Wich one of these trans is the better bang for the buck?
I understand that GM quit manufacturing parts for the 420 so
finding parts for it can be a real pain and I hear it shifts bad and has a lot of gear noise, is this true?
I know that the 420 has a lower first gear(7:1), but has a large hump on the side of the case so it is hard to get U-joint clearance, also it is 1.50" shorter than the 465 and the adapter kit is cheaper, all you need is a plate!
On the other hand the 465 is a much newer trans, made untill "92" has a 6.55:1 first gear, parts are available, but the full adapter kit is over 500.00! Does anybody know how this trans preforms, does it shift better, does it have a lot of gear noise?
I like the idea of haveing i shorter trans and lower first gear, but do not want to deal with not being able to get parts!

Any input would be great, I want to do this swap rite the first time!

thanks!

go to www.ih8mud.com for an analysis
you can use the search button.....to SEARCH

and find this stuff.http://www.off-road.com/jeep/tech/convtrans/gm/
www.pirate4x4.com/forum/showthread.php?s=&threadid=29209&highlight=sm465+vs+sm420
www.pirate4x4.com/forum/showthread.php?s=&threadid=20596&highlight=sm465+vs+sm420
www.pirate4x4.com/forum/showthread.php?s=&threadid=1715&highlight=sm465+vs+sm420


the feature acutually works.

Originally posted by macgyver
go to www.ih8mud.com for an analysis
you can use the search button.....to SEARCH

and find this stuff.http://www.off-road.com/jeep/tech/convtrans/gm/
www.pirate4x4.com/forum/showthread.php?s=&threadid=29209&highlight=sm465+vs+sm420
www.pirate4x4.com/forum/showthread.php?s=&threadid=20596&highlight=sm465+vs+sm420
www.pirate4x4.com/forum/showthread.php?s=&threadid=1715&highlight=sm465+vs+sm420


the feature acutually works.

how true!

anyhoo, what you are using this truck for, and what kind of truck is it would be good things to include in this post...

You don't buy parts for an SM420, you buy another one!

These things are bulletproof.

They do shift worse than a Toyota tranny, but not that much worse than an SM465.

I recommend the SM420 for the cost and ease of installation factor.

Both are 1:1 in final drive.

There are cheaper plate adapters for the SM465 or you could buy my sm465 + adapter in the forsale section:D

Shift pattern on the cruiser 4 speed and the SM420 are identical. The hump clearance issue only comes up when you use the plate adapters and then there are ways to deal with it.

Of course, shorter is nice but then cruisers have front driveline angle problems before they have rear driveline angle problems.

Originally posted by Tankota
There are cheaper plate adapters for the SM465 or you could buy my sm465 + adapter in the forsale section:D

Shift pattern on the cruiser 4 speed and the SM420 are identical. The hump clearance issue only comes up when you use the plate adapters and then there are ways to deal with it.

Of course, shorter is nice but then cruisers have front driveline angle problems before they have rear driveline angle problems.


Huh???:confused:

Spaceghost has adapters for the SM420 for $100 a piece.

Hump Clearance? Perhaps with the 79+ body tub there might but on a standard tub there are no clearance issues with a 420 and a plate adapter. Shifter linkage issues are common to any aftermarket tranny swap...

With the LC motor reversed springs in the front, 55 springs in the rear I have a 32" front DS and a 27" rear DS. Driveline angle problems are because you have not rotated the pinion properly. Not because of where the tcase is located.
Most of the other front DL problems I have seen were a result of doing a shackle reversal and not getting a long slip shaft...

how do I get a hold of Spaceghost so I can get a adapter?
I need a short trans assy because I am also going to use a ranger torque splitter so I have 27% overdrive, this unit is 7.50" long so things are going to be tight! I will most likely end up with a 20" to 21" rear driveline.
Here is the breakdown,

SB350
GM bellhouseing 6.50" in length
Ranger T/S 7.50"
SM420 10.50"
adapter plate 1"
3spd T-case 5"

Should work out just fine! (I hope!)

Hey, just wanted to say thanks for all the imput, I'll be going with the SM420. I found about four in my area for aroud 100-200 bucks each.

Thanks again!

Spaceghost has adapters for the SM420 for $100 a piece.

