3 speed with SBC

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Jan 25, 2006
If doing a SBC conversion in a '71 FJ40, what are the pros and cons of leaving the 3 speed tranny in the rig. It is going to be primarily a daily driver with limited highway travel. Thanks

propilot said:
If doing a SBC conversion in a '71 FJ40, what are the pros and cons of leaving the 3 speed tranny in the rig. It is going to be primarily a daily driver with limited highway travel. Thanks


It will work, but I think you'll be much happier with a 4 speed. 4 speed transmissions are easy and cheap to come by. I would spend the extra $$ and do the 4 speed with the sbc conversion. Have you thought of installing a GM 4 speed (sm420 or sm465) if you plan on wheeling the rig?

Pros of leaving 3 speed.. cost
Cons of leaving 3 speed.. less gears for street use. Gears are spaced further apart than 4 speed (toyota, not SM420/465).
3 speed cons ...

No 1st gear synchro
No 1st gear synchro
3 gears? who wants just 3?
EVERYTHING w/ the 3 speed is a CON.

If you are swaping to a 350 you will have to buy at least one adaptor any way. Add $200 to your project and pick up a SM trany and be done with it.
Thanks for all the info. I am leaning towards finding a 4 sp tranny with transfer case. SOR advertises an adapter by Mark's that will bolt a SBC right up to the Toy components. Since I am not going to be doing any serious off roading this should work fine. Any thoughts?
My first cruiser had a 350 with a 3 speed (68). I also ran basicly stock tires. It was not something you wanted to drive very far on the freeway. At 60 mph the rpms were way too high. My recommendation is that if you plan much freeway driving, invest in a 5 speed. Second best is to run bigger tires to get the rpm down but a 5 speed get you a low 1st too!

NV4500 is what I'd like.

With the 4 speed I'm running now, it's the same ratio as the 3 speed. It's just direct engine RPMs. Had to do a long trip the other day, and bout to do it again in a couple hours, GPS readout at 70 MPH I had the 350 at 2900 RPM. Got better mileage though. ;)

What is the redline on a 350 again?
I have the SOR adapter from SBC to 3 spd. definately not a long distance rig, but I don't mind it. As stated above, the final is the same on the three and four, so you are just splitting up your gears a bit more. 4 speed will require a bit more work, but depending on what you use it for, it should be fine with the three.
I burned up a 3-speed behind a SBC on my 74.... of course I have a heavy foot :D
you'll get better mileage with a 4 speed as well, don't have to rev as high to get to the next gear (not a huge problem with sbc but at least you wont have to lug it to keep your mileage up)
Like MSAHR, I too blew up my 3 speed. The funny thing is that it worked fine behind a 283 for about 4 years for me, and however many years before that for the PO, but about 3 months after I swapped in the 350 it decided to lose a few teeth on the 2nd gear. Definetly a pathetic excuse for a transmission. I had nothing but problems with the clutch after I swapped to a LC 4 speed after that (this was with a Downey bellhousing adapter and a the LC/Chevy Ceterforce clutchpack). Great transmission though. I finally decided to to go GM all the way and went with a SM465. I really like this setup but the SM is not as good on the street as the LC 4 speed. It has some clunky shifting, but I think that might have to do with the shifter itself, I need to work on getting it a bit tighter. My favorite setup so far though. :grinpimp:
Ugh! I remember the guy who wheeled his SBC, 3 spd, 40 at Cruise Moab.

The 1rst gear ratio was not ideal, so he launched it at obstacles requiring crawl.

Well, he rolled it over on its back climbing an obstacle. He was transporting a relative stranger in the back. It was not funny. Pics were in the TT...
I have had 2 sbc with 3 speed cruisers and so long as you don't have a heavy right foot, they work just fine. I run 33s so my millage is a little better (how good can it be, it's a cruiser anyway?) Would I go the extra cost for a 4 speed ? No I would do the 5 speed if I was going to spend the extra $.
I had that setup in my last cruiser. It is not user friendly with driving around town, although it will work. If you can spend a little more cash, I would recommend the SM465 just incase you ever want to have some extra low gearing it would be available.

Just my 2 cents, good luck !

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