T-86 direct replacement 4 or 5 speed?

Hi there

I have a 67 jeepster commando with aT86 3 speed transmission. Looking for a direct replacement 4 or 5 speed to hopefully increase fuel economy of my 225 odd fire. suggestions?

 

your best bet would be to get an overdrive for the transfer case if you have a d18.
any tranny swap will involve some modification and adapters. i would imagine that if you searched the forum for t86 or transmission you would find some good info on the topic.

i am not very familiar with that tranny or the commando drivetrain so i may be mistaken.

chris

 

4 speed might only get you a lower first gear as 4th gear will be 1:1 final drive
same as T86 3 speed
5 speed will get you an overdrive in 5th
prob not an easy swap at all $$$
I seem to recall a Saginaw 4speed that might be an easier swap,if you just have to have a 4 speed; the ratios aren't that great for wheeling though
what do you plan to use your Jeepster for ?
mostly highway use ?
if your Jeepster is still stock, it will have a D20 t/case, which won't accept a Warn overdrive

 

still would be easier to swap in a d18 and an offset rear axle then to try and get a 5 speed in there. i am assuming that the poster wants overdrive for mpg (that is a bolt-in direct swap), but perhaps not.

perhaps the auto tranny that came stock on a lot of commandos would improve mpg? that may be the cheapest route available.

 

the auto is still a 1:1 final and the pumping losses tend to actually decrease MPG.. besides who cares about fuel economy.. it's a 40 year old jeep.. if it's that much of an issue buy a $500 geo and get 40 MPG for less than any swap you could make..

BUBBA

 

i am sure it isn't that important to drjeepster either, he was probably just curious what trannys would bolt in and if any of them were better.

basicly the answer appears to be none.

chris

 

the swap mentioned above would prob be the easiest to do;
then you could add an o'drive

 

Now, I'm not a big fan of swapping stuff, but if you absolutely want a five speed, here is a way to do it.

Get a CJ-7 drive line with the 6 cyl engine, trans(5sp), transfer case. If you swapped in that stuff you'd have what you are wanting.

You could probably sell the v-6 (if it is any good at all) for a good part of the drive line cost. Keep the exhaust manifolds and exhaust pipes and sell them separately.

Between the two you would be pretty far along cost-wise.

I have been wanting to do that with an old cj5, but every time I get a good candidate for the swap I find I'd rather fix it than cut it up.

 

Putting an inline 6 into an early CJ or Jeepster Commando is not advisable, unless you want to move the firewall back. Too long.

There's no easy way to get an overdirive gear without a lot of effort or expense. Probably the cheapest would be a Ford SROD (single rail overdrive) 4-speed from an 80s Granada or such. Not common, but available. Still requires a lot of effort to adapt to your existing engine and driveline.

IMO a different transmission isn't going to affect your fuel mileage that much. Aerodynamics is the biggest problem, not gearing. Reducing your top speed by 10mph will help a lot. Fuel injection would also help, but that's not straightforward on an oddfire V6. If it were mine, I'd drive it and enjoy it for what it is, not what it's never going to be (ie an economy car).

 

Re putting an inline 6 in a cj.

Well, I am not a big fan of major swaps.

That said, I don't think you would have to push the firewall backwards -- seems you could go also go forward. That's what jeep did.

Now, if you did it with a pre'72 CJ you'd have a shorter distance from the grille to the front bumper, and might have to use 72 and newer fenders and hood, but I've seen the later model fenders/grille/hood installed on a mid 60's jeep, and while it looked a little strange at first, it wasn't really bad.

I'm going to get a chance to do some measuring and side by side comparison in the next month or so.

If you look at a postal jeep, for example, you can see that there isn't really that much more room required. Postals used the pre 72 fenders and hood and an oddball grille. It looked to be offset around 1 - 1 1/2 inches or so.

It is unlikely that I'll ever try it, but it would be interesting to see one done.

 

I'm not sure ... every early-CJ I6 conversion I've seen (Chevy 230, Ford 170, Studebaker) has had a big hole in firewall. I know that the small block Buick V8s (300, 340, 350cid) will fit in a CJ or Jeepster Commando if you cut back the grille to move the radiator forward. In general, I6s are 50% longer than V8s...

I'd say the bubble grille from a postal is good evidence that you can't put an AMC I6 in an early CJ without cutting the firewall (at least without changing the fenders. grille and hood). The 72 and later CJs add a full 5" to the front sheet metal, in addition to moving the radiator closer to the grille. All this extra length was needed for the 232/258, not for the 304 (or so I've heard). I'd also expect that later fenders on an earlier frame would have severe tire interference problems - Intermediates already have interference problems because the frame was lengthened less than the sheet metal (3" v. 5"), and on an 81" frame, that interference would be even worse.

