You Want Lower Gearing?

What about the Tera Low conversion kits?

By Grumpy Miller

Ever since I bought an old '78 CJ three years ago my wife, Pam, has been suggesting to me that she needs lower gears in her '95 YJ. With my granny-low T18 transmission and the 4:10 rear-end gearing I have a 64:1 crawl ratio. Pam's crawl ratio was fairly good at 42:1. I thought she drove just fine with what she had. Besides, she drives better than me anyway! A man needs an edge. I mean how would it look? Your wife gets a rig that is as capable as yours, clears every obstacle on the trail, and then you come along banging, clanging and hanging up on every little rock outcropping. I mean, I don't know if my fragile psyche could take such humiliation.

Details...

1. The Tera case on the right is nearly identical to the original but uses a 5 planetary gear system. The original Tera kits came with a three planetary gear system that was found inadequate with the added torque of the lower gear ratios.

2. The 231 transfercase is a very simple two-piece design. Rather than a new gear set the Tera 231, 4:1 reduction case is one half of the transfercase

3. Tera recommends a tail shaft eliminator kit when installing their 4:1 kit. This changes the drive shaft to CJ style, requiring a new drive shaft this t-case already had the kit installed so we were already one step closer. The original tail shafts are chronic leakers and if you damage a rear drive shaft you can't remove it without having all the tranny fluid drain out through the back of the case. Many times I have seen someone limping out of the bush with plastic bags tied around the back of the t-case. If you are not in the market for the lower gears I recommend the tail shaft kit as soon as you can afford it. I guarantee you will do it anyways once you break that first drive shaft

4. The stock gear forks are reinstalled into the Tera t-case.

5. Make sure the seals are well seated into the case before assembling

6. Silicone gasket sealer is applied to the case half's before assembly.

Oh well! I finally agreed that she needed lower gearing. Her whining had finally gotten to me. Must have been a weak moment. I guess I should be grateful for the three years I've had playing the part of "the big dog" in the family. Gone are the days of "Gee, I made it up. How come you couldn't?" Besides I'll still have bigger tires and that front locker. I know she's a good driver but hopefully I'll still be okay and she won't make me look too bad. Do you think I could appeal to her better nature and ask her to screw up every now and again so's I could look good??? Hardly! Can you imagine the laughter that would come out of that little woman if I ever even suggested such a thing?

On with the story. We talked over the various options as to how to accomplish her lower gearing. We narrowed it down to some optimal choices: NV4500 with granny low, rendering a 73:1 crawl ratio; the 4.3:1 Atlas II transfer case, rendering a 68:1 crawl ratio; or the Tera Low 4:1 transfer case conversion kit, rendering a 63:1 crawl ratio. Both the NV4500 and the Atlas II transfer case are excellent products. However the NV4500 would require adapter plates and new drive shafts, front and rear. Pricy!! The Atlas II would also need an adapter plate and a new front drive shaft. Not quite so pricy but still hurting. On the other hand, the Tera Low 4:1 gearset could be had for approximately $1,400 Canadian with no adjustments to driveshafts. Tera Low suggests the addition of the JB tailshaft kit for your NP231 transfer case and the use of a CV rear drive shaft. However, since Pam had installed these items some years ago to help correct driveline angles, all we needed was the Tera Low conversion kit.

The beauty of high ratio transfer cases is the fact that with the transfer case in high range you still have all your normal gear ratios for normal and highway driving. You suffer a little with a loss of speed in low range. However, most of the low range 4 wheel driving that Pam does is slow speed. Isn't that what low range is for? She very seldom ever used 4th or 5th gear in low range. As a result, what is she losing? Besides, if she wants to go faster in 4 wheel drive, she can shift into high range 4 wheel drive. It's easy to do with the NP231.

Our choice made, we had the kit delivered to the good guys down at North Shore Off Road (NSOR) in North Vancouver (who incidentally are distributors for Tera Low products) and a couple of days we later went down to their shop to witness the installation. O.D., who does most of NSOR's fabrication work, was assigned the task. His fabrication work is excellent. Waste of good talent since no fabrication is required, but who am I to complain.

The kit is fairly simple. A new front half case for the NP231 including a new planetary assembly with input shaft plus a replacement output shaft front seal and some other minor parts. Boy does the new half case look nice. Well built and looking a lot stronger than the old half case. The installation was easy. The instructions provided were more than adequate. Some parts (shift sector assembly, shift rail, shift sleeve, output shaft front bearing , etc.,) had to be removed from the old front half transfer case and installed into the new one. From start to finish, O.D. spent about 3 hours and that included replacing some driveshaft U-joints and welding up the exhaust. As usual, NSOR did an excellent job. No problems. Both O.D. and I feel the back yard mechanic can handle this job easily.

The next day we headed over to Sooke, B.C. for the Island Rock Crawler's Rock Crawl. The idea was to see how the gears performed in real life. Every night back in camp I listened to Pam exclaim to anyone within earshot: "I love these gears! This is wonderful! Can you believe how easy I went through Cleavage Rock. I can't believe how much more control I have!! This is so much fun, I love it." Obviously, the Tera Low conversion kit has made a big difference to the trail capability of her rig.

Based on our limited experience to press time I would say we have made an excellent choice with the Tera Low. However, I don't know if I can take all of Pam's exuberance. Maybe I was better off before just listening to her whining. Back then I also didn't have to worry about being shown up by a woman. Well, most of the time I didn't. Unfortunately, its too late now. Wait a minute, what's that I hear. Is Pam whining again? "I need a front locker, this limited slip is no good."

Sources:	North Shore Off Road 1520 Richmond Street North Vancouver, B.C., V7J 1B2 1-604-988-7677
Contact:	Tera Manufacturing Inc. Midvale UT www.teraflx.com 1-801-256-9897