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MG TD TF 1500 - XPEG crank shaft

Looking for opinions. I know the WSM states "no regrinding the crank shaft" for XPEG engines. OK that was 60 years ago and for some of those years there were no new crank shafts available. So what is the practice today, go ahead and regrind it or buy a new one. And does anyone know why the factory decided to allow regrinding for XPAG crank shafts and not for XPEG crank shafts. Is anyone using a reground crank in their XPEG powered MG at this time?. Thanks for any help in advance.
F. Driver

Found my crankshaft was cracked and bought a new one made from forged billet by Phoenix from Brown and Gammons (UK) when neither Abingdon or Moss had anything in stock. I did a lot of digging into the subject at the time (this winter) and would be happy to recount my findings if you want to call me. Kind of a long story to recount by email. I'm in Quebec, 514-946-2445.
T W Moore

As far as I( am concerned, regrinding an XPEG crank is fine, as long as you don't go too far. I have run a .040 crank in a TF for 55,000 miles, and it was fine.

I always thought that MG was trying to use up stocks of XPAG parts when the MGA was planned or made, and so they recommended replacing crank if they were worn. I've never seen any evidence of weakness in an XPEG crank.

Tom Lange
MGT Repair
t lange

+1 Billet for peace of mind.

Matthew.
M Magilton

Yes they can be reground and used in XPEG. I could be wrong but I thought the factory XPEG cranks were nitrided or treated in some other way (shot peened?) and that is lost in a regrind.

Do have it crack tested (front web especially).

Bob Schapel
R L Schapel

What is the technical,(manufacturing), difference between the Stock XPEG and XPAG crank? Anyone have that info? PJ
Paul S Jennings

I thought that the later XPAG cranks were made from better material than the earlier ones, and that the XPEG cranks were essentially the same, and therefore interchageable.
Dave H
Dave Hill

According to literature I have (Wilmer and Clausager), MG changed the crankshaft material from one steel forging material (unidentified) to EN100, a low alloy steel of moderate properties. (AISI 4340 Ni-Cr-Mo is the "gold standard" material used for many hi-grade crankshafts, including the "billet" crank made by Phoenix). This change was made in April 1953 at TD27551.
I theorize this was done to reduce the failure rate on TC/TD cranks which is evident in archive anecdotes. etc. I suspect that the "no regrinding" instruction was another step to reduce crankshaft cracking (and probably stimulate spare part sales). It is easy to badly regrind a crank in several ways and the consequences of sloppy rework would be reflected on MG.
And they wouldn't get the spare part sales.
The combination of lack of a torsional vibration damper, high piston velocities, and North American roads with much higher cruising speeds were all contributing factors in the situation. It is interesting to compare the TD/TF crank to an MGA crank: although essentially the same displacement the MGA is considerably more robust.

T W Moore

I heard pretty much what Dave posted. The later XPAG cranks were better & hence more desirable, so much so that they were referred to as "100 ton cranks". Cheers
Peter TD 5801
P Hehir

So, are we saying the later cranks are of a chrome moly material? Were the connecting rods upgraded during that period? PJ
Paul S Jennings

No, the later EN100 cranks were of low alloy steel - much better than the early ones, but not up to the specn of a modern billet crank.
Dave H
Dave Hill

In the process of rebuilding my XPEG engine. Block head and crank all good. I like you had read that the XPEG crank could not be reground (page A 24 of the workshop manual). But with the advice from this forum and other experts I decided to go for the regrind rather than a replacement crank. I will let you know of my progress.

D Lamb

Thanks for all your comments. I took the crankshaft in for crack testing and regrinding today. Got my fingers crossed. Fred
F. Driver

Hi:
A quick and free test for your crank is to hang if from a rope by one end and then hit it on one of the counter wrights with a small hammer. It should ring like a bell. If it does not it is cracked. I have tried this on a crank that was magna-fluxed and showed up as cracked. It did not seem to matter where you attached the rope, you could not get it to ring.
I remember when the last TC cranks were available from the MG dealer in the late 60's; they were listed at $45 plus shipping.
Godspeed in Safety Fast
Jc
John Crawley

This thread was discussed between 04/06/2015 and 06/06/2015

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