I just bought an M38A1

[Deadguyllc]

The T90 is not synchronized between 1st and 2nd gear. The T18 has a granny low 1st, so you start in 2nd. Are you saying it would lower the values of the Jeep because it isn't original? It is authentic to the era, it came out in 1955, and the Military used it in some trucks.

 

[modified]

no offense, but your pissing in the wind to mate a T-18 to your stock F134. It can be done but its not a direct bolt on by any means.
-you'll need to do your research as to which of the dozen varieties of t-18 best adapt to your mod
-you'll still require to obtain or fab an adaptor plate to t-case and bellhousing (I don't believe anyone makes a t18 adaptor to f134 bell because its a cost prohibitive swap)
-machining will be required of the input shaft and flywheel bushing for mating
-exhaust routing will be an issue
-existing steering box location will be an issue
-existing M/C location may be an issue.
-evasive modification of your tub floor to is likely.

look into the SM420 or T-98 if your still bent on swapping out the 3 speed

and man, what is it you want to hear as answer with the overdrive?
You got great guys expending there experience and time to help you along on your conceived aspiration with this A1, The fact we run these on our own vehicles is testament to its worthiness as an add on. have you taken the time to follow the links and research the discussions mentioned on post # 15.17.18 of your thread ?

 

[modified]

It is authentic to the era, it came out in 1955, and the Military used it in some trucks.

not authentic to an M38A1

 

[quickfarms]

I agree with billf about the t-18 lowering the vaule of the vehicle.

My personal opinion is that the m38a1 should not be modified using parts that were not originally installed on it by the factory.

I make a small exception to this rule for safety. Seatbelts and gamma goat lenses are safety items.

The overdrive is easily removed.

Why do you want to replace the t-90?

I have found that as long as the jeep is rolling you can start out in second gear with out a problem.

I have also found that if from a strat you shift into either 2 or third first you do not get the grinding.

If you are having issues with the steering and brakes then this jeep is not up to factory specs.

Steering issues are a result of all of those individual tie rod ends and the bell crank. everthing must be tight. This includes the king pin bearings, which are often overlooked, the adjustment on the bell crank and steering box.

This jeep should have 10" drum brakes from the factory. If I am not mistaken they are maunally adjusted. I would first inspect the whole system and bleed and adjust the brakes before you condemn them.

The drum brakes work great if they are in good condition. I have three jeeps, one has manual drums,11" front and 10" rear, the second has manual 11" drums at all four corners and the third is a modern LJ with factory power disc brakes and I have found that it takes more pedal pressure to stop the jeep with the factory disc brakes that is does to stop the 11" drums. on dry pavement I can lock all four wheels on each of the jeeps if I want too.

Now a little bit of information on braking systems. The majority of the 18 wheelers use drum brakes on all corners.

Drum brakes work great is they are properly adjusted, in good condition, you keep them dry and keep the dirt out.

Disc brakes are better is you like to play in the water.

 

[Deadguyllc]

You guys have convinced me, I am sticking with a T90. Mine might need a rebuild, or maybe I just need to practice double clutching more! I'll be getting an overdrive from Herm too.
So, that means the only change I am making to the M38A1 is new brakes up front. The truck has no vacuum assist, Austin is nothing but hills, and although I have been assured the brakes are practically brand new, it still won't stop without plenty of clearance, and a very heavy foot.

 

[BillF]

You should be able to go from first to 2nd without double clutching and without grinding gears. Now going from 2nd to 1st you need to double clutch, or wait until you stop, which is what I usually do with my m38. First is so low you don't usually need to down shift into anyways, I have only had to do it once and it was on a very steep hill and I was not going fast before climbing it so I had zero momentum.

 

[BillF]

I wonder what is wrong with you brakes. My 9 inch brakes work fine in my m38. I cant stop in plenty of time, unless I just drove through deep water.

 

[Deadguyllc]

Well, the guy that rebuilt mine, swears it was all good.
The steering linkage is visibly shot, and I had to get new tie rod ends, a new pitman arm, a new steering box, a new steering wheel, working gauges, new shocks, new tires (the old ones were dry rotted), and in an effort to further clear up the horrible death wobble, new military rims. The left side front spring hanger is bolted through the frame, and in the one spot the frame has rust on it, the tail end of the hanger pulled through the frame.
He swears the tranny is good, but if you just read all the rest wrong with it, I have my doubts. It grinds upshifting from first to second. Not every time, but most of the time. I've tried higher RPMs, lower RPMs, shifting fast, shifting slow, it still happens. It doesn't pop out of gear, yet.
I have to virtually stand on the brakes to get them to stop the truck, worse than the drums on my CJ5!
I went ahead, and had Novak conversions put together a T90, mated to a Dana 18, mated to a Warn overdrive. At least the engine is brand new, the body is in great shape, and with all the rest I am doing, I'll have a completely new truck by the time I am done.

 

[dodgedougak]

Ditto on Herm the Overdrive Guy! He overhauled my M38A1 trans and was great to work with. Really knows his stuff.

 

[BillF]

Check your clutch adjustment, that could be your problem.