I've seen a few good smashed engines at work but never busted one of my own.

Back to the 1100 crank,
Mines a 1100 and it revvs to 7000, i've been told they break about there.
Mines been crack tested and balanced so i suppose that helps.

Is the cause of that one in the pic breaking known?

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Dean Hutton's first car was a Mini.

Usually a fatigue crack in a 1098 or 1275 crank starts from one of the big end journal's fillet radii.
It's most important when regrinding them that the radius is kept as big and smooth as possible.
It's a bit hard to tell from that pic but it does look a typical failure.
To improve fatigue life we used to mask up all the journals up then shot peen the crank webs and fillet radii, back in the 70s.

Here's a couple of pics of what happens to a gearbox when a bushfire goes through your Mini shed.. sorry I can't get the 2 pics to post but the links work.

http://home.exetel.com.au/zoomini/zoomi ... 718-40.JPG
http://home.exetel.com.au/zoomini/zoomi ... 719-40.JPG

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I see you had Photoshop Version .001

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1275 flat chat down back straight, bit undergeared, a bit over revved.

Cross flow ventilated gearbox, new design.

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Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

Here is my effort







Since found that it also put a small crack I'm the block .... Grrr another 1275 block

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I am the son of the STIG

HOTBRICKS
http://hotbricks.org.au/

'65 NCF MINI.....
'69 MINIMATIC.... 9 year resto still on the go

I'v got 1 also

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Stop Licking the Dog...I Don't Care Who Started It

I managed a set of bent conrods in a Magna V6 (work car) in a Harvey Norman car park in a rain storm, just drove thru a small dip and it stopped, water had splashed over the bumber and into the intake.

Slightly off the topic

Customer towed in a late model BMW a week ago because they drove it into flood water.

So we took the plugs out and started trying to turn it over, but it wouldn't budge, so we jacked it up and oil started running out

There is a hole big enough for my hand to fit through in the side of the block.
So remember peoples, if your not sure wether its low enough to drive through, don't try it! Especially if you own a nice expensive BM
Back on topic,
why so many broken cranks? Just plain abuse?

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Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

old age... fatigue,,, ecxessive high rev abuse.... poor harminic balncer condition,,, i can go on & on

most crack right through the oil hole & edge of journal (as all the photos are showing) ...on the edge of sharp fillet,,, that`s why newer (less fatigued) cranks with large/broader fillets are far better

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Good stuff guys!

I've never broken a crank, I'm a bit more gentle than that. I've only ever destroyed a diff pinion (car still worked ok though) and took a whole bunch of teeth off an idler gear (once again car still worked fine, if a little noisy).

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T