Menu toggle

Brake Vibration.

J

John Maddox

New member
I had this years ago with my 993 but in my case it was corrosion on backing plates. I suggest you try and find a member locally to you who can swap wheels just so you can eliminate tyres from the equation. Attend a Region Meeting to see if anyone there has a 993.
 
Would welcome any feedback on the problem I have with the braking on my 1994 C2 993.

Had a vibration under braking. Suggestions were that, possibly, the disks were warped and that most likely the plates in the
calipers had lifted causing the pads to sit unevenly.

Had the disks changed and new pads fitted and also the plates sorted, as they were lifting.

I have a good solid brake pedal and at high speeds good retardation without vibration. At slower speeds, however, a vibration
occurs which is very noticeable. Went back to the guy who did the work to have the run-out checked. There was a very, very
slight run-out but not enough, in his opinion, to be the cause.

I don't believe there is a problem with wheel balance or with the tyres (Pirelli PZero) although age may be a factor but there is no
vibration evident at other times, only when the brake is applied. Could get new tyres but that could be an expensive way of
finding out!

I'm confident that the work has been carried out correctly. The 'indie' who did it comes well recommended; he knows his stuff
and has serviced this car for many years but cannot offer a solution.

I really do not want to go down the expensive route of changing parts in the hope of finding a cure.

Any suggestions, please?

 
I had a similar problem with my 993, cleaned the front discs with brake cleaner and it was cured. I think it was caused by me always washing the car before putting it away for a few days, corrosion or zip wax who knows was on the discs and I wasn't using them aggressively enough to clean them up. So only noticeable on slow speed usage. HTH
 
Hi Maurice, thanks for the reply. The 'indie' checked the suspension when he first looked at the run-out towards the end of last year and could find nothing wrong. He checked it again prior to the MOT on the 1st June and, again, found nothing amiss; as it passed the MOT I have to presume the tester also gave it a good check. If I brake hard at 60mph - I've done this regularly thinking it might help bed the disks and pads in - the braking is rock solid with no vibration. The vibration is through the steering and occurs at low cornering speed although not necessarily on corners, more at a slowing down speed to negotiate a corner or stop. Thanks.
 
Hi Cater_Racer, must admit I hadn't thought of brake cleaner. However, mine's a bit of a garage queen so doesn't get used that much to get dirty to warrant regular cleaning! Mindful that corrosion occurs in those circumstances though I always dry off the brakes after washing the wheels but I'm fairly sure this is not the cause this time but I may take your advice and give brake cleaner a try. Thanks.
 
Evening John, I take your point about the backing plates. I would hope that the 'indie' would have considered them as potential culprits. I was there when he checked the run-out and didn't think to look when the car was on the lift with the wheels off but it's something I can do now. The chance to try another set of front wheels would be ideal. I was reading of someone with a 944 doing much the same and he was able to prove the point conclusively. I'm in Harlow so if there's anyone close who would be prepared to do this I'd be more than happy to talk to them! Thanks.
 
Kirk had this problem on his Targa. Had the bushes on the wishbones changed at its gone. I have the same issue on my Targa. Thought it was the discs but all cleaned etc and still vibrating at low speeds only. had my wishbones checked and found there is quite a lot of play in the bushes so the next thing to get done. They are 19 years old now Graham
 
Got to be wishbones. Had same problem, was as cheap to have recon wishbones as to have new bushes and fixed it immediately. Andrew
 
Seem to recall that the mating face of the wheel should be left unfinished. If the wheels have been refurbished and the mating face powder coated or painted it can cause an imbalance under braking.
 
Just to confirm what Graham said. I had a low level vibration through the steering wheel when braking gently from 60mph. Had the issue checked and it was thought to be brake disks but I was not convinced. Calipers were relatively new so I ruled this out. At a PCGB day at the Swindon PC my car was put up on a ramp and the lower front wishbone bushes checked. On a visual inspection the bushes looked fine. However, the technician used a lever to move the wishbone and the problem revealed itself.....soft rubber bushes which were easily compressed. Replaced bushes and not only is the vibration now absent but the steering feels more direct with better turn in. If you want to know what the options are for replacement please PM me as new wishbones from Porsche are around £300 per side plus labour plus a geo. Kirk
 
Afternoon John, I'd read somewhere (probably on here or another forum) about cleanliness of the mating faces between the wheels and hubs and checked both fronts but found nothing to be concerned about. The wheels haven't been refurbished, certainly not during my ownership. I cleaned the mating faces again just to be sure but it had little effect, unfortunately. Thanks.
 
Afternoon Kirk, Andrew, Graham and Phelix, problems with bushes sounds promising - and different. I witnessed the 'indie' checking the front suspension when he set up the run-out checks and all seemed fine. As I said in an earlier reply, he checked it again for the MOT on 1st June and, like the tester, seemingly found nothing awry. However, I will forward all your replies to him for comment and see what he says. As an aside, thinking back all those years ago when I had a 3L Capri the model was known to have problems with vibration when braking. All the usual suspects but as memory serves, the inner bushes on the track control arms were deemed to be the cause, even though wear was not always obvious but changing them seemed to provide a cure. Good stuff! Thanks to you all. Kirk I will PM for options as you suggest.
 
Another vote for worn bushes here. Paint on the wheel's mating face with the disk can cause brake vibration, but that tends to happen more the faster you are going, and seems to get worse as the brakes get hotter. "Shimmy" under light to medium braking seems to me more likely to be bush-related.

 
Les,

My car got through two MOT tests without comment on the wishbone bushes. I would confirm what Graham said that the bushes looked fine on visual inspection. However, using a lever (large screwdriver) showed that the bushes had become soft and compressed laterally far too readily.

Regards,

Kirk

 
May I suggest the Powerflex replacement bushes ...

[link=http://www.powerflex.co.uk/road-series/products/993+%281994+-+1998%29-125/1.html]http://www.powerflex.co.uk/road-series/products/993+%281994+-+1998%29-125/1.html[/link]

[link=http://www.powerflex.co.uk/black-series/products/993+%281994+-+1998%29-125/1.html]http://www.powerflex.co.uk/black-series/products/993+%281994+-+1998%29-125/1.html[/link]

They're cheaper (no need to replace perfectly good metalwork), firmer and much longer-lasting.

It's Good to Torque

1997-P Black 993 Manual Varioram Carrera 4S Coupe

KW Variant 3 coilovers RS setup - Wavetrac LSD

Powerflex bushes - JZM performance chip

Bergvill T-Light HID - CG-Lock lap harness

Carnewal Front Protection Bar - Shell VP N+

 
Thanks Matthew, part nos. and all - very helpful.

I'm still hopeful of trying another set of front wheels to eliminate wheels/tyres from the equation although I fully expect to have have to

rebush the suspension. Now I have this recommendation it's made it a bit easier.

Rgds

 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top