Easy (or Relatively Easy) 4 speed swaps for 66 CJ5 V6 with D18 transfer case.

Are there any easy (or relatively easy) 4 speed swaps for 66 CJ5 V6 with D18 transfer case. I am new to modifying, have had a few jeeps in past but left them stock.

 

in terms of modifying, take one step at a time and ask the members here as you go (I have). I listed a few links that you can read that should give you a better idea.
as for which one is easier, depends on which one you find. they all require a transfer case adapter (GM 420/465 and ford t 18. Both I believe can be bolted to the pre71 bell housing fairly easily. The ford requires a weld on the housing and a machined bearing retainer. (this is covered in the novak site)




this one is really good,
http://www.earlycj5.net/forums/showthread.php?76000-Buick-225-4spd-tranny-swap

http://www.earlycj5.net/forums/showthread.php?103688-SM420-vs-T18

novak site:
t18 http://www.novak-adapt.com/knowledge/t18_t19.htm
adapting the ford to the buick http://www.novak-adapt.com/catalog/adapters/engine_to_transmission/ford_to_gm.htm

sm420/465
http://www.novak-adapt.com/knowledge/sm420.htm
http://www.novak-adapt.com/knowledge/sm465.htm

sm420 install this is on the old site no longer available: no pictures sorry
http://web.archive.org/web/20080415033730/http://www.earlycj5.com/tech/trans/SM420/sm420_swap.php

 

The T15 is a 3-speed. You mean the T18?

The T18 is probably the most popular 4-speed swap for a CJ. It was used in some models of Jeeps, so you can find T18s that are already adapted to your transfer case. But none of them will bolt up to a V6 without modification. You can also adapt the Ford T18, which is a little easier on the engine side, but requires an aftermarket adapter kit.

The GM truck 4-speeds (SM420 and SM465) can bolt up to the V6, but they also have to be adapted to your transfer case.

There's no really easy route.

Most Jeep owners want one of the truck 4-speeds with a compound 1st gear. They are big and heavy, and shift slowly and heavily. But the super-low first gear is great on the trail, and they are pretty much bullet proof in a a light chassis like a CJ.

 

Thanks for the helpful posts. Now just have to some searching and shopping.

 

thanks timgr I don't know why I was thinking t15 was a four speed.

 

another approach can be had here.
http://www.earlycj5.net/forums/show...of-O-brien-4-Wheels-West-is-still-in-business

this a transfer case upgrade to 3.6 : 1 gears.
some machine work, cost is comparable.
only changes are to the transfer case. it bolts right back in.

 

I've come up with this from some research I've done from Novak Conversions. The Jeep T98 is probably the best direct bolt up solution with only one adapter needed for the engine. The T98 came factory married to the Spicer 18 only with the small input bore versions. If your transfer case shifter is a single lever, then it won't work because your input is the large one. If thats the case, then the SM420 would be the next easiest swap with only one adapter needed for the transfer case. Here's some info from Novak Conversions about the Dana 18.

"Later Civilian, 1955-1971 In 1955 (this varies by a year or so on some models; no doubt while Willys-Overland was using up its remaining inventory) Jeeps received the Dana 18 with an 1-1/4" intermediate shaft. This improvement was not indended to increase the shear strength of the pin, but to increase the bearing area and the number of bearings. Free needle rollers, then, replaced the earlier and significantly fewer caged needle rollers. The locator bore continued to be the 3-5/32" diameter."


"Final Civilian, 1966-1971
The "large case" version of the Dana 18 was the most improved version of all. It was only found behind the Buick V6 engine with its T86 and T14 transmissions. The case casting used was that from the Dana 18's progenitor, the Dana Spicer Model 20. This case featured a 4" locating bore and a single stick shifter and new front output cap. The front output assembly did not provision for a shifter mounting point, as the shifter was anchored to a transmission bracket. The internals were essentially identical with the standard Dana 18. This version is best thought of as Dana 18 guts in a Dana 20 shell. Individuals can build a "Super 18" by copying this version."

Here's some info from Novak about the SM420 and it's GM capability.



"Engine Compatibility and AdaptabilityGM
As the reader will conclude, the Chevrolet and General Motors SM420 will marry directly to a GM style bellhousing. This includes early (1955-1967) Chevrolet / GMC truck, Chevy car, Buick, Oldsmobile and Pontiac bellhousings . It is important that you measure the locating bore on the bellhousing to confirm the 4-11/16" diameter before performing the swap. If you need to join this transmission to a GM truck bellhousing (versions from 1968-1991) with the 5-1/8" bore, it can be done. Novak offers a bellhousing locator sizing ring, part #BR4. We also sell new, billet steel SM420 bearing retainers turned to the dimension you require."

