I lost two front teeth...

I will start with... the jeep is a 1960 cj5 with a f134 and a t-90 transmission.

I went for a short drive the other day, and it was cut very short. I made it about 2 blocks, stopped at the stop sign, and when I took off and hit 2nd gear things went bad. I got a loud banging coming out of the drive train. I got pulled over and tried first and second gears and got a serious clunk out of the drive train that kind of went along with the movement of the jeep. I tried reverse and it was still there. I pushed the jeep about a block and decided to try third gear and it was fine, and didn't make any noise at all. I limped it home in third and put it away. The next day with the help of my 3 and 5 year old sons, we pulled the floor and the top of the tranny. I very quickly found the problem. The input shaft gear was missing two teeth and they did a number on the bottom gear cluster. I am not sure what caused the problem, everything has been working great and there was no indication that there was a problem.

The transmission is a t-90 I kind of pieced together. It has 16 teeth on the input shaft gear. I changed the front seal to a newer style seal, also changed the front bearing to a sealed bearing. I found the correct input shaft on walcks and it said I needed a 35 tooth bottom gear cluster. Is there anything I need to check into when I go ordering parts for the jeep. Is there anything I need to worry about when doing this transmission. I plan to order the small parts kit with the gaskets and the bearings, the input shaft, and the gear cluster. Thanks in advance for all advice.

 

We're these "aftermarket" gears? If so that would be the first suspect. I'd try and find originals if possible, but I remember someone was looking for a short 16 tooth gear a while back and couldn't find one. Was that maybe you?
Did you just replace the input or the input and cluster gear? If just the input I wonder if the input and cluster were slightly mismatched in pitch or otherwise. Can you post pics if the damage once you get it apart? It might give clues as to what caused the failure.


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Sorry left a lot of details out. I took transmission out of a 64 tux, it had a column shift. I also took transmission out of a 60 cj5 and made 1 because the tux trans was cracked. I did replace the front shaft and cluster together, both out of the tux. I did this about 2 years ago and it has worked fine up till now.

 

Saw a very similar failure in a Muncie m20 before. Turned out the trans was run without a pilot bushing for a while. Failed in a new install with a pilot bushing.

 

I was the one looking for the 16 tooth input gear a while back. I ended up getting a crown piece from 4wheel parts. I have several thousand miles on it so far and it's holding up well.

I think allot of walcks stuff is omix ada stuff. Not impressed with the quality with omix parts.

http://www.4wheelparts.com/Drivetra...x?t_c=12&t_s=239&t_pt=101357&t_pn=CROJ0936448

 

Thanks for the link. It is nice knowing there is more than one vendor for these parts.
I will likely get started tomorrow night tearing things down and will try getting pics of carnage posted.

Walcks says this input gear is a later version 66-71 with a low first gear and higher 2nd and 3rd. I guess that kind of explains why 50mph was not a problem with the 5.38's.

 

3rd gear is still 1:1 ratio regardless of the tooth counts in a T-90. In effect the input shaft is locked to the output shaft. No effect on top speed.
It will affect the crawl ratio though (how slow you can go and torque multiplication).


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[h=2]This is the actual description on the ad for the front shaft gear at Walcks.

Description[/h]This is the input shaft with the low first gear used in 1966-1971 4 cylinders. This input shaft was used when the gearing was changed to go faster with the higher gears. The input shaft has 16 teeth on it and is used with a 35 tooth cluster gear.

 

the description is more likely referring to 4.27 or 4.88 axle ratios where as we have 5.38:1 my f-134 never had issues pulling 50 mph in direct it just buzzed at 3200 rpm doing so. post pics, there are a few vendors that can source a used transmission or the parts to get you up and running.

 

Yes, they are referring to the axle gearing change which is why they went to a lower first gear. Look at your transmission. In high gear (3rd), the input and output shafts are locked together as I said above. That does not change amongst any of the versions of T-90, T-86, T-14, T-98,T-18, and on until the advent of the T-5 in the 80's. high gear ratio does not change in any of these except the T-5 which has an overdrive gear. The rest are still 1:1 ratio high gear.


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http://www.novak-adapt.com/knowledge/t90.htm

A little light reading for ya. It will explain the gear differences in the t90a and t90c

 

I agree with nickmil that the drive gear is 1:1 (which I thought was the case with all manuals) and anything above the drive gear was OVER drive. Hence the word OVER.

 

There are a few manual transmissions that do not have a 1:1 ratio gear, all gears are under driven or overdriven, but none used in Jeeps from the factory that I'm aware of. The Ford SROD and RUG overdrive transmissions are an example of this.
Most front wheel drive manual transaxles also don't have a 1:1 ratio gearset.


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Thanks for the clarification, I was basing it on everyone saying how they couldn't get over 45 mph... that's another big can of worms. Time to get a tachometer.
I have moved everything around in garage to support the project. Pretty bad when you pull a 13 ft boat out of garage and still don't have a lot of room. Bikes, lawn mowers, tillers, motorcycles, all the important stuff like pedal tractors, scooters, gator and tractor power wheels, and every other kids toy they threw a fit in the store and couldn't live without. Finally enough room for the moment.
Tomorrow I will borrow a cherry picker from friend and start removal process. Is pulling engine first the easiest way?

 

If it were mine I pull the floor pans and drop the tranny/t case/x member as a unit. Leave the motor in

 

This would be the easiest way to get it out. I just pulled mine and used a motorcycle jack i picked up at a garage sale
http://www.sears.com/craftsman-motorcycle-atv-jack/p-00950190000P?prdNo=4. Just cut a piece of plywood to sit on the two rails and the tranny / transfer case will sit sorta even on them to pull it out. Remove the transmission top cover with shifter to get better clearance.

good luck

 

When you leave the engine in, how have you supported the rear of the engine since the motor mounts are in the front?

 

I put a piece of wood under the oil pan , close to the flywheel and use a bottle jack to support the weight.

 

take a look at this link.
some ideas on how to handle the removal of the transmission and transfer case.
look for my picture. it shows the bottle jack under the oil pan in the back ground.

http://www.earlycj5.net/forums/showthread.php?104354-New-and-about-to-replace-Clutch

 

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