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Brake rethink - inspiration required
TimC - 7/9/07 at 07:25 AM

Morning all

I have a bit of an issue that means that I need to rethink my rear brake set-up. Because the car is destined for the track, there's no handbrake, just a hydraulic line lock which acts on the front.

Plan A was to use Fiesta Mk1 calipers with the standard sierra discs. The problem is that the fiesta calipers foul the spokes of my wheels. Not good. So, I'm now need another cheap and light solution. I was thinking about perhaps using bike brakes but I'm open to all good ideas. I've bought spacers to try to do the job but quite frankly it's not a good solution.

The only other thing that I can think of is rear wheels with less offset. Does anyone have a 6/7" x 13" ET5 or 6 wheel tha they could lend me to try?

Cheers

TC

britishtrident - 7/9/07 at 07:31 AM

Use a shim spacer or if the fouling isn't bad "dress" the caliper with a flap wheel in the angle grinder.

Remember with Fiesta calipers as he pads wear the clearance will increase.

RazMan - 7/9/07 at 07:43 AM

I agree - a spacer would seem to be the cheapest and easiest solution.

TimC - 7/9/07 at 08:04 AM

You mean a well spacer yes? I bought some slotted ones from RD and they are a bit nasty imho. Looks like it'll have to be hubcentric jobbies. In fairness this might work-out ok. I'm only using 6x13"wheels so they may struggle to fill the arch.

speedyxjs - 7/9/07 at 08:05 AM

How about take out the whole brake system and go flintstones style that would save alot of weight

TGR-ECOSSE - 7/9/07 at 09:15 AM

We had sierra discs and ka calipers on the back of our stock car saxo and we used an angle grinder to "modify" them to stop them touching the wheel.Probably spacers would be better. The do get better as the pads wear down.

britishtrident - 7/9/07 at 10:56 AM

quote:
Originally posted by TimC
You mean a well spacer yes? I bought some slotted ones from RD and they are a bit nasty imho. Looks like it'll have to be hubcentric jobbies. In fairness this might work-out ok. I'm only using 6x13"wheels so they may struggle to fill the arch.


Hub centric spacers are only really needed for cars the use wheel bolts -- they locate the wheel until you get a couple of bolts in.

All you need are solid spacers sometimes called competition spacers or blue book spacers--- depending on how bad your caliper fouling is thin shim spacers might be enough.

[Edited on 7/9/07 by britishtrident]

RazMan - 7/9/07 at 03:42 PM

quote:
Originally posted by britishtrident
Hub centric spacers are only really needed for cars the use wheel bolts -- they locate the wheel until you get a couple of bolts in.


Definitely wrong IMO - solid spacers take the centre bore away from the hub which
a) removes the support that the hub gives

b) allows the wheel to be potentially off centre which produces wobble.

TimC - 7/9/07 at 05:54 PM

I'm now on the look out for well priced hubcentric spacers!

britishtrident - 8/9/07 at 07:35 AM

quote:
Originally posted by RazMan
quote:
Originally posted by britishtrident
Hub centric spacers are only really needed for cars the use wheel bolts -- they locate the wheel until you get a couple of bolts in.


Definitely wrong IMO - solid spacers take the centre bore away from the hub which
a) removes the support that the hub gives

b) allows the wheel to be potentially off centre which produces wobble.



Hundreds of millions of cars have run on the roads without using the hub for centre location, thousands of cars have raced without it, and the MSA have never had a safety problem with it.

Using the hub for location causes a lot of roadside problems with stuck wheels.

The wheel is centrered by the tapered wheel nuts, as for support the weight of the car (and drive torque) is transfered by static friction between the wheel andthe hub.

RazMan - 8/9/07 at 08:58 AM

I can only speak from my own experience. I once fitted plain 25mm spacers to both Minis and Escorts in the past with new wheel studs of the appropriate length - both cars wobbled violently above 60mph until I refitted hubcentric spacers which were fine.

Surely the hubcentric spacer market is successful for good reason or why would manufacturers like Eibach command very high prices for their products? They boast that their spacers are machined to high tolerances to prevent balancing problems and ensure that the wheel is accurately positioned on the hub.

The tapered wheelnuts only centre the studs - not the wheel / hub. You only need to be off centre by a fraction of a mm (easily done on extended studs) to produce a pronounced wheel wobble. Have a word with your local tyre fitter and even he will confirm this - it's basic dynamic theory.


[Edited on 8-9-07 by RazMan]

gottabedone - 9/9/07 at 10:17 AM

Trident is right on both accounts.

The last time that the wife had a flat, I had a hell of a job getting the bolts out and the wheel off the hub (bolts had been beaten in with a windy hammer as they do these days).

I looked at hubcentric Adapters for my GTM a while ago so that I could loose the Rover wheels. They were expensive but the difference in the lower cost of the wheels made it a bit more appealing. I was pointed towards a H & R stuff which is supposed to be good.

The hubcentric adapters are made to replicate both the hub and the type of wheel that you are using. It just moves the mating surface outwards. They generally only cost £30 to £40 for most normal cars. Obvious considerations would be more strain on bearings the further out that you go.

good luck

Steve

TimC - 9/9/07 at 01:50 PM

Job done - jus bought top-notch Eibach ones on ebay - still a lot of money but better than the £75 rrp.