swapping gears in a dana 20 tcase

I was wondering the other day as I looked at a dana 18 laid on my shop floor next to a dana 20 I am going to install soon if you could swap the gears to get the lower gear set, or if it would be easier/cheaper to put in a bronco dana 20 set of gears in my jeep dana 20 case. I know going from 2.0:1 to 2.46:1 isn't a huge jump but every little bit helps right? Any insight?

 

Re: swaping gears in a dana 20 tcase

AFAIK your only option is to mix D20 and D18 gears, and use the Bronco D20 gear.

We've discussed this before, and there is at least one article on the web about regearing the D20 with junkyard parts. Search and you will find.

 

Re: swaping gears in a dana 20 tcase

Thanks Tim, tried the search, but must not have put in enough/right info. I will be more detailed this go round.

 

Re: swaping gears in a dana 20 tcase

Have you seen this one?
http://www.jeeptech.com/convxfer/2.46-20/
According to Nick, the PN cited for the Bronco gear here is wrong. At least one place sells the gear you need new or used (depending on availability). Duff Broncos maybe? If you call R&P they could probably fix you up with the right gear.

 

Re: swaping gears in a dana 20 tcase

No I hadn't seen that particular site, but I think I was getting close. Thanks for the extra help. So really all you need are the gears from a big hole, large intermediate gear shaft dana 18 and the "top slider gear" from a bronco t shift dana 20 (with the right tooth count)- the later gear replacing the "top slider gear" from the dana 18 gear set. Right?

 

Re: swaping gears in a dana 20 tcase

Yes, if that's what the article says. I have not done this - I've only read about it.

 

Re: swaping gears in a dana 20 tcase

If you want lower gears, and can afford the swap, the Terra Low is AWESOME. I put that in my 74 cj5, and what a difference. Also, it only affects 4WL, leaving the existing ratio's for 2 and 4WH. That suits my situation perfect, as I often drive it fair distances to where we're offroading, and the higher ratio's work great on the pavement. One additional piece of info though, my diff gears are 3:31....VERY high. It has a 350 chevy in it, so it works out ok, but that's pretty high gearing. Now with the Terra Low, the low gears work very well.

Steve

 

Re: swaping gears in a dana 20 tcase

Be careful there is some wrong info on the net regarding the correct gears for the swap. Do yourself a favor, search titles only for -low range t-case question-. Nickmil gives the correct information regarding the needed gears. The hard part is finding the bronco gear needed. I have searched E-Bay and posted in the Buy-Sell forum and have been unable to find one for sale.

 

Re: swaping gears in a dana 20 tcase

I think LarryD is right. The article in timgr's link is correct except it has the wrong Dana number for the Bronco Gear. The correct number for the upper slider is 18-8-37. Bronco Graveyard sells it for $150.

http://broncograveyard.com/bronco/i-11625_rear_sliding_gear__dana-20.htm

 

Re: swaping gears in a dana 20 tcase

What they said. R&P sometimes has the gear available but it is dependent on availability of the gear at the time. O-Brien's was making the gear also at one time. Not sure if they still are. Last known address for I have for them is:

O'Brien's 4 Wheel West
1302 Hidden Court
Roseville, CA 95661
916-773-3278

The gear #'s needed are as follows:

18-8-23 input gear from a 29 tooth 18
18-5-9 intermediate from 29 tooth 18 or T-shift Bronco case
18-8-24 from a 29 tooth 18 or T-shift bronco case
18-8-22 from a 29 tooth 18
18-8-37 slider from a T-shift bronco case

The 18-8-58 is from the later J-shift early Bronco case and has the wrong pitch/tooth count on it.
I've done this conversion countless times and it's a good one. Can be hard to come up with the Bronco slider gear though.
There is some grinding needed on the inside top portion of the case to clear the slider gear and sometimes around the rim on the inside of the bottom cover opening. Also some grinding may be needed to get the intermediate gear in the opening as well once the front output shaft and gears are installed. It's not a huge deal but takes a little trial and error. Nickmil

 

Re: swaping gears in a dana 20 tcase

Thanks for clearing everything up guys. You all are a great help. Thanks for the specific numbers Nick. The search begins!

 

Re: swaping gears in a dana 20 tcase

If you happen to find a bronco dana 20. You do not need all those 18 gears. I just swapped all the bronco gears. Worked fine. The only gear you thenl need to come up with is the output gear for your tranny.

 

Re: swaping gears in a dana 20 tcase

"out put gear of your tranny" this is the bull gear that bolts to the output shaft of the tranny right? Also, did it have to be the T shift or J shift specifically, which one if so? Thanks for all this info guys.

 

Re: swaping gears in a dana 20 tcase

Transmission output gear, bull gear, transfer case input gear, all the same, just different name for the same thing. That gear needs to be from a 29 tooth 18 transfer case. 18-8-23 part #. Nickmil

 

Re: swaping gears in a dana 20 tcase

Wow, I didn't know that. It sure would make it easier to only have to find the doner Bronco transfer case and the correct bull gear. I assume that like the mixmaster Dana 18/Bronco 20 swap, the entire Bronco Dana 20 gear swap can only be done with a T-Shift Bronco Dana 20?

 

Re: swaping gears in a dana 20 tcase

If you find a whole case, you would want the earlier T-shifter (66-early 73) because it has the 2.46 ratio.

 

Re: swaping gears in a dana 20 tcase

you might have just as good of a time finding a scout dana 300, as you would the bronco gears.


just something to think about.

I tera-low'd my 20 and it was one of the top 3 modifications i've done. great results.

 

Re: swaping gears in a dana 20 tcase

I found a guy that has the factory 3 speed mated to a T shift style bronco dana 20 from a 70 model EB. Will this have ALL the gears I need to do the low gear swap. I am a little confused as to if the bull gear on the 3 speed is the correct one I will need for the swap??? I asked the guy to look for the stamped part numbers on the gears that you guys posted here but he said that the set up is still in the truck. Any help will be much appreciated, thanks again, you guys are great.

 

Re: swaping gears in a dana 20 tcase

You will need the bull gear from the 29 tooth 18 transfer case which is the 18-8-23. The T-shift Bronco used a gear with the right tooth count and pitch, obviously, but does not have the necessary recess in the bull gear for the nut and washer to retain them on the transmission output shaft. They can be machined in but why not just get the right gear? The # on the T-shift bronco by the way is 18-8-33. IIRC the reason the Bronco gear doesn't have the recess is because they are retained by a snap ring instead of a nut and washer. Nickmil

 

Re: swaping gears in a dana 20 tcase

So my choices are to find the correct 18-8-23 bull gear from a dana 18 transfer case OR machine the bull gear on the back of the factory bronco 3 speed to a accept the washer and nut that would hold the bull gear on the back of my jeep tranny, which would then bolt up to the modified jeep dana 20 now holding all the bronco dana 20 gears? I think I got the idea now