clutch housing to flywheel bolt size clarification

[Ron Pilger]

Have an original 37 flathead in a heavy truck. It would have the 11 inch clutch. I need to order a housing and 9 inch clutch disc for use in mating this same engine for transplant and usage in a rebuilt 39 (car) transmission. Wil the bolt sizes which hold the clutch housing in place be the same between the passenger version and the big Ford truck? Any other issues for me to consider in this swap? THX.

[Mart]

The bolts themselves will be the same. They are a 5/16" bolt about 7/8" long with a short thread and a long plain shank. Roughly equal thread/shank ratio.
The bolt circle diameters for bolting the clutch pressure plate on are different though.
9" - 10-3/8" bolt circle diameter
10" = 11-3/8".
11" = 12-3/8".

Each pair of holes have 32 degrees between them regardless of clutch size.

Mart.

[Ron Pilger]

Thanks, Mart. Very helpful info.

[Bored&Stroked]

Always make sure that they thread down into the flywheel and don't bottom out before they fasten the plate down and secondly that the "shoulder" or smooth upper part of the bolt is into the flywheel. The flywheel should be drilled to accept the shoulder (it is part of what centers the clutch plate). You might check with ThirdGen Auto or VanPelt - they probably have them.

[Ron Pilger]

Also solid advice. Thx

[V8COOPMAN]

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Originally Posted by Ron Pilger

Have an original 37 flathead in a heavy truck. It would have the 11 inch clutch. I need to order a housing and 9 inch clutch disc for use in mating this same engine for transplant and usage in a rebuilt 39 (car) transmission. Wil the bolt sizes which hold the clutch housing in place be the same between the passenger version and the big Ford truck? Any other issues for me to consider in this swap? THX.

I'm assuming that you're talking about PRESSURE PLATE fasteners. If so, just make sure that you use REAL Pressure Plate fasteners with that special shoulder, designed for that purpose. Jeg's has quite a selection, as does Michael at "3rd Gen Automotive".

Picture BELOW! DD

[Ron Pilger]

Yes, Thx. V8Coopman