Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > Porsche 964 & 993 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 388
964 Brake Disc Warp Issue

After a bit of feedback...

When I bought my 964, it had been sitting unused for a while, so I installed new rotors front and rear, and new pads and did a full flush.

After a not long time, I noticed that when coming to a stop, the car would "lurch" slightly... There was no pulsing at the brake pedal.. just the lurching. I also found at low speed when turning sometimes, I had a slight intermittent squeak coming from the rear but as soon as I touched the pedal, the squeak went away.

So I thought perhaps my rear calipers might have had a sticking piston.
I used the opportunity to upgrade to the 993 rear calipers and installed new seals and freshened them up at the same time. I had the rear discs machined again, and away we went. Braking was smooth and quiet.

A few drives later, and the slight lurching and intermittent squeak is back!

Is it possible that a worn wheel bearing could cause this?
Or how about a poor quality rear disc with non-uniform consistency throughout the surface?

Any other suggestions?

Mike
Old 12-12-2017, 01:16 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Nov 2000
Location: TN
Posts: 115
Could also be a bad wheel bearing, which can cause excessive runout
__________________
Iron Hill Restorations
Specializing in vintage Porsches
Home of the 914 Umbrella Cover
'91 964 Targa guards red, cashmere
several 914's and loads of parts
Old 12-24-2017, 03:49 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 388
I thought this might be the case too... so I had the car inspected by a porsche specialist and they confirmed all bearings were good.

Sine then I have now fitted a new pair of stop tech discs and pads to the rear.. and will do some miles to see if the issue returns.
Old 12-24-2017, 03:54 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Jan 2018
Posts: 2
Mike, I had this same issue when I bought my car. I suspect the PO may have got sick of chasing the problem too....
I spent lots of money trying to track this down, with the problem returning again soon after each fix.
I finally fixed it by having the rotors machined whilst on the car. 5000kms since and hasn't returned. There was obvious run-out on both front rotors as they were machined (even though they had recently been turned off the car).


Old 01-01-2018, 09:12 PM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 388
Thanks for the reply.. interesting that it was fixed by machining whilst still on the car.. does that suggest that the discs were not mounted properly perhaps?
Still if it fixed your issue, then who's complaining!

I have stop tech rotors front and rear now.. I still need to bleed the system but my initial impression is that braking "bite" has reduced greatly... will see as time goes on.
Old 01-02-2018, 01:43 AM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Jan 2018
Posts: 2
I tried a new set of rotors/pads and checked mounting and cleaned surfaces.
Also rebuilt calipers in case something strange was happening with uneven piston movement. It took 3 workshops involvement to get it fixed.
A frustrating and expensive beginning to ownership but very happy now.
Old 01-02-2018, 03:37 AM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,550
Garage
Check the hub flange with and without rotors total indicated run out with a dial indicator mounted on a magnetic base.
Cheaper than replacing parts.
__________________
1993 964 C2 still makes me smile
1996 318ti (269k miles)
2011 Silverado for hauling (32k miles)
Old 01-02-2018, 05:54 AM
  Pelican Parts Technical Article Directory    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Oct 2013
Location: Prescott, AZ
Posts: 691
Mike, I had a similar problem years ago that turned out to be tires. They looked fine but had taken a "set" from inactivity, and no matter how long I drove the car it still had the symptoms until I got new rubber.
__________________
1990 964 Coupe
1986 Carrera 3.2 Targa
Old 01-02-2018, 06:51 AM
  Pelican Parts Technical Article Directory    Reply With Quote #8 (permalink)
Registered User
 
ischmitz's Avatar
 
Join Date: May 2002
Location: Santa Barbara, CA
Posts: 4,452
Garage
Send a message via Skype™ to ischmitz
Different Porsche but similar problem in the front on my 74. Under hard braking the front would start to vibrate. Definitely from the brake rotors. In my case it was simple "pilot error" when installing the rotors. I didn't properly clean the hubs and the build-up simply caused the rotors to seat improperly. I ended up getting a set of new rotors and all is fine now.

Measuring TIR (run-out) with a dial gauge is the way to go and would have caught this. And it'll nicely differentiate between a bad bearing if run out is already high on the hub flange versus a warped disk.
__________________
'74 Targa 3.6 (not stock ) - '01 C4 (almost stock) - '00 ML430 (stock)

I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs
Porsche "Hammer" or Porsche PST2 - I can help!!
How about a NoBadDays DualChip for 964 or '95 993
Old 01-02-2018, 02:29 PM
  Pelican Parts Technical Article Directory    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,550
Garage
^^^^.
Yep. Got to make sure the hub surface is clean, burr and rust free and hub flange machined surface is not bent.
__________________
1993 964 C2 still makes me smile
1996 318ti (269k miles)
2011 Silverado for hauling (32k miles)
Old 01-03-2018, 08:28 PM
  Pelican Parts Technical Article Directory    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 388
Quote:
Originally Posted by RedCoupe View Post
Mike, I had a similar problem years ago that turned out to be tires. They looked fine but had taken a "set" from inactivity, and no matter how long I drove the car it still had the symptoms until I got new rubber.
Hi, I thought it might be something like that.. but when I first had the issue, I bought new rotors as I had just bought the car. Then it happened again.. so I got the rotors machined... then it happened again! So I bought complete new rotors and will see how this set goes..
Old 01-05-2018, 03:15 AM
  Pelican Parts Technical Article Directory    Reply With Quote #11 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 06:23 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2017 Pelican Parts LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.