T-86 or T-14 what would you Do???

My T-86 in my 1966 CJ went bad on me from the case to the main shaft and so on. I have can either rebuild the T86 for about $400 or I can get a rebuilt T14 for about $600. So, what am I better of doing. I know the main difference is the synchronized 1st gear. How much better is it to have that? if there are any other suggestions or any other trannies you reccomend please do so. Oh, I also have a small block in the jeep. I use it on and off road.

 

T14 hands down, better 1st gear (2.8 versus 3.1 in the t14) ratio and syncro'd 1st gear. And also in my honest opinion a little, very little bit stronger.

 

Ideally, I'd say neither. I'm not a big fan of the T-14 (ratios 3.1, 2.61, 1) because of the big gap from 2nd to 3rd. 2nd just isn't usable as a passing gear, and is so close to 1st that you can easily start off in 2nd all the time. If you want a 3-speed, I'd say go with a T-15 (3.0, 1.83, 1) - that 3.1 1st gear that Mike likes in the T-14 is only 3% lower than the first gear of the T-15, and the T-15 has a much more usable 2nd gear, and it's strong.

I know the T-15 to V6 swap can be done but I don't know the details. The bolt pattern is the same as the T-14, but the splines, pilot, and stickout are likely different. Maybe Nick knows what's involved.

 

I don't know much about synchro vs non-snynchro, but i do know that with the T-86 I had it always grinded when going into first whether i was at a dead stop or downshifting. Is there a way to stop this? How important is it to have a synchronized 1st gear(wheeling, streat driving etc)?

 

The syncro is what keeps you from grinding gears.
Jeeps don't need passing gears.
The t15 is much stronger but not sure what is involved in swapping one to a v6.

 

IMHO
The T86 is craap.
When I took mine out it reminded me of a small sewing machine
No syncro 1st.

Just my opinion.
Time to go sm420.
Worth every penny spent.
2nd gear is syncro which you use as first on the street anyway.

IMHO....

 

if you have a small block chevy, or really anything, and you are gonna go through the work of swapping tranny, I say go with SM420 also, since it's 7.0:1 first for super crawling, or SM465, which is also nice at around 6.5:1 (somewhere in there) but it's bigger and heavier, or T18, as it's also around 6.5:1 first. Be a bit more money for them, but just save the money until you can afford it, it will make you smile every time you jump in your jeep and you'll never wonder about a better tranny swap again.

 

My experience:

I currently have a T90 (same as the 86?) behind the V6. It has held up (don't know why).
Friends have a comando with the T14, it shifts nice.... Probably not any more strength.

The advantage of the T90/86 is that parts are in expensive in comparison to a T14.
When I wanted overdrive in my jeep I had to go back to the T90, something about the output shaft... I wanted to use the T14 with it's lower first, until I realized the fortune in parts.

-Hill

 

i would take the T-14, if not look for a deal on a T-90 or SM420. the T-86 is weak. i've never heard one good thing about them. except some of the parts interchange with the T-90. it all comes down to what you use it for.
heavy offroading= SM420
daily driver/ light offroad= T-14/T-90

 

I'm happy with the t14. even the factory switched out to the t14 after couple years. you will need a new input geat on the transfer, as the spline counts are different (6 on t84/86/90 and 10 t14) and shorten the rear driveshaft and lengthen the front about 1/2-5/8".

the OD solves the 'passing gear' issue. Herm will take your t86aa as a core on a t14.

 

Yes. The T-86 is basically a T-90 with a bevel-cut 1st and spiral (IIRC - definitely different) splines on the main shaft. You can take all the guts from a T-90 and put them into a T-86 case, but none of the gears are interchangeable.

A straight-cut gear will be somewhat stronger than a bevel cut gear, but I think in this application the strength difference isn't significant. Bevel gears are quieter than straight-cut gears, so I expect the T-86 bevel-cut 1st was done only to eliminate the whine a T-90 has in 1st gear. Don't know why they changed the main shaft splines.

 

First pic is a T-86 ,second pic is a T-90

 

Hmm. Maybe you need the spiral cut splines so that the bevel 1st gear will mesh when stationary.

Thanks for posting the pics O.G. - that shows the differences very well.

 

I agree with both timgr and trickpatrick. I've found the strength of the T14 to be marginal at best and have seen a number of them (my own as well) break under normal driving. The ten spline output shaft can be a bugger to find bull gears or OD's for as well. A swap to a stronger three or four speed, IMO, would be money well spent.

 

We swapped out the t86 for a t14 in our 67, haven't had to many problems yet, but don't really like the gearing. Will be pulling it and installing a T18 or sm465 soon. The 4 speed is really worth it, if Your already looking at spending 600 on a t14, I'd put 450 in to the 4 speed adapter, and 50 into the trans, Got my t18 for around that. 100 for rebuild kit and a few other parts and rebuild the trans yourself. Really not that bad on the t18. The sm465 is alot heavier, and harder to rebuild do to pressing on bushings etc. I've done both, but haven't run the sm465 yet so the jury is still out on the sm465.

 

If you just want to get back on the road I'd suggest the T-14 or T-90 as suggested. If you want an upgrade, a T-18 or 465 would by my recommended. I would not put a T-86 back in there from the stand point of parts are just too darn hard to come by and expensive when they are found....I just had to part a T-86 out because the parts I needed simply weren't available in this area to rebuild it. Nickmil