Flathead ****** won't shift when hot

[Kevin - Illinois]

I was at the local parts store and was approached by a guy who said he had a 40 flathead in which he just had the ****** rebuilt. He said that the ****** shifts great when cold, but after the car has been ran a while it grinds when shifting. He said that he is running 90 weight oil in it. I'm a bit new myself to the V8 flathead 3 speed set up. In my 4 banger 31 coupe I used 600w from Snyders...

What is the recommended fluid for the 3 speed in the summer?

What else could be causing his issue?

Thanks!

 

[34PKUP]

Sounds more like a clutch problem, ( input shaft still rotating while clutch is engaged)

 

[GreenMonster48]

Sounds more like a clutch problem, ( input shaft still rotating while clutch is engaged)

Seconded.

 

[51 MERC-CT]

Seconded again or would that be 'thirded' ?

 

[rotorwrench]

SAE 90 is normal for summer use in the later flathead V8 cars. Early V8 cars seem to use the SAE 140 gear lube for summer. 600W steam cyclinder oil was only called out in the model A years. It didn't have an SAE rating but was most likely near the SAE 140 viscosity.

 

[Mart]

Is he talking about all the shifts (1-2, 2-3 etc), or just shifting into 1st at a standstill?

Mart.

 

[Kevin - Illinois]

Thanks everyone for your input! I left the guy a voice mail and haven't heard back... I think I'll concentrate on my 53 Mainline...