q-trac swap?

[twrightjeep]

hello everyone. i have a 78 wagon 360 ,th 400, q-trac. i want to swap in a better t-case. is there a np 205 that will just bolt rite up with the correct pass. side drop? i have access to a centered rear axle. the th 400 is fairly fresh and i dont want to rip it apart to change the output shaft. any help? thanks.

[FSJ Guy]

hello everyone. i have a 78 wagon 360 ,th 400, q-trac. i want to swap in a better t-case. is there a np 205 that will just bolt rite up with the correct pass. side drop? i have access to a centered rear axle. the th 400 is fairly fresh and i dont want to rip it apart to change the output shaft. any help? thanks.

How about another working QT?? :D

Really. I like them as t-cases. When put together right, they are pretty stout.

[fulsizjeep]

Welcome to the madness! :cool:
I'll let others speak up on the 205 options... There are a couple.

Don't try to talk them out of a swap Ethan. That makes more QT parts for fools like us. ;)

The T400 and Quadratrac union is unique to Jeep. The T400 bell housing is unique to the AMC engine. There is a 10 spline tail shaft that is only for QT. So, you have to tear down the T400 to change the tail shaft to for a different transfer case. The adapter is also unique between the T400 and QT.

[wickedwagon767]

No other transfer case will bolt up in place of a quadratrac without modifications

You will have to completely dissasemble the transmission to change the tailshaft (last part to come out, and first part to go in during a rebuild) to the correct one. The Quadratrac uses a looooooong 10-spline tailshaft from the transmission. The NP205 when used behind a TH400 trans used a 32-spline tailshaft. You will have to find this tailshaft and re-rebuild your transmission to get it in there. Then you will need to source the TH400 to NP205 adapter/coupler. (2) kinds exist. One has a "racetrack" pattern on it that resembles a "figure 8" used in the 1970's and early 80's. The other is a round 6-bolt version used in the mid-late 80's.

On top of that you will probably need to modify the transmission crossmember to get the 205 to fit and you will need to cut a hole in the floorboard for the 205 shifter.

You will have to have driveshafts rebuild or custom made to work with the 205

That is the general-smear of it

:D

[twrightjeep]

i appreciate the replies. and the whole reason for a swap is to go to part time, i realize the q/t is kitable and i was just hoping that something else would bolt up. i think i will source a th 400 with a dana 20 and go that route. all the 20's ive had were fairly strong.

[jeeping1974]

I ran a part time QT case from BJ's Offroad and it held up nicely. Only reason why I swapped it out for a D300 is, I want the option of a lower low range and twin stick for more wheeling options. Easiest and cheaper way is to get a TH400 with a D20 like you talked about.

[FSJ Guy]

That's an awful lot of work just to get PT "ability".
If you really want PT that badly, put locking hubs in the front and stick the QT in E-drive and forget it.

[BRUTUS]

Send a PM to Waggthis (Dustin). he recently put a 205 in his waggy without much hassle. I still don't understand completely how it bolted right up and I don't know off the top of my head which auto trans he has (not an auto trans guy).

[twrightjeep]

thanks man....... i'll ask him

[Dmntxn77]

Like said before, there is no way to just bolt up a 205 to a amc th400 without changing either the tranny tailshaft, or the 205 input. I have never heard of anyone changing a 205 input to fit the qt 10 spline shaft.

BTW, its a 7 hour drive, but I have a AMC th400/d20 combo in my parts rig if you are interested.

[WaggThis]

i have a 1971 wagoneer with a Buick 350 and a Th400 / dana 20 and all i did was drop the dana20 out with the adapter and went to the junkyard and got a Np205 out of a 1978 chevy that had a th400 in it also and took it home rebuilt it and put it in.

i did have to build a new crossmember and have the drive lines adjusted and i have been driving it for 1 year now +moab with no problems:thumbsup:

[Dmntxn77]

i have a 1971 wagoneer with a Buick 350 and a Th400 / dana 20 and all i did was drop the dana20 out with the adapter and went to the junkyard and got a Np205 out of a 1978 chevy that had a th400 in it also and took it home rebuilt it and put it in.

i did have to build a new crossmember and have the drive lines adjusted and i have been driving it for 1 year now +moab with no problems:thumbsup:

Its not the same....

[elbastardo]

That has got to be the simplest swap i have heard of yet:thumbsup: The hardest part of the swap would be the 400/205 adapter availability.
What flange is the AMC 400 output?

[wickedwagon767]

Its not the same....I haven't seen the length of the output shaft from a TH400 that was bolted to a Dana20 ,but GSMikie told me they were 32-spline back when I was looking into a Dana20 swap.

It may very well be possible. The length of the output would be the maker or braker.

[Dirtball]

Or... you could get a GM Turbo400 to AMC engine adaptor from BJs, find a T400/D20 combo from a GM, bolt it all up, and go... you'll still have DS and mount concerns, but this might be easier than having to gut two trannys just for the output shaft...

[wickedwagon767]

The only "GM" TH400-20 combo I'm aware of is the BOP TH400-20 combo used in the late 60's early 70's FSJ's and there are factory adapters available to use those behind an AMC V8

I know GM used a Dana20 in the Blazers/Burbs/Pickups during the same time period,but as far as I know it was only behind the TH350

[elbastardo]

I ran a SBC TH400/D20 combo in my 64 for a fiew years, the only thing jeep was the Tcase, and it was a 32 spline input.
I have a buick 350 400 20 combo setup that is keeping the property value down, LMK if your interested

[BRUTUS]

That has got to be the simplest swap i have heard of yet:thumbsup:

No kidding! Dustin was getting it in Moab and if there was any incompatability between the two we would have heard it!

What flange is the AMC 400 output?

It would have to be the 6-bolt round pattern.

[Ralph Rogers]

On a side note, what about the offset of the rear end for the QT compared to the center of a 20 or 205, 208, .......... etc?
will that cause any problems?
Ralph

[cajun_lad]

Casey ran a QT with a centered diff for a while w/o problems. I would imagine doing the reverse would be ok as well. As far as I understand it, u-joints don't care about left to right or up and down, as long as they are within their operating limits, it's fine.

[wickedwagon767]

On a side note, what about the offset of the rear end for the QT compared to the center of a 20 or 205, 208, .......... etc?
will that cause any problems?
Ralph

You would think someone would have binding issues with that setup,but everyone I have talked to that has a centered dana20 case and a Q-trac rear axle (or vice versa) hasn't noticed anything other than some driveline vibration at freeway speeds

[Dmntxn77]

There is no negative effect. The dirveline does not know.

My 79 with a D20 had an offset pumpkin from the factory.. Maybe not as offset as the QT rear, I never measured it, but eitherway, it was offset to clear the fuel tank.