Sm 420 Or 465 On 4.3l V6

I've grenaded two healthy t-90s behind F-heads.

 

Nearly all GM engines are the same when bolting up to the T-90. The 4.3L requires a Chevy bell, and the Buick needs a Buick (BOP) bell, but otherwise they are the same from the T-90's POV. All of this is covered on the Novak web site.

The T-90 requires less effort to shift. The Borg-Warner 3-speeds are relatively easy shifters. Any of the truck 4-speeds will be tedious to row in traffic.

 

T90 is absolutely misserable to drive in any traffic. Non synchro 1st gear is a major pita. You are on the right path with a 4 speed truck transmission. Look around enough and you can find one with all the adapters already purchased out of a project that someone has given up on. Patience is your friend.

 

Just throwing an "Option C" out there...

Another trans that should bolt to the 4.3, is short in length, has excellent shifting characteristics, is fully synchronized, has good gearing (3.5:1 first gear option)... is the Saginaw (car) 4-speed. The t-case adapter is in the price ballpark of the SM420's. The only drawback is, some people aren't too keen on where the shifter comes out of the floor since this is a side-shifter, but it never bothered me. It was one of my favorite transmissions.

50-1000 : GM Saginaw 3 & 4 speed transmission to Jeep Dana 18/20 transfer case (with 6 spline drive gear),adapter kit. | Advance Adapters

 

I've had one in my cj behind a dauntless for 17 years. First and reverse are relatively strong, and I don't beat up on the smallish second and third gears. Non synchro first isn't a big deal with a v6 & 4.88's, you can accelerate from almost a dead stop in second gear.

 

I never knew the Saginaw car 4 speeds had a 3.5 :1 1st. I bet that would make a pretty sweet trans combo to a 4.3 and decent gears. I bet it rows through the gears pretty slick. I need my dump truck trans in my CJ-6 but for regular use I bet that Saginaw would be the cats meow.

 

There are grooves machines into the splines on the input shaft.
3 grooves = 3.5:1

 

My '71 had a Saginaw in it when I got it. I liked it except for the external linkage. I often had mud and sticks and junk packed up in there. But, that was mostly my fault. She went around town pretty nicely with that trans behind the 225 and 3.73 gears.

 

Car 4 speeds are not fun unless you a 5 foot tall and 120 pounds. The shifter always ends up under your right leg. Once you jog them over the linkage gets really sloppy fast.

 

Hurst shifter in mine brought it up to standard height and kept slop in check. Not sure if that's an option that's still available?

 

If you want a car 4-speed, the Jeep T-176 is an option. It is the Ford passenger car "top loader" 4-speed with a top shifter, adapted to the Dana 300 transfer case.

The close-ratio T-18 from a CJ is already adapted to a transfer case, but you'd need the Novak adapter for T-15 listed above. It's not the same as the Ford T-18 in terms of adapting to GM engines.

 

I agree in a flatfender. Had a 52 with a m20(?) in it. That put the shifter against my knee/thigh in second. My Saginaw had a tall shifter in it that wasn't bad but yes, just a little sloppy. Not as sloppy as a truck 4 speed though.

 

Novak has an adapter, G9N, that mates a T90C or T90A to the 90 degree Chevy bellhousing. It's $294 and is 3/4" thick. Doesn't require any modifications to the T90. This is what I'll be using to mate a Chevy 153 4 banger to the T90 in my A1. The T90 won't break behind 100hp coming from the 153.

The 4.3 uses the 90 degree bellhousing.

 

I probably have a couple of them. I dont even keep them anymore as not many people are mating a t90 to anything but an F head anymore.

 

One of the G9N ones? You probably have a customer. Hang on to one and I'll get it in Puyallup in March.

Agreed the T90 isn't too popular. I'm keeping it because it (and the rest of the drivetrain) will live behind the 153 and I want to keep the A1 fairly stock, or at least stock-looking. Also, I'll be putting in the T90C gears. I like the quick shifting of the T90 and don't mind non-synchro first. But if I put a 4.3 in anything, I'd opt for the truck 4 speed, probably a NP435. I've found them to be the smoothest shifting of the lot.

 

Perhaps, if you are trying to stay with off-the-shelf" parts. I've been running the same Hurst comp plus shifter in my 3B for 40 something years and it's still nearly as tight as when new. I made my own off-set aluminum cane for it after I adapted it to a bolt-on configuration (the older versions did not have a bolt-on cane) and it has no ergonomic defects. I also made my own shift linkage for that using rod end bearings (heim joints) and 4130 rod. Those ends have worked perfect for maybe 25 years. I don't have a very good photo of that cane.


There is probably a 3" horizontal off-set towards center right above the floor.


My current version of the Muncie car 4 speed isn't really GM. The only GM part remaining is the side cover. Case and gears are Auto Gear Equipment (AGE) with Advanced tail housing/adapter and main shaft. Ist gear is not as low as I would desire at 2.56:1 but with the M22 bevel cut alloy gears and nodular iron midplate, it's pretty much bullet proof and LIGHT. AGE now has a 2.88:1 1st gear version available but that's not enough lower to justify the cost for me. A big caveat on this is I have an engine that will idle over just about anything at 500 rpm. It's the ONLY reason this works for what I use the Willys for.


Perfect Jeep transmission? McLeod's 5 speed IMO. 2.95 1st gear but a 0.63:1 5th, all in a package almost identical to the Muncie M20's and rated at 500 ft-lbs. But I suspect the probability of someone building a adapter kit for it is ZERO.

 

I'm still trying to sort out in my head how the Hurst type shifter and and linkage would mount up with a transfer case vice a tailshaft housing mounting pad. The only thing I can think of would be some kind of heavy duty bracket that would span between the rear of the transmission and the rear of the TC to mount the shifter on.

 

The shifter bolts to the adapter housing. You can see one of the bosses on the above photo.

 

Okay, that makes sense. Thanks!