Regearing the Dana 20

Regearing the Dana 20

cjbilly

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East Central Indiana
Vehicle(s)
1984 CJ 7 with rebuilt AMC 360/ 2 bbl. with Turbo 400 and Dana 20 transfer case (twin sticked). Dual red-top Optima's. Lokar shifter with rebuilt/modified tranny. Dual Flowmasters out the back.
1985 Dana 30 and 1986 CJ Dana 44 with 3.73's. Steering box brace. Central axle, tranny and transfer case breather box. Detroit locker (rear) and ARB (front). 35x 12.50-15 MT/R's on 15 x10 ION alum. simulated beadlocks.
Has anyone attempted to improve the low-range gear ratio of a Dana 20 from 2.03:1 to 2.46:1 or lower?
To keep cost down, they used parts from a Jeep Dana 18 and 20 along with a bronco 20.
 
I regeared my Dana 20 TCase with the TerraLow kit and I love it. Stock gearing is 2 to one for 4WD Low. I think that's far too much of an overlap.
The TerraLow kit puts the gearing at 3 to 1.

Here's my gearing:

................1st........ 2nd..... 3rd .....4th
T-18A .... 6.32 . . . . 3.09 . . .1.69 .....1
4WD Low . 12.6 . . .. 6.18 . . . 3.4 ..... 2
TerraLow . 18 . . . . . . 9 . . . . 5 . . . . . 3

You can see with the stock Dana 20 if I am in 4WD low the only time I get lower gearing is when I am in first.
In other words if I have a stock Dana 20 in 4WD Low then 2nd is the same as 1st with the TCase in high.
3rd in Low is the same as 2nd in high.
See what I'm saying? There is too much overlap.
Yes my T-18 has a wider range than most trannys.

IMO the best TCase would have a 4 to 1 low. There would still be a little overlap even without a wide ratio T-18 Tranny.

My TerraLow kit cost $850 and it was well worth it. The kit replaced every gear in the TCase so it was also an excellent rebuild kit. It was actually very easy to do.

Edit: I don't know anything about using parts from a Jeep Dana 18 and 20 along with a bronco 20. :confused:
 
Last edited:
Great information.
I was trying to go the cheap route. It appears the only opinions available for the Dana 20 is either my junkyard build 2.46:1 or the Teralow 3.15:1 kit that you bought for $850.00. I already have all three (3) transfer cases.
I don't know if anyone makes a 4:1 kit for the Dana 20 . If so, that would be the way to go depending how deep your pockets are.
 
I don't know if anyone makes a 4:1 kit for the Dana 20 .
No one makes a 4 to 1 kit for the Dana 20 . To change the gear ratio the drive gears have to be smaller and the driven gears have to be bigger.
To install the TerraLow 3 to 1 kit you have to grind the inside of the case to allow the new gears to fit.
It's just not possible to fit 4 to one gears in there.
 
Has anyone attempted to improve the low-range gear ratio of a Dana 20 from 2.03:1 to 2.46:1 or lower?
To keep cost down, they used parts from a Jeep Dana 18 and 20 along with a bronco 20.

I'm not 100% sure but I believe Jeepy did something like this.
Maybe he'll check in here soon.
 
I know a lot of people wish Lomax made a 4:1 kit for the 20, and Im really surprised they dont. Their Dana 300 kit is bulletproof...and about $250 less then the TerraLow conversion.
 
I know a lot of people wish Lomax made a 4:1 kit for the 20, and Im really surprised they dont. Their Dana 300 kit is bulletproof...and about $250 less then the TerraLow conversion.

No one makes a 4 to 1 kit for the Dana 20 . To change the gear ratio the drive gears have to be smaller and the driven gears have to be bigger.
To install the TerraLow 3 to 1 kit you have to grind the inside of the case to allow the new gears to fit.
It's just not possible to fit 4 to one gears in there.http://www.jeep-cj.com/forums/f2/regearing-dana-20-a-7411/#ixzz195V3ZD5l

Wow, I just had a feeling of Déjà vu
 
Yeah I did the bronco gear route. If you find the "right" Bronce case, with the 33 teeth big gears, which I seem to get lucky and find, then that is all you need for the 2.46 conversion. But you need to try and get the input gear off the bronco tranny (actually off of it's adapter) as well.
Doing this mod I did have to grind out the case to make room for the gears. And I had to take a little bit off of the middle part of the input gear so the nut would go all the way on. Did that on a lathe. Not enough removed to weaken the gear.

The Nutter link someone mentioned works the same way, you just use most of the parts from a late Dana 18, and then just buy the remaining Bronco parts individually (saves you from having to find a bronco t-case).

If you have the money to spend on a preferable 3:1 conversion, then do that. But if you don't, the 2.46:1 coversion can be really cheap.
 

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