robmug

Brakes...I had new discs and pads (front and rear) fitted recently to cure a very irritating vibration under braking. (yes, I have read the articles re 'warped' discs).

The new discs and pads solved the problem, but now it has recurred. This has NEVER happened to me before on any car, so I don't think it is about how I use my brakes.

My questions are:

1. I think that the caliper plates (I've read about this problem, where the steel and alumnium corrode) on the front may need removing (Shirley's of Meriden commented when they did the fronts that they had to grind the pads to get them to fit...something I was unhappy about at the time, but which was not resolved...). Could this be causing my vibration by causing the pads to not release fully, therefore leaving hot pads to imprint on my disc?

2. If it is this. how much does it cost to fix?

3. Is it worth going to Autofarm to try their disc skimming machine that skims the discs on the car - aimed at releiving exactly this issue - see http://www.autofarm.co.uk/new.php3/BrDisc.html
Does anyone have any experience of this?

4. Should I try 3 before the expensive option of the caliper repair?

Christer

to answer 4: don't do 3 as a shot in the dark. They shoul dbe able to inspect the discs so that you don't waste that money which you could have used for 4.

I have never had this, so can't share personal experience. I have noticed though that my front discs at least have a carrier-overhang now which I take to mean that I will need new discs soon. Another upgrade opportunity? Oh yes.

robmug

Christer - upgrade! I know...I think I should have put drilled discs on the front, even if only for visual effect. Hindsight!!!

Good point re my questions...hadn't actually thought of that!

Phil Raby

Rob

You should NEVER grind pads to make them fit - yuck!

If the base plates are lifting you should be able to see this once the wheel is off. However, it sounds like yours are doing. It's a relatively simple job to sort out - I did a feature on it a while back. You could do it yourself or get a specialist to do it.

Hate to say this , but Christer is right - first thing is to get the baseplates sorted then see what things are like.

If the disc is slightly out of true, then skimming works so long as your discs are not worn to the minimum thickness. I had my fronts done and it made a great difference. It also gets rid of any grooving.

Finally, Autofarm is about five miles from me, so let me know if you're coming down...

Cheers

Phil

robmug

Phil - I thought you'd done a feature on it...can you remember which issue? How much did it cost to do?

(BTW, have CHP considered doing a search facility on their website so I can track articles down. There's nothing worse than remebering an article then having to go back through EVERY issue (normally twice) to find it...)

...and I agree, grinding tjhe discs was an unnaceptable shortcut...one of the reasons I've stopped using them.

Finally, my holiday week starts 4th August, and as I'm unbelievably impatient, I may make a trip to Autofarm before then! I will let you know...be good to meet up.

Phil Raby

Rob, it was March 03. Let me know if you don't have it. After that was published, we had a letter from a guy in Sweden (I think) who said he'd saved money be refurbishing the old baseplates - personally I'd rather buy new ones at £25 a wheel.

PM on its way too...

Phil

robmug

Thanks Phil. 'course I've got it! Can' I justify somehow that it'd be cost effective to upgrade to big reds?

Phil Raby

Well, big reds do look rather good. Other than that they're not much advantage apart from the small matter of increased braking power...

Phil

joey bagadonuts

This may not appply but I did have the shudders after switching to Pagid Orange pads. I brought it upon myself, though. After swapping pads, I jumped into the driver's seat and released the handbrake. Since my driveway has a slight slope, the car started to roll a bit so I applied the brakes. Well, anyone who's switched pads knows that unless you've given the system a couple pumps, there's no hydraulic pressure.

After pushing the pedal to the floor, I immediately stomped on it to halt the car. Of course, that left a very distinct Pagid imprint on my rotors. The pads worked marvelously for three track days, but on the fourth the shudders appeared. On the advice of some Club Racers, I decided to switch compounds. The next time out, I used Hawk Blues and, voila, problem solved.

Rob, If you're using OEM pads, then maybe the plate issue is the source but check the rotors for imprints. It's possible a shop attendant may have made the same mistake I did.

johnfm

Rob

Big Reds will be a waste of money on a non-track, tiptronic cabrio (all IMHO).

The amount of money you are spending on cosmetic upgrades, you could part ex and move over to a 993 with the drilled discs etc etc.

If your car is a keeper, spend spend spend, but if you are thinking of eventually moving it on, you won't see much of your $$$ back.

FWIW, money spent on suspension upgrade (lowering springs/bilstein HD's) would be better spent than on big reds IMHO. Hey, why not get your calipers refurbed and powder coated red (9M do this).

robmug

Joey - thanks for this; sounds likely...are you suggesting that different pads may 'grind' off the imprint?

John - I'm not really thinking of upgrading. All my improvements are very carefully weighted on a cost/benefit basis. Aiming for 80% of the improvements for 20% of the budget.

Phil Raby

Don't want to talk you out of an upgrade, but if the overhang is only slight you can restore the discs by skimming. First thing is to measure the thickness with a micrometer and see how much life they have in them. Skimming only takes a tiny amount of material off.

Cheers

Phil

joey bagadonuts

Yes, that's apparently what happened when I switched to the Hawk compound. Keep in mind, that these pads were used at high temperatures caused by frequent, hard braking at the track, so a compound switch alone may not be sufficient to remove the imprint.

Good luck!

Christer

Phil

Don't worry you would not be able to talk me out of an upgrade! I have been looking at this upgrade for some months and am going to do it for 2 reasons:

1. The car itself is being upgraded slowly but surely and with more power I think it only sensible to have more powerful brakes.

2. I have only managed to get brake fade once with the current setup. Once was enough, I almost had to buy new underpants.

I would rather be on the safe side.

Phil Raby

Glad to hear it! Big reds I hope, better to spend money on them than new underpants

Phil