3 speed to 4 speed

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I have a '73 fj40 w/ a 350 and a 3 speed transmission and transfer. If I go to a '79 4 speed and transfer, will it bolt right with the same adapters that I have now? I have a gm bellhousing with a spacer between it and the transmission and a crossmember bolted to the transfer. Wouldn't the higher gear of the 4 speed transfer make the 1:1 4th gear better on the road than my 3 speed? Please help
 
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Both 3 and 4 speeds have a 1:1 final gear as is the TC. There will be no difference for on road travel. All you will have is closer spacing between each gear. For better road travel your only choices are bigger tires, changing the rear ends, or putting in an overdrive unit (which could include a 5 speed such as the NV 4500). If you opt. to get rid of the 4 speed and TC drop me a note ... I can use them both.

Good luck.
 

woody

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it's a different adapter completely, plus you'll need driveshaft length changes.

the 4-speed t-case is 1:1, same as the 1:1 ratio of the 3-speed t-case. top gear in both trannies is 1:1. You'll notice absolutely zero different at road speeds, other than the slightly quieter gears in the trans/t-case.

In town, the 4-speed is nicer shifting and gives you that "middle 30mph gear" that the you are missing now.

If your focus is offroadability, then swap in the SM465. If it's streetability, the Toy 4-speed is great. See http://www.advanceadapters.com for options on bellhousings.
 
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you're missing the best part about the 4spd:

SYNCHROs!!!! you'll actually be able to shift from 2nd down into 1st without stopping.

also, it (outside of the adapter) is one of the cheapest trannies that you can swap for the 3spd.

i was going to do the same swap, but now that my 40 is out of commission for a while, i'm probably goin to go nv4500 or try and find/figure out how to put in a h55.

jonathan
jmalphr@clemson.edu
 

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