I have the '78 ironcase RUG 3sp OD installed in my '68 F100 and I'm hearing and feeling a sound like partial engagement of the tranny especially when decelerating. It sounds a lot like when the pinion nut came loose on my old differential and you get that grinding and clashing sound when decelerating. I checked and its not the pinion nut and checked for proper alignment of the shift linkage. Motor mounts, tranny mount, clutch, pilot bearing and driveshaft all new. Any ideas?

 

When does it girind my 85with the same tranny is currently having the same problem. mine will sound like the clutch is grabiing when slowing down. I thought my rear end was going to walk out . My new clutch has only been in there 3 weeks and i think there something with the throw out bearing or pilot .where did you get your clutch kit from?

 

Both of you sound like you have the same problem, right? Except inliner has an early-RUG and bigreave has an RTS - basically the same setup except for the overdrive (RUG - side-mounted & RTS - top shift). When coasting the power transfer is forward which brings to mind (to me) the following:
(1) Pilot Bushing not on-size
(2) Pressure plate loose (remove dust cover check bolts)
(3) Tranny bolts have backed off from bell housing
(4) U-joint needles are missing or bad (sometiimes can't tell by looking and this happens quite often upon any removal)
(5) Carrier Bearing (sometimes called Swing Bearing) was damaged upon removal of front driveshaft (unless shortbed)
(6) Too much play (backlash) in ring/pinion

Like I said - power transfer forward at coasting - this is all I can come up with. Maybe someone else can step in and add more.

BTW - Did you both do your own work or have it done? If shop work was done, take the work order back with you and have them do a check.

 

Inliner - here was what was wrong with bigreave's ride:
https://www.ford-trucks.com/forums/s...hreadid=138044

 

No, my problem wasn't the rear- end, I just insalled a newly rebuilt one and had a new drive shaft built up for the tranny. I took the top cover off the tranny and worked the shifter while watching what was going on. It turned out to be a badly worn syncro. Most of the teeth on the syncro was worn away and where there is a square notch cut out on the inner part of the syncro there was a big chunk broken off. I drained the tranny oil and it looked like someone ground up a gold brick and poured the powder into the oil. If that had been gold I'd be rich! I went to the salvage yard and pulled a 3 speed off of a van that was in better shape which I have in the truck till I can get the OD rebuilt.