crankshafts

[bill griffiths]

I recall reading some while ago that there were developed for racing Bristols
some crankshafts which were polished all over and which had bolt on counterweights.

I read also that there were doubts about the counterweights and the prospect of failure.

Can any kind person remind me where I might have seen this information, and whether there were actual failures or just some anxiety?

Regards, Bill

[Geoff Dowdle]

Bill, the majority of 100 series type engines had bolt on counter weights
except the Arnolt BS engine .

The crank in your D2 is a replacement bought from BCL by Mort Shearer in the
late 70's . From memory it is a LeMans type crank that it polished all over
possibly ex a 450 , I have not heard that they had problems with these
cranks but only the small nose cranks probably with the rubber dampner.
I'll happily swap it for a new D2 Velasco crank that I have.
Regards
Geoff D

[kfitzgerald]

I had a bolt on crankshaft in an Arnolt that I raced. The crankshaft bent spun a bearing and damaged the block. The block can be line bored and fitted with new bearings, but I am not a fan of the Bristol crank. The dampner weight on one end and flywheel on the other move stress to the middle. If the engine is used at 5k plus rpm, I think you can expect damage.