help installing Terra Low Kit in D18

Progress and results of Terra Low Kit in D18

Broke the gears in my D18 wheeling, I think low range shifter was not fully engaged, so upgrading to the Terra Loe Gear Kit. Actually I am getting a D20 large hole (4 inch) case to install gear kit and keep it a D18 configuration with the offset rear output and twin shifters. Any DO's or DON'Ts ? Also plan on using Amsoil 75w90 synthetic in the T18 and the D18 with the new gears, any thoughts?

Thanks
Tiptop

 

Aren't there some good D18 rebuild instructions on the net? There are instructions on the Novak site, but isn't there another?

 

If I ever get moving this morning I'm going to the shop to work on my d20 tera low setup. I'll post some pics of the grinding. Seems very straight forward.

Kevo

 

18's are pretty self explanatory really.. the only real high tech part of the whole thing is setting bearing pre load on the rear output shaft, which is not hard st all just takes a dial indicator and some patience... Oh and make sure to use some form of thread sealer around the bolting as most of it penetrates the oil containing portion..

BUBBA

 

By the way that is a 20 case with 18 stuff.. but not the tera low.. i ain't that rich.. haha..

BUBBA

 

Here ya go!

http://www.willystech.com/wt/Model18TCase/Model18TransferCase.html

 

Here are 2 artciles about installing the Tera low into a dana 18.

http://www.off-road.com/jeep/tech/convxfer/terad20/tera.htm
http://www.jeepsunlimited.com/modules.php?name=News&file=article&sid=79

I'm thinking very seriously about doing this myself before Tellico next year.
Let us know how it goes.

 

Well I went and dismantled, cleaned and ground on my t-case today at work. I was hoping to assemble a new t-case and leave my old one as is in case I need it for a spare, but as it usaully happens when working on jeeps things didn't go as planned. So now I'm rebuilding mine with the tera gears and hopefully later on I will reassemble the new case with stock gears etc...

Its very straightforward working on these old things. I think the hardest issue for me on these has allways been getting the front output cover off. Keep in mind I'm working on a D20. I figured I would just post pics here instead of starting a new thread since there 'almost' the same.

Some pics of grindage:


I ground more than I needed to just for the heck of it. Also found this one little spot that might cause an issue and ground it down a little also.


I used a die grinder with a cutoff wheel and made fast work of it.


When doing these kinds of projects its allways good to remove any burrs or high spots from gasket areas in order to get a good seal.
I start by chamfering all bolt holes


Then I run a tap into all threaded holes


Notice the edges have burrs where others have used chissels and screwdrivers to get the cover off. That creates high spots. Sorry its a bad pic.


So I run a flat file across the surface to get it smooth and flat


I had done all this previously last time I rebuilt it and had no oil leaks. I didn't use gaskets on anything and just used some good quality sillicone sealant.

Hope this helps a bit.

Kevo

 

Progress update. Installed the D18 Terra Low kit into a D20 case with large hole and the needed 1 1/4 shaft. Did not have to grind case at all, but did grind end of 4x4 shift rail just a bit to clear low range gear. Clearance is also close at low range shift fork boss where shift rail goes through to low range gear, (1/16 to 3/32) I left it at that. I also question as to whether you really need a large hole or even a 1 1/4 shaft hole. The gears fit in through the oil pan, but I suppose a small hole may not have room for the low range gear. I actually set shafts and gears in to my old small hole case and it seemed to me they would fit. As for the 1 1/4 shaft hole, I am thinking you could use a 1 1/8 shaft with the caged bearings inside the Terra Low Intermediate gear instead of the loose needle bearings. I measured inside diameter of a stock intermediate gear from a 1 1/8 shaft case and it was the same as the Terra Low Gear. Although I would think better wear with the 1 1/4 shaft since larger bearing surface, any thoughts? Also I have heard of D18 cases cracking at intermediate shaft hole. I am concerned about this, do not want to wreck $700 gears, and actually ordered a D18 case Girdle made be Tri County Gear that is suppose to strengthen it. $125 with out overdrive and $85 with overdrive. Have not recieved it yet, and now just remembered that I really do not have a D18 case, I used a D20 case. So the girdle may not even fit - anyone know? Also anyone know if a D20 case is stronger or heard of any D20 cases cracking? Also I am no longer going to run my overdrive, but instead use a Dana PTO and eventually set up a rear PTO Winch. Any thoughts if bolting in a overdrive or pto to the rear inspection hole strenghtens case?

Plan on being able to road test in a few days. Will update again.