MTFCA Forum

What is best way to modify A cranks for use in a T?
Asking about the rear flange specifically. Thanks Dan

I was told Russ Lideker (spelling?)in Texas I believe does this. You may want to try and contact him. I know 2 people who did he did engines for. I believe the rear flange is welded back on but personally I have no experience. Just what was told to me. I believe you also have to dimple the pan slightly in several spots for clearance.

I'm running a full length A crank with my BB RAJO - I was never keen on cutting the rear flange off and putting it back together - that was 30 years ago !

The proper way is to cut off right at the flange, use the left over (approx. 3/4") and machine down and thread it. Then machine the flange and do the same with matching fine threads. Do a bevel inner/outer on the back side, drill 2 each 1/4" holes 180 degrees apart right at the threads and install hard pins. Then weld like a mad hatter after a preheat and re-machine smooth. DONE! With no silly shifting of the block and everything fits correctly!

See these threads for info about Les Schubert’s taper-n-shrink method:

viewtopic.php?t=17385

https://mtfca.com/phpBB3/viewtopic.php?t=24724

^^^^^^^^^^
I’ve always been intrigued by Les’s taper fit approach. The simple fact that the heat treat is not affected is reason enough to strongly consider this method! I intend to try this next, or maybe carve a crank from billet. We’ll see…

I have only shortened 2 cranks. The 1st was done long ago with primitive equipment and undeveloped skills. We had heard of a technique where a hole is bored thru the rear main, then a transmission spud pressed in and welded at both the radius and the inner web. WAAAY too much work! It hasn’t broke… but the owner hasn’t really driven it much either.

The 2nd was a threaded flange crank that broke in a motor that I had bought. Let’s just say the thread didn’t hold up after the welds broke. There were no cross drilled pins, and what ultimately proved to be inadequate. I put a heavy chamfer on the main journal, worked the flange back into position, and TIG welded the fillet on full heat. Back to the lathe to trepan an annular grove all the way to the previous fillet, and another TIG weld from the back providing a full penetration TIG weld using 308SS filler rod. This crank put up with a ton of abuse in my speedster, and is still pulling around a TT to this day. So far so good…

I don't know if any one still does it, but we used to use Homelite Bearcat outboard motor cranks in Crosley motors. The Bearcat crank had
no flange it was tapered for the outboard flywheel. We would make up a flange and mate it to the crank using a friction welding process.
It should work on a Model A Crank. We never broke them after the process.

Jim11787 wrote: ↑

Thu Feb 13, 2025 2:47 pm

I was told Russ Lideker (spelling?)in Texas I believe does this. You may want to try and contact him. I know 2 people who did he did engines for. I believe the rear flange is welded back on but personally I have no experience. Just what was told to me. I believe you also have to dimple the pan slightly in several spots for clearance.

"Lilleker"

Over the years I’ve used three different methods. They have all worked.
First I used the Full Penetration welding approach and after 45 years it still survives
Then I “invented” my taper/shrink approach and it works well
I have also used the “Shift the block ahead 5/8” and it works well too!