Borg Warner 1339 Musings...

So, if...a big if, a person wanted to run an auto in a 75 cj6 behind a 304 (say for instance because none of his three daughters can really drive a manual), and if it seems that TH400's with Quadratracs are fairly common, what would be the biggest problems encountered with the conversion?

Specifically:
What would it take to plumb the vacuum system?
Is there a way to make it work with the centered rear axle (CV joint perhaps)?
Is the big saucepan looking piece that sticks out about as far as the rear yoke the indicator that it has the low range option? I looked at the picture on Novak's site but they don't show a picture of one without low range so I am not sure what to look for.
Am I likely to encounter overheating problems with the additional transmission cooling load (stock 304)?

Any other thoughts? Thanks.
Frank

 

Might be better to find a t400 with a 20 that would be a direct bolt-in.

 

I wasn't even aware they had those. I just thought all auto jeeps were q-tracs back then. More stuff to google.

 

1972-73 commando do have a th400 and dana 20 and some wagonneer during these year.

 

The cases back to 67 just used a different adapter to bolt them up. A 72 to 75 j truck or Waggy would pretty much be a bolt in swap.

 

Ok, yes, the big saucepan thing is the low range. It's a planetary transmission that bolts to the back of the transfer case. The QT without the low range is a BW1305 and with is a BW1339.

The offset output will be a problem. With the extra length of the TH400, you may not have enough driveshaft length to allow a centered axle with an offset TC output. Wagoneer owners do it fairly regularly, but that's a longer driveshaft, and sometimes people report vibrations and such. If you ask on the Wagoneer sites, you will get confident responses yes and no.

1973 was the first year for the Quadratrac, and it was optional in '73. The TH400 came with the Dana 20 before that. You could look for '71-72-73 Wagoneers or J-trucks with an automatic or as above, the '72-73 Commando could be a donor.

Around 1974, AMC switched to its own case design for the TH400, bolting directly to the AMC engines. Prior to that, they used the "universal" case originally intended for the Buick nailhead motors, with a ring adapter between the transmission and engine.There was also an adapter that holds the converter end to the crank. Even the AMC case transmissions need a bushing in the crank end to support the TH400 convertor end. With the nailhead transmissions, you will have trouble finding a replacement convertor and/or flex plate if you need one. The AMC-case transmissions are fine re parts.

Parts for the Quadratrac are an issue. Since the chain drives both front and back wheels, the OEM chains wear out in say 60-100K miles. The OEM source is gone, but there is a USA-made replacement ... $250. Pretty much all the rest of the service parts are gone, so you probably should put parts units away if you want to keep driving a Quadratrac Jeep. Read here about the Quadratrac - Jeep QuadraTrac

The other junkyard swap would be from a '80-up 304 (or 258) CJ-7 with an automatic. That would be a TF999 (again, an AMC case, the A999) and a D300. Some have used the A727 from a '80-up Wagoneer, but I hear conflicting reports. Supposedly the A999 was chosen for the CJ-7 because its pan does not stick out like the A727, avoiding driveshaft interference. IIRC the A999 was used in the early XJ and the YJ, but those would be driver's drop, and you'd have to adapt a passenger drop transfer case (with the obvious option being a 300).

JMO - both the TH400 and TF727 are strong but inefficient. It's appealing that you could grab a compatible transmission and transfer case from a single vehicle, but with today's emphasis on fuel economy, it's not a very appealing swap IMO.

 

Not really what you asked, but....teach them to drive the manual. My wife learned when she was 14 or so, she can drive anything, if it starts.

