transmission opinions?? who's got one...

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I am running a '72 FJ40 with a SBC 307 and a stock three speed tranny that is nearing the end of it's life.

The question is which is the best replacement / upgrade?

I hear lots about the options so I thought I'd ask and see if there is an overwhelming appreciation for one setup over another...

I am basing by options on the assumption that with a SBC a chevy tranny will be the easiest install with more options opposed to modifying a toyota non-usa 4 speed to a SBC and to a 3speed tranny.

From what I read the:

SM420 and SM465 is a good way to go for the gear ratio, simple conversion, cost, and reliability.

NV4500 also has a good gear ratio PLUS the OD (for my 500 mile trip), more complicated conversion, higher cost adapter and tranny, and good reliability.

TH700R4 automatic. Don't know much about it. Automatic with a lock-up. higher cost, slightly lower first gear than a TH350, better hypothetical mileage on the freeway?. (I hear rumors it can be undersized behind a V8, and a little finicky about it's setup, can get hot in OD)

TH350 automatic transmission. Been around longer than me. Reliable, least expensive automatic. No lockout? Lots of tech write ups....

Any other options I am missing that are reasonbly measured against these four?

Andy
 
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There's another option and thats the stock 4 speed and transfer. It is the easiest install and the most reliable hands down. Also the cheapest no adapters.
 
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awp_cruiser said:
The question is which is the best replacement / upgrade?


Andy
Best would depend on what you want out of it. Ease of installation? Off road performance? On road performance? Cost?

SM420 would be hard to beat for ease, cost and off road performance, but for just driving around town it would be just like your 3 speed.
 

wngrog

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No adapters? He has a 307 Chevy small block.......

Cheapest would be Small Block adapter to 4 speed and case if you get a good price on that setup. I see used small block chevy adapters all the time for around $300. Used 4 speed and transfers vary, but $500 is TOPS on that. Of course you may find both for $100 or so.

700R4 will take huge abuse. I heap it on mine with 375 HP and 42s.

If you want a standard, do the toy stuff. If you need gears, get an ORION.

If you want an auto, to the 700R4 and keep your 3 speed transfer case.
 
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for a yera now i have been making the 4l60 auto fit the 2f motor so far i have just finished making the bellhouseing and mounts. Having that od got to make a differance.New main shaft to fit from auto to transfer case is next. Sorry a4l60e is a 700r4
 

Cruiserdrew

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I agree with Pin-Head. You have almost all you need for an SM420 install already. This is by far the cheapest, strongest tranny you can get. The 7:1 first gear for off road is absolutely great. They used this tranny for up to 2 1/2 ton trucks so it is way stronger than a Toyota 4 speed. The highway gearing is the same for all of the 3 and 4 speeds- 1:1. The autos and the NV4500 are long and may introduce driveline issues unless you move the rear axle back.
 

65swb45

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For a 6 banger, I'd recommend an H41 Toyota tranny. But since everyone knows a V-8 can't lug down as low as the Toyota 6, if you want to crawl, you should go with the Muncie, and save yourself the extra heat and braking issues of the autos, along with the REALLY short rear driveshafts.

420 is awesome in the rocks, but a BITCH if you do much street driving. Worse than a 3speed IMO.
 
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Thanks for the thoughts. I do plan on running it as a daily driver, granted my commute is less than 10 miles, but I'd like to build an all around ride. I am willing to sacrifice a little of each, on road and off-road performance, to get an all around solid runner.

Limited funds and time are the goal but not the objective. So, if the the 420 is cheapest and easiest, "replacement", what is the killer upgrade?

Auto with an orion?
 
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