Not trying to be argumentative here, but there are so many worthy I4s and V6s that fit easily into the early CJ engine compartment, that one would be punishing oneself needlessly by choosing to swap in an I6. Why hasn't anyone swapped a Dodge V6 with an NP435? Even many V8s (ie SBC, SBF, Buicks) would be vastly easier than swapping an I6 - unless, of course, you cut the firewall.

 

Simple but expensive, Keep the V6 get a NV4500 with GM bolt pattern adapter to Dana 300. You end up with a low gear and overdrive but good luck finding an NV4500 inexpensively.

 

Wow! Quite a few suggestions. Thanks. Planned use of the Jeepster? Hmm...Well I plan on painting it hot pink and cruising da hood, install a 'la cuccaracha' horn under the hood, drop it to the ground and put a chain steering wheel in place of the stock. NOT!!!

Want to lift it enought to put 32s on her, take her pig hunting in Central California, use it as a the official Pack 84 vehicle and take it to car shows to raise awareness of the local scout pack and hopefully drum up support. Otherwise it'll be my daily driver. The reason I wanted to possibly swap out the trans was primarly to gain in economy. At least that was my hope.

No automatic transmissions for this jeep, thank you. I'm sure auto transmissions are fine and work well, but for me it just isn't right.

One reason for owning an older Jeep in the grand state of California is that it is way cheaper to register and insure on older vehicle in this state. taxes are based on original purchase prices..

 

Also, I plan to keep the 225 in place as it is a strong running engine. I've read up on this thing and it was Buicks answer to the Dodge slant Six. If any one here know about the slant six you know it was near impossible to destroy, even if you ran it without oil. I know I tried it once. No it did not die, didn't even score the cylinders. Please do not ask me how that happened. From what I understand the 225 odd fire has the DNA of the Slant six and can last as long as one changes oil and spark plugs. I'm not willing to try the running it without oil stunt though..hey I was 18 then.

 

In answer to the jd7, thank you for the suggestion. So far I have found nothing inexepensive about this jeepster, nothing except maybe the jeep itself. Got it for 500.00 a the local American Legion. Some guy was in need of drinking money and hey, I was looking for a classic. I got a totally trashed transmission(literally in pieces), wasted transfer case, flat springs, one dead rat and a used condom...yuck. Frame was straight, engine fired up with a new battery and liquid mechanic. 20 minutes of smoke..solid runner. I love the lope of the odd fire. she sounds cool.

 

$500 is a good starting place. Better than some that I've had. If you got a trashed trans and transfer case then I'd look into some of the swap suggestions. Check here for info also: www.novack-adapt.com and www.advanceadapters.com . Plenty of stuff there that can be done. Oh yeah I don't think there is any such thing as a cheep Jeep, at least I never had one.

 

What rear end gearing do you have? I'd expect that you have 3.83s, and probably won't gain much from an overdrive. Look for a tag under the cover bolts front or rear, or if those are gone, the tooth count is stamped into the ring gear.

If you are interested in the SROD 4-speed, R&P sells an adpater and can tell you more. I'd be more inclined to replace a hammered T-86 with a T-14. The T-14 was used in later V6 CJs and Jeepsters, and has a synchro 1st gear. I understand you can also take the guts from a T-90 and put them into a T-86 case - probably the cheapest way out.

I don't know about the slant six thing ... Buick engines are reputed to suffer from oiling problems when tired, especially if run dry Certainly the early slant six that had the steel crank was nearly indestructible.

 

The T-14A/dana18/od/offset rear end would be a good (and easy) swap.

 

Before I say anything else-welcome to the forum!I've got basicly the same model jeepster (1968) as you.As far as milage goes I'm thinking a HEI ignition and better flowing exhaust.I have the T86 with a dana 20 transfer so I'm looking at the GM 420 to replace the T86 some day when life slows down, the stars line up ect.....Advance Adapters is local if you are in the central coast (Paso Robles).Good luck.

 

While I would agree with you, I've found the t14 trans to be weak at best. The fact that the origional drivetrain is toast gives you a few more options. The nice thing about the Commando is it's longer wheelbase, allowing a few more options thatn the CJ. The problem is that any adaption you decide on will require copious amounts of cash to lube the process. My suggestion is to plan out the repairs and gather to cash to do them right. Don't skimp on the trans. V6's pump out a lotta torque. An accedential cluch drop in a sticky spot can grenade an early 3 speed in the blink of an eye. While t150 can be adapted in, a four speed or better will last longer. With your criteria of an overdrive, You can look at the Ford trans mentioned above with an adapter or the NV4500. On a side note, a good running V6 with a direct drive trans, driven modestly, will net MPG's in the upper teens and low twenties. I drove my CJ cross country(before all the mods) and pulled 23MPG.