View Single Post
  #182  
Old February 3rd 2012, 09:50
evilC's Avatar
evilC evilC is offline
Registered User
 
Join Date: Jun 2008
Location: UK Where Leics is more
Posts: 644
Hi Dave,
I see your kafer bar but does it have the strut that connects to the frame horn at the inner trailing arm mount? Are you running heat exchangers?
I have been pondering this installation for some time and I sat down with my friendly structural engineer and crunch a few ideas and numbers:
To retain the heat exchangers the strut from the tranny cradle needs to bend around the heat exchanger and connect to the damper top bolt bracket. this bent strut needs to be stiff in bending so a thick wall tube will be required but the loads are relatively light. We did also discuss adding braces back to the cross bar but decided that put the bar in too much bending.
Your arrangement looks suspect from the photo. The tranny strut should not connect to the crossbar as again this will put the bar into a bending stress. Without the forward strut to the trailing arm mount the load from the tranny strut will apply a bending moment to the upper damper bolt that is only 10mm diameter. This load is cyclic and expect the bolt to fatigue especially as a rally car will flex the frame horns unmercifully. The position of the tranny strut on the crossbar accentuates the bending moment. Because of the geometry, the forged damper strut will also be put in lateral bending.
Sorry to be negative and if I have got it wrong I apologise but it easier to discuss this now rather than at servicing on an event.

regards

Clive
Reply With Quote