Buick 225 4spd tranny swap

I was wondering if anyone had any input on what the best 4spd tranny would be to put between a 225 motor and spicer 18 tcase. No matter how much I read, my opinion keeps changing between the t-18, sm420 and sm465. Anyone else have an opinion on what would be the cheapest/easiest option?

 

Cheapest depends on which one you can get the best deal on. I wanted a SM465 but found a NOS SM420 for $60 so that is what I chose. A lot of times though it is the adapter that costs the most money. Sometimes you can find an adapter and tranny combo for sale from someone who didn't finish their own conversion.

 

You've asked for opinions and they will fly! This choice is often made by which tranny is available to you locally and/or the pros/cons of each. It sounds like you have already researched the pros & cons so here is my opinion.
I chose the Ford T-18 for my swap because I found a good one locally. I was able to inspect it prior to purchase. It had an extremely tight feeling shifter. It's parts are easier to find than a SM420. The sheet metal work for the hump should be less involved than the SM465.
I've driven and owned Chevy trucks with SM420s. The shifter is sloppy feeling IMO. I've driven a big Bronco with a T-18 and it had a very precise feeling shift. I looked at an SM465 and it was HUGE. I didn't want the additional task of machining my bell housing to fit that beast either.
My choice had little to do with cost - they are all expensive once you factor in the adapter. You'll probably want to change your clutch linkage as well, and there's more cost. I went with Novak's hydraulic clutch bracket that uses factory CJ cylinders.
The modification to the GM bell housing to fit a Ford tranny looks easy and straight forward. See http://www.novak-adapt.com/knowledge/ford_to_gm.htm

Good luck and keep us posted with your progress!

 

When I did this with my 5 I decided on the SM465, in part because of Novak's 1" thick SM465/Dana 18 adapter. The machining of the bellhousing and the transmission bearing retainer was easy and cheap at a local machinist. I was really happy with this combination.

 

Thats some great advice. Please keep it coming! It sounds like they are all good tranny's. I didn't know if there was a certain combination that would bolt right up to the bellhousing and save me the cost on one of the adapters. It seems that everything is about $1500 to convert. I've got alot of T18's and sm465's around the area for about 100 bucks each. This usually includes the bellhousing and tcase which maybe I can sell. Would there be any advantage to finding a Jeep t18?

 

The Jeep T-18 will be the lowest cost, because it's already set up to bolt to a Dana 20. About $200 for the short shaft kit from Parts Mike. NB the T-18 from an '80 or later J20 will not work without a TC adapter. Your most likely donor is a '79 or earlier FSJ (J-truck, Wagoneer or Cherokee). Most of these have the V8 and a very long input shaft. This is the route that Lynn took.

 

I don’t know anything about the T-18 so I won’t comment on that.
I do, however, love my SM420 but if I had this swap to do over again I’d do it with an SM465. The 420 has a few drawbacks, mostly due to it’s size and age, that aren’t an issue with the 465.

 

Re drawbacks to the SM420, might one of them be that there's no synchro in 2nd gear? I was looking at Herm's site, and he lists only two blocking rings required for the SM420.

 

the 2nd gear synchro is part of the gear I believe

 

There is a second gear synchro, Item #43 of the attached diagram, and I’m sorry but I’m not familiar with the term blocking ring.
The problems I have with the SM420 are:
1. Age, parts availability is getting worse all the time.
2. No reverse light switch except for the last two years of production, which of course isn’t the one I have.
3. The big one, literally, is it’s size. See that huge bulge on the passenger side, the side opposite of the PTO cover? That’s where the Counter Shaft and gears reside, Item #63. That bulge limits:
A. The size of the front drive shaft yoke.
B. How close the transfer case can be to the back of the transmission, meaning it makes for a longer combination than a Dana 18 to SM465 combo.
C. And how the transfer case is clocked. Mine with an AA adaptor is actually clocked downward to help the front output yoke clear it. Even with the proper adapter you still have to grind on the transmission housing to clear the front drive shaft.

I love my SM420 for the super low gearing and strength and if someone had their mind set on one I wouldn’t try to discourage them from it because overall it’s still a very good transmission but these are the drawbacks I’ve found to it.

 

BTW, I’ve got the SM420 shop manual stored on my hard drive if anyone needs a copy.

 

Corveeper. I'd love a copy of the manual.

 

PM me your e-mail address and I’ll send it as an e-mail attachment.

 

http://www.kinzers.com/don/landcruiser/transmissions/

Better yet, the SM420 and SM465 shop manuals are at the above link available as a zip file or as individual jpg’s. That’s probably where I got them.

 

2 points a to add, the reverse switch can be added to any one of them, the sm465 also requires a ton of grinding to make it fit. I have adapted both of those. The sm420 has sycros for 2nd to 3rd and 3rd to 4th, I don't know if any of them have a syncro that would go from 1st to 2nd, that would be a heck of a jump when you let the clutch out after downshifting from 2nd to 1st..

 

As far as bellhousings go, it looks to me like a SM465 would bolt right up to my 225. I don't know if my 225 bell housing is the original one or not, but my 225 bell housing has the 5-1/8" locating bore. This matches the SM465. My SM420 has the 4-11/16" locating ring which means that I need an adapter ring. No big deal though since it is only about $35. The SM420 needs the bottom two transmission mount holes of the bellhousing drilled out with a 17/32" drill bit. This took me all of five minutes to do with a bit that I borrowed from work. I have the "special" top cover on the SM420. This was good and bad. It meant that I had a back up light switch, but the front cover also stuck out the front of the transmission just a bit. I used a file to notch the bell housing and then they bolted right up together. So bottom line is that a SM465 would have simply bolted to my 225. The SM420 cost me an additional $35 adapter and about an hour in the shop to get it to bolt to my Dauntless.

 

If your sm465 bolted to your bellhousing someone had already bored it out, that is not normal in any way.