Email: mike@mikesjeep.com
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Intro....If you happen to own a Jeep like mine, you know how crappy the gearing is. With a first gear of 2.99:1, a transfer case low range of 2.03:1, and ring and pinion gears of 3.5:1, it works out to a wonderfully tall 24:1. With this setup, it takes a lot of clutch-work to tackle a tough obstacle, and I still don't have good control. To improve on this, I first looked into converting to a T18 transmission. This tranny was available as on option in the CJ's, so it seemed simple, but after some research, I realized it's not that easy. To make it work, you pretty much either need a donor Jeep to scavenge all the parts from , or find a Ford transmission with the "good" gear ratio and convert it. Since I don,t have a donor, and I couldn't find a T18 with the "good" gear ratio without pulling them and turning the shaft, I passed. My next idea was to put lower gears into the Dana 20 transfer case. I've heard that it's possible to install the lower gears from a Dana 18 into the '20 case, but I've never seen or heard of anyone who actually did it. Tera-low is coming out with 3.15:1 gears for the Dana 20 in April, but I want to do something before the Easter Jeep Safari, so that's out for now too. (I have since installed the Tera-low gear kit. Click Here to read the article.) Now I'm back to the transmission. I called Advance
Adapters for some advice. They were extremely knowledgeable and
helpful! They suggested I use a NP435 from a Ford truck. The NP435
has the same bolt pattern as the T150, it has a 6.69:1 granny gear, and
they're easy to find. I would have to convert the output shaft to a short
one that will mate with the Dana 20, but that's the case with almost any
transmission. (sorry about the pun) The T150 is 9.25" long, whereas the
NP435 is 10.875", but when I bolt on the adapter for the Dana 20, it will
end up being 14.125" long. This length will require new drive shafts, but
my front drive shaft is garbage as it is, so now is the time to do this
before I buy a new one. The position of the shifter lever for the NP435
is fairly close to what I have now, and I can extend the t-case linkage,
so with a little luck, I shouldn't have to work on the floor at all. I
have no clue how the skid plate thing will work out, but there you go.
I called around to the local junk yards, and came up with a slew of possible victims, with prices between $150.00 or $250.00. I picked one up for $150.00 from a rolled 1983 full-size Bronco. I chose this one because the truck was there from a wreck, rather than old age. When it came time to order the adapter kit for the tranny, I remembered a little 'editor's note' in an article that Advance Adapter reprinted in one of the catalogs I got from them. The note said that the adapters are available from JB Conversions, so I called them. They offer the same Advance Adapters kits that Advance sells, but they are considerably cheaper. Advance sells the kit for $525.00 whereas, JB was at $420.00! This was true for all the parts I needed. Since I have to take apart the tranny to put the short output shaft in, I called Border Parts to see what type of rebuild kits are available for the NP435. They suggested two kits. The first is a small parts kit, catalog #290-50, that has the little c-clips, and washers. The second kit, catalog #TK127, contains all the bearings, seals, and gaskets. I ordered these and received them in just a couple of days.
Some Important Points...1) The Ford NP435 has the same bolt pattern as the T150. 2) The NP435 is 10.875 inches long, T150 is 9.25 inches long. 3) The Adapter will add an additional 3.25 inches to the overall length. 4) I will need to get new drive shafts. 5) I will need to extend my transfer case linkage MORE......... | |||||||||||||||||||||||||||||||||||
Email: mike@mikesjeep.com