Hot Rod Forum banner


  • 0
  • 0


  • 0
  • 0


  • 0
  • 0

1988 Suburban TH-700R4 to SM-465 Swap. - Nov 12, 2009

At this point in the swap, I have been receiving questions about the particulars of this swap.

1. What are the weight differences between the two transmissions?
A. The weight of the TH-700R4/4L60 (according to an internet search result) is 155 pounds, the Muncie SM-465 is 175 pounds, BUT, you also have to remove the 4 pound flexplate and replace it with a 30 pound flywheel, 1 pound clutch disc, 2 ounce pilot bushing, 10-15 pound pressure plate, replace the 6 5/8-inch flexplate to crank bolts with 6 1-inch bolts (.5 ounce?) remove the shorter driveshaft to carrier bearing, and replace it with a longer driveshaft, add about 5 pounds with the clutch pedal, and probably another 5 pounds with the bellcrank and all related clutch linkage components.

2. What are the gear ratio differences between the 2 transmissions?
A. The TH-700R4 was geared 3.06, 1.63, 1, .70, and 2.90 reverse.
The SM-465 is geared 6.55, 3.58, 1.57, 1, and 6.54 reverse. Although some sources list third gear as 1.70 and reverse as 7.0:1, I will have to check and see what I have later and correct this journal entry if need be.

3. Why did you want to put this old transmission in your Suburban?
A. I am at a point where I am not actively bringing an income to my household. I have several of these transmissions around here. I have parted out a few trucks over the years that had this transmission or other manual transmissions in them and had the forethought of saving a few of the necessary parts to possibly do this swap later on. I essentially wasted third and fourth gear clutch packs (and who knows what else) on the TH-700R4 that I removed from the Suburban. I chose to do something different.

Because I can!

4. How can you have so many parts just "working" to fit your Suburban, I never seen a standard shift Suburban?
A. I am working with a GM truck division vehicle, they aren't anything special, they have the same parts down to the little nuts, bolts, and screws as the trucks, and full size Blazer/Jimmy line from the front bumper to the rear of the 2 front doors, and everything exactly the same from the front bumper to the rear of the rear doors on the Crew Cab trucks, and the exact same rear body components as the full size Blazer/Jimmy.

There isn't anything "special" about any particular model in GM's truck lineup from this era, but since it's a 1988 and a non light-duty pickup, it still retains the previous body style as the 1973-1987. The Chevy/GMC full size Blazer/Jimmy Suburban and Crew Cab pickup trucks didn't switch the body style designs to match the rest of the trucks in GM's truck division until 1992, meaning several of the same parts (with a little fabrication here and there, could be swapped between the Blazer, Suburban, and pickup from 1973 to 1991 and still look factory done.

PLUS, since this body style was manufactured for so long, and so many parts interchange, I can have replacement parts available for a cheaper price than many other vehicles, why not.

5. How do you know so much about this type of project?
A. I have been a "hands-on" type of person all my life, my dad helped me by including me in all kinds of building and repair projects, there are many others out there that have no clue as to how to fix much of anything, and there are others that could do some of the things I need help with- in their sleep, so to speak.

I have also owned more than 35 trucks, Blazer/Jimmy's or Suburban's within this body-style range that spanned from 1973 to 1991, and have been lucky enough to retain the knowledge gained from all the repairs I have made to my own vehicles, reading parts catalogs, or service and repair manuals to know either by memory first hand or by forethought to check the information out and be able to most of these things without much difficulty.

Photo 1 again shows the TH-700R4 I removed.

Photo 2 again shows the Muncie SM-465 I installed.

Photo 3 shows my son Andrew imitating me, and without my prior knowledge of him doing it until I found this entire scene, he had found everything he evidently needed to do whatever he was doing to his Jeep. He's pretty darned handy for only being 4 years old.
There are no comments to display.

Album information

Photo Journal
Album owner
Date created
Item count
View count
Comment count
0.00 star(s) 0 ratings

Album privacy


Can view media items
Can add media items
Album owner only

Share this album