"While the Muncie 420 can be used with any GM engine having the "regular" GM transmission bolt pattern, this transmission installs more easily with the open bottom Chevrolet bellhousings because the lower holes in the transmission case are threaded rather than drilled for clearance. The threaded hole case cannot be modified, so the lower attaching bolts must be installed from inside the bellhousing."


"This is minorly inconvenient on full circle (one piece) bellhousings such as Buick V6
and 1962 and newer Chevrolet V8. The lower bellhousing holes must be drilled for bolt
clearance (17/32" drill) and the clutch release arm, bearing, and bellhousing must be
assembled to the transmission and then assembled as a unit to the engine. While this may
not be convenient, it is not difficult and the results are worthwhile."

 

Looks like the Ford T-18 can be bolted up to a GM bell housing without an adapter with some modifications. Here's the link to Novak for that info.
http://www.novak-adapt.com/catalog/adapters/engine_to_transmission/ford_to_gm.htm

 

Recheck your info about the 18 case with 20 internals. Inaccurate statement.


Sent from my iPhone

 

Great effort, yet includes misinformation.

The standard Jeep version of T98 requires the use of 2 or more adapters.
At least one for the bellhousing and one for the transfer case.

True of CJ's but not true of all Jeep models.
Some Gladiators used T98's with large hole transfer cases.

Jeep never built a D18 with 2.03 ratio, D20gearsets.

SM 420 is likely considered the most complex of 4 speed modifications if done well.

See DANA MODEL 18 TRANSFER CASE PROGRESSION
http://z4.invisionfree.com/CJ3B_Bulletin_Board/index.php?showtopic=3134&st=0#entry2604802

 

All the info I posted was directly from Novak.
http://www.novak-adapt.com/knowledge/model_18.htm

 

I understand.
From what I tell the Novak site is an excellent database in fact one of the very best.
Yet still I find a small percentage of the information to be potentially misleading.

 

I do not agree about the sm420 being complicated, I have done a sm465, (2) sm420 and a t18.
By far the most complicated is the sm465 as the entire transmission has to be disassembled to do it right.
The sm420 for the most part is a bolt together with the exception of grinding on the transfer case.
There are reasons to not use an sm420, but complexity is not one of them!

 

To clarify, I was not referring to the use of the "off the shelf" long adapters.
Here I am specifically referring to documented attempts to mate the SM420 to a D18 via short adapters.
The installation of short adapters entails custom fabrications plus undesireable propeller shaft concerns.

 

I'm curious about the reasons.

Thanks.

Waggs

 

So I guess my initial question of "an easy swap" is wishful thinking. Would love to just find a t14 or t86 just to get it back on the move again.

 

Front propellor shaft to transmission case clearance issues, noise of the transmission itself, parts can be hard to come by. There were 3 versions I'm aware of and certain parts for some versions are not readily available or available at all. Couple this with they haven't been manufactured since 1967 and you can see potential issues. The only reason to use an SM-420 is if you absolutely need/want the 7.02 first gear IMHO. Otherwise there are better options. Again, IMHO.


Sent from my iPhone

 

Take you time in deciding, and figure out what the plans are for the jeep. This is what is going to dictate which way you go for a transmission. If you go with the four speed route, just go one step at a time and I'm sure one of the members who have done that swap (what ever that transmission it may be) can help.

Also, keep an eye on craigslist I sometimes see t14s come up make sure you get the front adapter with it. If you're going the three speed route.

 

Do you have a transmission at all? Where are you located in the country?

Herm the Overdrive Guy sells rebuilt transmissons dthat would get you on the road comparatively quickly. http://hermtheoverdriveguy.com/?page_id=1308 If you have a T-86, they are not complicated as such things go. You can rebuild them with T-90 guts and have something functionally equivalent to the original T-86.

 

Having went the T86-90 route recently, I wouldn't recommend it...I would have preferred a 4 speed but my jeep is my only vehicle & at the time, I was in a jam, so I figured the T86-90 would be the best way to go. If I wasn't in too much of a rush I'd give R&P a call & ask them about this. http://shop.rp4wd.com/product/red-transmission it might cost a little more than doing the T86-90 but IMHO it might be the better way to go.