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Brake disc warping.

Posted: Wed Mar 25, 2009 9:00 pm
by MyQuest
Suffering with juddering front brakes on my 99 XK8 and being less than impressed with Jaguar replacement disc prices, I pondered on the best way to skim or grind them back to true.

Although it looks crude, I bolted an angle grinder to the cross-slide of my lathe and with a few (noisy and rusty/dusty!) runs to and fro, cleaned and trued up the discs.
Measurements were still well within the tolerances shown on the inside of the discs.

Ear defenders, goggles and a breathing mask are essential. My wife thought I’d been shoveling cocoa….

I noticed on one disc there were two ‘U’ shaped wires pushed between the inner end cooling slots – (with legs facing towards the periphery) - balancing weights?

Proof of pudding – firm and smooth braking. (I'll try to put the ‘before/during/after’ photos on here -once I've sussed out how!)

Next - the rear discs.…

Michael

Posted: Fri Mar 27, 2009 11:26 pm
by BestGear
Hi Michael

I am surprised you managed that trick with an angle grinder!

Why did you not use use a tool on the post?

Out of interest, I just got a pair of Mintex front discs and pads delivered for £103 for my XKR which are 325mm diameter... thought that was a good price delivered.

David

Brake disc warp

Posted: Sat Mar 28, 2009 3:46 pm
by MyQuest
Hello, David.
I tried a normal tool at first but found it:

A) VERY noisy. (Was ordered to stop frightening the birds and animals..!)
B) It did not return such a uniform finish, due to low lathe speed. (I'm amazed how heavy they are!)
C) It became hot very quickly and blunted the tool. (Assume the discs are cast steel?)

At the moment I am working the rears, plus (with a boring tool), skimming the drum portions. (Quite a lot of corrosion in there and not much of the surface has been 'seen' by the brake shoes - I guess they don't get much rotational use).

Michael

Posted: Sun Mar 29, 2009 10:44 am
by BestGear
Hi Michael

Yes, noisy - I can relate to that!

You should have posted a picture of the grinder mounted up for a laugh!

They are a fair weight - I just painted mine last night for fitting this morning and they are heavier than they look - as commented by the courier who moaned about carrying them to my door.

As an aside - I was surprised to see that the pads fit several BMWs too...

David

Posted: Sun Mar 29, 2009 4:33 pm
by D_Doran
David, I bet you got the Mintex discs and pads from ebay! Seller somewhere in Manchester. I did the same last year and have been VERY impressed with them so far, and very good cost compared to the main stealer prices for discs alone!

Posted: Sun Mar 29, 2009 7:36 pm
by bobwnm
Hi guys,
has anyone tried the new (kevlar?) pads? supposed to be lots less brake dust and cleaner wheels.

Bob