Sometimes the ideas with the best intentions have a habit of biting you!

When I initally got the car it came with Wilwood 4 pots up front along with 283mm discs with writing on it to confirm. However, it is still on the stock S1 wheels and in order to clear the calipers it had some wonderful Grayston spacers fitted. Great for showing off the 4 pots, not so great for putting the wheel on, potentially causing vibrations in addition to the wheels catching the arches on some occasions.

My RST is still on the stock wheels but it is on trackday esque tyres, which are a tad wider. This may have exaggerated the issue somewhat! With the wheelbolts having less threads I saw a few options:

1) Try another set of calipers
2) Trim the arches, and get some new front wheel bolts.

I decided for some reason to go with option 1. So with delight I bagged a set of 4x4 Cosworth calipers. Great I thought. Fit 'em on, job done.

Whilst they do fit and the wheel now clears the caliper without spacers etc. I have another issue. Unless I fit the carrier in a certain way it does catch the disc. With the caliper on I think it does. It is not enough to stop the wheel spinning but IMO it is catching.

Have any of you peeps come across this issue before? Looking at the calipers it seems this issue has happened with these calipers previously judging by the groove marks. Do I carry on or alter the discs (or buy another set) or grind a tad more from the calipers?

Here are pics showing the issue:



Note the grooves in the carrier:








Any help would be appreciated .

 

You need to do a stud ad nut conversion. Also dont use the cheap spacers, You want the expensive hubcentric spacers. When you put them on the hub the spacers give you another 'lip'. I got mine from Burton power. I cant remember what size I bought maybe 16mm? Either way if I know a company that can shave a couple of MM of I would chop off up to 5mm as I sure I needed 9mm to clear my Highspec 4 pots.

http://www.burtonpower.com/wheel-spa...6mm-spt16.html

I see they do 12mm ones now. I bought mine a year ago.

http://www.burtonpower.com/wheel-spa...2mm-spt12.html

 

Not the question asked, but hey.

As per your question, you need 1mm washers between the carrier and the hub to centre the disk in the carrier.

See the sticky on cossie brakes.

Lee

 

My carriers have massive grooves in

 

Indeed. Putting larger spacers on would destroy the arches and tyres quicker, and I would still need another set of wheel bolts, not to mention the interesting handling characteristics of a wider front end unless I fitted spacers all round.

I saw the sticky and they have the 1mm spacers fitted between the carrier and caliper.

In that case I guess mine are not as bad as that.

Some progress. Whilst making the disc spin I put a flap wheel on the edge of the disc ensuring I evenly attacked it (well, as evenly by eye!). Whilst they are tight they are not catching! I may well get the discs turned down 1-2mm from a machine shop should they catch in use.

However, maths must be out! According to so called sums on the tinterweb these should be a big improvement over the Wilwood Supelites despite the extra weight.

The pad area of the Wilwoods is smaller than that of an S2 RST pad and quite a bit smaller than a 4x4 Cossie pad. That is before you get to the piston size. If you go off Wilwood's way to calulate things:

https://www.rallydesign.co.uk/pdf/de...pot_brakes.pdf

Total Piston Area (TPA) = 3.142 x r x r x n

where
r is the radius of the pistons
n is the number (sliding calipers are assumed to have two pistons for this equation).

If you look at my Wilwoods the piston diameter is 34mm, giving each piston a radius of 17mm meaning:

TPA (Wilwood) = 3.142 x 17 x 17 x 4 = 3632mm (squared)

With the Cossie calipers it is:

TPA (Cosworth) = 3.142 x 30 x 30 x 2 = 5656mm (squared)

For the timebeing I have fitted TRW pads to aid in cleaning up the surface of the disc. They are barely worn but the Wilwood pads occupied very little space on them. I figured the TRW pads could do with taking a beating over something nicer! I shall report back on how the car brakes in due course over the 283mm Wilwood setup).

It will be intersting to see if the maths does add up...

 

It's difficult to tell from the pic, but it looks like the washer is too thick. Is the rear face of the disk catching the carrier?

Lee

 

Sod that just do as i mentioned. Not sure on above quote for????? He asked for help i gave it. He listed options I answered his options..... Anyway moving on.....

Fit the wilwoods back on, Fit stud and nuts 60mm studs, buy the 12mm hubcentric spacers as i linked and jobs a good'un. You removed better brakes and fitted not so good brakes.

No fu(king around, banged them on and no problems since fitting.

 

I filed the carrier a little so the top of the disc didn't foul the carrier.

 

Mark, I think your calipers were better items than my Wilwoods. Even Rally Design say that to match a stock S2 RST caliper you need a 4 pot caliper with 1.75" pistons ideally ; mine were 1.37", well below S2 caliper, but possibly better than an S1 item (which is what my car is). With my car being an S2 the wheelarch trims go quite a way into the wheelarches. With Hi-Specs and different wheels I may considered it, but I do like to keep the look of my car original and not think about speed bumps etc. and potentially avoid destroying tyres.

Anyway, after some massaging they are fitted with TRW pads, albeit of the 60.5mm width, and not the more usual 58.2mm. One thing is for sure ; the braking has improved immensely. I can now brake very late into corners. However, I may have to think about what to do with the rear of the car! I can see why the TVR Chimaera guys love this setup for a budget system. Braking from 80 brings this car to a very swift halt, something I would have been saying a silent prayer for with the Wilwoods!