Dearborn transmission not shifting when hot

Have a 1960 Trojan ski bee with a 292 interceptor and Dearborn type "c" transmission I believe. Transmission was rebuilt 2 yrs ago and has only been used for a few weeks.

the transmission shifts great when engine is cold. However after riding for awhile the transmission won't go into fwd or rev after shifting into neutral. Once everything cools down it will shift again.

Replaced the fluid. I am using Napa type fa in it.

Any help would be appreciated.

John

Maybe it isnt a type "c" since I have the dual stage oil pump. The guy that rebuilt it did talk to Jim Harris from back east. He said he was able to get all parts but one and he machined a bushing for it.

Do you think the transmission cooler could be plugged and the oil isnt getting properly cooled. Just a thought.

Engine oil is 10/30. Transmission oil is napa type FA.

As far as running once I shift to neutral, when docking, is when it wont go back into fwd/rev. I would try to put in fwd/rev when coming in. Once docked an it sits and cools down it would work properly.

Going to pull cooler tomorrow to see if weeds are blocking flow. Dont have IF reader

The transmission oil bottle has no weight information on it.

What engine oil do you recommend for this engine?

As far as the dearbo type, when you asked for weight of oil I never new transmission to have a weight and that is why I said 10/30 running in the engine.

talljhon wrote: As far as the dearbo type, when you asked for weight of oil I never new transmission to have a weight and that is why I said 10/30 running in the engine.

John,
The A & B dearbo's shared oil with the engine and the reason I asked about the weight.

So, what 10-30 brand are you running? As mentioned, make sure it's got the correct amount of ZDDP for the flat tappets. I run Valvolene VR1 20-50 in all my engines. Others prefer other brands.

talljhon wrote: I just bought some of the valvoline vr1 20/50 to change to. I am confused because my transmission has a dipstick where I and my father have always put tranny fluid in. Am I wrong in doing that?

Since you have the dip stick on the trans and you use the FA fluid, you have the C Dearbo and not the B with the dual stacked oil pump IN the engine.
Did removing the leaves from the cooler help?

Still had problems. Found that the pressure from the transmission part of the oil pump is very low when transmission wont shift. If I bleed the air out by disconnecting the line the pump will have pressure and shift.

Trying to get the different types of transmissions figured out. This is what I think, correct me if im wrong.
Type A - One piece Bellhousing and Tranny, Dual Stacked Pump uses engine oil and DOES NOT have a dip stick
Type B - One piece Bellhousing and Tranny, Different type of dual stacked pump, the oil and transmission fluid sides of pumps are separated by "O" ring, uses type "F" fluid and has dip stick. Jim Harris told me this is what I have a few years ago.
Type C - Not one piece, not sure what type of pump it uses. uses offset gear

That being said I have a spare oil pump for a type A but not a type B. Do you know where I might be able to find one. Haven't talked to Jim yet.