 

Tim wrote an excellent description of the QT. The vacuum control is used to lock the front and rear drive together for "emergency" use, otherwise, there is a differential between the front and rear outputs for regular conditions. Keep in mind, the QT was a full-time 4wd system, not selectable (unless you installed an aftermarket Milemarker kit). Plumbling the vacuum system is very simple. Just pull a vac line from your intake manifold and you will need the "emergency" switch that was in the donor's glovebox or dash. There is a single vacuum pod that actuates the locking mechanism.
As Tim said, the Morse chain supply has dried up, and the Omix replacements are, in my opinion, only good for a show vehicle that is rarely driven. Other than the chain, the QT is nearly indestructable, and the chain is not weak- just scarce.
I agree, you will need an offset rear axle in a 104" chassis to use the QT. The trans/TC donor CJ7 would likely have the axle too.
You will need a trans cooler for the TH400, either in the radiator tank or external. You may have to upgrade your radiator anyway.
As Daryl said, a Commando donor TH400/D20 would be the way to go, especially if you can find the trans with the AMC bellhousing used with the QT. The only regative is the D20 is only a 2:1 reduction for low range vs 2.6:1 approx for the QT. You cannot just swap the AMC TH400 (used with the QT) to bolt up the D20. The QT version and the D20 versions of the TH400 had different output shafts that are specific to the transfer case used. If you are comfortable building these transmissions, the internals can be swapped around to configure it to your needs.
I have a project in the garage with an AMC 360/TH400/QT, so I am partial to this system. If you have driven vehicles with this system, you will know how capable they are, both on and off road. You will want the BW1339 version with the reduction/underdrive case.
As you see, nothing is that simple, but it can be done. Yes, it might be easier to teach your daughters to drive a stick!
-Donny

 

Once again I am impressed by the wealth of knowledge people are willing to share here (everyone listed above). I do have an offset 44 axle available but don't know if I really want to go that route. Another option might be to give up on the 304 and go with Chevy stuff, 350, 700r4. I like keeping things original to some degree but I also could gain a low first gear, an overdrive, and tbi if I gave up on the AMC original angle and stole the running gear out of a 91 Blazer that a friend is storing /abandoning here. As far as teaching my daughters (all adults) to drive a stick, that's not likely to happen. They can run my GPW with the SM420 around the hunting club in 4 low, but they would never be able to drive in two high on pavement, and I don't have the patience to teach them all now.

 

Too bad you traded the 350 and 700r4 for the Jeep in the first place. It really is the perfect drivetrain especially if you throw a 300 behind it. The reason a 360, t 400 and a 20 is enticing is that the whole setup can still be found for almost nothing in a J truck or waggy.

 

The Morse chains originally supplied by Borg-Warner have been out of production for several years now. Story is that the tooling wore out and they chose not to continue production. Owners were finding NOS chains n parts houses, dealerships, etc. for a few years, but that's pretty much gone. As Donny mentions, the import chain (Crown or Omix) does not last very long ... there was a period when that was all that was available. BJ's has now introduced a USA-made chain that supposedly is sourced from Ramsey (according to forum discussion - BJ's is not saying). First reports are good. BJ's also has some internal parts (sp. cones) that had never been supplied individually. QuadraTrac BW1339-BW1305 Parts

JMO - these are currently boutique parts and I predict that they will be available for maybe a decade at most. It's true that these cases work great when they are in good repair, but I would not choose the BW13xx for any car other than one that came with it - their future is too uncertain. If you want full-time, I don't know of any passenger drop cases that would work for a CJ ... you could pick several different New Process full-time cases if you went to a driver's drop front axle.

 

Great info in this thread. Wish I had a fraction of the knowledge you guys possess. And then, a functioning memory bank to remember it in. I copied much of this into an email to myself. Thanks folks.

It is a shame that those parts are so expensive and hard to come by. I've been in a couple JeePs with the Quadra-Trac (a Wagoneer and a CJ-7) and was quite impressed with their ability. That Wagoneer, with stock size street tread, went places that still stick in my mind as impossible for a bone stock vehicle.

 

This is only a few hours away
67 Jeep V8 drive train

 

One of the highest torque gas motors ever made. These are the transmissions that I have been using forever with a Buick v6. They are a direct bolt in. The 67 is a really good year as it is completely vacuum modulated and doesn't have a kick down switch on it. Don't let anybody tell you they are too long either. I have put more then a dozen of these transmissions into flatfenders behind a v6.

 

Next transmission in my 2A is going to be automatic for sure

 

Power steering brackets included too. It's been for sale for 2 months. I'm sure the price is negotiable