Early cj, 5.38's not low enough

[gliryan]

So I've had my postal, a 1970, out wheeling twice now, and both times I really felt like the gearing wasn't low enough. This last time really showed it as I really focused on the clutch to get me over stuff. I'm running an F head, a 3 speed (can't find casting model number…), stock axles with 5.38's, d18 tcase, and 33" tires. The motor has plenty of power to move the jeep around, but the gearing just isn't there. Has anyone else dealt with this issue? And what are my options?

I'm looking to move to wider axles, and likely 4.56's for gears as I can get some for a good price. But with the current drivetrain I just don't think thats a good option right now.

I looked at my tire rotation vs drive shaft rotation today. At first I thought I had 2.73's, but after thinking about it and researching it again I re-tested and got ~5.38's (only did half the test the first time). So the axle tags are likely correct.

 

[tarry99]

So I've had my postal, a 1970, out wheeling twice now, and both times I really felt like the gearing wasn't low enough. This last time really showed it as I really focused on the clutch to get me over stuff. I'm running an F head, a 3 speed (can't find casting model number…), stock axles with 5.38's, d18 tcase, and 33" tires. The motor has plenty of power to move the jeep around, but the gearing just isn't there. Has anyone else dealt with this issue? And what are my options?

I'm looking to move to wider axles, and likely 4.56's for gears as I can get some for a good price. But with the current drivetrain I just don't think thats a good option right now.

I looked at my tire rotation vs drive shaft rotation today. At first I thought I had 2.73's, but after thinking about it and researching it again I re-tested and got ~5.38's (only did half the test the first time). So the axle tags are likely correct.

Well if 5:38's are not low enough why would you want to go to 4:56??
Pull the cover off one end and count the gears to make sure.
I do not believe you can get anything lower than 5:38's. The 4-banger and 5:38's were pretty standard but not with the 33" tires which makes the overall gear taller.
The only other solution would be bigger motor / more power ,a granny low Transmission or getting a Dana 20 Transfer Case which in 1970 you may already have a 20 and putting a 3 to 1 tera gear in it.

 

[Incommando]

As you call it a postal I assume you started with a 2wd '70 DJ5. What was the donor year for your drive train when you converted to 4wd? Or at least what axles did you use? If you swapped in something from the F-head/D18 era they are probably a D25 or D27 front /19 spline 2-piece axle Dana 44 rear? If so 33's are really pushing your axles and the axle swap is probably a good thing. If you retained the '70 rear axle there is a 50/50 chance it has the stronger flanged Dana 44 . The tranny should be a T-90 or a T-14 . Knowing the year of the donor might narrow that down but for a few years the availability overlapped. I am betting T-90 as from the Limited experience I have with them the T-14 was used behind the 225 & the T-90 behind the 134. I am sure that there was probably some variation, though. it wouldn't be a jeep if there wasn't...

The factory used 5.38's to turn even the stock 28"-ish tires and that is lowest ratio available for for the D25/27/30. You can get a 5.89 for a Dana 44 if you swap to a set of Dana 44 's front & rear but that is not a huge change. IIRC the 134 when fresh made like 60-70 horsepower at the flywheel and probably only put a max of 50 hp to the ground, and that is probably being generous. A lower gear set in the low range of the Transfer Case will help off-road but for the drive train & tire specs you listed the on-road performance is probably hard to live with, too. Turning 33's is a bit of an issue for that low of output. The only answer then is more power. I think you are seeing why engine swaps were common in jeeps.... With the short snout on a Kaiser-era DJ a swap to a jeep 225 V6 (an option in the CJ of the era) or a later 231 (3.8) Buick or 4.3 Chevy V6 might be the way to go to get your jeep to be more user friendly.

Swapping in a '71 or newer postal grille would more easily allow you to do a V8 or even I6 swap as it moves the radiator forward. V8 swaps are possible with the short-nose CJ's as-is but they have their own set of issues that the longer nosed versions do not. Of course more power brings on its own issues with cooling and drive train strength. My 2A was ok with the flat head 4 but once a swapped in a 225 I started twisting axle shafts in the rear D41 ( early version of the Dana 44 ) with 32's.

 

[gliryan]

Its just a postal body on a CJ frame. I'm not 100% on the year of the frame, but believe it to be around '70. C channel frame, rear Dana 44 , front d27, not sure on the Transmission but I have been told it is a T-90 , and it has an offset rear output tcase so d18. It didn't come with a motor, so I put in an F head. I do have a 360 sitting here…just didn't want that much weight or do that much work to get it in.

I've been extremely surprised I haven't broken anything yet on it. There are a couple times it has started bouncing really bad front and rear before I could get on the brakes. I've got a front hub with two bolt holes stripped and one broken off to boot. The rear is a two piece Dana 44 . I've even got 1" spacers on all corners to help out with width, it's just too narrow from the start though. I really want some 60" wide axles under it, and getting 5.38's for them isn't a certainty. I'd like to keep my F head, just want to see what other options I have for lowering the gear ratio.

