re-building calipers?

makaio · 03-09-2002, 05:19 PM

I'm planning a complete overhaul of my brake system, which I'll perform sometime this summer.

Most of the process I feel pretty comfortable with, but changing the seals on the calipers kinda has me scared.

On a scale of 1-10, 10 being the hardest, how would you guys rate rebuilding the calipers? Should i find another set of SC calipers and practice on them?

MJM911SC · 03-09-2002, 06:41 PM

Matt,

Rebuilding your calipers is about a 3 out of 10. Seals shouldn't scare you. Toughest part is lining up the piston. I have made a 20degree template out of thick paper for the task. I also have the complete set up for doing the job. You can practice with a set of extra SC calipers that I have.

eMail me if interested,

Mike M

Gunter · Gunter's Garage

Some people pop out the pistons while the calipers are still on the car. If you take them off, there is a trick to popping out the pistons. You need compressed air and two C-clamps. Put each C-clamp loosely over each piston and blow compressed air into caliper. Safety glasses! That way, both pistons come out evenly. Clean and blow out calipers and pistons. I had to use a fine crocus cloth to clean pistons. Install new seals. Put a little brake fluid on the seals and install pistons with the correct off-set. Make sure that the off-set is in the correct position. You have to think in terms of left and right. It's not that difficult, just a little messy. I did the bearings and rotors in the front at the same time. The Haynes manual tells you how. Cheers.

Gunter · Gunter's Garage

Some people pop out the pistons while the calipers are still on the car. If you take them off, there is a trick to popping out the pistons. You need compressed air and two C-clamps. Put each C-clamp loosely over each piston and blow compressed air into caliper. That way, both pistons come out evenly. Clean and blow out calipers and pistons. I had to use a fine crocus cloth to clean pistons. Install new seals. Put a little brake fluid on the seals and install pistons with the correct off-set. Make sure that the off-set is in the correct position. You have to think in terms of left and right. It's not that difficult, just a little messy. I did the bearings and rotors in the front at the same time. The Haynes manual tells you how. Cheers.

makaio · 03-10-2002, 08:12 AM

I read the procedure in the 101 projects book last night before I went to bed. It made everything very clear.

The part I really didn't understand at first was the 20 degree indexing. But after looking at the pictures, it makes sense.

My next question is: Is there a factory tool for measuring the 20 degrees, or do I just have to make one?

Clark Griswald · Clark Griswald's Garage

Just make one. Cut a little peice of cardboard into a 20' angle.

Then just hold it up to the caliper to check the angle.

makaio · 03-10-2002, 08:22 AM

I smell what your cooking Clark. Thanks!

Jdub · 03-10-2002, 09:15 AM

Matt:

Just did this job. You can pop the pistons using a floor-style bicycle pump that has the flip-down lever to clamp the Schrader-style end on the valve. What you will do is reduce the size of the pump by using 3/8 and 1/4 tubing that will fit perfectly into the caliper-side hard line threaded hole.

Mail me for details. Get good caliper paint and clean that puppy prior to pulling anything apart. This is a fun and very satisfying job. You should also consider stainless lines if you've a desire for them. The rubber ones are just as good in my opinion. That said my wife treated me to the DOT stainless ones.

How are the rotors? If rotors, than how are your front bearings? It goes on and on!!

John

Early_S_Man · 03-10-2002, 09:23 AM

Matt,

The best set of instructions in print are in the Bentley air-cooled VW (Beetle, Bus, or Type 3) service manuals, which your local library may have copies of. They specifically mention 'brake paste' that is simply Dow Corning 111 or equivalent, to lubricate the rectangular cross-section seals, and Ate used to include a tiny 1 gram tube of unmarked silicone grease in their rebuld kits for the master cylinders!

makaio · 03-10-2002, 09:28 AM

John, first your avitar freaks me out!

I'm planning on replacing or re-building the whole system pretty much. I have had a soft pedal like feel since right after I purchased my car. The brakes work great, but I can tell they are sub-par. I have flushed and bled the brakes many times to no avail.

Here's my list:

Rotors fr & r; there're getting thin.
Pads; no brainer
s/s brake lines; I have them now, but don't now their age.
re-build calipers; dust seals are starting to crack on most.
M/C; I believe this is the original, almost 25 yo.
New front bearings; cheap insurance
Flush hard lines per Warren's instructions with isopropal alchohol.

Since I'm doing the labor myself, I'll save a bundle. And I'll have piece of mind when I start Time Trialing more next year, that my brake system is up to par.

