disc rotor thickness

[straylight]

mine is down to 8.5mm before machining. I'd say a bit has to come off it. How thin is too thin ?

replacement disc rotor is on its way in any case.

tia

[straylight]

kinda' answering my own question here, but a local brake mechanic has data that indicates 9mm is the minimum.

and he can sell me a pair of new rotors for $144

sounds like a bargain.

stu

<edit>...and it was too good to be true, he had the wrong part# for the NOS rotors, so before you all start trying to import brake rotors from Oz, be warned, the computer says yes but he shelves say no

[gmsclassics]

Hi Stu

DBA still has them listed in its catalogue but has data for reference only - obsolete!

DBA 173 Specifications
Diameter 221
Height 37.5
Thickness 9.5
Min Thickness 9
C/Hole 67
Bolt holes 4

Can you find any secondhand ones from a car being broken? They don't seem to wear much with normal use, at least mine haven't.

Even the BMW E21 320/323i vented rotors I've been running on my race car (DBA 378) have suddenly disappeared from the market and I can't find a source or anyone who will special order. I used to have a choice of Brembo and another brand, both have gone. I've slightly over skimmed my last set, but they would only do that once they knew they were for the track and not the road. At 5.5kg each that will cost a fortune in freight from overseas, assuming I can find some.

Geoff

[straylight]

thanks Geoff, I'm sourcing some from a friend who has a few put aside. 9mm min is confirmed then, many thanks.

My RHS disc is really badly grooved from an incident a few years back, so that is the only one I'll replace for now.

stu

[Toledo Man]

Shouldn't brake discs be replaced in pairs? You should also fit new pads with new discs. I know that cost is more of an issue (it is the same over here). By comparison, I was able to buy brand new discs and pads for my Astra for £40 from a local motor factor. I wish Dolly ones were as cheap.

[straylight]

point taken, but all I'd be doing is replacing the existing ones with unmatched disc rotors anyway, since the origin of the replacements will not be known or even pinpointed to being off the same car.

If I got my hands on two new ones, you betcha I'd do both and invest in some decent pads as well.

[xvivalve]

http://www.ebay.co.uk/itm/281389415871? ... EBIDX%3AIT

You could always ask for carriage costs...they've had them listed for a few months now...get all 4 shipped and sell a pair on...

[straylight]

just got my hands on a 2nd hand rotor. Stamped onto the inner is a code "Mininum thickness 325", presuming this is 325 thou, a bit under the 9mm in the DBA data.

the rotor is good to go, should be back on the road this weekend in time for a club "observational rally".

stu

[trackerjack]

Shame is the rotors are way too thin to start with and should never have been accepted even when new.
Some people are making huge sums out of Dolly discs (rotors).
Good luck Stu.

[straylight]

thanks Jon,

test run today to work and back, a mere 30km run (temp in the high 20's) in the city. Car pulls alarmingly to the right under brakes. I replaced the RHS rotor, so that is obviously working, now I need to have a look at the left.

Good to be in the sprint again. Only things wrong are the speedo (still not working), the leak in the exhaust from the engine pipe join near the gearbox and a slightly sticky throttle cable.

The kids at school loved it

turns out another teacher owned a succession of TRs, starting witha 4, 4A, 5 and 6. He sold them all due to a failing business. he was very pleased to see it in the carpark.

stu

[Jon Tilson]

Suspect one of your caliper pistons on the left could be sticky. New seal kit and a clean of the piston should sort it.

Jonners