65 912 brakes

terry@bigbadtoy · 11-11-2002, 05:15 PM

My 65 912 has partially seized brakes - will move but she likes to stop on her own! Rebuilt or new calipers seem very pricey - any resources that you have would be appreciated. Rebuilds seem to be in the $450 price range.

Has anyone used a rebuild kit? experiences? Anyone have a resource for the procedures to remove/replace calipers or how to rebuild.

This is the first step in restoring this original German market 912 that I brought back in 1968. Any and all suggestions will be greatly appreciated.

Atlee · 11-11-2002, 07:51 PM

If you find the pistons frozen in the calipers (97% probability),
take out the bleeder valve and replace it with a grease fitting. Pump in the grease and out comes the piston. Usually one side comes out so take out the O ring, clean up the piston and cylinder, replace it, clamp it in position and repeat the process to push out the piston on the other side.
Rebuild kits for all four calipers will cost about $100.00
Search this site. There is a good description of the re-assembly process.

Go For it...........Ron

Morrie · 05:42 PM

I agree with Ron that you should rebuild. My '67 had completely frozen calipers and I successfully rebuilt all four- for around 80 bucks.

Tips:

DO NOT split the caliper halves- they are very difficult to reassemble and the rebuild kits do not typically include the parts.

You don't necessarially need to contasminate the calipers with grease. If the pistons move at all, Air pressure will likelu push them out. I just used the car's brake system, lifted the caliper off the rotor, clam,ped one piston, and pressed the other out with a helper on the brake pedal. Use a stick to hold the pedal down and you won't loose much fluid.

Polishing the pistions so that there is no corrosion where they contact the seal is critical for a leak free job. I used 2000 grit sandpaper lubed with WD-40.

Use this opportunity to replace your flexible brake lines. Just make sure to get a good set of flare wrenches and don't twist on the solid steel feeder lines.

Go For It!
Morrie
67 912 Coupe

Atlee · 06:05 PM

Yeah!.. am all in agreement with Morrie about using Brake Fluid pressure or Air to free the pistons, the lube grease system was a suggestion when all else fails. ( I got 6 out of 8 before I had to fire up the grease)

And of course I replaced the brake lines with nice teflon lined stainless.

Ron

atlporsche · 11-15-2002, 04:00 AM

my '67's were just boat anchors...REALLY BAD....people said they couldn't possibly be that bad, but they were....rusty all the way up inside. (They sat with 0 fluid for years)

anyway. scored a set (all 4) off a 912 registry for sale ad for 170 bucks.

there's deals to be had out there.

sjd
who just got rust free california doors off a '68 for 400 bucks...(I couldn't buy all the repair metal for that much.)

Morrie · 11-15-2002, 05:39 AM

With the brakes partially working, I think just the brake fluid in the system will push them out. I recommend wrapping the caliper in an old towell to prevent brake fluid from getting on the paint. This method requires no tools to speak of, so the investment is low.

You'll be fine

Morrie

terry@bigbadtoy · 11-26-2002, 04:13 PM

Thanks for all your suggestions - as soon as I can get heat in my garage, I will put your ideas to work. If you can think of anything else.....

Another question - at your suggestions, I also plan to put in new brake lines - any thoughts as to rubber or braided and are there any pitfalls to the project. I have done brake lines on old trucks but this will be a first. Again, thanks

Terry

Morrie · 11-27-2002, 06:28 AM

Brake lines.... first of all, replace them, no doubt about that. Swollen lines can pinch off fluid at the caliper and cause it to lock and burn up agianst the rotor.

As to what type, most folks go for the SS braided ones. Remember, they have a rubber core and don't last forever but are supposed to be more durable than rubber and supposedly provide a more solid pedal feel due to the rigidity.

There are "off road" and "DOT Approved" versions. IMHO, the DOT approved ones buy you little or nothing and just cost more. Some say that there is a "Whip Test" the off road ones don't pass. If you're concerned, spend the extra 10-15 bucks and get the DOT ones.

As far as replacement goes, make sure you have a good set of metric flare wrenches and DO NOT twist on the steel feeder lines. Fronts go on easy, rears require some tricks to get to them around engine mounts and the like. Left rear requires removal of the engine mount, right rear is best done by taking the Tee box loose from the chassis and repositioning it slightly. Removal of all flex lines from the calipers themselves is pretty straight forward, just be sure not to twist the steel lines.

Good luck and let us on the BBS know if you run into any trouble... we'll help you out!

Best,
Morrie
67 912 Coupe

terry@bigbadtoy · 01-18-2003, 11:18 AM

Hi gang,

I started the brake project but did not get very far. I removed the clips pins and spring thing but cannot remove the pads

. I made a wire hook set up and used a sliding gear puller but would not budge. I squirted some PB Blaster into the area - any ideas. Thanks

Terry

Morrie · 01-19-2003, 07:00 AM

You need to somehow get the pistons in the calipers pushed back enuf for the pads to be lifted out the top. The trick is to NOT pry agianst the rotor as it can be damaged easily... you can put alot of pressure on by levering and not know it.

If you can move the pistons back just a little you can ease the pads out by slipping the end of a phillips screwdriver into the hole in the pad and levering carefully on the caliper housing. Have the bolts that mount the caliper loose but not off when you do this. That way the caliper can shift in or out on the rotor, giving you the max available gap. Once the first pad is out, the second one is a breeze.

PB blaster is the stuff....

Good Luck!

