T5 Transmission Questions

A friend of mine has a CJ7 with a 5 speed T5 that chucked 3rd gear.

Reading the site everyone seems to want to replace the T5 with other options. Having been in the Foxbody Mustang world for a longtime I understand the limitations of the standard T5 however these transmissions were also installed in the Mustang with a 225 HP V8 and certainly more torque that than a 258 Jeep. Mustang V8 owner's beat on their STOCK T5 transmissions just as much or more than CJ Jeep owners with similar results.

A Busted Transmission!

I know everyone has "Opinions" regarding the reliability of the T5 transmission and that's great HOWEVER in searching the site that's all I find are just that "Opinions". I have not found any threads addressing the proper rebuild, installation of all the available T5 upgrades, re-installation of that upgraded T5 in their CJ, the results they experienced over time with a correctly rebuilt and upgraded T5 transmission and the performance of this upgraded T5 transmission in their CJ Jeep. Given the upgrades that are now available for a T5 rebuild to include the steel front bearing retainer, the upgraded counter-shaft retainer, better gears and better synchro's among many other things leads me to my questions:

1. Why not rebuild the original T5 rebuilt with all the available T5 upgrades available and re-install this upgraded and rebuilt T5 back in this CJ7?

2. Given the fact of T5 use in the Foxbody Mustang with higher HP and torque why wouldn't a correctly rebuilt and upgraded T5 also be a good 5 Speed Transmission behind a 190 HP 4.0 engine swap as this would make the engine swap SO MUCH easier not having to deal with all the issues and expense that arise when replacing a T5 with an AX15 or similar 5 speed transmission?

3. Once again anyone have any REAL EXPERIENCE doing just what I have suggested versus just their opinion?
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CJ-8.com Member
You seem to be a T5 guy.

In my "opinion," you should rebuild your friend's T5 with all the world class upgrades, and have him run it.

In my "experience," the T5 doesn't hold up very well in a Jeep. I had one behind an upgraded 258/4.10 gears/32" tires, and the bearings started growling. I had it rebuilt, and within a year, the bearings were growling again. I replaced it with an AX15 (which was not a difficult swap), and it ran just fine for the rest of the time I had that Jeep.

We have a member here who loves his T5. He keeps a spare in his garage, so when (not if) it goes out, he can swap in the spare, and take his time rebuilding the other one for next time.

Keep in mind, "opinions" are generally based on experience... nobody just arbitrarily decided to crap on the T5.

If your friend's Jeep is a street driven CJ7 with a stock engine, stock tires, and stock gearing, a rebuilt T5 will probably last as long as the original one did.


Typical Know-it-all
CJ-8.com Member
Here's my experience with the T4 and T5: I daily drove my CJ when I had both, maybe 25 miles/day. I had the T4 for about a year before it went out and I replaced it with a T5. I had the T5 for about a year and a half before it went out and I replaced it with a T176. I've had the T176 now for 3 years and I'm not at all concerned about it.

The failures could have been a result of poor gearing choices, but that leads you to the conclusion that the T176 is more forgiving when it comes to gear/tire/trans mismatch.

Like @CJ7Pilot says - most of us do what we want to do with our Jeeps, some are more open to others to suggestions. A rebuilt T5 based on your preferences is probably going to be a great transmission. It wouldn't be my preference after my experiences, and I've been more than happy with the T176 and all of the mods required to get it to work.


CJ-8 Member
CJ-8.com Member
I’ve daily driven a CJ7 with a T4, and a CJ8 is my current daily with a T5. The T5 is very smooth and I enjoy driving it on the road, but I’m on stock axles, stock gearing, 2.5” lift and 32s. It isn’t perfect, and I don’t think I would work it any harder than I am now in stock form. I would trust the others opinions around here since they have more experience than I do with the T5, but I know that it is a good transmission for a very mild build.
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No I am not a T5 guy. I had many bad experiences with T5's in Mustangs and therefore I am aware that a T5 is a marginal transmission at best. About the only good is that they are a true 5 speed overdrive transmission.

