T400/QT to T18/D20 swap... anyone done it?

[woodsboy00]

I threw this in modified, didn't think it belonged in stock.

I have a '76 with 360/400/QT, want to change to change to a '79 T18/D20. I'll have complete vehicles and all access to all parts off both. Everything except for '79 axles. Questions

1. Anyone for see any problems? I know the d20 can be ran behind the 400 with an output shaft change. I want the 4 speed specifically. I know the rear 44 is pass offset, how much longer (making the rear driveshaft angles more severe) is the t18/20 versus the t400/20 set up?

2. Anyway my drive shafts would bolt up? Or a combination of the '76 and '79 driveshafts? I'm guessing I'm not that lucky....

3. How bad is it to get the clutch pedal assembly set up on my '76 auto?


That's all I can think of for now... I tried searching and found next to nothing on the subject.

[tgreese]

What is the '79 vehicle - J-10, NT Cherokee, WT Cherokee, some other Jeep?

Re the engine, transmission and transfer case, it will all bolt in if you use enough parts from the T-18 donor and the donor is a FSJ. The only way the driveshafts will work is if the donor is a FSJ with the same wheelbase as your Jeep and you use the driveshafts from the donor. If you have a FSJ donor, the donor's front driveshaft will fit.

There has been a lot of discussion about whether the centered output of the D20 will work with the offset rear axle used with the Quadratrac. I would think it would be ok, but it definitely depends on the length and angle, sp. how much lift you have. There's a chance you'll need to find a centered rear axle. IIRC member Dr. Marneus went through this, and his project is documented here and on IFSJA.

Re the clutch, the sled bracket that the pedals hang from have different PNs between the manual and automatic cars. You may be able to put the manual pedals in the automatic bracket, but I think you'll just have to try it. Note that there is a mid-year change in the 1979 from the old ball-joint linkage to a linkage where the rod end is simply bent at a right angle. The early design is more like your '76, but I'd think at worst you you have the type-2 linkage and you'll have to move over everything connected to the pedals.

[woodsboy00]

Thanks for the info. Sorry about the missing info.

Donor is a '79 cherokee. All would be swapped into my '76 cherokee. I think it actually used to be a 400/QT jeep that was converted to t18/d20

[tgreese]

Well, I was describing the factory T-18 equipment. A conversion could have many different donors.

The factory T-18 for the Cherokee has a long input shaft and a spacer that adapts the Jeep T-18 case to the Jeep T-14/T-15 bell housing. The spacer moves the shifter stalk back into the FSJ cabin. Any other T-18 will likely have a short input shaft that will put the T-18 stalk under the dash, if you keep the factory position for the V8. That can be dealt with, but it's not as tidy as converting with the proper factory parts.

[woodsboy00]

I'm family certain the t18 is from another FSJ. It has the shifter perfectly placed in the cab