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MG Midget and Sprite Technical - Crank Numbers

With Prop's issue with his Crank I tried to find out what was the standard Crank numbering. I have an EN16T.
Is this info in one of Vizard's book (still in the mail)
Just interested.
Allan
Allan Jacks

Allan,

The EN designations such as EN40 and EN16 are an obsolete British material spec, but still in common use. For some info see here http://www.westyorkssteel.com/EN40B.html and http://www.westyorkssteel.com/EN16.html . The T in EN16T refers to a strength grade, not sure about the B in EN40B.

With some digging around on the web you can find the equivalent US specs AISI IIRC. One that springs to mind is EN24 (later renamed 817M40, and no idea what the new European EN number is) which is common here and the US equivalent is 4340.
David Billington

David,
Thanks for the info. What is the normal Crank used in the 1275 midget.
Thanks,
Allan
Allan Jacks

Well I bought it...and thank you for the website with the cool info


it is EN40BU....the u is the heat treatment...not sure of the En or the B or for that matter the 40 but accordng to the site you gave its a 61-65 rockwell hardness

when I get it, Ill past some pics of it...no more broken crankshafts for me...lol


prop
Prop

Alan - the EN16T cranks are the normal standard (for want of a better word).

I have run one of these for donkeys years, regularly revved to 7k and generally thrashed the ar*e out of the engine and have never had a problem. TBQH in 20 years I have never seen a crank go; but the fact that it happened to Prop shows that it can...

The only reason that I am using an EN40 in my new build is it will be slightly higher than any A series specs and I am just being safe.
Toby Anscombe

Accidentally buzzed a balanced EN16 crank (centre strapped) to 8,200 - as advised by the Stack tell tale. Crank covered many thousands of high rpm miles since. In fact pre 5-speed and 4.5 diff I regularly ran the engine to 7,500rpm.
Daniel Thirteen-Twelve

I sure hope I am the 1st. last and only person to break a En16 crank...in stock fashion, and this wont become an on going growing issue due to age, time and milage, or we will be dinosours for certian.


Besides its kind of cool having the title....

prop
Prop

As long as you are hoping, Prop, why not hope that it only happens to you once? I don't think you covered that part...
David "thorn in the side" Lieb
David Lieb

Daniel - Show Off! ;-)
Toby Anscombe

Daniel,

I've done much them same at hillclimbs. Tending to drive by ear the putting a helmet on I tended to rev my engine higher than I normally would but I haven't a Stack tell tale to say how high. The crank is the EN16 1098 big main crank and is tufftrided and polished as well as balanced and centre strapped. I've done about 65k miles on it and no telling how much someone else did before me. Ultimately given enough miles at high RPMs the cranks are likely to go as you can't do much about fatigue except try and prepare the crank so that fatigue cracks are less likely to start.
David Billington

Hey david,

It was ither hope for that, or world Peace, LOL

Prop...what am I, A freakin Jennie, lol...Prop
Prop

The later EN16T cranks were not tuftrided - according to OS&M Horler discontinued for 1974.


I've not snapped a 1275 but have broken a couple of 948 ones - both went at the front - probably partly due to no vibration damper/ poorer material/ excessive revs !! and not balanced - well this was over 35 years ago - no money for a highly prized 'red crank' then (or now)!

Richard.


richard boobier

I'm into Austin 7's. The crank (EN16) has no centre bearing and it flexes so much at high rpm that you have to shave 20 thou off the top of the two centre pistons to stop them slapping the head. They break regularly and you are going to find that 80% of the ones in use are already cracked to some degree or another. EN40 Phoenix cranks solve the problem at about £600 a time.
rob multi-sheds thomas

This thread was discussed between 21/10/2008 and 24/10/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.