leading on from another thread, just how many people have broken cranks?
Turbo Mini Forums

I have just wondered what state of tune the engine was in, what power and what rpm it often saw. also how many miles/engines had the crank seen.

I just thought it would be a good guage as to what prep work might be considered when building an engine, and partly just how much stick you can give a crank before it lets go. after reading the yellow bible it seems they take more than they get credit for.

Gavin Wakely on this forum cracked a forged crank in a road car running 145 Swiftune bananas with no nos or turbo.

Any crank can break but you would be very unlucky.

Paul

I seriously doubt it!

What about 84mm cranks? Anyone experience of these letting go?

i've seen a few broken cranks, normally off miglias/sevens but mainly ones done by MED as they failed through the MED stamping on the web.

after some complaining they stamped the other end and yes it failed through the letter stamping again.

as for revs, a seven can rev to 10,000 rpm but then the rods tend to fail first or the flex in the crank and stretch in the rods allow the pistons to touch the valves and at that revs well things tend to break!

my mate chipped his suzuki swift so it could rev to 9,200 and a week later lost compression on most of the cyls, the top rings had gone due to the extra revs/rod stretch allowing them to 'touch' the wear lip at the top of the bore...it boggles the mind but it does happen

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

I snapped a 998 crank between number 3 and 4 journal. Still haven't figured out how that happened. The engine had a 295 head with 1275 sized valves and 266 cam (wasn't me, previous owner) and needed reved. The centre main cap broke in two aswell.

Never happend to me or anyone i know! Theyre pretty bullet proof imo

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

I've not snapped one yet......

Team Racing

My mate broke a standard 998 crank across the web, cause was horrendous amounts of wheelspinning out of junctions and other such abuse.

Saw a Snapped crank at ACs. Was from a road rebuild, wasn't an overly tuned think it had a MG Metro cam.

It went from the balancing cuts made in one of webs beside the 1st main journal. Was obviously concentrating the stress and just went.

I remember seeing a crank my mate Andy broke across a web - its a while ago now but it was a standard 998, the only mod being the lunatic behind the wheel. Apparently the thing still ran but was making a slight knocking noise!

Rob