StanUK951

Hi. I've just registered and am a '86 951 owner which has some light modifications from London, England. I recently followed the advice from some of you guys and flipped the o/s driveshaft when it started making a thumping noise - all is well again now!

I have a weird braking problem where sometimes it feels as if the servo isnt working properly, especially when I start braking immediately after hard acceleration. The pedal feels 'wooden' and requires a lot of effort. It also seems to affect the heater/air-con as when its on position 3 or 4 the heater fan will stop if I apply the brakes fairly hard!! I've changed the little servo on the heater flap thingy but to no avail.

Any help very much appreciated.

951Tom

Sounds to me like your brake booster assist isn't holding a vacuum. To test it turn off motor, push brake pedal 3-5 times. You should feel the pedal pump up and get harder. Then while holding pressure on the pedal, start the car. The pedal should drop down an inch or so. If it doesn't, you've either got a vacuum leak or a faulty brake booster. Hope this helps.

StanUK951

Thanks Tom. I went straight out and tried what you said and it seems to be holding pressure, though I thought it felt a bit soft so I might try changing the front pads and fluid and see how that goes. Thanks again!

Bri Bro

Stan, please read this part of the test again (see below). You said "it seems to be holding pressure".


Then while holding pressure on the pedal, start the car. The pedal should drop down an inch or so.

StanUK951

Thanks beab. I did get it! I pumped the pedal 10 times then held my foot on the pedal whilst I started the engine. The pedal did drop a bit, but it did feel a bit soft. In other words the pedal didnt get as hard to push down, and the travel in the pedal didnt decrease, as much as I would have expected. Thats why I thought I would try and bleed the brakes and change the pads (in case someone had fitted some cheap OR high temp racing pads as the brakes sometimes feel better as they warm up). Whatever the problem is, I'm sure all is not right in there somewhere and my garage (a good local Porsche specialist and racing garage) couldnt find any problems - though I'm not sure how much time the spent looking as my bill was escalating at this point!!

If you (or anyone else) has some further advice though I'd love to hear it!!

StanUK951

I should also add that Steve (the guy that owns the garage and who is a widely respected technician in the Porsche world over here in England and a racing driver) confirmed he thought there was a problem (he shouted 'Bloody hell!!' when he tried to brake hard into a corner after coming off hard acceleration!). So its not me being overly concerned!

Peckster

I thought you guys yelled that all the time. No?

StanUK951

Along with 'Corr Blimey Guvnor' and 'fackinell mate' and various other cockney expletives!

P.S. My brakes still dont work properly - any other ideas or have I stumped you all!!

951Tom

There's a plastic venturi y-tube under the intake manifold that the brake booster vac hoses connects to. I found mine in two pieces and had to glue it back together, but I didn't have your symptoms. Maybe yours is broken/clogged???

booster

I would do a complete brake makeover, change fluid and pads also resurface rotors and check the calipers to make sure they are functioning correctly and also check the brake lines going to the calipers (the flexible ones) they can expand during hard braking they maybe need to be replaced. Just my 2P. Cheers...

Bri Bro

Stan :
I would replace the Master cylinder, it is good routine maintaince and it just might fix the problem. Check and see if you can spot brake fluid on the braker booster directly below the master cyclinder. If it is leaking, it will soften the paint and just rubbing it will take the paint right off. If there is fluid, it is a tell-tail sign of a bad master cyclinder. I also have had master cyclinders fail without leaking.

My catalog shows the 944T (86 only) is $89 new! In 87 it jumps to $112.

Ok, tell me if this looks right
$89 = 101.749 EUR = 62.42 Pounds(GBP)

StanUK951

Looks alright to me beab. Though I think the car had a new master cylinder recently(ish). I will check it out though. I think I will try some new pads, fluid and braided hoses too and that valve under the inlet manifold. And if none of that works I'll just steal the brakes off my Dads 993 Turbo

In the meantime keep the suggestions coming!! And thanks for the help guys - I'll let you know when I finally sort it.

Peckster

It's real pain with these cars when you can't pin a problem down. But I find throwing money at it will solve the problem eventually.

jp

951Tom

Stan,

How much was the heater flap servo motor? I need one for my floor vents. Did you get the brakes figured out?

Thanks,
Tom
'87 951
'86 Supra

StanUK951

Tom,

The motor was only a few quid, about £8.00 I think so about $15.00??? I dont think it was much anyway.

Haven't had time (or the money) to do anything with the brakes and I'm going on holiday this Saturday for a weeks skiing in Austria so I cant afford to "throw money" at it!! When I get back I will get braided hoses, new front pads (maybe rears), new racing/hi-temp fluid, and just generally check the operation of the calipers.

Has anybody used those fancy brake bleed nipples (speed bleeders) I saw on the <a href="http://www.paragon-products.com" target="_blank">Paragon Products</a> website? Anyone used them? What are they like?