Downshifting With 3-Speed

The transmission on my '65 (3 speed on the floor, F134) shifts nicely when going from neutral to reverse, neutral to 1st, 1st to 2nd, and 2nd to 3rd. However, downshifting from 3rd to 2nd just grinds, and 2nd to 1st will work but is tricky (have to feel for the cogs to align and then engage). I have tried double clutching but to no avail. I am new to Jeeps (have not driven a Jeep since I was a kid) and am wondering if this is normal, or is there an issue with my shifting technique, or is this an indication of a clutch or transmission problem?

 

The 2nd and 3rd gears are both syncromesh, so they should shift under normal conditions without clashing.

First is not synchromesh, so the only way you can downshift is to double clutch and match gear speeds. You really don't need to shift into 1st while moving. Instead, start off in second if you are rolling, and only go into 1st from a dead stop. Even with my later 3-speeds with synchromesh 1st, I hardly ever shift into first while moving. It's just not needed.

If the blocking rings are worn, downshifting will then clash if you don't match gear speeds. To match speeds on a 3-2 downshift, clutch in and shift into neutral, then clutch up and increase engine speed to match the gear you are shifting into, then clutch in and shift into 2nd. With a little practice, you can do this with no clash.

The blocking rings are like a clutch that matches the speeds of the meshing gears. They wear out eventually, but you can put off a rebuild if you are willing to do a little extra work and double clutch. If having to double clutch bothers you, then rebuild the transmission and refresh the blocking rings.

Also, make sure that your clutch is disengaging completely.

 

Ditto what Don & Tim said.
If you can depress the clutch and shift from neutral to reverse, then I think your clutch is OK.

 

Ditto again - I inherited a spare T90 with a Utility Wagon years ago with a broken case as the previous owner had done a poor downshift into 1st. A complete stop was always my rule as I was not good at double clutching and a poor college student who couldn't afford a rebuild or another transmission as it was my DD. I had replaced the rings prior and that really helped. Tim's description is spot on for the shifting procedure which I got better at (not real good) with fire apparatus.

 

Thanks, I will try the shifting procedure as described above. This particular Jeep won't get much usage so a shifting procedure is preferred over a rebuild.

 

Here's a great vintage explanation of levers, gears, transmissions and synchronizers from Chevrolet 1936. The T-90 transmission has synchronizers on 2nd and 3rd gear only. After watching this video you should have a better understanding on the internal workings of a transmission.

http://blog.hemmings.com/index.php/2013/02/01/tech-101-how-gears-work/

 

Timgr summed it up.

I love double-clutching - I can pretend I'm driving a race car or 18 wheeler.

 

Great video, thanks!

 

Went for a ride this morning. After several attempts, I was able to make a few 3-2 shifts, not clean shifts, but did get the job done.

The clutch pedal does not feel right to me - does not have nearly as much travel as I would expect - the pedal seems to hit the floor too soon. I will look into that later today.

The transmission is rather noisy is 1st, more so in 2nd, and quiet in 3rd. Any idea what this would suggest? Time for a rebuild?

 

"The clutch pedal does not feel right to me - does not have nearly as much travel as I would expect - the pedal seems to hit the floor too soon."

That could explain the shifting problem right there - as Timgr suggested.

Noise is relative. Early jeeps are noisy mechanically if you are used to modern passenger cars. But I wouldn't expect 2nd to be especially so.

 

1st gear in a T90 is a straight cut gear, so it has a definite gear whine.
This is completely normal. Second should not be noisy-you may have some bearing problems going on there.

 

Indicative of counter gear bearings and/or thrust washers being worn. Time for a rebuild. Check the shaft closely for wear and the 2nd gear bushing as well.



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It is always hard to describe a noise, but I can say this is not a whine. Sounds like a bunch of nuts and bolts in a coffee can on top of a washing machine at full bore on spin cycle.

 

I don't posses the knowledge, skill, tools, facilities, or desire to tackle a rebuild job myself. Any idea what this would cost at a typical independent repair shop (in the event I need a rebuild)? Also, is this something any skilled mechanic can handle, or would these be best left to a person who specializes in older transmission?

 

Novak and others have rebuild guides you can google. Or, last time I checked a rebuilt/exchange unit was not too awful expensive. Parts kits are about $600. Maybe you can find a good used unit.


http://www.willystech.com/wt/T90rebuildguide/T90rebuild.htm
http://www.novak-adapt.com/knowledge/t90_rebuild.htm
http://www.thefcconnection.com/t-90_transmission_rebuild_guide.htm

 

A rebuild kit should be in the $150-275 range depending on what it comes with. If you were local I'd either help you with it ir do it outright for $100 plus parts.
I'd find someone local if possible that knows older transmissions. Many transmission shops just don't know what to look for on the older transmissions. Another option is to purchase one from one of the vendors listed here. R&P, Partsmike, Novak, etc. are possible sources as well as others.


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I tackled my first T90 and the Transfer case at the same time at 19 years old with a factory service manual (1977). Very sound advice previous on finding an "old timer" that can guide you. They are not that complicated. I was able to buy off the shelf parts from Hausman (I think) in Louisville, KY which now you can't go to the dealer but the parts and kits are available as noted above. If you do go for it, watch those little roller bearings. That stands out many years later as the biggest "issue" I had at the time getting them set and in place. Overall not bad and I have 2 here in my garage waiting for rebuilds which I will do. Also you don't need a lot of room (My mom didn't particularly care for my work in the kitchen!) but parts cleaning is a necessity and can be problematic if you use combustible solvents. Best wishes on your decision.

 

if you let off the gas suddenly in either 2nd or 3rd, does it pop out of gear?

 

"if you let off the gas suddenly in either 2nd or 3rd, does it pop out of gear?"

Or jump out when holding back/coasting downhill?