The Ford Barn

Russ/40 · 10-29-2019, 03:02 PM

Hello, I have been working on the rear float a motor addition to my 39' transmission in my RPU. I have decided to stop for some advice. I was able to adapt the FAM rear cushion casting to the V8 clamshell by elongating the two side holes to match the 1/4" smaller measurement on the V8 clamshell. That has gone well. When I did so, the casting at the rear of the mount sits about 1/8" apove the crosmember. That takes me to the point where I have to raise the transmission to make room for the rubber cushion at the top of the FAM.

Thats where I lack the install instruction for how high do you jack the transmission for the cushion. I attempted to jack the assembly up. It did go up about 1/2" relatively easilly. At that point I was lifting the whole truck. I still have the stock rear motor mount, so I was concerned about cracking the flywheel housing.

Should I loosen the 4 rear mount bolts, raise the trans a little more or should I make the cushion to fit the existing gap between the crosmember and FAM, then drop the transmission to a resting position on the crosmember? If I do the latter, the rear cushion will be thinner than photos of other installations, which I dont think matters, as long as there is some tension there.

Your expert experience as well as any observations are welcomed.

wmws · 10-29-2019, 03:41 PM

I have no experience in doing this but I would definitely loosen the rear motor mounts before jacking and then see how far the trans will go up without forcing.

duke36 · 10-29-2019, 04:42 PM

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With FAMs on a larger and heavier F150 tranny, the rear adapter can't be used so we use an angle and approx 1/8" pad on the cross member so as not to stress the rear mounts, etc. With your tranny, you may want to shave the rubber cushion as stated and per post 2. Check that the engine front pulley aligns with the crank hole and no stress on the rear mounts. Also check for adequate gap between the univ. clam shells / torque tube area and the cross brake shaft.

10-29-2019, 03:02 PM	#1
Russ/40 Senior Member Join Date: May 2010 Location: Santee, California Posts: 3,505	Return to the Rear Float a Motor Thread Hello, I have been working on the rear float a motor addition to my 39' transmission in my RPU. I have decided to stop for some advice. I was able to adapt the FAM rear cushion casting to the V8 clamshell by elongating the two side holes to match the 1/4" smaller measurement on the V8 clamshell. That has gone well. When I did so, the casting at the rear of the mount sits about 1/8" apove the crosmember. That takes me to the point where I have to raise the transmission to make room for the rubber cushion at the top of the FAM. Thats where I lack the install instruction for how high do you jack the transmission for the cushion. I attempted to jack the assembly up. It did go up about 1/2" relatively easilly. At that point I was lifting the whole truck. I still have the stock rear motor mount, so I was concerned about cracking the flywheel housing. Should I loosen the 4 rear mount bolts, raise the trans a little more or should I make the cushion to fit the existing gap between the crosmember and FAM, then drop the transmission to a resting position on the crosmember? If I do the latter, the rear cushion will be thinner than photos of other installations, which I dont think matters, as long as there is some tension there. Your expert experience as well as any observations are welcomed.

10-29-2019, 03:41 PM	#2
wmws BANNED Join Date: Feb 2013 Location: Coatesville, Pa Posts: 719	Re: Return to the Rear Float a Motor Thread I have no experience in doing this but I would definitely loosen the rear motor mounts before jacking and then see how far the trans will go up without forcing.

10-29-2019, 04:42 PM	#3
duke36 Senior Member Join Date: Jun 2015 Posts: 1,414	Re: Return to the Rear Float a Motor Thread Sponsored Links (Register now to hide all advertisements) With FAMs on a larger and heavier F150 tranny, the rear adapter can't be used so we use an angle and approx 1/8" pad on the cross member so as not to stress the rear mounts, etc. With your tranny, you may want to shave the rubber cushion as stated and per post 2. Check that the engine front pulley aligns with the crank hole and no stress on the rear mounts. Also check for adequate gap between the univ. clam shells / torque tube area and the cross brake shaft.