offset rear diff

[LewMan]

o.k. were all j10 and j20 rear diff. offset a few inches to the passenger side to accomodate both the qtrac and non-qtrac set ups? if so, were all years that way? what the hell else would a person be thinking about at 3:00AM on a Friday night?

Lewman

[ChicksDigWagons]

The D20 J's weren't offset. The qtrac J trucks were, but its really not a drastic offset and if you weren't distinctly looking for it you might almost not notice. In the greater scheme of things you can get away with either or for either application. The compound angles are not going to be excessive IMO.

[ChicksDigWagons]

Oh, I think this is where I'm supposed to say "This isn't Hardcore Tech" biatch.

But I'm not real good at being an asshole.

[LewMan]

Thanks for trying! I've been flamed by the best, I'm not skeered!

I'm buying a '78 j20 qtrac and will swap out the t400 tailshaft to accept a part time transfercase, possibly a 205 or just a stock jeep transfer.

I want the ffd60 but was worried if the offset would mess me up, after the 4-8" suspension lift.

should i run cv joints to absorb the compound angle?

is that hardcore enough 4u or do i have to talk 4link???

lewman

[ChicksDigWagons]

Originally Posted by LewMan

Thanks for trying! I've been flamed by the best, I'm not skeered!

I'm buying a '78 j20 qtrac and will swap out the t400 tailshaft to accept a part time transfercase, possibly a 205 or just a stock jeep transfer.

I want the ffd60 but was worried if the offset would mess me up, after the 4-8" suspension lift.

should i run cv joints to absorb the compound angle?

is that hardcore enough 4u or do i have to talk 4link???

lewman

Actually, it would be better to run a non CV driveshaft because there is no way you can get the pumpking pointing directly at the output of the T-case so there is always going to be some vibration from the rear U-joint with a CV style joint at the T-case end. With two U-joints you can keep them balanced even with compound angles.

It sounds like you're planning on keeping the D60 in the J-truck, with that kind of wheelbase its pretty much a non-issue anyway. I'd be different if you wanted it in a CJ5 or something with an ultra-short wheelbase.

[jpnjim]

I disagree with J-trucks using D20 T-cases not having their pumpkins offset.

My 73' J4000 rear (SF D60) is the D20 version, and is slightly offset.
I've seen the QT version of this same SF D60, and it's much more offset.


My understanding is the offset was done for gas tank clearance on non-QT vehicles.



edit,
I searched around a little for this, and there's alot of conflicting info out there.

So I'll just stick to the fact that my D20 equipt J4000 rear is slightly offset, and have seen the same SF D60 from a QT, and it was greatly offset.

[Brink_]

I had always thought they were offset to clear the gas tank. Regardless of t-case. But I am no expert on J trucks. Just know what I have seen on 3 or 4 of them in person. 2 were definately D20's and were not centered.

[Skorch]

I have a 1969 commando with a 1970 jeep wagoneer rear axle 3.5 inches offset to passenger side.It has a cv upper with a 33 inch long driveline and has no vibration at any speed up to75 mph. Hope this helps

[LewMan]

[QUOTE I'd be different if you wanted it in a CJ5 or something with an ultra-short wheelbase.[/QUOTE]

yes, I did this with a '77 cj7. born v8,t400, qtrac. I swapped in '74 axels front and rear (rear was center diff.), '74 transfer case (don't know what it actually was), adapter plate (advance adapters? t400 to jeep transfercase) and the appropriate t400 tail shaft. worked great after building the motor .30 over. pretty good project for a 16 y/o!

no problem with vibration. still have the cj, sort of, and was thinking of using some of those parts for the j20 project. that's what started all the hubub.

o.k-question: do some FSJ's with part-time use a stock adapter plate with t400 to part-time transfercase? can this adapter be found in junkyards? AA gets a high dollar for this.

thanks for all the info.

lewman

[ChicksDigWagons]

There is a stock TH400 -> D20 adapter, but is supposedly pretty weak. I've chosen to stick with the Q-trac behind my TH400...its not the best, but it gets the job done!

[rustywagoneersdotcom]

run the QT til you pop it, then worry about swapping!!

the QT's were used in some serious race and rally iron...
admittedly, they were brand new, and factory supported race teams.

peace!
Dave

[Grantshire]

QT axles are offest to the greatest degree because the QT rear output shaft is in line with the front output shaft and not the transmission (like the old 18 TC). Manual tranny and earlier autos had slight offset for coffin style gas tank under the driver's side. When the FSJ's swithced to the AMC 20 rears they became a centered differential. Jeep switched back to a Dana 44, but centered this time, during the last years of the big Jeeps (86-91 for the Grand Wagoneers). If you can find the last of the J trucks they also had a centered Dana 44 (at least the J10 did).

[Brian1]

I have a rear 44 from a late 70's J10 and the yoke is offset to the pass side by 6". The truck had a Dana20. This axle is for sale if anyone is interested (PM me)