• Welcome to H4O! For a reduced ad experience, please login or register with the forum.

Regearing for 37's--cost and gear selection?

twinmill28

Spilled Milk
Messages
1,545
Location
El Centro, Mehico (Way So Cal)
I'm towing a 6000 pound travel trailer and running 37's on the factory 4:11 gears. What's your recommendation for new gears (size and brand) and about what should I expect to pay?

I was originally thinking 4:56's but 4:88's seem to make more sense. Thanks
 

alrock

El Diablo
Staff member
Messages
10,442
Location
Scottsdale
PM D. Kinsey and/or Timgco if you need info. I believe both have done it but both have sold their Hummers and are less likely to see this.
 

GreatDaneHummer

Well-Known Member
Messages
994
Location
Chicago
4:88 gear is optimized for 37" tires. I used Yukon gears for building up my 14 bolts. They are a well known company and I have not been able to mount up the axles so I can't say anything else on function yet. I think CJ at Thorparts have used them many times. I paid $239.50 for each
 

Big2dabank

Well-Known Member
Messages
1,216
Location
Central Florida
Since you tow often, you may want to check around to see if you should stay with 4.56 instead of jumping to 4.88s.

I personally think 4.56s are perfect for 37s and 4.88s are perfect for 38s. Unfortunately, I am still running my 4.56s with 38s now and its a slight bit sluggish, but hardly noticeable and there is still plenty of power through all of the gears when I need it. I still tow occasionally so I am not quite ready to go to 4.88s because I think it would keep the rpms a little too high for towing long distance, but thats just my opinion.

Here are a couple of quick gear ratio calculations for you.

For stock tires and gears;

(4.10 x 60mph x 336)/ 33.6 inches = 2460 rpm 3rd gear
2460 x 0.696 (overdrive) = 1712 rpm


For 37s and 4.56
(4.56 x 60 mph x 336)/ 37 inches = 2485 rpm 3rd gear
2485 x 0.696 (overdrive) = 1729 rpm

For 37s and 4.88
(4.88 x 60 mph x 336)/ 37 inches = 2658 rpm 3rd gear
2658 x 0.696 (overdrive) = 1850 rpm


For 38s and 4.88s
(4.88 x 60 mph x 336)/ 38 inches = 2589 rpm 3rd gear
2589 X 0.696 (overdrive) = 1802 rpm
 

twinmill28

Spilled Milk
Messages
1,545
Location
El Centro, Mehico (Way So Cal)
I guess I should have also said I tow this trailer up a steep interstate incline (heading into the mountains from El Centro toward San Diego and currently the truck almost doesn't have enough umph to pull it off--especially as the temps go up my speed goes down and the truck really hates it.

So my understanding is that the 456's or 488's will help with these mountain climbs? thanks for all the inputs
 
Top