Rear Calipers and IVA

[deecee]

Has anyone succeeded in passing IVA using lightweight rear calipers in place of Sierra ones? Need them to fit inside 13" wheels. I understand the Wilwood Powerlite/Handbrake calipers probably won't do. What about HiSpec SVA Ultralite handbrake units?
Cheers David

[matt_gsxr]

I'd ask hispec for confirmation of their callipers. It used to depend on which centre you went to but the rules have been unified a bit with IVA.

You can do it with Sierra callipers. You need to change the disks to Escort Mk3 front (non-ventilated). These are 240mm diameter, but importantly they have more dish on them which brings the disk inboard. Then you need to sort the spacing out on the calliper (assuming you have Sierra drum braked hubs, this is just spacing of the disk adapter plate). The only flys in the ointment for this plan is that the escort disk is heavier than the Sierra disk, and that you need to take a couple of mm off the hub, so need some kind of rotating cutting method (I used an angle grinder and rotated the hub against it, but a lathe would have been better).

If you are building a Phoenix or Striker then you also have the problem of the lower suspension through bolt (actually a threaded rod with nuts on), as the ends can get close to the wheel, and so may need some delicate angle grindery and caution when mounting any balancing weights.

I have 13x6 compomotive revolutions which fit using the above approach.


FWIW: I am investigating fitting the even smaller mk1/2 fiesta front disks on the rear. These are even smaller (and much lighter), but will need more butchery to the hub. If that works then I will post it up.

Matt

[adithorp]

I passed SVA with Wilwood powerlite h/brake calipers. I used the drum to disc conversion from RallyDesign. When I build it initially it didn't have enough leverage with the modified sierra lever. So I put in another link in the tunnel that multiplies the leverage and they now work great.

I'm on 13" Compomotive CXR rims





adrian

[adithorp]

Matt, I think (not certain) the RD conversion uses Fiesta discs. You need the hub flange reducing in diameter to fit.

adrian

[matt_gsxr]

Adi,

From your photos it is clear that you have a 4 post lift. I am jealous, imagine putting that extra pivot in lying on your back on your drive!


Anyway, I am fairly sure that the RD kit uses disks that are 240mm diameter, and you have to take a couple of mm off the diameter of the hub. It doesn't break into those 2 big holes though. Given the Ford propensity to reuse bits and pieces, the Fiesta disks that you are talking about could easily be the same as the escort mk3 front disks that I am talking about. The annoying thing is that they are actually heavier than the original Sierra disks.

If you go with the disks from a Fiesta Mk1/2 small engined variant (221mm from memory). Then you also have to trim the hub but a bit more and it does break into the holes. The disks are lighter though with dishing that is between the 252mm Sierras, and the 240mm. I haven't done all this yet but I do have a pair of disks in the shed and so am on the look out for a couple of spare hubs that I can butcher.

Just trying to sneak ahead a few kg.




Matt

[adithorp]

I bow to your geekiness! ...but I measure tommorow. Deffinatly didn't cut into the big holes.

Edit, Now measured... 240mm, all hail the geek!

adrian

[deecee]

Many thanks all and especially Adrian for the pics. I had not seen/thought of this system before. I have recently placed an order with Jeremy for a J15 so shall ask him to incorporate it into the build.
David