NP435 / T-18, T-19 parts interchange

[pollock]

Not talking internal parts here.........

I'm thinking about replacing my C6 with a T-19. I have a few leads on the T-19 gearbox only.

I need to know if the following parts are the same for T-19 and NP435:
bellhousing
flywheel
clutch pressure plate/disc
shifter

All this is for a '71 with a 390. I already have a clutch pedal and linkage assy.

[averagef250]

All the same except the shifter.

What T-19 are you using? Ford used mostly close ratio T-19's. If you have one of these you need to make gearing considerations. They are not a bolt in replacement for a T-19 or 435 since they are designed to start in first gear. You want to run a steeper rear gear with a close ratio tranny than you would with a granny tranny.

[mrtleavitt]

The T19, T18, and NP435 are all direct replacements. I just replaced my NP435 with a T19 last winter. They use the exact same bell housing, clutch, flywheel, and speedo. The actual shifter is different between these trannies. They look identical when installed but the part of the shifter arm that enters the tranny is different lengths. You do need to do some math and figure out gear ratio though. There are 3 T19 gear ratios in existance that I know of for a fact. The first gear is synchronized which is nice. Just from my own experience, if you'd like to completley do away with a granny gear, use a T19 that has a 4:1 first gear ratio with 3.0 differential gears. Very nice set up for a 2wd daily driver that never tows. My advice is put the tranny in and then deal with rear end gear ratios to get where you want it to be.

[pollock]

I'm looking at a T-19 with a 5.11:1 first gear. Not sure what my current axle gear is.

I definitely want a synchronized 1st gear. I don't use my truck for towing. It's more of a hot rod/less-than-daily driver.

I didn't know a 4:1 first gear was available. That would probably be best for me. Is there a way to tell what the ratios are without removing the transmission?

[mrtleavitt]

Not really. If the truck was running you could drive it down the road and figure out the ratio with the diff gears known, but most of the time, like in a junk yard, the only way is to split the tranny from the motor and turn the input shaft in 1st gear then count the revolutions of the output shaft. Kind of sucks, but that's the only way I know of. The 4.1 gear ratio is the most rare, but I've found several on '83-'85 F250 diesel engines

[averagef250]

Every 80's Ford T-19 I've ever seen has been the close ratio 4:1 first version. Every 80's Ford with a wide ratio tranny I've driven has had an NP435.

[mrtleavitt]

When I was hunting a tranny, 5 out of 5 of the 80's fords in the junk yard had the 5:1 ratio T19. I wish I lived where you did and I might of found a used one and then rebuilt it!

[ToughOldFord]

I don't understand the T-19. It doesn't make any sense to have to shift that extra gear and not gain overdrive. My '85 has the T-19 and the only gain it has over the NP/T18 is that you have to shift an extra gear to get to the same place. Is that really a gain? No. If I'm going to have a final gear ratio of 1 to 1 then I might as well have the NP/T18.

[mrtleavitt]

Ya, but when you change the diff gears to a higher ratio like 3.0, the end result with the 1:1 4th gear is equal to the overdrive with low diff gears. So the T19 with higher diff ratios is faster, easier, less expensive, and if you don't care about a granny gear, better!

[ToughOldFord]

You'd get the same results if you changed the rear gears with a T18/T19. There isn't anything you gain with a T19 except the annoyance of shifting an extra gear with the same end result.

[mrtleavitt]

No, you don't get the same result because some T19s have a different gear ratio. If you were to use the 6:68 1st gear ratio T19 then ya, you're just wasting your time since that's the same ratio as the T18, but when you get a 4:1 or 5:1 first gear ratio T19 (plus 2nd and 3rd are a little different ratios as well), compared to the super low 6.68:1 first gear on the T18, you get to use all 4 gears which means instead of using 3 gears to go from 0 mph to 80 mph, you can use 4 gears so you get better gas mileage instead of lugging around in a high gears, plus your power is distributed better which is the main reason I did this setup. That's why most cars today have 5 and 6 gears instead of 3 or 4 like they used to. Trust me, I had a T18 with 3.50 differential gears and then switched to a higher ratio T19 with 3.0 diff gear ratio and it is a 100% better setup! On my truck now I can use the gears as follows:
1st- 0-20 mph
2nd 20-45 mph
3rd 45-60 mph
4th 60-100 mph
This is when I'm getting on it. Shifting about 4,000 RPM. So you can still cruise 4th gear at 35 mph if you are in town. This setup is impossible with my old setup (unless you can get a FE engine to rev to 8,000 rpm).
My old gearing was as follows:
1st Never used
2nd 0-20 mph
3rd 20-45 mph
4th 45-100 mph

