Greg Cozier

I'd like to fit rose-jointed rear axle radius arms to my FB.

Obviously the fact that the top links are not parallel will cause binding.

I cannot alter the bodyshell of the car due to historic regulations.

I might be able to get away with mounting the top links to the OUTSIDE of the body bracket with a longer bolt and spacers. By my measurements this will bring the top links parallel and I have room between the wheel and inner wheel arch.

Does anyone have any experience with this or pictures of anyone else's work?.

Greg Cozier

My C to C measurements are as follows:

Bottom axle brackets - 41.25"
Bottom body brackets - 41"
Top axle brackets 46.25"
Top body brackets - 42.25"

If I bolt the top links on the outside of the body bracket like a GpB car I can get 45.5"

j9fd3s

iTrader: (3)

the bottom links are pretty easy to do with rose joints, and it works quite well. we've also done the Watts link, and that helps a bunch too (the pinion angle rotates with roll) for the upper links we just leave them alone, and things work fine

the factory competition upper links were longer, and adjustable, but i think they still used rubber bushings (the competition axle had a different bracket i think).

Greg Cozier

Thanks!

The RX7 competition manual says the top links retain rubber to stop the binding but obviously simply having rubber won't eliminate binding, only allow some roll as it increases exponentially.

I'm building a tarmac historic rally car so really need to dial out all of the binding for max roll and traction, hence my idea. I'd like this car to generate so much rear end traction it picks up the inside front wheel like an Escort

The Group B cars had similar top link mounts to what I'm suggesting but the links were about 3" longer and mounted further forward on the inner wheel arch. Obviously shorter top links will cause the pinion nose to rotate downwards in acceleration. Can't avoid that without altering the bodyshell which I can't do.

j_tso

iTrader: (2)

The Group B car cut the body and welded boxes for mounting points to make the links parallel and equal length.

Another forum member has done the same in this thread
I posted a photo from the FIA homologation documents in there as well.

Greg Cozier

Scroll down to the B&W service park picture. You'll see the bottom link connected to the original mount and the top link bolted through the inner wheel arch forward of the original mount..

https://rallygroupbshrine.org/the-gr...mazda-rx7-gsl/

kurtf

iTrader: (3)

See mustanghammers build thread post #13:
https://www.rx7club.com/build-thread...-build-992966/

i copied that detail but do but do not have as good a photo. I have 0 offset wheels on my EP car so clears fine.

Greg Cozier

Thanks Kurt.

That picture looks very similar to the Factory Group B top link location.

I think I will have enough latitude with the rose joint spacers on either side of all eight rod ends to dial out any bind whatsoever.