5-Speed to 4-Speed
 

I am getting ready to change the tranny in my 1988 300-6 from 5 speed manual to a 4 speed manual. My 5 speed lost reverse and I purchased a 1992 truck that had a blown head gasket but good transmission. Has anyone in this forum done this, and do you know of any potential problems, or shortcuts?

Any advice would be very helpful.

You found a '92 with a 4 speed in it? What engine does it have?

4-speeds were still available in 92, according to the owner's manual.

Just take whatever parts on the '88 that don't work with the 4-speed and replace them with the correct part off of the '92. Some areas of concern would be the driveshaft, cross member, and clutch slave cylinder.

Wow.. didn't realize that, though it was either the M5 or ZF by that time.

As long as the donor truck was a small block, you should have all the parts you need between them.

The 4spd was still available in 1993 as well. My friend had a 1993 F-150 with a 302 and a 4spd.

Yes, it is a 4 speed in a 1992. I did not realize is was hard to find. Both trucks have a 300-6.
Is the 4-speed a better transmission? How does it compare to the ratios of the 5 speed?

The 5 speed has an integral bell. 4 speed has a separate bell.

A 4 speed in '92?

Either a granny low, with 2-3-4 something like a 3 speed, with 4th direct. Gaps between gears will be wider, and no OD. So how did your 5 speed do in 4th? Because that is your new high gear.

If by chance it is the OD 4 speed, it is geared something like a 3 speed in 1-2-3, with a huge gap 2nd to 3rd, which you won't like much at first, but will grow to hate, and 4th is OD, similar to your 5 gear.

IMO, you should find another Mazda box, or a ZF.

Otherwise, you need to find a juice clutch set up bell, and face possible trans mount and ds issues.

The problem with your current trans might be as simple as shift forks. Top cover comes off to reveal these.

More gears, more better. As for what is a "better" trans, the granny iron case 4 speeds are stronger. The OD's are weaker.

Check the pics here. '92 should be Mazda or ZF 5 speed. Beats me:

http://www.motivegear.com/tech_info/...nny_guide.html

I will take your advice and see if I can fix the 5 speed.
I hate mounting issues.

Is it possible to check the forks without removing the trans?

Yeah-the T18 four speed was an option for 1992 F150s . Per the dealer brochure and the Ford Service Manual. The fourth gear was direct and the first gear was a granny.

The C6 tranny was also available in the F150s in 92-per the Service Manual. But the 92 brochure doesnt show this.

If the shift tower of the M5R2 is removed-the forks come out with the shift tower. The shift tower can be removed from transmission without removing the transmission from the truck. Just remove the transmission floor plate around the shift lever from inside the cab. The floor covering has to be removed to access the transmission floor plate. Then remove the shift tower with the shifter and forks in it as an assembly.

The first gear in the M5R2 5 speed is 3.90:1. Overdrive is .80:1

The T18 first gear is something like 6.40:1. The T18 is a real truck transmission-as long as the truck isnt driven at high speeds, long distance in high gear (1:1). Henry realized this and wouldnt equip a T18 truck with any axle ratio lower than 3.55. No stock equipped 1992 T18 F150s with 4.10 gears in the axle.

The T18 is an improvement of the old T98A truck transmission of the fifties and early sixties.

All who added their two cents... Thanks.
Your advice has been helpful.
I will attempt a repair to the 1988 5 speed trans, and put a head gasket on the 1992. Hopefully I will end up with two trucks. Since I gave only $275 for the 1992 it won't take much to turn a profit.

a 92 for 275$ thats a good deal.

Too funny! :-missingt And too true, too. Been there, done that--and will a 2.47 (Or was it a 2.41? It was the highest rear I'd ever even heard of, in any vehicle--ever) rear axle ratio, too!

Too funny! :-missingt And too true, too. Been there, done that, in an '81 F-100--and with a 2.47 rear axle ratio, too! (Or was it a 2.41? It was the highest rear I'd ever even heard of, in any vehicle--ever. At the time, it was higher than the rear in a Corvette--I checked. LOL)

I'd fix the Mazda, if I could, or get another one. They drive really well, IMO.

Too funny! :-missingt And too true, too. Been there, done that, in an '81 F-100--and with a 2.47 rear axle ratio, too! (Or was it a 2.41? It was the highest rear I'd ever even heard of, in any vehicle--ever. At the time, it was higher than the rear in a Corvette--I checked. LOL)

I'd fix the Mazda, if I could, or have it fixed, or get another one. They drive really well, IMO.

Good luck.

Success - Almost
 

I was able to find and fix the problem with reverse in the 5 speed. However, when I was putting the transmission top back on a small pin fell out. It is about 1/2 inch long, 1/16 inch in dia. and rounded ends. I cannot find any place to put it.

Any ideas???