I have a couple of Dana 20 's here, enough to make one good one. Is the low range lower in the 18 or the 20? I also want to go up to 35" or 37" tires. This only gets driven on the road around town, never at highway speeds. I'm too scared for one reason haha. When going with a Transmission with a granny gear do any of them have the correct bolt pattern already to bolt in? And I really really don't like the newer grills. I'll modify this one and move the radiator before swapping…



slightly worried about tippin over here…

 

[tarry99]

I have a couple of Dana 20 's here, enough to make one good one. Is the low range lower in the 18 or the 20? I also want to go up to 35" or 37" tires. This only gets driven on the road around town, never at highway speeds. I'm too scared for one reason haha. When going with a Transmission with a granny gear do any of them have the correct bolt pattern already to bolt in? And I really really don't like the newer grills. I'll modify this one and move the radiator before swapping…

The 18 has 2.46 and the 20 is a 2.0 but if you wanted to go to a Tera-Low 3.0 gear you would have to use the large hole 4.00" Dana 20 case, which can be converted to offset drive by using your D-18 parts.
35's & 37"s will just make your under powered problem even worst.
Don't know what king of bell housing you have , but it would be doubtful that any granny low truck 4-speed would bolt up without an adapter.
Flat out you do not have enough power or gear multiplication to make this work.
Put the V-8 in , that will solve some of your issues..........

 

[gliryan]

What are the granny gear Transmission options? I'm not too concerned about keeping my offset tcase setup, especially when I go with the ford 8.8 rear I have or any other rear end for that matter. I really don't think I'm under powered that much, just need lower gears! But seriously I think I've got enough motor for just crawling around, I'd like to just get the gearing setup more appropriately. Right now it just moves too fast down the trail. At most wouldn't mind going up to a v6, the v8 is pretty heavy... Problem is finding a setup that will fit in the short early cj frame. I wish this was easier...

 

[tarry99]

What are the granny gear Transmission options? I'm not too concerned about keeping my offset tcase setup, especially when I go with the ford 8.8 rear I have or any other rear end for that matter. I really don't think I'm under powered that much, just need lower gears! But seriously I think I've got enough motor for just crawling around, I'd like to just get the gearing setup more appropriately. Right now it just moves too fast down the trail. At most wouldn't mind going up to a v6, the v8 is pretty heavy... Problem is finding a setup that will fit in the short early cj frame. I wish this was easier...

Go to Novakadapters.com they have lot of good info on there for transmissions and such. You said you had some Dana 20 's there so that is normally a centered output TC so your set there.
Putting a 6:32 low gear T-18 Borg Warner Transmission . in there would help you only in low gear. The Tera-low 3.0 gear for the Transfer Case would help in every gear but I would still pull the cover off of the rear end and verify that gear ratio.
Then I would start looking at gear charts and crawl ratio's to give yourself a better Idea where you need to go on the gearing.
Plenty of V-8's & V-6's in CJ's they will fit.

 

[Incommando]

I am sure that someone will pipe in that they run 44's on a 2-piece Dana 44 /d27 combo but those 33's you are running make those axles time bombs. If all you want is improved off-road ability I believe you can get a tera low low range set for a d18. Run around in low range all day and start off in 3rd if ya need more wheel speed. High range will still suck though. Once yo figure out what tranny you have now you can probably find a jeep T-18 that may bolt in or you can adapt another T-18 or similar tranny. With lower low range gearing and a granny first gear your crawl ratio would increase greatly. Not going to be cheap but nothing worthwhile usually is...

 

[tarry99]

I am sure that someone will pipe in that they run 44's on a 2-piece Dana 44 /d27 combo but those 33's you are running make those axles time bombs. If all you want is improved off-road ability I believe you can get a tera low low range set for a d18. Run around in low range all day and start off in 3rd if ya need more wheel speed. High range will still suck though. Once yo figure out what tranny you have now you can probably find a jeep T-18 that may bolt in or you can adapt another T-18 or similar tranny. With lower low range gearing and a granny first gear your crawl ratio would increase greatly. Not going to be cheap but nothing worthwhile usually is...

Incom,

The Dana 18 won't work with a Tera-Low gear because the input side of that case is only 3.1562".......need to do a Dana 20 case with the 4" input to get those gears inside. You can take the D-18 gear set and stick it into a Dana 20 case and still make it an offset drive. Works good.........

 

[Incommando]

Depending on the year of the D18 ( the year of the OP's is unknown) they apparently do make a D18 low range kit:

| TeraFlex Suspensions

Details:
This kit reduces the 2.43:1 stock lowrange ratio to 3.15:1. This kit works on ‘66-71 CJs, utility wagons and pickups. CJs older than 1966 require a large Dana 18 or 20 Transfer Case housing from a ‘66-79 Jeep®.

Although I could be mis-remembering, I am fairly sure that the CJ's of this era still used an off-set rear diff. If so the D18 mentioned above would also be off-set?

 

[tarry99]

Depending on the year of the D18 ( the year of the OP's is unknown) they apparently do make a D18 low range kit:

| TeraFlex Suspensions

Details:
This kit reduces the 2.43:1 stock lowrange ratio to 3.15:1. This kit works on ‘66-71 CJs, utility wagons and pickups. CJs older than 1966 require a large Dana 18 or 20 Transfer Case housing from a ‘66-79 Jeep®.

