914 Rear Brake Caliper Problems

steve356 · Post by **steve356** » Sun Jan 14, 2007 7:24 pm

When I imported my '74 914 from the US, one of the rear brake calipers was binding badly, so the car was pushed into the garage and I got on with other jobs. Eventually I have got around to trying to sort the problem with no luck !
With handbrake cables disconnected, I have set the venting gaps several times with the manual adjusters (innner & outer) on both rear calipers, and each time I put my foot on the brake to settle the pads both rear brakes lock on solid and wont release. I have backed right off with the adjusters, reset everything again, and still they lock on.

Am I missing something ?????? .......... I'm not used to these manual adjusters, but setting seemed straightforward enough.

The only thing I can think is that the flexible rubber brake hoses have broken down internally and are acting like a one-way-valve.

Hoping for your collective 914 wisdom before I buy some new hoses.

T.I.A.
Steve

abm914 · Post by **abm914** » Sun Jan 14, 2007 7:32 pm

Steve

It could be the flexible hoses but it could also be the handbrake arm rachet mechanisms in the calipers.........

I think that you can only get to this by spliting the calipers though

If you've got the cash or you've had enough - Mittelmotor - new calipers and handbrake cables + clips and pins..... + new EBC green stuff pads from the UK.

steve356 · Post by **steve356** » Sun Jan 14, 2007 7:50 pm

abm914 wrote:Steve

It could be the flexible hoses but it could also be the handbrake arm rachet mechanisms in the calipers.........

Not sure what goes on inside these particular calipers ...... is a rebuild straightforward ?? ....... Anybody got an exploded diagram ?

Thanks
Steve

Derek · Post by **Derek** » Sun Jan 14, 2007 7:57 pm

I have the same problem at the moment.

I have stripped my problem rear caliper and in my case traced the problem to a split dust seal which has allowed rust in the bore of that caliper half. The rust is just in the top of the bore above the fluid seal.

I will start the rebuid next week and can let you know how I get on.

There is plenty of info available on the 914 tech section at pelican parts.

fourteener · Post by **fourteener** » Sun Jan 14, 2007 9:38 pm

Sounds like, as Derek says, rust on the piston. The tolerances are tight enough that any rust will make the piston bind in it's bore -the fact that brake fluid is hydroscopic does not help.
I have had some past success in freeing callipers by repeated extending and retracting the pistons. To do this remove the pads and put some thin pieces of wood in place of the pads and then press the brake pedal so the pistons extend out of there bores by about 10mm and then lever/clamp all the way back in. Repeat until free
If the pistons are not too pitted and yours are not frozen solid by the sound of things it's worth a shot.

porker914 · Post by **porker914** » Sun Jan 14, 2007 10:06 pm

Steve,
The whole rebuild is actually quite simple but you do need the correct tools and have to be methodical about how you do it. I recently rebuilt mine and used an article from the old 914club.com. try searching on 914world.com as all the old threads are on there now. The one I used had lots of step by step photos. If i find it I will post the link.

David

porker914 · Post by **porker914** » Sun Jan 14, 2007 10:19 pm

Steve,
Here is the thread I used hope it helps.

David

http://www.914world.com/bbs2/index.php? ... 24229&st=0

steve356 · Post by **steve356** » Mon Jan 15, 2007 1:15 am

Thanks to all for the info ...... looks like I'll probably have to rebuild !

I'm not up on suppliers for 914 parts yet ....
Roger Bray seems to have rebuild kits on his website ..... any suggestions for other 914 parts suppliers gratefully received.

Thanks
Steve

Racecraft76 · Post by **Racecraft76** » Mon Jan 15, 2007 5:36 am

mittelmotor, pelican parts and roger bray are the three I use for parts

Derek · Post by **Derek** » Mon Jan 15, 2007 8:31 am

Roger Bray kits only have the two main seals in the kit's. I had to source the other seals myself.

Depends how much you need to strip your caliper.

porker914 · Post by **porker914** » Mon Jan 15, 2007 8:45 am

Steve,
I bought all my parts from Mittelmotor, I bought every possible seal and also new adjusting screws to complete the full re-build.

David

steve356 · Post by **steve356** » Mon Jan 15, 2007 12:18 pm

THANKS EVERYONE !!!!!!

Steve

abm914 · Post by **abm914** » Mon Jan 15, 2007 10:44 pm

Steve

If you're desparate i have some new seals from Mittelmotor, not using them at the moment so would just need them replaced. There is a new (reconditioned set on ebay at the moment from Jim (Stateside).

Ad.

porker914 · Post by **porker914** » Mon Jan 15, 2007 11:12 pm

If its the ones on ebay for £275 they are not worth it as you can fully recon your own for less than £100 and to be honest learn alot about how the calipers work.

go the re-build route and as Ad says they are in fact recons anyway not brand new. I emailed stateside about these about a year ago and had quite a dubious answer as to if they were new.

david

steve356 · Post by **steve356** » Tue Jan 16, 2007 9:04 am

Thanks for the generous offer Ad .......I'm OK for time on this and will order all the parts needed when I strip the caliper and see what I need ...thanks again though.

I did spot the ones on ebay, but don't want to spend £275 even if they were new !

As David says, I'll learn about these calipers if I rebuild them and I may even enjoy

doing it.

Thanks again to all.

Steve