Rear brake disc conversion.

[Po79]

Po79.

[viva les vegas]

This is why I posted a question a while ago asking about the sizes of the centers of rear axle hubs/halfshafts. I've been looking at using Vectra C and Signum rear calipers (keep it in the family so to speak ) as the Sierra ones I've found are just silly prices.

[Po79]

Po79.

[viva les vegas]

I had been thinking that maybe a kit could be put together, one kit suitable for all from the 1159's-2300's. I've got basic plans in my head, but need help to get them onto paper, and need to know if all the back plate bolts have the same dimensions.

[Jon-HPF]

This may not be much help, but there have been some rear disc conversions done .
I think Jon Sharpe ? has done quite a few for his own and members cars - dont know if hes a VVoc member though.
The ones ive seen done , normally have a locating bracket welded onto the axle (do away with backplate) with a set of discs redrilled at 4" pcd fitting over the end of halfshaft.
when you consider the lack of availability of OHC drums and their price when they are available - it does make sense to look at a disc conversion.
Jon

[Po79]

Po79.

[Jon-HPF]

Po- Ohc 10" discs fit directly onto the ohv hub , but you need a pair of ohc stubs (knuckle joint) - the bit that swivels on top and bottom ball joints - you will also need a pair of ohc calipers as they are different to the ohv ones (not by much but ohv ones wont fit - even when u change to ohc stubs) .
Ive recent done this conversion and posted a write up + pics - in the mechanical section about 25 down from the top

I dont think the front discs will fit over the rear halfshaft , as the discs DONOT have any pcd alignment - they just bolt to the back of the front hubs- its the hubs which carry the wheel nuts.

In board viw of disc held to the hub with 4 bolts - these are not the pcd.

[Hosted_Picture][/Hosted_Picture]

[viva les vegas]

when you consider the lack of availability of OHC drums and their price when they are available - it does make sense to look at a disc conversion.
Jon

Hi Jon,

Thats my reasoning exactly. I would hope to use standard viva discs on the rear to avoid to much work redrilling other makes of disc to 4 inch pcd and as rear discs need to be less powerful than the front it makes sense to use viva discs if possible with different calipers.

Also instead of welding the caliper brakets to the axle I would be looking to use an adaptor plate bolted to the backing plate bracket holes to make things easier and just a simple bolt on bolt off job.

Do OHC front brakes fit onto the 1256cc front axles or are there different bolts hole etc?

Po79.

That's what I was thinking of doing too again, great minds and all that

[Po79]

Jon, your right about the OHV discs not having 4 inch pcd as it the hubs that do.

I really don't know why I wrote that!?

I've got a feeling that I'll have a hard job finding the OHC front stubs and calipers so I'll prob just look at something from a different car (thats if I ever do any of this).

Po79.

[viva les vegas]

Another problem I envisage if using Viva discs is that they'd be far too close to the wheel to be able to get a caliper around them. I've been looking at something with a bit more of an offset, like Pug 406 rear discs. Also, I think we might need slightly longer studs, but that'd be a bit of trial and error me thinks.