Morrie

terry@bigbadtoy · 01-25-2003, 05:15 PM

I just received the caliper rebuild kits and DOT stainless brake hoses (from Pelican) and am ready give the pads another shot as soon as the temp is obove 0 and I have a few hours the family business can spare me. Thanks for the tips.

cgarr · cgarr's Garage

I just rebuilt all my calipers, very easy, I had one piston that was stuck, I compressed it in with a C clamp to move it then popped it out with compressed air, 150 lbs at least, be carefull, oh and get some caliper grease for the rebuild. AND Let me know when it warms up on that side of the lake so I can start working back in the garage too.

Craig

David McDonald · 01-30-2003, 08:47 PM

Keep seeing a lot of references to $400.--+(each) calipers-----dream on---I just bought and installed a pair of newly rebuilt front calipers for my 66 912 for $85.-- ea. purchased from Don Erbe Co. in Oceanside Calif. (brake supply specialist--incl. hard-to-find)----didn't price them, but suspect the rears $$ would be in line with the front----check my math, but seems to be less than $400.-- for all four------they have a refundable core charge of +/-$35.--ea.
I found this source after fighting tooth and nail w/the frozen old ones (had to use the brake systems hydraulic pressure as a tool to force the pistons out ) and then rebuilding them (yes you can split the halves --loosen while still attached to the caliper mounts--then be "very" careful not to let the new O rings drop-out or become misaligned during re-assembly)----.After rebuilding, my son missed a gear and overrevved the engina causing some valve damage --so it sat for another year till I could get to it & by that time I knew what was ahead to get the brakes working again (rusty caliper bores)----so I went all the way this time (like I should have the first time).

terry@bigbadtoy · 01-31-2003, 03:58 PM

David

Thanks for the info on rebuilt calipers - I have the kits, so I may be sorry, but I will give it a shot before I go the rebuilt route.

terry@bigbadtoy · 02-08-2003, 03:01 PM

It did not warm up, only10" of new snow, so I started anyway. New problem (at least for me)

I cleaned the whole caliper with alk and with air pressure, I got one piston out. First question, is it better to do one at a time or both at once? I cleaned up the first one, used some 2000 grit paper to get the little bit of discoloring (rust) rubbed down (a tiny bit on the edge of the piston and a little more on the inside of the cylinder beneath the seal groove)- it is smooth but still can see the dark spots. I cleaned with alk and put caliper grease on everything, inserted the internal rubber and tried to put the piston in. The instructions said it should go in easily. I got it in a 1/4" or so and had to use a C clamp to get it the rest of the way in. There was no spring bounce or movement of any kind until I used air pressure to remove the piston. What to do next? Should I try to use more 2000 grit to take more down or ????

The piston I did not remove yet would move in with a C clamp and out with air pressure to its starting spot, but did not pop out. I suppose the next step, assuming I can get the other piston to go in, would go out to the cold garage and hook it up to the brake system.

Thanks for your help.

Morrie · 02-08-2003, 03:39 PM

Hi Terry!

I have been there buddy! Mine are back together and work great so lets assume I did it close to okay...

First of all, rust on the cylinder that the piston goes into is fine. The piston doesn't touch the side walls anyway! Remove the old seal, clean up the cylinder walls with sandpaper like you said, and make sure the groove where the seal sits is good and clean so the seal seats properly. The seal is what keeps the fluid behind the piston.

Second, pitting and corrosion on the pistons is fine, with one critical exception. There nust not be any corrosion where the piston moves in and out on the seal. This will create a leak. If you cannot get the piston shiny smooth in the area where it contacts the seal, you'll need to get some new parts or a different used one.

Third, don't let anyone tell you the piston will just slide in. They don't. There is a guide pin in the center of the caliper case that the piston rides on. Inside the piston is a spring / clamp assembly that will push th episton right back out as you press it in. You need to apply alot of pressure straight on with a clamp to force the piston spring down on the shaft. Make sure to aligb the pistons correctly too. The perscribed angle is in relation th level on the rotor, not the caliper. make sure its aligned before you press the piston in.

Finally, use the brake system to push out that other piston. Unless your brakes are in top condition, air is a long shot. Hook it up to the brake system, clamp the piston you just finished down in place (leave the dust boot off for now so you don't damage it) and wrap the caliper in an old towel. The towel will keep brake fluid from splattering when the piston comes loose and will keep the piston from falling on the ground and getting damaged. If your flex lines are old, replace them at the same time. Old lines can contaminate your calipers or, worse yet, pinch closed and burn them up. For general use, get the original rubber lines- a VW shop will have them. SS lines look cool and sound fancy, but inside they are rubber and there is no way to inspect them, they just need to be replaced periodically.

One last note. If you still have a single circuit master cylinder, consider upgrading to a dual circuit system for safety sake. That way if some part of your handywork fails, you won't be left witgh only a hand brake.

Good Luck and let me know if you need anything else!

Morrie

terry@bigbadtoy · 04-22-2003, 05:22 PM

bump for Marky Mark

HarryD · 04-23-2003, 07:05 PM

I have one rear rotor for an early 912 (68 or older). almost new. Will sell cheap.

snowman · 04-26-2003, 08:03 PM

YOuall don't need brakes to go fast. If the problem is very severe go to S calipers and brakes. Make sure to use vented rotors.

terry@bigbadtoy · 07-10-2003, 04:31 PM

Bump for Allshowauto for his brake problems