'79 cj7 identification help

[jeepno4]

Just purchased a 79cj7, not sure if it is the standard cj7, or the renegade or laredo. Thinking it may be Laredo, seats look like they may have been top of the line when they were new, now, not so much. Without the decals I can't tell for sure. Does anyone have a link I can check the VIN no. on. It does have the 304 with the TH400 automatic w/QT, if that helps. I would also like to get some opinions on the quadratrac. Thinking of swapping with Dana 18 and new tranny, but not till I get to try out the QT. This is my first CJ, haven't even had it long enough to get it dirty, but I soon plan on fixing that.

Any help will be appreciated, Thanks!

[Jim_Lou]

Welcome!

The special models like Laredo and Renegade were trim and option packages. I'm pretty sure there is nothing in the VIN that would tell you that. It would take a registry where you could look up the original invoice or build order for your serial number to find that. As far as I know that went away long ago, but I could be wrong.

Will is our resident Quadratrac expert. He has one that he beats the tar out of regularly with good results. The QT has two peculiarities - the chain and the fluid. The chain is more or less a wear item that needs to be replaced periodically. If run too long it will stretch and eventually start to slip under power. They're neither expensive nor difficult to replace. The fluid is specific to the QTs and substituting can cause problems.

Will can tell you more when he checks in.

[TeamRush]

You will find a plug dead in the bottom of the Borg Warner 1305 or 1339 Transfer Case,
Always a good idea to remove that plug, use a screwdriver to feel for the chain slop.
Excessive slop, and it's time for a new chain.

That also give you the opportunity to refill the lubricant, which probably hasn't been touched in years...

Switching to a Dana 18 isn't as easy as it sounds, the rear axle is a passenger side off set to match the Borg Warner transfer case output to the rear.
That can cause some drive shaft fitment problems.

Since you have a Narrow track width Jeep,
And since Jeep used a Dana 44 in the narrow track flavor until '74 or '75, it might be a good idea to start by watching for a stronger rear differential if you intend to wheel it much.

The D-44, IF found for reasonable money, it would be a good upgrade if you switch to a manual transmission and Dana 18 or Dana 300

-------------------------

The Q-Track can be a very tough customer. They get a bad reputation because people don't service them.
With a good chain (NOT something from 'China') they get around just fine.

Your TH 400 is the 800 pound gorilla of automatic transmissions,
But there are a couple of things you need to look for to keep it alive.

One is the 'Kick Down' switch on the throttle linkage.
There should be an electrical switch on your throttle linkage under the dash,
And that connects to an electrical terminal on the drivers side of the transmission case.
That switch MUST be working!

Without it, you WILL burn up the clutch packs in short order.
This particular transmission doesn't use the traditional throttle valve (Cable or linkage to trans) so you must make sure that switch is working.

The other thing is the 'Vacuum Modulator' on the passenger side of the transmission, front.
Without that vacuum modulator hooked up and working, the transmission will 'Shift Stupid' either way late or way early...

These vacuum modulators occasionally need replacement, the diaphragm inside gives up, and you start sucking transmission fluid through them.

There are two kinds,
There is a LARGE stupid looking kind, which usually has a 45 degree elbow attached to the case, then the modulator sticking up at about a 45 degree angle... (front drive shaft clearance)

Or they have a neat little vacuum modulator sticking right out of the case.

The two are NOT interchangeable.
The different canisters will interchange,
But the spool valve inside the transmission is different (Longer) when the Elbow adapter and large canister is used,

And the spool valve is shorter for the smaller, direct bolt on canister.

--------------

Either way, there is an adjustment screw in the vacuum nipple on the canister.
If it's shifting way too early, remove the vacuum line, turn the screw in a couple of turns at a time until you get it shifting where you want it,
If it's shifting too late, then back the screw out,
Don't forget to put the vacuum line back on the nipple!

One other word of warning...
Most of these I see, some PO (Previous Owner) has removed the steel vacuum line down to the canister.

There is supposed to be a steel line, with rubber vacuum line at both ends to connect between manifold and line, then line to vacuum modulator.

If they have run a vacuum line all the way down, the vacuum line contracts under vacuum and expands under less vacuum,
And that TOTALLY SCREWS WITH THE SHIFT POINTS,
You CAN NOT buffer that vacuum signal like that and expect the transmission to shift correctly,
And that line replacement happens WAY TOO OFTEN...

Steel lines are easy to fabricate, just buy a stick of brake line and bend it to fit, cheap and easy!

This should get you up to speed with your PO as far as the things they commonly do wrong you need to look at right away...

[Jim_Lou]

Jeep used the AMC 20 rear axle in narrow track form until at least '79. In spite of the abuse heaped on it, under a stock Jeep it's a suitable piece, and with one-piece shafts is a very good piece.

[Raduckal]

also the manual transfer case for that was the Dana 20. you could look for a Dana 300 or whatever if you are thinking of a new transmission.

[LEVE]

I hope this works, it's a little light reading about the Quadratrac from CJDve who loved the Quadratrac:

Off-Road Forums & Discussion Groups - Search Results

[TeamRush]

AMC 20 started in '76 for sure, and lasted through to '85
I don't know about '75, haven't owned one, but I know it was still D-44 in the rear through to '74

The DJ mail Jeeps used D-44 Rears well after everything else went to AMC 20, I've seen D-44's in the rear of DJs until the late 70s.
I have to assume they were stock since who would swap a D-44 into a mail jeep?

[jeepno4]

Thanks for all the info. I am considering keeping the QT after some research last night on my own. Seems like a decent set up. Going to check the chain and change all the fluids this weekend. Thanks again!

[WILL]

Originally Posted by TeamRush

Switching to a Dana 18 isn't as easy as it sounds, the rear axle is a passenger side off set to match the Borg Warner transfer case output to the rear.
That can cause some drive shaft fitment problems.

Since you have a Narrow track width Jeep,
And since Jeep used a Dana 44 in the narrow track flavor until '74 or '75, it might be a good idea to start by watching for a stronger rear differential if you intend to wheel it much.

The D-44, IF found for reasonable money, it would be a good upgrade if you switch to a manual transmission and Dana 18 or Dana 300

-------------------------

Just a little correction here. The dana 18 is an offset rear output transfer case too. To swap it in, you'll need a TH400 to dana 18 adapter kit which will also require taking the transmission completely apart to change the output shaft. There was a factory adapter used with the dana 20 which uses the same case as the last dana 18 but it is said to be weaker than the aftermarket adapters.

I do like the QT transfer case. I've had my 79 CJ7 since 1994. I have changed the chain out a few times. When it starts jumping under heavy load, it is time to change it. TCL-1 is the correct fluid to use with it.

I moved the vacuum switch from the glove box to next to the headlight switch to make it easier to reach.

I have swapped most of the drivetrain in my jeep but have kept the QT. I have a 700r4 in front of it now. I also used dana 44 axles from a 1975 Cherokee that had a quadratrac. I have lockrights in both axles. In full time mode, the torque steer is terrible so I put locking hubs on the front and leave the transfer case locked (emergency drive) while on the road.

[TeamRush]

I STAND CORRECTED.
I saw dana 18, was thinking Dana 20 since that's what I deal with most.
Sorry, brain fart.

I can't keep Dana 18's straight, large pinion, small pinion, this and that...
I throw a 20 or 300 at them and get it over with!