Monday morning crank … Before the furnaceman had sobered up
Isn’t this a bit of a know weak area on the VHPD cranks? Something to do with taking a standard crank and carrying out the tuffriding? process, makes it much stronger, but more brittle.
I know this is kind of blasphemy, but Simon Erland, love him or hate him, used to use a standard crank. Certainly we didn’t break one, even with Sean drivng and a sequential gearbox on the end of it!
Breaking through this web on stock cranks are common.
Causes often are (as I understand):
- Using a poorly-balanced chutch/flywheel assembly
- Lots of high-shock cycles (aggressive standing starts / clutch dumps
- Using a non-damped crank pulley
- Extended running around the crank resonance point at ~7200RPM.
HI folks, this is actually a standard crank (unless when tuftrided rover gave a different part number??) but was fully balanced inc. all the other components by VB. Janspeed claim (my friend used to work for them) that this is a common failure when they used to build engines for the rover race series (btcc???) however, I have spoken to Steve Smith at VB and although he has not visually seen the crank, he has never known one to fail. Possibly a faulty crank???
Im a little bit reluctant to build the engine with another standard
crank if this is going to happen again! For info, I was running the standard TVA but with a machined off pas pulley.
Thanks, Ben.
FWIW I’ve seen aftermarket steel cranks fail at the same point. It’s not a strength issue and the stock crank is more than up to the task. The issue is more to do with a destructive resonance in the crank at a certain RPM. Simon Erland (such as he is) has some good insight into this, and it’s here that his input is actually rather missed.
Yeah, love or hate Mr Erland, the 1.8 K series of his that I had in my car would see 9,300rpm in every gear with a standard crank. And when the engine did fail it was not the bottom end that was at fault.
Thanks for your input guys - its given me a bit more confidence to think that the standard crank isnt a bad piece of kit. I’ve been told that a number of times but you can see why I have my doubts.
Well, I’ve been busy with the engine this weekend and have also stripped the oil pump down and it appears that not one component surface has picked up any metal particles. I plan to send my new (standard) crank to VB with the clutch cover plate and pulley to be balanced so hopefully, my engine will be back together soon. I’ll keep you updated about the broken crank as I plan to submit it to the metallurgy lab at work.
Thanks
Ben.