I have a 1980 F150 4x4 with the 300CID inline 6, with a 4 speed manual. I would love to swap in a 5 speed, to get an OD gear... this 4 speed is just not good for any distance driving at all.

I have been searching through the posts for a while now, and haven't really found this application anywhere.

Is it even possible? Any suggestions about what I need to find to accomplish this?

Thanks in advance for any advice anyone can give... If more info is needed, please ask!

Thanks!!

 

For starters, the trans needs to be from another 4WD. A 2WD trans won't attach to a transfer case.

The simplest options would be to get an M5OD or a ZF5 trans from a late '80s / early to mid '90s Ford truck with a 300 six cylinder, or a small block V8 (302 or 351W). The newer 5 speeds have integral bellhousings so you need one from one of those engines to mate up with your 300.

The M5OD (used in F-150s and Broncos, and possibly some light duty F-250s) isn't a particularly strong trans, but it's OK for a half ton that's not used too hard. The ZF5 (used in F-250s and F-350s) is plenty strong but shifts a little heavier (and will likely cost more). Either one should attach to your transfer case with no problems. Assuming you currently have a hydraulic clutch, it shouldn't be too hard to get the clutch hooked up.

There are other options. I put an NV3550 (out of a Jeep Wrangler) in my Bronco. That took some work to adapt to a Ford bellhousing and probably wouldn't work with your existing transfer case. Or an NV4500 is another popular swap, but again would be more work than one of the Ford transmissions.

Another option (although not necessarily a cheap one) would be to change axle gearing. Your engine doesn't care whether the trans has overdrive or not, it only cares about the final drive ratio. If you currently have 4.10 gears, swapping to something like a 3.08 or 2.73 would be the equivalent of getting a 0.75 or 0.66:1 overdrive (respectively). Obviously that will make your low gears taller too, so it might not be a great option for you. And if you already have 3.55 gears it might not get you as much as you are looking for. But unless you can set up your own gears figure on about $1000 / axle to regear, so it's not a cheap option on a 4WD.

 

Thanks for the reply!
Yep.
Nope. Mechanical clutch; not hydraulic in 1980.
Yeah, this doesn't sound like much fun....
Well, first is SUPER LOW, I can maybe get up to 5 MPH out of it with the motor turned tight. So, final drive gearing may just be a good option. Thanks for the suggestion, I didn't even consider or think about that.

 

Welcome to the forum, alexmoen!

Perhaps there is another solution... replace the "granny" low 4 speed with a 4 speed manual OD transmission. You will exchange the low 1st gear for something like a 0.71 O.D. With this combination, you can have relaxed cruising and return quite good gas mileage.

If you currently have 3.55 gears [popular with 4 WD], the final drive would be approximately 2.52.

 

Ah, another good suggestion. Did not realize there were multiple 4 speeds available.

Any idea what the "name" of the overdrive 4 speed was?

 

I believe SROD for that year. Someone else will confirm or correct this information.

 

The granny first gear isn't intended to be used in daily driving, it's for getting going while pulling or hauling... use gears 2-3-4 for normal DD-type driving.

 

Granny gear is just that...."slow,hard", walking gear to plow, tow, etc.

 

The "granny" gear in some transmissions isn't used much, but that doesn't mean that it can't be used much. If the axle gears are tall enough that you can't start easily in 2nd, there's no problem with using 1st. And if the axle gears are that tall then starting in 1st isn't quite as annoying as it is with lower axle gears.

Having said that, 1st usually isn't synchronized in trannies like that (the T19 I think is an exception), so having to start in 1st can still be pretty annoying. And again, I'm only offering up axle gears an another option, not necessarily as a good option. If it were me I'd probably go with a ZF5 if I could figure out a good way to go to a hydraulic clutch (or could convert the ZF5 to a mechanical one, didn't Gary do something like that?).

And by the way, in my Bronco the non-Ford trans actually made things easier. I still had to deal with the bellhousing, but Advance Adapters took care of me there. It made the mechanical clutch linkage a non-issue (since the bellhousing I used was off a Bronco a with mechanical clutch). And since I was swapping to an Atlas transfer case it was just a bolt-on to the Jeep trans, while a Ford trans would have needed an adapter.

 

The t19 does not have a synced granny gear, second gear is definitley geared to be your daily first (atleast with my 3.50 gears).

How much work was it putting in the jeep trans? I see part out cherokees with the 4.0 all the time for less than $500 for the whole thing.. might be worth looking into.

 

T-18's don't have synchro 1st, but T-19's most definitely do.

T-19's were only available behind the big engines. (why else PTO windows on both sides?)
The 2wd version was typically 4.02 and some 5.11 first, but the 4wd behind 460's had a 6.32:1 first.

Cite: http://www.novak-adapt.com/knowledge/transmissions/manual/t18-t19/

 

As ArdWrknTrk said, the T19 does have a granny gear, but it's synchronized. You still usually would start in 2nd with it (when not loaded)

 

Some stuff in this thread I don't agree with. The t19 being synchronized was straightened out, but you still can't really use it on the gas trannies, it's too much spread between granny 1st and 2nd gear. The diesel trannies are a little closer, but they still don't work that well. I would not plan on using the granny gear on any gas engined 4speed as a start out gear on a regular basis.

I don't agree with using a 4 speed overdrive tranny. Yes you can, but their reliability record is not that great and the 5 speeds are common enough to where it does not make sense to put one of those 4 speed OD in place. And people that have the 4 speed od trannies have the same complaint as I mentioned in the first paragraph, the gear spread it too great between some of the gears. You lose too many rpms going from one gear to another, which kills your forward progress when pulling a heavy load.

I think the 5 speed is a good idea. I have no actual experience using the M5OD tranny, I have heard rumors it's not that strong, but I think it would live behind a six. I would go ahead and convert to a hydraulic clutch, if you get a donor you will have all the pieces you need to do the conversion.

 

My truck was stupid slow with that gear and the 1356 T-case in low

6.32 x2.69 x4.10's = 69.70:1!

The jump to 2nd didn't make any sense.
Just start in second (or third, if empty)

 

My mistake, I have a T18 in my truck.. that dyslexia. I used that granny gear one time, barely touched the throttle after letting out the clutch with none and the truck jumped so dang hard I thought something in the drivetrain would have went. Nope never again, unless I'm pulling something heavy.