The Ford Barn

Tim Ayers · 12-22-2023, 11:02 AM

Quote:

Originally Posted by Kube

I'm fairly certain the offset is different so grinding the earlier fork IS NOT a viable alternative.

Offset and length of throw I believe. Totally incompatible.

Seth Swoboda · 12-22-2023, 12:13 PM

I found one of these ground down forks in a box of transmission parts I have recently. I wondered if or how well that worked. Then I thought, why not just get the 3in shift fork? Sometimes folks try to see what they can get by with....

rotorwrench · 12-22-2023, 03:26 PM

The 91A shift fork has a different dimension due to the late style synchro shift collar. If someone tries use the earlier 2nd-high fork in a top shift gearbox it may not shift as far as it's supposed to. The side shift transmissions use a different fork from top shift types. There are two designs of synchronizer hub used after the 91A type came out. One uses slide plates and spring rings and the other has plates with detent balls & coil springs. Parts don't interchange. There were several 2nd gear and mainshaft designs so the gear has to match the mainshaft being used. This can cause problems like locking up during shifting. There are some synchro blocker rings out there that are out of spec. That could be a problem.

If you don't have Mac VPs Ford transmission book then order one. It helps ID gears and other parts.

Tim Ayers · 12-22-2023, 04:05 PM

Quote:

Originally Posted by rotorwrench

The 91A shift fork has a different dimension due to the late style synchro shift collar. If someone tries use the earlier 2nd-high fork in a top shift gearbox it may not shift as far as it's supposed to. The side shift transmissions use a different fork from top shift types. There are two designs of synchronizer hub used after the 91A type came out. One uses slide plates and spring rings and the other has plates with detent balls & coil springs. Parts don't interchange. There were several 2nd gear and mainshaft designs so the gear has to match the mainshaft being used. This can cause problems like locking up during shifting. There are some synchro blocker rings out there that are out of spec. That could be a problem.

If you don't have Mac VPs Ford transmission book then order one. It helps ID gears and other parts.

All that you say is true, but the OP is saying he can shift the transmission by hand with the cover off without issue.

12-22-2023, 12:13 PM	#22
Seth Swoboda Senior Member Join Date: May 2010 Location: Southern Illinois Posts: 3,811	Re: Who rebuilds ford flathead transmissions I found one of these ground down forks in a box of transmission parts I have recently. I wondered if or how well that worked. Then I thought, why not just get the 3in shift fork? Sometimes folks try to see what they can get by with....

12-22-2023, 03:26 PM	#23
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,464	Re: Who rebuilds ford flathead transmissions The 91A shift fork has a different dimension due to the late style synchro shift collar. If someone tries use the earlier 2nd-high fork in a top shift gearbox it may not shift as far as it's supposed to. The side shift transmissions use a different fork from top shift types. There are two designs of synchronizer hub used after the 91A type came out. One uses slide plates and spring rings and the other has plates with detent balls & coil springs. Parts don't interchange. There were several 2nd gear and mainshaft designs so the gear has to match the mainshaft being used. This can cause problems like locking up during shifting. There are some synchro blocker rings out there that are out of spec. That could be a problem. If you don't have Mac VPs Ford transmission book then order one. It helps ID gears and other parts.