I was referring to the fact that there are plate adapters available for SM465s that are not as expensive as the AA style adapter.


Hump Clearance? Perhaps with the 79+ body tub there might but on a standard tub there are no clearance issues with a 420 and a plate adapter.

The "hump" that I was referring to is the bulge on the side of the tranny where the reverse Idler gear sits...not the tranny hump on the cruiser body. Every plate adapter that I have seen (Note: I have not seen them all) required grinding on the transmission and the use of a 3-speed driveline and 3 speed t-case flange.


With the LC motor reversed springs in the front, 55 springs in the rear I have a 32" front DS and a 27" rear DS. Driveline angle problems are because you have not rotated the pinion properly. Not because of where the tcase is located.

You are correct. When you lengthen your wheelbase by using different springs you can get rid of any front driveline binding problems that may occur with a SOA and a shackle reversal.



Heres some old info that I found in my computer

Check out the following webpage for a discussion on SM465s and SM420s:
http://www.pirate4x4.com/ubb/Forum5/HTML/001647.html


SM465
Source Vehicles: 1968-1988 Chevy and GMC, 1/2-3/4-1 ton, 2 and 4 wheel drive, pickups blazers and suburbans.

Advantages:
·Very heavy duty
·Easy to find

1st gear ratio=6.58:l (cruiser 4 speed 1st gear ratio=3.55:l)
Length=12 inches
Output Shaft: 2wd versions have a thick but short output shaft
(35 splines?) while the 4wd versions have a longer 10 spline output shaft.

Plate and Advance Adapters style adapters both available.
·I don’t have any personal experience with the plate style adapters for the SM465.
·When I did my SM465 swap I used the Advance Adapter which is 4.625 inches long. I was able to move my engine far enough forward to not need any driveline modifications. This resulted in my Advance Adapter transfer case crossmember staying in its original position.
oDrawbacks to the AA adapter: Expensive ($550-$650)

SM420
Source: 1947-1967 Chevy and GMC, 1/2-3/4-1 ton, 2 and 4 wheel
drive, pickups blazers and suburbans.
Advantages:
·Slightly lower 1st gear ratio than the SM465 (7.05:l vs. 6.58:1)
·Same shift pattern as cruiser 4 speed
·Shorter length (10 inches vs. 12 inches for SM465)
·Cheap plate adapters available (see drawbacks to this below)
·Relatively cheap transmissions (although they are a little harder to find in good shape than the SM465)

1st gear ratio=7.05:l (cruiser 4 speed 1st gear ratio=3.55:l)
Length=10 inches
Output shaft: All are 10 spline (same size and spline count as cruiser 3
speed output shaft)

Plate and Advance Adapters style adapters both available.
Plate adapters are cheap ($100-$300)
Drawbacks of plate adapters for the SM420
·Very little clearance between front output yoke and side of transmission which often requires grinding on transmission and some on front output yoke of t-case or using an output yoke and driveline out of a 3-speed cruiser
·Adapter works better with the 3-speed cruiser transfer case because the SM420 10 spline output shaft is almost identical to the cruiser 3-speed transmission output shaft. This means that the SM420 output shaft will fit into the gears in the cruiser 3-speed transfer case.
The cruiser 4-speed transmission has a 16 spline output shaft so an “adapter” input gear is needed for the cruiser transfer case. I believe that this gear actually came in a very few cruisers where the Toyota factory was in the middle of switching from the 3-speed stuff to the 4-speed stuff. A couple of companies sell the 4-speed t-case input gear that will accept the 10 spline output shaft of the SM420.

:rasta:

This is any easy answer: SM465
1. Newer
2. availabilty of parts
3. more transfercase options (not that it really matters)
4. smoother shifting, smoother operating
5. More available
6. Easier for linkage adaption
7. As strong as a 420, stronger if you consider the shaft splines..
8. Only real downful is that first gear is a tad bit higher, but not enough to change my opinion.;)

Jeff

Wow, thanks for all the info! Good solid advice(like this) is hard to come by! I am still going to go with the SM420 just for the fact that it is shorter and is dang near bullet proof. Having a stock length drive shaft will be a dream, the one I have now is only 17.5" . Can't wait!

Thank's again!

-Scott