1983 Jeep CJ-7 T5 Transmission Has Difficulty Shifting Into Second Gear

[60Bubba]

So now that my '83 CJ-7 is pretty much rebuilt, I'm having some difficulty with the gearbox. I know the T5 wasn't known for its durability, and this Jeep already has a couple things working against the stock transmission. First, I have the 4.0L conversion. That means more overall horsepower to strain the transmission, but less low end torque. It's probably more difficult to get rolling off the line with the conversion than it was with the 4.2L, assuming it was running right. Second, I have 33" tires on wide, heavy aluminum rims. Probably much more rolling resistance and inertia, plus the higher gearing.

EDIT:Forgot to specify, I have factory 3.31 with trac-lok rear (completely worn out and basically open)

That all said, I always had to slip the clutch a fair amount taking off from a stop, but that hasn't actually gotten worse. Now, I'm noticing some difficulty getting into second gear. From first, I can feel a tiny bit of gear clash as the shifter slips into the 2nd gear detent. From third back to second, I pretty much have to rev match to down shift, unless I slow to almost parking lot speeds.

My gut feeling is the 2nd gear synchro is probably giving up the ghost. If so, am I likely to damage the transmission in general if I keep driving it, or can I just keep using it but treating it as though it weren't synchronized to begin with? If I need to get things fixed, is this the time to conduct the transmission swap I've been considering?

I'm mostly driving on road, and will be doing no hardcore rock crawling. I want to maintain highway drivability, and I don't think I want an old school truck transmission. My first thought is one of the following:

1. World Class T5: I know some of these are used to replace the stock T5 in performance Mustangs. Is that a viable option here? From what I know about the Jeep T5, the housing flex is the big weakness. No idea if the World Class T5 addressed that issue.

2. NV3550

3. AX-15

I really don't know much about the pros and cons of options 2 and 3. My main goal will be to maintain 5 forward gears and the ability to handle the power of a 4.6L stroker which is my plan for this Jeep when the current 4.0L bites the dust. Also, cheaper is better, though I know cheap here is relative

[60Bubba]

I may have answered my own question about the World Class T5. Some searching indicates it isn't suitable for 4WD vehicles. It also looks like this is going to be expensive to swap no matter what. I hope I can find an alternative to a complete replacement.

I'd rip the T5 out and watch Moses's videos and try to rebuild it myself, but things are a tad busy right now. The Jeep is about to become my daily driver, I have a Master's Thesis due in 8 weeks, and I'm sitting in the hospital waiting on the arrival of child #1. I think more involved Jeep projects are out of the question for the foreseeable future...

[AZ.Jay]

Yeah Case it sounds like you're going to be pretty busy for a while, and not getting much sleep either Congrats on the new arrival!

[Moses Ludel]

Case, the passenger car (H.O. Mustang) World Class T5 required a modified 4WD output/mainshaft plus a transfer case adapter.  These parts, including the Warner WC T5 transmission, were once supplied by Advance Adapters.  Not available today, you're left with rebuilding your standard-duty T5.  Parts are available if you choose to rebuild.  I can estimate that your current transmission will have damaged 2nd gear synchro teeth.  The gear clash noise is actually steel-on-steel because the brass blocking ring is not bringing the 2nd gear to speed.  If this has gone on long, you'll typically find the synchro hub, brass rings, the sleeve and the gear's integral steel synchro teeth damaged.

 

The AX15, due to its availability, has now become the replacement for the NV3500/NV3550.  Classic Bronco and Jeep CJ owners are turning to Advance Adapters for adapters to mate a fresh or rebuilt AX15 to the 4.2L Jeep engine or a Ford small-block V-8.  Advance Adapters is a direct supplier for Aisin and the AX15, the contemporary transmission of choice for a stronger light-duty transmission.  Neither the NV3550 nor the NV4500 that I installed when producing the Jeep CJ Rebuilder's Manual: 1972-86 are available new.  The AX15 has replaced the NV3500/3550, and the NV4500 is available rebuilt through Advance Adapters.

 

Note: The classic NP435, SM420, SM465, T18 and T19 are great for off-pavement use with their extremely low compound 1st gear ratios.  (All but the T19 have a non-synchromesh 1st gear.)  For crawl ratios they approach the NV4500 or NV5600 six-speed league.  For highway use, however, the lack of overdrive is a liability.  Everyone wants big tires and low crawl ratio axles—overdrive is mandatory.

 

If you want heavier duty, the NV4500 is a consideration.  Your stroker 4.6L plans will likely hold to no more than 250 horsepower, which the AX15 can easily handle.  However, if you want bulk, stamina and a "truck feel" to your shifts, the NV4500 with overdrive is the most rugged 5-speed you could pick, true 3/4-ton and 1-ton domestic truck fare!  (See my CJ rebuilder's manual for details.)

 

It comes down to your aims.  If you do the AX15, that can fit to your 4.0L engine readily but will require an adapter clock ring to align the Dana 300 transfer case properly.  The clocking ring is available from Advance Adapters and remedies the offset clock position between the Dana 300 and the NP/NV231 chain drive transfer case.

 

Moses