F100 Project

[xlt351cOZ]

Hey out there, my name is Tim. Im from the Central Coast in New South Wales, Australia,and I bought a 1983 F100 XLT and it will be the start of a mild restoration. I am currently having it looked at by my mechanic and should get the details today. But the first thing I want to tackle is the transmission as it pops out of 3rd upon deceleration . I believe it has the New Process 4 speed gearbox in it. The 1983 model came with the option of a 351c with 4barrel Carb or a 250cu 6cyl . Mine is the 351c. The previous owner put an LPG system on it (dual fuel) and a 350 holley. for economy. I think this has to change as its all show and no go, but having said that its unmolested and was owned by a country bloke from western NSW so Ive discovered red dust everywhere. We will see how it goes. Anyway, Im glad to be part of the scene and look forward to the advice and banter

 

[Gary Lewis]

Welcome to the forum! We are here to help you, as well as share your journey.

I had an NP435 that would pop out of gear on deceleration unless it was crammed into gear. But sometimes the synchros make it very difficult to get fully into gear. My first move would be to drain and refill the tranny to see if better fluid would help shifting.

As for the 351C, lots of guys here love them. I like the family, but will use the longer-stroked M-block in Dad's truck. And, by the way, the best Cleveland guru anywhere is Tim Meyer, who has his own aluminum block, intake manifold, thermostats, etc.

[Ford F834]

Welcome to the group and thanks for sharing your project! I have a Borg Warner T19 four speed that like to pop out of gear while holding the truck back on downhill runs. Similar problem. I did a lot of reading and two flaws that I kept running into are fore/aft play in the main shaft, and a worn ball on the end of the shifter cane. Mine is fine in both respects, so I have something else going on... but those are two things that you could check. Since a worn shift lever tip can cause the problem, it follows that where it mates with the shift forks could also do it... mine isn't bad enough for me to dig into it just now, but that's where I plan to look next.

[PetesPonies]

Welcome to the group and thanks for sharing your project! I have a Borg Warner T19 four speed that like to pop out of gear while holding the truck back on downhill runs. Similar problem. I did a lot of reading and two flaws that I kept running into are fore/aft play in the main shaft, and a worn ball on the end of the shifter cane. Mine is fine in both respects, so I have something else going on... but those are two things that you could check. Since a worn shift lever tip can cause the problem, it follows that where it mates with the shift forks could also do it... mine isn't bad enough for me to dig into it just now, but that's where I plan to look next.

I have rebuilt a lot of manual transmissions, however, non like yours. So from a generic point of view . verify that the synchronizer is fully engaging onto the selected gear. Check any linkage. Hold the shifter so it doesn't fall out of gear while driving. Do you feel it trying to kick out or does it seem smooth holding it in gear? Any chance any carpet, rubber mat, rubber boot, is pushing back on the shifter lever? If all that proves nothing, then going inside is what needs to happen. There are several detents within the transmission, on shift rails to the slippers on the synchronizer itself. All need to be checked.,

[Gary Lewis]

I have rebuilt a lot of manual transmissions, however, non like yours. So from a generic point of view . verify that the synchronizer is fully engaging onto the selected gear. Check any linkage. Hold the shifter so it doesn't fall out of gear while driving. Do you feel it trying to kick out or does it seem smooth holding it in gear? Any chance any carpet, rubber mat, rubber boot, is pushing back on the shifter lever? If all that proves nothing, then going inside is what needs to happen. There are several detents within the transmission, on shift rails to the slippers on the synchronizer itself. All need to be checked.,

If you do want to rebuild it I have the workshop manual chapters for some of the transmissions here:

• Driveline/Transmissions/Manual Transmissions/General Manual Transmission Service

• Driveline/Transmissions/Manual Transmissions/NP435

• Driveline/Transmission/Manual Transmissions/T-18

• Driveline/Transmissions/Manual Transmissions/T-19

Note that yours may be a T-18 and not a T-19 since that tranny was only behind the 460 and diesel, but they are very similar transmissions.

[ArdWrknTrk]

Welcome to the forum Tim!

As already mentioned make sure the synchro's are letting it get all the way into gear and the detents are not burred.

Popping out of gear under power and on trailing throttle are different conditions so don't go chasing your tail.

The 351C is a fine engine that we didn't see enough of here in the States.

In fact the only ones I've ever driven were in my friends Panteras.

Not sure what the parts situation is down in Australia but I have a 600 cfm Holley on offer in the 'buy, sell, trade' section and will have a 650 Edelbrock on there soon (I hope)

[xlt351cOZ]

Welcome to the forum! We are here to help you, as well as share your journey.

I had an NP435 that would pop out of gear on deceleration unless it was crammed into gear. But sometimes the synchros make it very difficult to get fully into gear. My first move would be to drain and refill the tranny to see if better fluid would help shifting.

As for the 351C, lots of guys here love them. I like the family, but will use the longer-stroked M-block in Dad's truck. And, by the way, the best Cleveland guru anywhere is Tim Meyer, who has his own aluminum block, intake manifold, thermostats, etc.

Thanks for the advice Gary.

[xlt351cOZ]

Welcome to the group and thanks for sharing your project! I have a Borg Warner T19 four speed that like to pop out of gear while holding the truck back on downhill runs. Similar problem. I did a lot of reading and two flaws that I kept running into are fore/aft play in the main shaft, and a worn ball on the end of the shifter cane. Mine is fine in both respects, so I have something else going on... but those are two things that you could check. Since a worn shift lever tip can cause the problem, it follows that where it mates with the shift forks could also do it... mine isn't bad enough for me to dig into it just now, but that's where I plan to look next.

Thanks Ford F834,

I think I will be taking it to the Transmission guy for a look, and await the diagnosis

[Gary Lewis]

Thanks Ford F834,

I think I will be taking it to the Transmission guy for a look, and await the diagnosis

That’s a good plan. I used to think I needed to do everything myself. But I’m now finding that I can get s lot more done by hiring the pro’s. 👍

[Nothing Special]

....Note that yours may be a T-18 and not a T-19 since that tranny was only behind the 460 and diesel, but they are very similar transmissions.

True in the US, but then again, the 351C wasn't offered in trucks in the US, so I wouldn't bet on Australia having the same rules.

The T-19 has a synchro'd 1st gear while the T-18 does not. So it shouldn't be too hard to tell which it is by driving it. And I think I've read that T-18s have a single PTO plate while T-19s have 2. But take that bit of hear-say for what it's worth.