951 brakes question

A place to hang out and discuss all things Porsche.

951 brakes question

Postby Mike Cornelius on Fri Dec 10, 2004 12:45 pm

I own an '86 951. The brake peddle is firm but not real effective at stopping the car. :shock: The pads and rotors all seem fine. Could there be a clogged line or something like that? Has anyone experienced similar issues with their car? :?
User avatar
Mike Cornelius
Autocrosser
 
Posts: 61
Joined: Wed Nov 24, 2004 8:35 am

Postby Chris Moon on Fri Dec 10, 2004 3:19 pm

I've got some suggestions for more questions to ask.

Did the problem start suddenly? That is, were the brakes fine up until recently? Is so, what happened? Maybe the pads are glazed. Pads make a big difference in dust, noise and pedal feel, try a different pad.

Does pumping the pedal make a difference? If so, try bleeding again and be sure to bleed both valves at each wheel starting with the right rear.

Is there a vacuum leak? Maybe you're not getting any help from the vacuum booster.

:beerchug:
CM
'88 951 More Boost!
User avatar
Chris Moon
Member
 
Posts: 26
Joined: Fri Jul 16, 2004 11:24 am
Location: Mission Viejo

Postby Mike Cornelius on Fri Dec 10, 2004 4:08 pm

The pads are fine, and pumping the pedal does not help. How would I check for a vacuum leak or if the vacuum booster is not working properly. Is it something easy to do?
User avatar
Mike Cornelius
Autocrosser
 
Posts: 61
Joined: Wed Nov 24, 2004 8:35 am

Postby Chris Moon on Fri Dec 10, 2004 4:43 pm

Well, there's the old spray carb cleaner near the suspect lines trick. If you have a leak the idle should stumble and you would then know where the leak is.

Beyond that, I guess I'd suggest having a real expert look at it. The typically recommended San Diego shops are Dieter's and Black Forest. I'm in Mission Viejo so I usually go to Vision or Hergesheimer's.


:beerchug:
CM
'88 951 More Boost!
User avatar
Chris Moon
Member
 
Posts: 26
Joined: Fri Jul 16, 2004 11:24 am
Location: Mission Viejo

Postby Duram on Sat Dec 11, 2004 2:20 am

Put your foot on the brake when starting the car, you should feel the pedal sink down a little further once the car starts. If not then then there is a problem with the vacuum assist system.
Duram
Member
 
Posts: 11
Joined: Fri Nov 05, 2004 3:58 pm

Postby Steve Grosekemper on Sat Dec 11, 2004 11:31 am

To be sure on the vac. test, pump the brake pedal 10 times with the engine off. Then press the brake pedal firmly. Start the car and the pedal should drop. If it drops you have vac. to the booster.

Turn the car off. Pump the pedal 5 times. The pedal should become increasingly stiffer. If it is stiff the first pump you have a bad check valve.

You still didn't say whether these brakes have always been like this or it was a sudden change? This make a big difference.

Brake pads on a 951 can make a huge difference in braking. I have two 951's with two different "stock" pads, and one stops 40% better than the other, (and squeaks).

So what is the exact history of this problem, sudden or has it always been like this??
Steve Grosekemper #97
http://www.911SG.com
https://www.facebook.com/911steveg/
https://www.instagram.com/steve911sg/
PCA-SDR Tech Advisor/Scrutineer/Forum-Admin
1997 993S & 986S street cars & 911SC track car.
User avatar
Steve Grosekemper
Admin
 
Posts: 1381
Joined: Thu Jul 01, 2004 6:15 pm
Location: San Diego

Postby Mike Cornelius on Mon Dec 13, 2004 7:33 am

Steve,

It's been like this since I have owned the car - 3 months. I'm not sure what kind of pads are on it, they where fairly new when I got the car. I will try the vac. test first. The car is going into Black Forest this week. I'll let you all know what the problem was after they get a look at it.

thanks all
User avatar
Mike Cornelius
Autocrosser
 
Posts: 61
Joined: Wed Nov 24, 2004 8:35 am

Postby David J Marguglio on Mon Dec 13, 2004 1:15 pm

Hey thanks for the help Steve...but I'm taking to BlackForest.


