T-90 Popping out of second Gear.

[BruceG]

I'm going to rebuild it anyways and there is a good youtube video from Schnitzlehaus Which Novak has something to do with because he promotes the Novak master rebuild kit. Its less complicated when you see it being put together than reading it in the service manual. I think its based on Ricks rebuild? In any case it does pop out of second. Can't imagine its the synchros maybe a worn second gear? the rebuild kit comes with a new second gear. Any Ideas???

[Ryan_M]

Popping out of second is a common symptom of worn synchros. If you are planning to rebuild it this should solve your problem. Inspect everything once you disassemble the transmission. Replace all the synchros regardless of what they look like and the gears and other parts as needed.

[Oilleaker1]

Pay very close attention to the drive dogs on the gears where the synchro collar slides onto them. Any chipping or taper, replace the gear. Always replace at least the synchro collar with a USA made one. Stay away from Omix ada. Measure where the mainshaft fits the input rollers and where 2nd gear runs on the shaft. Replace if any doubt. Check the case where the cluster gear rotates against it with the spacers. If metal got in there and rotated, and chewed up the casting, you will have big problems. The T90 with the oil slinger up front is harder to work with. It's always in the way. The trick is to remove and re-install the front bearing while the input is in the case. There is a special puller that grabs the groove that the larger snap ring fits into. Going back together, have a helper tap the bearing on while you hold it. Lastly , weak poppet ball springs up in the shifter tower will also let it pop out of 2nd. See Mr. Hawkridge here. He's the go to T90 guy.  John

[BruceG]

How does the synchro make it pop out of gear? I thought its job was to slow up or speed up the gear you are going to  like a clutch? By the way I'm not second guessing you just trying to understand the principles!

[athawk11]

Bob W described this to me, but I won�t do it justice.  Suffice it to say, this phenomenon is the Achilles Heel of the T-90 Transmission.  If you have worn parts, and you decelerate while in second gear, the transmission slips out.  If I remember correctly, it has something to do with 2nd gear being helical in design.  If any of the above mentioned parts are worn, it loosens the desired tolerances.  The synchro blocking ring "inner cone" wears out and thus increases the tolerance between other components, causing slop...and slip.
   
In three different steps I replaced the following�

Round 1. �Replaced small parts kit and blocking rings. Still slipped out.

Round 2. �Replaced 2nd gear and shifting fork.  Still slipped out.

Round 3. �Replaced complete clutch hub assembly and added a shim. Problem solved.

You can�t see this damage until you take the tranny apart, so here are a couple photos of my old hub assembly and the new hub assembly�




[size=14]The moral of my story is� Don�t do what I did.  Go Big.  Go All In.[/size]
Tim

[BruceG]

I wonder if it was the shim or the clutch hub assembly that fixed it? also where did the shim go and how much free play and in what direction is too much? I wouldn't mind talking to you about what  I have. My cell is 413-441-2944 Thanks Bruce G. After 6 pm EST Again Thank you all for responding!!

[athawk11]

Oh, forgot to mention that I also replaced the springs and poppet bearing during one of these attempts.  This did not solve the problem either.

I�m not sure if the shim or the new hub assembly ultimately solved my problem.  After three attempts, I was just happy to not take it all apart again.  I will say�If you see the chevrons on any of the components look like mine did, replace the part.

Clearly, I�m not an expert with these transmissions or I wouldn�t have had to disassemble it three times.  I take that back�I am an expert at disassembly and reassembly.  Not something I wear proudly.

This is where I shimmed the case�right behind the rear bearing.




I can�t remember the full range of movement you want to see.  I believe Bretto here at the 3A mentions it in his transmission repair thread.  I made the shim to split the difference on his suggested range.  .013 worth of front to rear movement on the shaft.  To achieve this, I think I made the shim about .005 thick.




You could probably test this �movement� without taking the transmission or transfer case out.
 
Remove the PTO cover and main shaft gear that ties the tranny to the transfer case.  Try to set a dial indicator up to read the movement.  It might be a little tricky because you�re working inside the transfer case housing.
 
I don�t recommend it, but you might be able to shim excess movement by just removing the transfer case.
 
I would be happy to give you a call, but there are people here that are far smarter than I am on this transmission.
 
Tim

[Bob W]

Here is Willys' answer to the 2nd gear problem. Step 6 has solved the problem many times for me.

[bretto]

Tim you are an expert in my mind. 
I pretty much ran the gamut as Tim.  I think my fix was the new #2 gear and the shimming at the rear.
It's a thing of joy when not having it pop out of 2nd.
Oh and NOS or quality US made parts only.  That can not be said enough when dealing with T90 parts.

[Oilleaker1]

I smile all the way to the bottom of a steep Jeep trail in 2nd, when it stays in gear. Anyone ever put it back into 2nd by stepping on the gas? 

[Bruce_W]

Anyone ever put it back into 2nd by stepping on the gas?�

Oh, yeah. Many times.     Bruce