Firstfives.org

I have a long list of items to deal with on my new to me 1977 530i, but my priority is to get the brakes working properly and to smog the car (wish me luck ).

In regards to the brakes, the car pulls to the left when the brakes are applied. It is especially noticeable when coming to a complete stop.

I looked through the previous owner's records and found that they recently took it in for repair for this very issue. Though the repair shop recommended new front calipers, rotors and pads, they declined the work. Then they took it somewhere else and only did the pads and rotors.

In my first attempt to fix this, I took apart the front right caliper and pressed in each of the four pistons to see if they moved freely. They did. The calipers show no signs of leaking, but the dust boots are torn.

Next, I figured that the flex lines may be worn (collapsed), so I replaced them with new stainless braided lines. After bleeding the brakes, I tested the car and the problem is still there. The old brake lines did not seem restricted when I blew through them.

So, what is next? Rear brakes? Could there be corrosion in the hard lines? Could the master cylinder be the culprit?

Thank you in advance.

Blaise

Your problem is likely in the right front caliper. A search on 'sticking calipers' here will reveal a lot.

I looked up the caliper rebuild kits on www.realoem.com and have the part numbers.

What is a good place to buy these?

www.autohausaz.com or www.pelicanparts.com
My guess is that autohaus has them cheaper. Be careful when you're using compressed air to get the pistons out, as they will eject themselves with some serious force. I usually put a piece of wood in front to absorb the shock. When you remove the pistons, check for gouges or burrs on the piston or on the wall of the brake cylinder. Usually, just some scotch pad and solvent will get off any buildup on either surface. You can attempt to fix scratches by wet sanding with VERY fine sandpaper if necessary. Oh, and you should definitely rebuild both sides. Use a good brake fluid with low hydroscopic properties (Castrol LMA is one of the best for the price).
Someone else may be able to speak more thoroughly on this, but it has been my experience that when a master cylinder is going bad, you will often get a blow by effect when braking. When you brake initially, you will have good pressure, but as the pressure in the cylinder increases, fluid will blow past the worn or ruptured seals. The pedal will go to the floor, and there will be almost no assisted braking.

autopartswarehouse.com is another place.

Dot 4 fluid, any parts place.

Remove the brake pads. If stuck, open the bleed fittings. To get the pistons to push out, close the fittings, pads out, push the pedal. The pistons will move out to the rotors leaving not much left in the calipers to be stuck.

If you split the calipers, know that the rebuild kits don't normally feature the little teeny O ring that seals the passage between the halves. Not likely to be unusable, but it is a risk.

While apart, painting with high temp paint is good to delay rust.

Monster great best advice: Get the Napa vice grips for the brake line connectors. ( See Peter's FAQ ) The open end 7 mm wrench with the section cut out is sold by people who sell new brake tubing and fittings.

If you don't listen, you deserve everything you get.

Yo Blaise.

If your master is old, it is the culprit. It will be blowing chunks of old varnish sludge down through the rest of the lines and your clutch lines too.

I found this out personally after I went through my brakes WITHOUT changing my old brake master.

My clutch master went a couple months later and when I changed it I saw the piece of varnish sludge that poked through the rubber.

I also have a right front caliper that sticks sometimes now.

I have space to pull over on my commute and have been banging the caliper with a hammer and pipe to un stick it when it happens.

A new master and calipers are surely the way to go, but I just ordered caliper rebuild kits for the front and a new master and am going that way. Car is old and I gotta watch how much I throw at it right now, unfortunately.

I'd think you have a piece of varnish that came from the master that is stuck somewhere in that caliper.

Good luck and welcome to the Preservation of the German Fine Art Club.

Cheers!

Interesting.

I ordered caliper rebuild kits and stainless lines for all four wheels. I am also getting some better pads for the front, but that is just to get a better bike and less brake dust.

Once I have the calipers off, I will flush the system with the pressure bleeder and see if it runs clean and flows to each wheel evenly.

I also thought that it might be related to suspension bushings. If one side control arm is more worn than the other, it might affect the steering upon braking.

More soon.

If it's only pulling when you are braking, that maybe it's not the caliper itself, but the alignment somehow like you suggested.

If the caliper was stuck, it would be pulling that way when your not braking.

Have you spun the tires when you had it jacked up and also applied the brakes then a few times? That may help you out as well. Maybe one is stuck open or not closing completely leaving the other one to do all the work.

Good luck. You'll love it once you get the kinks worked out.

I'd make sure the tires are spinning freely when the car is jacked up first and go from there.

Might also be a warped disc is the culprit, but then it would really shake when your braking.....

All good points. I will do some front end checks soon.

The pads and rotors are new from the previous owner.

I need to tune the car and get it ready to smog...so I can register it. First things first.

Brake parts on the way.

Cheers,

Blaise