[ToughOldFord]

My point is either way you're ending up with the same final gear ratio only with the T19 you're using one more shift to get there. That's a waste. If you're going to have to shift more you might as well gain something, like an overdrive.
My '85 has the T19 and it's annoying and I'd love to scrap it. Not that I'll do that kind of work to upgrade to a T18/NP, but if I ever do upgrade it'll get the ZF. See? I'm not lazy nor afraid to shift more gears, but if I have to I'd better get something out of it. I think the whole reason for the T19 being built was because of the confusion the granny gears cause. Too many people think taking off in second isn't the way to do it and they, understandably, do not like taking off in first. The NP/T18 shift patterns really should have been L-- 2
1--3
That would have taken a lot of confusion out for the layman.
Bottom line is if I'm cruising @ 70mph my truck doesn't care if I have a T19 of T18, the mileage is the same as the RPMs are the same. The only difference is if I have the T19 it took 25% more shifting to get there.

[mrtleavitt]

Ya I get what you're saying. The 4th gear is the same but when you change the differential gears from a 3.50 to 3.0 you're [u]final[/u] drive at the tranny is still 1:1 but your overall ratio has changed. If you were to change this gear ratio in the differential and still use the NP435 or T18, the 2nd gear that you normally start off in would be way to high and you'd burn up clutches fast. So to get rid of this, use a T19 and then since 1st gear is lower than a T18's 2nd gear but higher than T18's 1st gear, you can start off in 1st instead. My setup that I have with the T19 and 3.0 diff's, when I am in 4th gear, my rpms are exactly the same as an FE with a NV4500 overdrive tranny is in 5th gear at 75 mph. The tranny and tire size aren't the only things to take into consideration with rpm, the differential gears are just as important as the tranny ratio. So you must look past the tranny's final drive and also add in the differential's gear ratio. So the only thing to lose is the granny gear.
I think you're right with the original logic behind the creation of the T19. But Fords never came with a 4 speed with this high of a differential gear ratio. So I think that a 4 speed with low diff gears is pretty pointless unless for towing or crawling but to solve that problem you could either keep the diff ratio and go to an overdrive tranny, or change the diff gears and keep the T19. The end result is identical with the exception being the granny gear.

[averagef250]

There is a big difference between a wide ratio 4 speed and a close ratio one. IF YOU GEAR THE FRIGGIN TRUCK CORRECTLY!!!

It's the same difference between a dodge diesel with their wide ratio NV4500's and a Ford Powerstroke with a close ratio ZF. Gas engines don't care as much with the wider powerband they have, but drive two identicly geared diesels, one wide and one close ratio and there's a huge difference, especially when towing or when real exceleration is needed.

The problem with the 80's ford T-19 trucks is that they won't lug like the newer trucks will. The diesels are non-turbo and the carb or early EFI trucks don't make smooth power down low so tall rear gears aren't very comfortable.

You absolutely have to change the rear ratio to take advantage of the 4:1 first gear in a close ratio T-19. If you have 3.50 gears and 31" tires a 4:1 first is useless. It's now just in between a granny and second ratio in a 435 or T-18, not comfortable at all for takeoff unless you have a real heavy load. If you step up to a 3.25 or 3.00 rear gear you gain quite a bit more functionality with that 4:1 first. The downside with that rear gear though is that even though the T19 is a close ratio tranny 3rd and direct are still pretty far apart especially so with a tall rear gear. So if you do up the ratio enough to take full advantage of first gear you get the downside of an even bigger jump between 3rd and direct. This is fine for a light truck or something that never tows, but will not be fun if you have some weight behind you or have a small engine with a narrow powerband.

[mrtleavitt]

Nicely put!