Sorry, that just stuck me as funny!
Personal driving coach to:
Maria Sharapova
1993 Martin-thrashing RS America
2004 Cayenne
User avatar
David J Marguglio
Time Trialer
 
Posts: 398
Joined: Mon Jul 12, 2004 2:33 pm

Postby Steve Grosekemper on Mon Dec 13, 2004 5:52 pm

I thought it was pretty funny as well. But there is more than enough work to go around and it works out fine since I will be spending the majority of my week reaching into my magic bag and massaging some more speed into Martins C-2. (No-points magic, that is)
Steve Grosekemper #97
http://www.911SG.com
https://www.facebook.com/911steveg/
https://www.instagram.com/steve911sg/
PCA-SDR Tech Advisor/Scrutineer/Forum-Admin
1997 993S & 986S street cars & 911SC track car.
User avatar
Steve Grosekemper
Admin
 
Posts: 1381
Joined: Thu Jul 01, 2004 6:15 pm
Location: San Diego

Postby Pete Millikin on Mon Dec 13, 2004 6:40 pm

For those keeping score.....that is one apiece for Mr. Margulio and Mr. Grosekemper. For a moment Steve I thought you were going to be massaging Ms. Sharapova instead of some old car.
86 Carrera 3.2L #178
User avatar
Pete Millikin
Time Trialer
 
Posts: 312
Joined: Wed Jul 07, 2004 8:59 pm
Location: Escondido, CA

Martin's C-2

Postby Greg Phillips on Mon Dec 13, 2004 6:55 pm

So you are invloved in a pointless exercise of car massage ? :roll:

Greg
User avatar
Greg Phillips
Pro Racer
 
Posts: 1590
Joined: Wed Jun 30, 2004 11:41 am
Location: Coronado

Postby Pete Millikin on Mon Dec 13, 2004 8:12 pm

I wouldn't call it massaging or pointless but next to a 6' tall blond pro tennis player it kinda seems that way.
86 Carrera 3.2L #178
User avatar
Pete Millikin
Time Trialer
 
Posts: 312
Joined: Wed Jul 07, 2004 8:59 pm
Location: Escondido, CA

Postby Jad on Mon Dec 13, 2004 10:53 pm

Speaking of tennis, anyone else get the very stylish and completely un-usable as a calendar thank you calendar from Porsche?
Jad Duncan
997 S Cab - Sold
996 "not a cup car" Sold
Tesla Model S
Porsche Taycan
https://www.goldfishconsulting.com/
User avatar
Jad
Pro Racer
 
Posts: 1788
Joined: Wed Jun 30, 2004 11:03 am
Location: Del Mar

Postby Mike Cornelius on Tue Dec 14, 2004 9:25 am

Steve,

Nothing against you or your shop - I would actually love to have you working on my car. My choice of shops is driven by location. I happen to live in North County, and it is just much more convenient for me to take it. With that said - I did do what you suggested and the pedal did not drop after pumping it 10 times and starting the car. Also, the pedal was stiff the first pump after turning the car off. So, it sound like a bad check valve and there is no vac. to the booster.
User avatar
Mike Cornelius
Autocrosser
 
Posts: 61
Joined: Wed Nov 24, 2004 8:35 am

Un usable calendar...

Postby Jackie C on Tue Dec 14, 2004 11:12 am

Hey Jad,
I got my calendar yesterday. They've grown in size and replaced the medallians that used to be attached with a CD that contains a nice screen saver. I am sure you were as disappointed as I was that there wasn't a single 944 sketch in the lot!
Blue skies,
Jackie
Jackie Corwin
User avatar
Jackie C
Time Trialer
 
Posts: 454
Joined: Tue Jul 06, 2004 11:46 am
Location: Vista, CA

Next

Return to General Discussions

Who is online

Users browsing this forum: No registered users and 69 guests