Caliper rebuild time?

[Pillow]

Hey guys,

Quick question for you all just to calm my diagnostic fears and concerns.

Problem: front brakes dragging rotors once the calipers get hot. Will go away after tapping the brakes but returns a few seconds to make a dragging sound.

Solution:
1. Rebuild the calipers because they might not be retracting right.

2. The master cylinder is keeping pressure on the front circuit for some reason? New MC time.

3. Long shot, but the vacuum assist is failing somehow and applying pressure to the MC plunger rod.

I have inspected the bearings and they all look great. At first I thought they were shot and making the wheel wobble and bump the pads creating the sound, so I have a box of fresh ones from Pelican collecting dust.

Thanks and any suggestions are very much appreciated,

[Targa77]

I have been told that the rubber lines going to the calipers will cause this as well.

[Pillow]

Good thought, and you are correct. But I inspected them closely last night and could find no signs of fatige, bulging, or cracking.

In this case I do not think the rubber lines are the problem.


Thanks,

[JDaniel]

If you decide to rebuild the calipers (it's easy) and you have the original rubber oil lines, change them. They are relatively inexpensive... and even easier to R & R. After 20+ years of use who knows how clogged they are, or when you may split one.

[Pillow]

Good point. It is always good insurance to do it all when you are in there.

Shoot I guess I will do the whole thing since I am in there; caliper rebuild, rubber lines, rotors, and pads.

... Hopefully that will do the trick...

Thanks,

[Pillow]

Oh, what is the secret tool to get the star head bolts out of the calipers?

I would hate to screw them up

[AirCooledExcellence]

You don't need to split the calipers in order to rebuild them!. All you need is new piston seals and covers, you can order the whole kit from Pelican.

Cheers,

Tim.
____________
1983 SC Targa

[old_skul]

You *could* disassemble the calipers, but it's not necessary or even recommended. They'll never stop leaking if you do.

Just remove the dust covers, pistons and seals from each side. Scotchbrite the pistons and cylinders, install new seals, and put the pistons back in with some brake fluid to lube. Install dust covers and you're done.

And yes, brake lines are cheap enough for you to want to replace them. Don't break a hardline!

[Pillow]

Gotcha

The calipers will not be split then... Not sure why I was thinking they needed split?

I have done 944 calipers before and they were easy, so hopefully the 911 ones will be more of the same.

Take Care and thanks for all the help,

[DavidPorter]

Dragging calipers can be a symptom of corrosion on the pistons and caliper bores, especially if the car has sat for a long time or hasn't had its brake fluid changed very often. This will be obvious when you take them out. If it's a small area you can clean it off with a fine abrasive. Just make sure to flush everything well.

[john_colasante]

Has anyone had the dust boots actually last more than one track session?

[Targa77]

I agree. I just had to replace my calipers because they had seized. The seals were all but gone. My car had sat for 10 years before I purchased it and I couldn't even move the caliper pistons at all.