time then!

[Duracel79]

I've had this with my easybleed every time. Works well to get fluid through the system and fill the calipers but it leaves the fluid a bit airated. So the pedal isn't there without pumping up.

Best way to finish is to remove the easybleed and let the system settle overnight. Then have a friend pump the pedal and hold pressure whilst you bleed a caliper. Make sure you lock off the nipple before the pedal gets to the floor to prevent any air getting back in. Repeat the pump up and bleed a few times for each caliper. This is the process I've used for years and works every time.


As for the sticking caliper, as people have mentioned it will either need a rebuild with new seals and pistons or you could try this.

Take the caliper off, remove the pads etc and carefully press the brake pedal to expose the pistons inside the caliper. Be very careful not to let the piston come out too far. With a small screwdriver lift the edge of the dust seal and inspect the piston. If you can see rust and corrosion then really only a rebuild will do.
If you are lucky and it appears clean and rust free, try putting small amount of clean engine oil inside the seal (do not use WD40 this dries out and goes sticky making things worse over time).
Carefully push the pistons back into the caliper(using G clamps or Stilsens etc). At this point it would help to exercise the caliper (pump the pistons out and push back in a few times). Then refit everything and hope it works better.

Bear in mind if you are not confident playing with brakes (a major safety point on any car) get a good mechanic to do this for you.

Hope this helps

Ben

[Eddie.]

Cheers mate, I'll try that tonight.

Okay, so I've found the master cylinder rebuild kit on the BMW Classic Parts website.

My confusion is with the brakes, I've got two options for calliper and their respective rebuild kits:



One seems to be called "ATE" the other is called "Lukas"

Are these just different types of calliper?!

Looking at the picture, I'm pretty sure mine is the "ATE" one.

Can anyone confirm this?

[Duracel79]

PS got my caliper rebuild kits and pistons for the E24 from Biggred here:

http://biggred.co.uk/catalogue.php

Ben

[Jeroen]

Yup, there are two types of brakes possible on your car, but Até it is then.

I have never experienced any problems using the regular Eezibleed on the pressure of a spare tyre, pedals always rock hard here. Just make sure to have enough fluid in the tank. Perhaps you are using compressed air or too much pressure?

...Then have a friend pump the pedal and hold pressure whilst you bleed a caliper. Make sure you lock off the nipple before the pedal gets to the floor to prevent any air getting back in....

Disagree here as this is exactly what ruins older brake masters. On a car that gets a major service on a regular basis this will work fine, but if your master hasn't been disassembled for a couple of yours right at the very end (fully compressed) is where the piston doesn't travel on a regular basis. Dirt buildup, mainly rust, will rip the inner seals to bits and cause loss of pressure and eventually brake fluid will leak into the brake booster.

[nas80]

its worth a shot, but I think it wont make a difference because if that's the same masters that's been in there for nearly 40 years, I bet that rubber inside the master has probably perished due to age.

Also I haven't ever seen a caliper besides ATE on an e21, I could be wrong though,

[Duracel79]

Yup, there are two types of brakes possible on your car, but Até it is then.

I have never experienced any problems using the regular Eezibleed on the pressure of a spare tyre, pedals always rock hard here. Just make sure to have enough fluid in the tank. Perhaps you are using compressed air or too much pressure?

...Then have a friend pump the pedal and hold pressure whilst you bleed a caliper. Make sure you lock off the nipple before the pedal gets to the floor to prevent any air getting back in....

Disagree here as this is exactly what ruins older brake masters. On a car that gets a major service on a regular basis this will work fine, but if your master hasn't been disassembled for a couple of yours right at the very end (fully compressed) is where the piston doesn't travel on a regular basis. Dirt buildup, mainly rust, will rip the inner seals to bits and cause loss of pressure and eventually brake fluid will leak into the brake booster.

Totally agree Jeroen, but if the master is in a state where it fails being pushed all the way down it should be replaced or rebuilt anyway (any of that muck/rust could enter the system and cause brake failure at any time).
Also if the master is old and at risk of damaging its own seals and Eddie has had the pedal go to the floor as he mentioned in the first post it will already of been damaged now.

[Jeroen]

I'm with you! And I suspected the master already because of the loss of pressure. It's just the thing that you may have rather ok brakes after a caliper rebuild. Then you're almost good to go (usually happens the day before you absolutely need the car) and then it would all be fine until you gave the master its final push. That's why I'd rather be a little bit more careful and rebuild stuff at a moment that suits me better, lol.

[Eddie.]

One of the issues making all of this a little harder, is actually finding what rebuild kit I actually need?

Nas mentioned that I have a M/C on the firewall, and 2 boosters on the passenger side, one on top of the other. He said this was a very early design.

If I want to rebuild it all, what do I need to buy? I can find a master cylinder rebuild kit, that is seemingly for my car, but do I need 3 of the same, or do I need a M/C rebuild kit, and 2 booster rebuild kits?!

Anyone able to shed any light on what parts I actually need?!