Early_S_Man · 09:52 AM

Matt,

The soft pedal may actually be caused by the stainless steel flex hoses, if they are the old, original-style with adapters at each end using AN-4 lines! All of the current SS lines use AN-3 hose, and most use swaged-on fittings and no adapters, and some users (and sellers) claim they don't cause the soft pedal of the old, original kits from the '70s and '80s. Funny, how the news of the soft pedal didn't get around until the AN-4 kits weren't being sold any longer!

makaio · 03-10-2002, 09:43 AM

I'll go check them Warren. I' post a pick.

Jdub · 03-10-2002, 09:54 AM

Matt:

I am a big junkie for the old vinyl...record covers of the olden days where whole design houses got their startup from a single, killer album cover. Dark Side of the Moon is a good example of a cover that made a design house.

This guy is from the classic "Court of the Crimson King" which, while spacey, was Allison Steele's #2 10PM leadoff in the heyday of B-side rock and WNEW in NYC. Cousin Brucie, all the rest...

But I digress...It sounds like you are getting to the heart of the matter with the parts you have slated to replace. I would advise heat tank for the hubs prior to well-place application of the punch tool to the races on your wheel bearings. You *should* have half-moon cutouts that give you access to the backside of the races, but mine does not despite what the manual says...

I would also consider replacing those lines along the lines of Warren's advice. I won't pretend to know the difference in the ends he is speaking of but certainly any stainless line is simply a rubber line encased; no more. They have just the same problems as any rubber style. I bought my DOT-style lines here at PP.

Good luck! Send me your old vinyl records! I just found "Peppermint Twist" by Mr Berry in my mom's attic: all striped and about 10" in diameter!

John

makaio · 03-10-2002, 10:22 AM

Thanks for all the help guys.

I'm going to buy it all here from Pelican. You just can't beat there service!

Here is apicture of my brake line connection. I'm sure the lines are part of the problem.

Early_S_Man · 03-10-2002, 10:56 AM

Matt,

That looks like an AN-3 hose just by the uncalibrated eyeball method ... An-4 hose measures 0.305" - 0.308" OD of the stainless braid, measured with a dial caliper.

Incidentally, if the SS hoses are more than 5-8 years old, they should be replaced anyway because of aging of the Teflon liner! I had two failures on my old test vehicle ... a '74 Datsun 620 truck, one right at the swaged end, and another in the middle of the hose where the long hose to the front brake cylinder did a lot of flexing and moving as the axle moved in and out with the turning wheels! My failures were experienced at about 8 and 12-13 years, if I remember correctly. The 'test' that began in 1978 was terminated in May 1994 when a 20-year old college student rear-ended my legally-parked truck out in front of the house ... the truck was 'totaled' even though still driveable (which I did for another month) ... but the '90 Cavalier was totaled and undriveable! My heavy, USA-made step bumper did its' job and was sacrificed ... but the carnage it inflicted on the front end of that Cavalier was amazing! My tail gate was still usable, though dented, and the right tail-light lens was broken!

makaio · 05-06-2003, 01:37 PM

Just a long over due update. It was my leaking master cylinder that was giving me a soft pedal feel.

Just wanted to let anyone know who might do a search.

redducati750 · 05-06-2003, 01:40 PM

i needed like 220 psi to get the pistons out of my ALum S calipers. It was a pain but not to complicated. Get a bottle of assembly lube also.

juanbenae · juanbenae's Garage

where did you detect the bad master cyl? did the brake fluid drain out of the overflow in front of the drivers side front tire? i just did my caliper rebuild last week and have the soft pedal syndrom. i have not gone full blown with warrens recomend of putting wood thinner than the pad in and applying the brakes. thats next, i also may drive it a bit to see if it "gets better" as also metioned here. i did spill a bit of brake fluid in the basin around the master cyl filler but the puddle of brake fluid is still draining a few days later. so how did you detect the bad master cylinder?

Series900 · 05-06-2003, 03:53 PM

Over the years I am a little less adventuresome with my fingers, calipers and compressed air! Now I just use my vacuum pump from FRP vac bagging, rigged up to a power master cyl and the pistons pop with out much effort at the bench. Iffin you get a stubborn one, clamp the other, and apply pedal pressure!

Damon @ SERIES 900
Sunapee NH

911 restoration-race fab-paint
2 Celette benches w/ porsche jigs

makaio · 05-06-2003, 04:22 PM

Quote:

Originally posted by k911sc
so how did you detect the bad master cylinder?

I changed everything except the factory hard lines, and the master cylinder, and I could never quite get the pedal to feel solid. It would stop great, even did a few DE's like that, but never felt rock solid, even after bleeding & flushing with Super Blue many times. But I never saw any leaks, the fluid never went down. Then, after purchasing my cab and feeling how the brakes were suppose to feel, I knew something was wrong. So I pulled the master sylinder, and sure enough, it was just barely leaking. Probably had been that way since before I bought the car. The leak was running down the back off the booster and into the pedal box area, that's way I never saw it either.

Sorry so long winded.