Disc warpage

[richardrimmer]

Hi All,
some of you may know that prior to the "not Abbeville" tour I had my RS serviced and new front brakes fitted. The pads were treated gently for plenty of miles including no heavy stopping all the way to Clastres. I started getting some vibration when stopping from 50mph with steady brake pressure (barely noticeable at low speed) so decided to get it investigated on my return.

The car was checked this morning by PC Swindon and they said one front disc had a small run-out and there was discolouration due to overheating! As I hadn't participated in the track antics I was rather surprised and then extremely disappointed when they suggested skimming my 2000mile old discs. I was less than happy with this as you can imagine and finally convinced them that they should be replaced. The PC is footing the bill for this as Porsche warranty will only skim them.

Has anyone else ever had discs warp from normal road use? Bear in mind that the car wasn't being used excessively hard and that they should be up to track day use, never mind anything the road can throw at them.......

 

[jason]

You are of course presuming that the OPC has a clue what its talking about....[&:]

What pads are you using?

I refuse to use an OPC for anything.....ever since the technician working on my 996TT came over and asked me if I could show him how you get the mileage readout!!![8|][][]

 

[pncarrerars]

Are you sure that they are warped? I had a similar situation & after much investigation found that the alloy hub was not true. Bought a new one & it was worse. In the end I got my local machine shop to true up the original which is now fine.

Pete

 

[RSL]

Hi Richard,

I too had a similar situation and thought it was the disc only to find it was a hub failure , replaced hub and all was perfect.
This of course may not be the reason for your symptoms.

 

[Dekker]

Hi Richard,

I had a similar problem that only showed up as vibration under braking which on investigation of the suspension I found that the drop link bush seal was weeping grease. Replaced these and the problem solved. I know that your suspension has some differences to a C4 but it maybe worth checking all the links with a gentle pull on a crowbar to see if they have any play.

 

[Melv]

Well if you would go to an OPC.....Get a second opinion...

 

[richardrimmer]

Thanks for the replies. I did inspect the disc in question at the Porsche Centre and it was clear that it hadn't bedded in properly as there was still some of the scuffed surface finish that new discs have visible. The line of this scuffing wasn't even all round suggesting their run-out check was correct. The problem only appeared after having new brakes fitted which suggests that is where the problem lies rather than in any suspension components. Pads are standard Porsche parts as I don't use the car on track.
The reason for using a Porsche Centre is that their prices for servicing are easily on par with independants if not cheaper having spoken to other RS owners. The Centre I use for our Cayman S also regularly has classic Porsches in for work ranging from 356s through '72RSs, 3.2 Carreras etc...The technicians are enthusiastic about working on the older cars.
I was more miffed that the finger of blame seemed to be pointing my way when I hadn't used the brakes anywhere near their potential.
If you guys don't use genuine parts, what are you using??

 

[h_____]

I'm using genuine parts, would like to avoid drilled disks - for different reasons to you, although there have been good solutions available in the past, not sure of the current options. If they sort it under warranty, then its not so bad.

I guess generalised comments about OPCs suggest they arent geared up to look after older cars. However, if you 've found one locally that can, then great. My local OPC has a team of techs that are largely young, and rarely see a car over 10 years old.

 

[richardrimmer]

Collected the car today, new front discs fitted as a good will gesture by the PC so back to bedding in again! Hopefully no issues this time.

 

[carreraboy]

Out of interest why use the OPC?

 

[Atgani]

Very decent of your OPC to replace "under goodwill" the parts they'd fitted only 2000 miles ago!
Sounds like either the afforementioned hub runout issue (quite common apparently with the alloy hubs) in which case there's a good chance it will happen again . . .
Or the other hand, it may have been poor bedding in leading to an inconsistent pad transfer layer.
The fact that you mentioned that a part of the disc still had it's cross hatching and localised overheating makes me think it may have been the latter rather than the former.

How long did you bed the pads in for ? and what process did you use ?

 

[Melv]

Best of luck!! What bedding in process did they advize?

 

[richardrimmer]

Didn't advise any particular process so I checked what I thought you should do which is approx 100miles of gentle use (but not too gentle) to give the pads a chance to bed in without glazing them.

Des, I used an OPC as the car has always had OPC servicing and I find their prices at least equal to and in some cases cheaper than independents. Swindon have loads of older cars through their workshops so I'm confident they know what they are doing. Plus we use them for the Cayman S.