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Noob Drivetrain ?s about my 79 CJ5

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Noob Drivetrain ?s about my 79 CJ5
H

huntnCJfool

Jeeper
Posts
110
Thanks
3
Location
Meeker
Vehicle(s)
'79 CJ5, 258 I6, Weber 38 DGMS, T18 & Dana 20, AMC 20 Rear, Dana 30 Front, Rolling on 31x10.5x15's
Hello all,

I am hesitant to post this ? but I cannot find any one resource after searching and looking at the sticky for Transfer Case /transmissions. I know one of you guys will just know the answers as well...

I am trying to figure out what my differential gearing, axles, Transmission , and Transfer Case are in my jeep so that I can understand more of the conversations as they relate to my jeep as I familiarize myself on the forums. I also am interested in locking up the rear with a LS or locker at some point so I am spending some time here to learn more. My jeep is all stock 79 CJ5 with the 4 speed and a single stick on the TC. I think I gather that this is the T-15 tranny, but thats about where my sleuthing ends.

Help me out?!?
 
A 100% stock 79 CJ5 would only have two manual transmissions: T-150 3spd, or T-18 4spd (6.32 1st gear). The automatic was a GM GM Turbo 400 attached to the QuadraTrac sytem. And no factory automatics were put into CJ5 's.

It would have a Dana 20 Transfer Case (2.03 low gearing), Dana 30 front axle, AMC20 rear axle. Most common gearing would be 3.54, but other options were available. All CJ5 's were narrow track axles. You can pull a differential cover and count teeth, or lift up the Jeep and spin the drive shaft to count rotations. The should be a marking stamped into the rear axle tube. The below site, has a code listing.

This is my 'go to' site for CJ info: The New Jeep Tech Pages!

Lot's of locker options available for the rear and front. For mostly street driving, it's hard to beat a regular Limited slip. More hardcore, slap in a Detroit Locker. But if you live in the snow/ice belt, and plan on driving the streets in that :dung:, I'd shy away from a full (hard) locker. Next step up: ARB airlocker or OX manual or Eaton electric locker. Not certain if all of those are available for the AMC20 and/or Dana 30 . All depends on what you are planning to use the CJ for, and how large your bank account is...
 
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Thanks HackFabrication!

I live on the west slope of Colorado and this is my daily driver & hunting rig so she sees it all. The detroit or similar would probably be annoying and at times dangerous for my needs. I like the idea of the manual Ox locker, not so high on electric air stuff....other than that LS is likely. From reading I gather I probably have the trac-lock LS in my jeep, but it is probably not worth rebuilding if I can spend the money on something more robust.

Nothing planned in the near future, I am going to watch the video in the sticky first.
 
The T-15 is a 3 speed.

The Jeep Tech page has pretty good info. Also, Novak Conversions Home has a lot of good drivetrain and ID info. Ol' Jeep's page has links to the factory service manual. I suggest downloading a copy for reference. It has a lot of good info as well as far as what combos were available.

The T-18 for that year has reverse right and down, non syncro'd 1st & reverse and a granny gear (6.32:1 first gear). On the road, it's basically a 3 speed, but the low first gear is great offroad.

what makes you say the LS is likely? I've seen very few factory LS, even though it was optional. Either way, if you are in need of a rebuild, I've been very pleased with my truetracs.
 
jp360cj said:
The T-15 is a 3 speed.

The Jeep Tech page has pretty good info. Also, Novak Conversions Home has a lot of good drivetrain and ID info. Ol' Jeep's page has links to the factory service manual. I suggest downloading a copy for reference. It has a lot of good info as well as far as what combos were available.

The T-18 for that year has reverse right and down, non syncro'd 1st & reverse and a granny gear (6.32:1 first gear). On the road, it's basically a 3 speed, but the low first gear is great offroad.

what makes you say the LS is likely? I've seen very few factory LS, even though it was optional. Either way, if you are in need of a rebuild, I've been very pleased with my truetracs.
Click to expand...

Thanks for the recommendations I will check them out. Maybe I am wrong I thought I read somewhere that the truetracs became standard gear at some point in the late 70's but I am sure I am mistaken. I have the dealer paperwork and it makes no mention of them.
 
huntnCJfool said:
Thanks for the recommendations I will check them out. Maybe I am wrong I thought I read somewhere that the truetracs became standard gear at some point in the late 70's but I am sure I am mistaken. I have the dealer paperwork and it makes no mention of them.
Click to expand...

TrueTracs were never used by the factory. They are made by Eaton (Detroit) and are a helical gear design Limited slip.

The factory Limited slip was a Track lock with a clutch design. They were never standard, always optional, and only offered in the rear. I've opened up at least 30 CJ rear axles (from 72-86) and never seen a track lock one. They definitely exist, just seem to be few and far between.
 
jp360cj said:
TrueTracs were never used by the factory. They are made by Eaton (Detroit) and are a helical gear design Limited slip.

