3.73 to 3.42 gears ?

M

Mazak

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Jul 30, 2017
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I have been considering changing my gears on my twin turbo truck to 3.42 . It needs to have a locker installed anyways because it's an open diff.

I don't plan on towing with it. It's an 06 with an automatic.
I am running 305 nitto 420s

What would be the pros and cons of going this route ?

Would a 1/4 mile time be quicker ?
 
I just swapped in 3.42s into my 2wd for track reasons as I’m going through the traps at 3500 rpm and it’s flat at those revs so I’m hoping it picks up the mph. Not sure there is a con to the swap especially if you’re not towing except for the cost in your case of swapping front and rear axles. Cruise rpms are lower at 1700@70 mph, I also have 285 tires. I just thought of a con at least for me, it won’t go into lockup until 55mph now. So far I’m liking them.
 
my experience is with 2nd gens, however owning 4 of them with both 4.10 and 3.54's makes this relevant.

swapping from 3.42's to 4.10's pre and post compounds was the best overall money spent on my green truck (600-700HP realm). The taller gear was great if you daily drive your truck and tow very seldom. I feel the best of both worlds is probably a 3.73 with an auto and 3.54's with a stick, as 4.10's are way to low IMO for a manual driver.

it would be hard for me to advise going to a 3.42 regardless. On top of the fact that the0.31 gear change is so small the return for the $2500-$3500 swap isn't going to be all that noticeable. I feel you could spend your money in better places.

egts are much lower while towing. smoke output fell substantially, towing is night and day, I do not beat my transmission to death towing or hot rodding as it shifts through gears instead of working through them. The big down side to the lower gear is highway driving. it is a pain, I do have to drive slower to keep the R's down.
 
59turbo said:
I just thought of a con at least for me, it won’t go into lockup until 55mph now. .
Click to expand...

overdrive will be at 44MPH when your getting groceries. with 4.10's and 33 inch tires. with a 47 series transmission
 
turbo2387 said:
overdrive will be at 44MPH when your getting groceries. with 4.10's and 33 inch tires. with a 47 series transmission
Click to expand...

Mine used to be 4th then lockup at 48-50 mph with stock size tires and 3.73. Lock up at 55 now isn’t that bad just takes getting used to.
 
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