My friends CJ7 has a 2.5 lift with 32 inch tires, stock axles, stock gearing with the stock 258. 90% street and highway driving.

His thing is "Overlanding" where the scenery and the destination is the goal of the trip not how big a rock he can crawl over therefore traversing the Rubicon is not in his future. I would call his use of a Jeep as a car with 4WD as he does need highway capabilities to get to the Forrest Service trails he prefers to explore. He does pull a small 5x6 converted military trailer with supplies and roof top tent during his trips for boondocking at night.

Thanks for the responses. I will suggest to him that he should consider rebuilding the T5 with the available upgrades. I will also suggest the AX15 upgrade as one and done solution.

The second question still stands:

Anyone using a T5 behind a 4.0 FI swap in their CJ?


Scrambler Junkie
CJ-8.com Member
I have blown up three T5's, all on the highway just cruising at a steady RPM. It doesn't matter what you do to the "guts" of this transmission, the case is still weak, will crack, allow the input gear to separate from the cluster gear, instant teeth in the bottom of the case, leaving you with 4th gear only.

In a stock (engine output/rear end gear/tire size/no heavy load in the bed), sure, the T5 will hold up.

Sure, everyone thinks of the Mustangs putting out higher power/drag racing with T5's causing them to blow up. I get that. I was busting mine at a steady RPM, sustained load going through them. I had Mopar MPI on a stock 258 (more power), 33" tires (larger then stock), and 4.10 gears (lower then stock). This kept the engine RPM at around 2300 RPM at 70-75MPH, the peak of the power curve. A few hours of this sustained load, BOOM.

There is only a small sliver of aluminum separating the input gear bearing from the counter shaft bearing. This is very weak design.

The other issue with the case: On a NWC T5, the counter gear runs on those weird thin metal sleeved straight roller bearings. The bores in the case will wear, then bearings get loose, cause the cluster gear to "walk", causing input gear to counter shaft gear misalignment, causing BOOM, 4th gear only.

On the cases, the case in my green Scrambler was still a "press fit" for the cluster gear bearings, which I also secured to the case with sleeve retainer, which is a step left out of most rebuild manuals. On the T5's I busted, the bearings could be tapped in with a hammer very easy. On the cracked case, well, the bearings slide in and out.

IF someone made a stronger case to keep the input gear from wanting to spread from the cluster gear, that would be ideal. Until then, just wasting money on all of the other "upgrades".

Another problem, with the cluster gear - over time/miles, the hardened bearings riding directly on the ends of the softer cluster gear metal cause the cluster gear bearing surfaces to pit, which causes noise, probably causes the bearing to get hot, too. This has happened twice to me:

1) My first T5 in my modified Scrambler went on countless long trips, including to Moab (wheeling for a week) and back home, no problems. On the way back from Michigan, cruising down the highway, the transmission started making a slight whining sound. Drove it home, took it apart, no problem except galling on the bearing surface of the cluster gear.

2) My green Scrambler (stock) had this same noise from when I bought it. When I rebuilt the T5, same issue with the cluster gear bearing surfaces. I actually found a used OEM cluster gear to install, don't get me started on made in China transmission parts.

I didn't start out hating the T5, I figured a fresh, correctly rebuilt one would hold up in a slightly modified Scrambler on cross country trips. It did, for about 10,000 miles. The second one lasted about 5,000, the third one a little less, finally AX15. Before the AX15 swap, I actually brought a complete T176 swap with me on a trip to Kentucky (Transmission, bell housing, both drive shafts, t-case shifter, floor plate, reverse light harness). That's how much faith I have in a T5, on a long trip, slightly modified Jeep.

In my "stock" (except for Mopar MPI) green Scrambler (3.31 gears, 30"tires), I rebuilt the original T5. I hope it holds up. If not, I have a T176 on the shelf, or I will swap in an AX15.

