Contemplating Gear and Engine Swap
Postmaster
Joined: Jul 2003
Posts: 2,711
Likes: 2
From: Pittsburgh
i ran 3.08's with a 435 and a 300 and 31's and never had an issue. I also ran 3.5's with 35" tires, a 300, a 435 and could launch just fine in 2nd gear and could do it in third with some fancy clutch work.
If you can't launch in 2nd with 3.08's and 32's you either need to learn how to drive or your truck has some major issue.
besides, the ZF doesn't have an extra gear inside the spread. instead of a 3 speed with an underdrive it's just a 3 speed with a not so underdrive and an overdrive. It has a slightly tighter spread, but at the sacrifice of first gear. If geared the same, the 435 is 10x the transmission in all ways except top gear cruise. the ZF needs 25% deeper axle gearing to equal the 435 in 1-4, but does take the edge in gear spacing.
HOWEVER- once you're towing and aren't using overdrive, the 435 again has the better gear spread and lower cruise revs.
and like i had said, a deep first gear was alot more important to me than an overdrive.
also with that torquey 460 it would definitely cover up the gear split between 2 and 3 with the 435.
I'd regear to 3.5's before even considering the ZF swap unless someone was practically giving it to me.
Justin
If you can't launch in 2nd with 3.08's and 32's you either need to learn how to drive or your truck has some major issue.
besides, the ZF doesn't have an extra gear inside the spread. instead of a 3 speed with an underdrive it's just a 3 speed with a not so underdrive and an overdrive. It has a slightly tighter spread, but at the sacrifice of first gear. If geared the same, the 435 is 10x the transmission in all ways except top gear cruise. the ZF needs 25% deeper axle gearing to equal the 435 in 1-4, but does take the edge in gear spacing.
HOWEVER- once you're towing and aren't using overdrive, the 435 again has the better gear spread and lower cruise revs.
and like i had said, a deep first gear was alot more important to me than an overdrive.
also with that torquey 460 it would definitely cover up the gear split between 2 and 3 with the 435.
I'd regear to 3.5's before even considering the ZF swap unless someone was practically giving it to me.
Justin
Lead Driver
Joined: Dec 2002
Posts: 5,491
Likes: 16
From: Kuna ID
I'm going from a C6 to 5 spd, I got 4:10's with 33" tires. If I already had a 4spd I probably wouldn't worry, the auto is so (embarassingly)sluggish with a load, and quickly climbs past 210* if I have to stop too many times. I am just sick of dealing with it. Besides, a stick is more fun to drive, and I have already made all but $50 back from the purchase of the parts truck. I still have more stuff to sell from it too. 