Although I could be mis-remembering, I am fairly sure that the CJ's of this era still used an off-set rear diff. If so the D18 mentioned above would also be off-set?

I'm sure that there are some D-18s that do have the large hole? Some say they were behind some of the V-6's but I've seen original V6 motored Jeeps with the small hole case........the Dana 20 case in itself is a little stronger and has some extra webbing.
Either way it is a way for him to get a better crawl ratio.

 

[gliryan]

I'll definitely look into the tera gears more. Right now though there is a 75 f150 for $800 a couple miles from my house. Has hp44 front, T-18 and married tcase of some sort, 9" rear end, and a 360w (big block) with 390 heads on it. I am going to take a look and see if its worth picking up and taking what I want, then selling and scrapping the rest. And there is someone I know with a T-18 /Dana 20 . Whats a combination like that worth?

 

[tarry99]

I'll definitely look into the tera gears more. Right now though there is a 75 f150 for $800 a couple miles from my house. Has hp44 front, T-18 and married tcase of some sort, 9" rear end, and a 360w (big block) with 390 heads on it. I am going to take a look and see if its worth picking up and taking what I want, then selling and scrapping the rest. And there is someone I know with a T-18 /Dana 20 . Whats a combination like that worth?

T-18 Borg Warner 4-Speed and a Dana 20 Transfer Case ?
T-18 must be the 6:32 low gear , that has a 17 tooth input shaft gear, you need to lift the cover to check or try marking and turn it over.
The Dana 20 would be a 2.03 low gear.

Its all about condition........pull the cover on the tranny and look at all the teeth and count the input shaft to make sure it is a 6:32. First and reverse are non-sycro and so if you look at the large sliding gear in the rear that will be Low gear check out all the teeth between it and the counter shaft and the reverse Idler........that's where it takes a beating with a "Cowboy" behind the wheel.
Like wise on the Dana 20 just need to check the gears inside.
I would assume this combo has a short adapter between the two 1"long if it has the longer version it may get to long to go into a CJ5 drive shaft length wise also the Dana 20 is a centered output.
A good used T-18 around $300-$500 and a Dana 20 $200

 

[Incommando]

I'm sure that there are some D-18s that do have the large hole? Some say they were behind some of the V-6's but I've seen original V6 motored Jeeps with the small hole case........the Dana 20 case in itself is a little stronger and has some extra webbing.
Either way it is a way for him to get a better crawl ratio.

troof

 

[gliryan]

I'll give it a look. I forget if it's easy or not to cut down the hp44's so they aren't so wide. I'll have to do a little more research. Otherwise I've got an 8.8 and can get a chev Dana 44 front and cut it down easily. Heres the truck ad, says it has the super low first.
1975 Ford F150 Custom

 

[tarry99]

I'll give it a look. I forget if it's easy or not to cut down the hp44's so they aren't so wide. I'll have to do a little more research. Otherwise I've got an 8.8 and can get a chev Dana 44 front and cut it down easily. Heres the truck ad, says it has the super low first.
1975 Ford F150 Custom

10-4 looks good for parts...................Keep in mind that your rear drive shaft gets shorter when you add the T-18 and the adapter to the Dana 20 also adds to the problem.........the shortest adapters out there keep the length of the T-18 & adapter at 12.87 inches plus the length of the Dana 20 .Some of these trucks had long tail shaft's on them.

 

[gliryan]

Thanks! I'll take a tape measure with.

 

[Incommando]

Of you are swapping everything over that Ford probably has a 205 Transfer Case . It is huge but is even stronger than a Dana 20 /300 although it has a Dana 20 -ish low range of about 2:1. You would need a driver's drop Transfer Case to use the axles from that truck anyway.

 

[gliryan]

Well I'm not buying the truck, he was fairly firm on $800 and I had no use for anything but the Transmission /case. I pulled the rear diff cover off and the gears were stamped 43-8, so yeah low gears…. So that sucks. A guy I know has a T-18 /Dana 20 that was in a short cj, so it has the short adapter. I'm waiting to hear back if it will bolt up to my f-head or not. If it does I may buy it. He says he needs $350 for it though, not sure if that's too much or not.

 

[tarry99]

Well I'm not buying the truck, he was fairly firm on $800 and I had no use for anything but the Transmission /case. I pulled the rear diff cover off and the gears were stamped 43-8, so yeah low gears…. So that sucks. A guy I know has a T-18 /Dana 20 that was in a short cj, so it has the short adapter. I'm waiting to hear back if it will bolt up to my f-head or not. If it does I may buy it. He says he needs $350 for it though, not sure if that's too much or not.

I don't think your going to find much that will bolt up to the F-head! If that is a Ford version T-18 there are two extra bosses that can be drilled and used for an attachment point..............but in either case the T-18 takes a bell housing face that is tall and not so wide to work with with since the Transmission has a lot of girth to it.
Having said that if you were able to change the bolt patterns on your bell housing I'm not so sure that you could find the correct input shaft length.
But never say never..........