Transmission choices...Blew 1 st in my T86...

1966 with a 225...I'm guessing it has a model 18 transfer case because it has the warn overdrive...what will work?

 

Perhaps the easiest thing is to put new T90 J parts inside your T86AA case.
Otherwise...

I'll start off by rating the 1946 -1978 CJ transmissions sequenced via overal strength and desireability.
T18WR / T98 / T15 / T150/ T14 / T90 / T18 NR / T86
You will note that I personally don't care for the T18 NR mainly due to it's ranging ratios.

Hmmm Looks like T86AA is in dead last place.

 

As Ken describes, all the guts of a T-90J will go in a T-86 case. Find a T-90A donor and buy the long input shaft, and put it all in the T-86 case. The T-86 and T-90 are basically the same design, except for the mainshaft splines and the gear bevels.

How much of an upgrade do you want? The only other transmission that strictly bolts in is a T-14 from a V6 CJ or Jeepster. It's an ok transmission - synchromesh 1st. Everything else requires some modification.

 

The PO of mine spent some $$ having the T86 rebuilt before I got it...I still think it sux...T18 or 98 in the future

 

There's actually a little more I should have added...I'd like to keep my overdrive & my transfer case could use a rebuild...I've been putting this off because other things had priority at the time but now I'm limping to & from work...it's my only vehicle. I was looking on ebay & came across this... http://www.ebay.com/itm/181180086556?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 would it work? $325 shipped ain't bad.

 

Keep in mind you also need to change one shift fork or change shifter tops to a T-90 top if you swap in the T-90 guts.

The T-86 and T-90 do not have the same bellhousing bolt patterns which is why people are telling you to swap the innards. This has been a common conversion for a very long time.


Sent from my iPhone

 

Thanks for the replys guys.

 

The T14 has a 10 spline output, which would require a different overdrive unit. I agree with the others about swapping in the T-90 internals, unless a 4 speed conversion is in your budget.

 

I'm going to have to deal with this with my T86 too...

Do you guys recommend doing this T90 internals swap yourself or do you just take it to a transmission shop and have them swap out the guts?

 

My T90 is at the repair shop, in fact my Jeep is at the shop and they took off the T 90 to rebuild.

It is heavy, dirty, you have to change oil, and it is plenty of parts. When you kknow the job it doesn't seem too complex, but it is a job.

When the gearbox is away, you can alos make some repair like clutch.

Sometimes it is pleasant to pay the expert, sometimes it is a pleasure to do the job with your hands...

 

Depends on the person doing the work. I would not hesitate to do one myself. What else have you done to your Jeep? A T-90 is pretty simple as transmissions go - repair is mostly about observing how it comes apart so you can easily put it back together. The R&R is most of the work involved. Once a transmission is on the bench, it's fun to work on.

 

It's not really in the budget, but so far it looks like a swap to the sm420 might be doable & more cost effective than trying to find a suitable t90...a guy on the local craigslist has a crawler project he's willing to part out. He's got a sm420, model 18 transfer case & AA adapter...(don't know which) whole group for $500. I'm still trying to get him to reply.
I'm gonna keep my options open for now & limp to & from work in 2nd & third...keep scouring craigs & ebay for something that'll work.

 

keep a look out on craigslist. I get alot of good jeep deals from there. people dont like to ship that kind of stuff. i got two t-90s and 2 spicer 18s for $25. t-14 is a good easy upgrade . its just 5/8" or so longer so youll have to redrill for the crossmember.

 

That's a good deal for trans, tcase, and adapter, and I think your OD would work-check the spline & gear tooth count.
Keep in mind you'd have to modify driveshafts, crossmember, floor pan, clutch linkage, etc.

 

New cross member, new floor plate or some modifications to existing one, and both drivehafts will need work for the SM420 conversion, along with the headache of the front driveshaft clearence. This will not be a weekend job and probably not for several other weekends. Personally, I would no longer put a SM420 in a Jeep. The SM465 is a stronger transmission, makes for a shorter conversion length, doesen't have the front driveshaft clearence issue, and is much easier to find parts for. Only downside is a weighs another 50 lbs.

The T90J guts will be far and away the cheapest and quickest fix even with the $500 deal.

 

After I blew 1st gear on my t86, I mulled the options and eventually went with a sm465 because I didn't want to do all the work of replacing gears if in the end, I was going to worry about the strength of the little 3 speed.

If I had to do it again I would because I use the granny gear alot, but it was an expensive and time consuming conversion for someone with a modest shop and novice mechanical skill set. If you just want to use the jeep for light offroading, and are happier driving the jeep than working on it....I would recommend just swapping in t90 gears.

 

OK...IF I can find a T90 in good shape, what would the next step be? Order a rebuild kit or gasket kit? What & from who would you all suggest? Is a press needed for rebuild?

 

A T86 version with T90 shift tower and gears:
http://hermtheoverdriveguy.com/?page_id=1415

T86 in stock configuration
http://hermtheoverdriveguy.com/?page_id=1418

T90 rebuild kits
http://hermtheoverdriveguy.com/?page_id=1444
http://hermtheoverdriveguy.com/?page_id=1448

You do not need a press to work on a T86/T90 and pretty simple transmissions as noted. About the only special tool required is a dummy shaft to keep the cluster gear needles in place during assembly. Can be made from just about anything, including a wood dowel, plastic pipe, or steel rod. It will depend on what tools you have to work with.

Perhaps if you don't have any experience with this task and want to minimize the downtime, just purchase Herm's converted unit. Cost may not be too different than finding a T90J input and a good T90 doner, along with a quality rebuild kit. And he does good work.

 

Middlefork,
I have a T90 I would give you. Good gears, but the syncros are out. Looks like N. Highlands is just north of Sacramento? I travel to Davis off and on, shoot me a PM if you want it, and we can try to work something out.