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The driver must have bad luck!
Lucky the casing can survie with a little welding!
5 gears intact!




Al

OUCH!

It looks like the owner had a very lucky escape all things considered.

Does anyone know why short stroke cranks usually go there?

mk1 wrote:

Does anyone know why short stroke cranks usually go there?

mark, id guess either a poorly balanced flywheel, or poor primary gear clearance - which cooks the oil at that end

my 970 broke at the same place

That pic brings back BAD memories.
I snapped a crank, same place as in the pic and that was a 1275 semi s/stroke.
Saved everything except for a crankshaft, obviously, and a flywheel housing.

That,s the point where all the load is from engine to transmission .

Bet any money it started with a crack in no4 fillet radius .

Also looks quite an old crank design , has it been reground ?

Bad grinding of fillet radius is a sure way to kill a crank .

That is one racing motor built in UK!




Agressive driver!

Al

251 ENG wrote:
Bet any money it started with a crack in no4 fillet radius .

Bad grinding of fillet radius is a sure way to kill a crank .

Yep,

Nice picture, but a very nasty looking crack.

Did you get that done at work Bob?

mk1 wrote:Nice picture, but a very nasty looking crack.

Did you get that done at work Bob?

Picture with the crank on Magnaflux MPI crack tester. I bought this crank via e-bay from a professional engine builder advertised as 'reground EN40B 1275S crank in good condition' As the picture shows it wasn't! there was a bigger crack on the other side of the same journal! Luckily I paid for it with my Visa card so was able to get a full refund after waiting about six months, the e-bay dispute system was a waste of time. It did reappear on e-bay with the same photos and discription later but was withdrawn before the auction ended, hopefully no one else bought it.
It did cheer up the crack test guy at work though..........he spends every day looking at hundreds of items looking for tiny cracks and along comes this gem.

Glad you spotted it!

It is the sort of crack that would not look out of place in a crack testing text book!

Does that crank still 'ring' if you hold it up and hit it?

Tim

Tim wrote:Does that crank still 'ring' if you hold it up and hit it?

I remember that's the first thing Jeff Goodliffe did to a crank of mine when I handed it over to him, many moons ago.

Its meant to be a poor man's crack test. Supposedly it will sound dull if its cracked, but I've heard that its very unreliable so it would be interesting to know how bad a crack needs to be to stop it ringing.

Tim

I have had very poor cranks that still ring, I reckon that using a set of divining rods is about as accurate as the "ring test"



For home use something like this;

http://www.pegasusautoracing.com/produc ... RecID=1207

is a far better bet.

did you buy it off that rite dodgy 251eng ebay seller geezer?


ive used crack sprays with work on uprights and when we did some precision tiging on a modular crank we built.good stuff.

[quote="littler"]did you buy it off that rite dodgy 251eng ebay seller geezer?


No it wasn't 251eng, but they do share the same christian name. The guy I bought the crank from obviously suffered from amnesia which meant that as soon as he agreed that the crank was cracked and he would refund the money he would forget the conversation when he put the phone down, and after his bank refunded the money he 'forgot' the crank was cracked and tried to sell it to someone else!

1071bob wrote: he 'forgot' the crank was cracked and tried to sell it to someone else!

he didnt sell to to a bloke in hong kong did he?

it might be the same crank

Rich,
I am sure the crank is not sold to Hong Kong, otherwise I must have seen it!
shipping a crank to Hong kong is expensive, and usually they bought the whole motor !


Al