Which brake discs do I need?

Post by **moggiesgalore** » Thu Sep 06, 2007 11:19 am

Hi everyone

I fitted the Ford based disc conversion to my car last year. It seems that the car has recently developed bad brake judder. I suspect that the discs aren't good and am going to buy a new pair.

My question is, what discs do I ask for at the motor factors? I know that they are Sierra/Escort based, but which model would be appropriate, 1.6, 1.8 etc?? They are vented.

Any help appeciated.

Post by **Orkney** » Thu Sep 06, 2007 12:25 pm

Check the brackets that hold the calipers first - well the bolts for slackness at least. If they were new discs then you shouldn't be having this problem?

Post by **bmcecosse** » Thu Sep 06, 2007 2:57 pm

Vented discs on a Minor - seems extreme, and i agree after a year you shouldn't be having this problem - unles you have been doing track days ? Either go back to the supplier of the conversion - or probably need to take a disc into your local Autoparts place and ask them to match it up - but of course it may need some machining to make it fit your car .
The judder may be worn/warped discs - or it may be soft/worn suspension bushes - so parhaps you should check them out first.

Post by **moggiesgalore** » Thu Sep 06, 2007 3:13 pm

Definitely no track use! I've done about 1000 miles since fitting them as replacements for the Marina disc set up, which kept giving problems with sticking callipers.
I have also just changed the suspension bushes as I wondered if they might be iffy and the steering rack is new.
Calliper mountings/bolts appear to be tight.
According to a guy at ESM the discs are machined specifically for the Minor.

Post by **bmcecosse** » Thu Sep 06, 2007 3:32 pm

Aye - I thought so - but they should very definitely NOT be giving any problems after 1000 miles. Can you detect any 'run out' on th discs as you turn them on the hub?

Post by **moggiesgalore** » Thu Sep 06, 2007 7:24 pm

Have just come in from removing the callipers and checking the discs for runout. It seems that the dial gauge test is showing at least 10 thou runout on both sides. When you rotate the wheel there is definite tightness in one part of the rotation.

My initial thought was that the discs need changing, but I then removed them, adjusted the wheel bearing and did a dial gauge test on the alloy hubs. These too are showing about 10 thou fluctuation on each side!

I think my next move is to replace the wheel bearings as the hubs don't seem to be running quite true. Never had this problem with the old Marina brakes. Progress indeed!

Has anyone else encountered this problem?

Post by **Robins** » Thu Sep 06, 2007 7:59 pm

I thought the discs were just normal sierra discs re-drilled for the minor stud pattern. Unless you opt for the ford pcd hubs in which case just normal sierra discs?
I do actually have this problem on my Mustang, makes the pads rattle in the caliper, but doesn't really help you does it. I did notice my morris discs have a very slight amount of runout but never caused a problem of judder.
I have the vented setup on both my moggies, I don't see why it's extreme BMC? If your going to have something you may aswell have the better option if it's available. Why upgrade a little bit, and then wonder if you'd have been better off spending a small amount more and have satisfaction. I mean, you wouldn't buy Asda's own bean when you can have Heinz would you really

.

Post by **Orkney** » Thu Sep 06, 2007 8:12 pm

Alloy hubs? you sure the discs haven't got hot & warped them? Quickest way to find out, whip em off and take them to an engineering shop and get them on a lathe and see whats out exactly - peeing in the wind as far as the bearings go if thats not the cause.

Post by **bmcecosse** » Thu Sep 06, 2007 8:45 pm

I doubt it's the bearings - and i believe the alloy hubs have a 'bad press' from the past ? But even so - 10 thou is not too alarming - I would imagine that would give you a long pedal (because it pushes the pads back into the calipers as it rotates) but shouldn't really cause juddering. Have you tried different pads - or even just swapping the pads about ?
I say 'extreme' for vented discs - because on a wee light car like the Minor they will never get up to anything like working temperature - and indeed this may be the cause of the juddering - the pads may not be up to temperature. I suppose it's worth a go - take the car out and really burn up the brakes till they stink - then let them cool off and see if it's any better.
If I had a very high power Minor (Vtec or Vauxhall or maybe even K series engine - then sure i would want vented discs for it - but not for an A series engine. Lads with Minis get this trubble too - they clamp on Mutro vented discs - and then wonder why they don't work very well!
Anyway - back to the main subject - try swapping/other pads and see what happens. Other possibility is to maybe make a cut across the pad (if it's plain flat) to let dust/debris/water etc escape - some pads have this as standard. All just ideas I'm afraid - i use brakes that don't give me any of these problems - they just stop the car.

Post by **youngun** » Fri Sep 07, 2007 10:59 pm

Alloy hubs with steel disks? Surely there would be problems with warping etc due to differentiation in expantion rates? Funny that, you would of thought that something like that would of been thought of when they were designing the "kit"!!

BMC, i dont think its extreme fitting a full vented disk kit. If your using your mog quite often, its nice to have assurance of a good set of brakes, because lets face it, moggys dont stop on a sixpence!

What i do think is extreme, is the price of the kits!
Ive got an old Sierra laid up in the hedge in one of me fields, might be worth hacking the brakes off that.....