On an "Overlanding" vehicle, nothing worse then a weak transmission. It would suck to have to swap one out in BFE, IF you bring a spare with you. I limped back home, twice, with busted T5's, first time about 150 miles, second time about 250 miles, 4th gear only.

They do make really neat sounds the first 15 or so miles once they blow, until the rest of the teeth shear off the input/cluster gear, then they quiet down, except for the occasional tooth getting sucked up off the bottom and getting thrown around by the other spinning gears.

There is also the "what fluid to use" controversy, with the NWC T5's. Well, I've blown them with three different types of fluid:

1) First one, galled cluster gear bearing surface, had expensive Mopar 6 speed manual transmission fluid. This fluid was burnt when drained, I guess caused by the heat of the cluster gear bearings rolling on galled surfaces

2) Blew one on gear oil, no bearing/fluid issues what so ever.

3) Blew one on ATF, again, no bearing or burnt fluid issues.

IIRC, there is/was an old AMC bulletin warning drivers not to drive the Jeep for long period of time in 5th gear until the fluid was hanged, I'll have to try and find it.


Legacy Registered User
SOA Member
I've also blown 3rd gear in two T-5s (I think the first time I blew one it was 3rd; it's been 20 years so maybe it was 4th). For the second one, I got lucky and found a WC T-5 on eBay for like $300 or maybe $500 that already had the steel GM front bearing retainer, with the CJ first gear, and Dana 300 tailshaft adapter. It was in some old transmission shop in Canada that had shut down and the current owner was liquidating everything that was left. I put this transmission into my CJ-7, behind a SBC 350, and so far it's still doing great (although it hardly gets driven anymore). I think the WC T-5 is a worthwhile upgrade. The problem is the cost in making one work in a CJ. For awhile, I remember Advanced Adapters was selling bolt-in WC T-5 upgrades; they were even listed in the 4WD Hardware catalogs. But for the cost of what they were selling for, there were other better options out there. Thus the WC T-5 fell by the wayside.


CJ-8 Member
CJ-8.com Member
Well I have 237,000 miles on my T4 without a lick of problems with several all day road trips, but no real hard core wheeling, just light to medium off-roading just bought a used T176 to install when I install a rebuilt 258. Don't want to take any chances. :)


Scrambler Junkie
CJ-8.com Member
I have 80Kish on my T5 in my tan Jeep. I've always run 31's with 3.31's so no bit strain on it there.

I've had a T176 sitting on the shelf for several years to swap in when (not if, but when) the T5 goes.

I've seen too many trashed T5's to have any faith in them.


Scrambler Junkie
CJ-8.com Member
Going from 32s to 33s is when my T5 went bang. When I swapped in the 5.0 it was just too easy to put in a T18. Been about 27 years on 35s without any trouble with that transmission (130,000 miles +/- so far).
This thread is filling me with confidence about the T4 in my new to me Scrambler. It is possible to put a T176 behind the AMC 150 right?


CJ-8 Member
CJ-8.com Member
This thread is filling me with confidence about the T4 in my new to me Scrambler. It is possible to put a T176 behind the AMC 150 right?
It is possible, the 150 and the 258 use the same trans mounting pattern I believe, and I know it can be done with the 258


Typical Know-it-all
CJ-8.com Member
This thread is filling me with confidence about the T4 in my new to me Scrambler. It is possible to put a T176 behind the AMC 150 right?
You'd need a bellhousing, trans, and F/R driveshafts. Of course, you may as well replace the clutch when you're in there, and rebuild the t176, and maybe the dana 300. That's how things go with cjs, there's no end.

Bellhousing: $1-150
Trans: $250-500
Driveshafts: $300
U-joints: $50ish
Clutch: $100
Rebuild kits: $100 ea depending on how deep you wanna go.

Time: a day to pull everything, a day or two to rebuild the tranny, a couple days to rebuild the T/C, and a day to reinstall.