Saturn OD won't work on a 20. AFAIK there's no OD trans that will fit in a CJ5. You need a low geared 4 speed like a T18, and some higher axle gears for the hiway.

 

Saturn OD won't work on a 20. AFAIK there's no OD trans that will fit in a CJ5. You need a low geared 4 speed like a T18, and some higher axle gears for the hiway.

A t18 has the same final drive gear ratio as his tranny has now which is 1:1. Therefor it will not help any for top end speed and only provides a lower first gear.

The Saturn overdriven which give a 20% reduction in rpm for each gear is only for the the d18 tcase but that tcase is offset output like the off set rear axle in your dads old jeep so swapping isn't an option either. A axle gear swap may be your only option.

 

A t18 has the same final drive gear ratio as his tranny has now which is 1:1. Therefor it will not help any for top end speed and only provides a lower first gear.

Correct. however, the lower first gear will allow you to run a higher axle gear for highway without sacrificing a decent crawl ratio. Accomplishing the same goal as using an overdrive to allow for lower axle ratio without sacrificing top end/highway driving

 

Correct. however, the lower first gear will allow you to run a higher axle gear for highway without sacrificing a decent crawl ratio. Accomplishing the same goal as using an overdrive to allow for lower axle ratio without sacrificing top end/highway driving

I understand that but now we are recommending a tranny swap with gear changes on both axles. Not a great recommendation. At that point it would be better to swap everything or buy a different jeep. I guess it would help if we knew what tire size and gear ratio he currently has or his intentions with the jeep too.

Another thing about having to use the granny gear on the street is you have to shift well before you can actually make your turn across traffic which can be dangerous. You can't cross even one lane with out shifting with anything over 6:1.

 

It sounds like you're happy with the gearing for offroad so leave it alone. There are two routes you could possibly take and both are similar in cost and involve swapping in an AX15 (YJ or XJ) or NV3550 (TJ) 5 speed.

The first option would be to find one of the above tranny's and adapt it to your D20. Your looking at the cost of the new tranny plus $700 for the adapter plus driveshaft modification.

The second option is to also swap in a D300 to put behind the 5 speed. The used tranny and t-case could probably be found for the price of the $700 adapter, the clocking ring to attach either to the D300 is $80-$170 (depending how good of one you want) but if you use the NV3550 instead of the AX15 you have to spend another $200 for a longer input shaft for the D300 (plus driveshaft modification).

So either way you're probably spending at least $1000 unless you can get the tranny and t-case for dirt cheap......but it's still better than $600-$1000 per axle to re-gear.

 

Get a 4 speed for lower 1st gear and bigger tires for increased top speed. The v8 doesnt care what size your tires are.

By the way 600 to 1000 for each axle re gear? Try 350.

 

Maybe with child slave labour in a third world country. The parts for my M20 were over $450 alone.

 

Check out http://www.novak-adapt.com/ they have a ton of good info and parts/adapters to give you an idea of what would work best for your setup. select the knowledge base to get specs and info on both t-cases and trans. As far as earlier CJ5's go, they are very short so your options are limited. I ended up going with a T-18, D18 tcase, and warn OD, with Dana 44s front and rear on 4.11 gears. Can cruise at highway speed and still have a 6.7 to 1 ratio in the granny gear. Good luck!

 

Get a 4 speed for lower 1st gear and bigger tires for increased top speed. The v8 doesnt care what size your tires are.

By the way 600 to 1000 for each axle re gear? Try 350.

Just because you pay $350 per axle doesn't mean that's the price for everyone. There is a thread on this exact topic and the average was $500-$1k per axle. This is labor and parts.

T18a has a first gear of 6.32:1

 

Parts alone for a re-gear can get close to $350.

 

There not cheap but the Ranger Torque Splitter from Advance Adapters is a way to gain overdrive with a Dana 20. My .02 is if you like the jeep and want to keep it save up some coin and do a NV4500/Dana 300 swap.

 

I really don't think any on the 5 speeds discussed above are gonna work in a CJ5-they're just too long. If anyone has installed one, please post up some pics. Even a 4 speed leaves you with a pretty short rear driveline, and the 20 Tcase has such a high output (compared to the 18) that driveshaft angles get pretty steep.

 

Well that leaves very few options then as a range splitter and O/D trans will add length to the drivetrain.

I guess another option would be to find another D18 and an offset rear end to use with the saturn O/D the OP already has. That would involve alot less cost unless the rear needs to be regeared to match what was taken out.

 

anybody selling a c4 to a jeep d18 adaptor?
if so please call or txt mike at
916-275-1439

 

OK, first we need info:
1 True tire size
2 Existing gear ratio
3 RPM's your running at your optimal road speed (real speed, not what the speedo says)
4 What RPM's your shooting for at that speed.
5 What kind of offroading your doing and how much do you do it.
6 Lift kit. This is critical when looking at transmission swaps due to acute driveline angles with the added length of most 5 speed OD transmissions.



With a tach, you may find the RPM's are where you want them, but the fan or other road sounds makes so much noise it sounds like the engine is over-revving. This means you may not need to do anything.

You may not need a crawling gear if your running sand on the coast or fireroading. This means you may be fine with the existing transmission and a gear swap or a switch to an OD transmission is in order to get the desired RPM's.

You may want to do technical wheeling or crawling which will require a very deep first gear. A standard 3, 4, or five speed may not provide a low enough gear to accomplish what your trying to do. This may mean you will need to go to an SM or T18 series four speed. Whether or not you need to re-gear will be will be known when you answer questions 4&5.

 

Swap the D18 guts into a D20 housing and then add the Saturn O/D. There is a O/D available for the D20 but it is very rare and was used on Bronco's.

 

The Saturn OD won't fit on the D20 casing.
If you meant to go the other way (D20 to 18), you are now running an offset driveline on a centered pumpkin.

 

The Saturn is junk. Send it to me and I will just put it on my Dana 18 and you won't have to deal with it ever again. But seriously, If it has the 26 tooth gear, I would be interested in buying it from you. PM me if interested.

 

You probably already have a dana 44 in the rear? Just pick up a off-set dana 44 housing and put your current carrier and gears in it. then get dana 18 and use the Saturn overdrive.
Besides having overdrive available, the dana 18 reduces your rear driveline angle because the rear out-put is dropped like the front. You also gain clearance by having both differentials on the same side. This allows you to offset on the trail and keep the rocks between your legs. The dana 18 also has a lower gear set than the dana 20. The dana 18 overdrive units are nice because they overdrive every gear. That way a jeep with a granny low first gear is more driveable on the street.

 

I would like to back up a bit......

I have a 74 cj5 with dana 20 transfer case. My dad wanted to give an extra saturn overdrive but i just learned that he has a d18 since his is a 53 m38a1.. I drive this a lot on the road and it barely goes 55mph yet the gears are pretty high for rock crawling. Any suggestions?:tea:

This doesn't make sense. Stock gears are 3.73. These are a great all around gears and should be able to handle street driving with ease. Given the V8, I'm thinking either you are running very large tires (engine bogging at speed, not over-reving)or there is some problem we are missing.
I really think some more info is in order before we go further. If you would be so kind as to answer a couple of the questions I posted earlier, we may be able to see what we are working with.

1 True tire size
2 Existing gear ratio
3 RPM's your running at your optimal road speed (real speed, not what the speedo says)
4 What RPM's your shooting for at that speed.
5 What kind of offroading your doing and how much do you do it.

 

You folks do realize the OP was 2 years ago, right?