t-14/225 or sm465/225

It's me again fellas. I just picked up a 4wd sm465 from an 81' chevy truck for $40. I would really like to use it with the 225. I only thought the t-14 would be easier to put in because it was factory. I think a granny tranny would be easier and better since I'll have to pull everything out anyhow. what do you think? 225 v6/SM465/ Dana 18? I want to use the novak adapter because it is only 1" thick.

 

Definately go with the 4 speed. Stonger transmission and a granny gear....What's not to like about that?

 

I love my sm420, I would have considered the 465 if they would have had the 1" adapter back then. Either is an improvement over the t-14. When I put the t-14 next to the sm420, it looked like the 420 could eat the t14 and spit out it's remains.

 

I would go SM 465 also. More options are always better.

 

The SM420 will make your Jeep more valuable in the long run, but you probably won't get back the extra money you spend to adapt the 4-speed when you sell it. One downside to the 4-speed, besides the cost, and the weight, is the extra effort needed to row it through the gears. If you get caught in stop-and-go traffic, the long throws, wide gate and heavy feel of the 4-speed gets old quickly. If you expect your wife or girlfriend to ever drive the Jeep, the 4-speed will make that unlikely. And, you're never going to use 1st gear on the street, so you may realize the payoff of having the truck 4-speed very seldom. In daily use, it's basically a really heavy 3-speed that's hard and slow to shift.

It's interesting to look at the gear ratios of some 3-speeds and the SM420

SM420.....7.0...3.60...1.70...1.0
T14................3.10...2.61...1.0
T15................3.00...1.83...1.0
T150..............2.99...1.75...1.0

I've owned Jeeps with both the T14 and T15, and I prefer the T15. With the T14, there's too long a jump from 2nd to 3rd; if you slow down on a long hill, 2nd is too low to keep up your speed. With the SM420, 1st is really low, so I'd expect downshifting from 3rd to 2nd would be impractical. You need that low 2nd because (I'd expect) the granny gear is so low that shifting up from 7:1 to 3:1 is too big a gap.

The T15 and T150 both have ratios that would work well in my opinion. The T150 is widely available and inexpensive, and has a Ford pattern which I believe can be easily adapted to the V6.

If you're concerned about gear ratios, you also have the option of the Ford T-19 truck transmission, which came in 3 different ratio combinations, has a synchromesh 1st gear, and would be about the same cost to adapt as the SM420.

T19.....6.32...3.09...1.69...1.0 (wide)
T19.....5.10...3.00...1.80...1.0 (middle)
T19.....4.02...2.40...1.40...1.0 (narrow)

The CJ-5 from 1971-75 used a T18 with a 4.02:1 1st gear, and these owners really liked their Jeeps because of the useful spacing between the gears. They particularly liked them for hill climbing.

The granny gear (be it 6.32:1 or 7.0:1) was originally designed for trucks to help get a really heavy load started, or on a steep hill. Except in a Jeep, there's no practical use for this gear ratio in a passenger vehicle. In a Jeep, when combined with low range, it produces a ratio that's only useful under really extreme conditions. If you think you need it, that's great, but you will be giving up some flexibility at any speed above a slow walk.

 

I would definitely go with the 465, I have one in my 71' and it is one of the best upgrades I have ever done to it. Just my opinion though.

 

I'm working on the Novak 1" adapter and SM465 trans rebuild this weekend. The only difference is I'm mounting it to a Chevy motor. You'll have too do some machining to get it to fit to the Buick bellhousing.

Pictures to be posted later.

 

Bellhousing opening needs to be enlarged for the 465. The 420 is a bolt in.