The factory Limited slip was a Track lock with a clutch design. They were never standard, always optional, and only offered in the rear. I've opened up at least 30 CJ rear axles (from 72-86) and never seen a track lock one. They definitely exist, just seem to be few and far between.
Click to expand...

Ok gotacha...at least I didnt ask what a truetraclock was!

Well that makes things simpler as it seems there are several different Limited slip options for me to look at for an open differential. I looked at my paperwork and I have the standard 3.54/1 gearing. So now I just get to research and save money up to have one put in before next winter.
 
I recently picked up a '79 CJ5 with the AMC 258 i6 / 4.2l and have been asking a ton of questions and doing all kinds of reading about this stuff too. I was also looking to build some new axles for mine and found that a Limited Slip diff is not good for icy conditions. The video in the sticky thread at the top is a great video. The open diff seems to be the best for snow/icy conditions so I have opted to go with the manual OX lockers for my build. I've also started a thread in the Build Forum to document my restoration / modifications. This is a really great forum with lots of knowledgable members!
 
JeeperChris said:
I recently picked up a '79 CJ5 with the AMC 258 i6 / 4.2l and have been asking a ton of questions and doing all kinds of reading about this stuff too. I was also looking to build some new axles for mine and found that a Limited Slip diff is not good for icy conditions. The video in the sticky thread at the top is a great video. The open diff seems to be the best for snow/icy conditions so I have opted to go with the manual OX lockers for my build. I've also started a thread in the Build Forum to document my restoration / modifications. This is a really great forum with lots of knowledgable members!
Click to expand...

Thanks for the advice and absoluetely this and other forums are super useful. I have only tinkered with my jeep (dash lights, other small electrical stuff) and this forum had the info I needed.

I plan to check out the video one of these days, but not really in a huge rush yet. From what I read it sounds like the manual OX locker may be what I am looking for. It is interesting that you say LS is not good for ice (what is though)?, considering how many modern LS trucks there are on the road. Why would that be?
 
What about the lunch box style lockers for the more casual wheeling? I will never be rock crawling, putting a lift or bigger tires on my jeep. I just need to have the ability to get traction to another tire in mud or snow when needed rarely.

Do guys put a locker in the front and then rolling in 2wd with open hubs the locker would be irrelevant in street conditions correct?
 
Apparently the trutrac and other Limited slip diffs don't work on icy surfaces because when you turn there is no grip on the road that tells the diff it needs to loosen up and slip a little. This keeps both wheels locked together and you end up sliding.
 
gotcha that makes sense. Kind of confusing that the guy in the video says they are work great for that and everyone else says no.
 
Snow and Ice are different. I didn't really get that until I saw the video and read what some of the guys here were telling me. Makes a lot more sense to me now. I was looking to put in some Detroit Limited slips but have since decided on the OX manual lockers.
 
JeeperChris said:
Snow and Ice are different. I didn't really get that until I saw the video and read what some of the guys here were telling me. Makes a lot more sense to me now. I was looking to put in some Detroit Limited slips but have since decided on the OX manual lockers.
Click to expand...

I hear ya, I guess the more I think about it putting something like that in THIS jeep just would feel out of the spirit. Having the big OX diff cover is just a bit offputting to me for THIS jeep if ya know what I mean. It is also a lot of money to put into this jeep as I intend to keep it stock.
 
huntnCJfool said:
What about the lunch box style lockers for the more casual wheeling? I will never be rock crawling, putting a lift or bigger tires on my jeep. I just need to have the ability to get traction to another tire in mud or snow when needed rarely.

Do guys put a locker in the front and then rolling in 2wd with open hubs the locker would be irrelevant in street conditions correct?
Click to expand...

One of the issues with the 'lunch-bx' type is the stress/load placed on the carrier that was never built for it.
A clutch type LSD would work very well for you.
I say that, as someone who was born and raised in Colorado.
I do play in the rocks here in the Mojave, and run a ft & re DL's.
LG
 
Lumpy Grits said:
One of the issues with the 'lunch-bx' type is the stress/load placed on the carrier that was never built for it.
A clutch type LSD would work very well for you.
I say that, as someone who was born and raised in Colorado.
I do play in the rocks here in the Mojave, and run a ft & re DL's.
LG
Click to expand...

Thanks Lumpy. I assume you recommend the clutch type over the gear type for the reasons JeeperChris and I were discussing in snow and ice?

Would you reccomend going aftermarket for the diff, or do you think picking up a trac lok like this: https://www.ebay.com/i/123602854249...&rk=3&rkt=16&sd=113282219111&itm=123602854249

and rebuilding would be sufficient?
 
Yes on my clutch type LSD.
The AMC trc-loc is a joke.
Look at the Yukon Dura-Grip clutch type LSD.
What's your tire size?
LG
 
Lumpy Grits said:
Yes on my clutch type LSD.
The AMC trc-loc is a joke.
Look at the Yukon Dura-Grip clutch type LSD.
What's your tire size?
LG
Click to expand...

Stock wheels, 215/75R15. Won't be going much bigger either as she will stay manual steering with the OEM rims.
 
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