Axle rebuild 3:73 or 3:55

Arnoldb.1

New member
Joined
Mar 22, 2018
Messages
24
Reaction score
0
Location
Celina,TX
I’m having to rebuild my rear end on my 2wd excursion, wanted thoughts on gears. It has 3:73 in it now was wondering would 3:55 be better fit?
I don’t tow anything, just hotrod diesel play truck I daily. As I add more power was wondering if the 3:55 would be better fit?
Dieselsite built trans
Completely modded Turbo
******** tunes
175/30 swamp injectors
Adrenaline
Those are the highlights
 

fordfreak4life

New member
Joined
May 18, 2011
Messages
1,926
Reaction score
0
3.55 is alot of gear for a 4 spd trans but I ran them in my 97 and still towed with it. If you do alot of interstate driving it will definitely help you out. Drag racing I think it will probably hurt you some

Sent from my VS995 using Tapatalk
 

Arnoldb.1

New member
Joined
Mar 22, 2018
Messages
24
Reaction score
0
Location
Celina,TX
Yeah that’s what I was thinking too. Could be the tuning or the pcm fighting the hydra, but I feel like the truck really isn’t using 1 at all, only for a second, so I had a thought maybe the 3:55 would make it pull 1 more and have a 1,2,3 vs the mostly 2-3 I’m getting. Again probly need more tuning on the shifts or a PCS controller
 

Lt.Dan

Member
Joined
Dec 29, 2015
Messages
421
Reaction score
1
Location
Visalia, CA
I have 4.10s and 35s, and mine gets out of 1st before 8mph when normally accelerating. Tuning can take care of that though, no need for a controller.
 

Arnoldb.1

New member
Joined
Mar 22, 2018
Messages
24
Reaction score
0
Location
Celina,TX
Stock tire height, truck 2wd has a Djm suspension 3/3 drop kit with Heilwig swaybars front and rear. I have a Detroit Trutrac for the rebuild.
 

JCart

Member
Joined
Jun 9, 2011
Messages
509
Reaction score
2
Location
Kamloops, British Columbia Canada
Stock tire height, truck 2wd has a Djm suspension 3/3 drop kit with Heilwig swaybars front and rear. I have a Detroit Trutrac for the rebuild.

Oh Sorry Arnoldb, didn’t see Ex 4x2... not towing, possibly better mileage if not in rocket mode ripping around and stock or lower profile tires I’d do 3:55s. What turbo you running?
 

b00stleak

Member
Joined
May 22, 2011
Messages
65
Reaction score
0
Location
Edgewood, NM
I always like taller gears. I know I am in the minority. Turbo torque is a marvelous thing, once you're spooled, the taller gear will pull harder and longer in my opinion.
 

Kowboy

Member
Joined
Sep 28, 2017
Messages
44
Reaction score
1
Location
Idaho
I have an OBS with a ZF-5 42. The factory gears were 4.11 with 33" tires. I have owned the truck for 24 years, about 5 years ago I had 3.55 gears installed, before at 2000 RPM in OD I was at 58 MPH, now at 2000 RPM I am at 70 MPH, but I could no longer start off in second gear. I had to always use first. If I was loaded heavy 10 - 12000 lbs on the trailer and I was on a hill I had to put the transfer case in 4 low. I was not liking this at all, neither was the clutch, I was debating on going to 3.73. I started looking at options and decided to install a ZF-6. Going to the 6 speed is night and day verses the 5 speed. It has made driving the truck a joy again. Empty I can start in 2nd again and even did 3rd once when I was not paying attention.
I say all this to make a comment to my experience. I was hoping to be able to cruse at a higher speed on the highway and get better MPG. I can cruse at a higher speed but there is no MPG improvement. I attribute that to the fact that I am going faster and there is more wind drag, when I am stuck having to travel at 55 - 60 I do see a gain in MPG. I am very pleased with the 3.55 gears and would do it again. But consider the primary use for your truck. I think that when I am loaded I might get better MPG with the 3.73, but I am not willing to spend the money to find out.
Good luck on your decision, When you are done let us know how you like the change.
 

Arnoldb.1

New member
Joined
Mar 22, 2018
Messages
24
Reaction score
0
Location
Celina,TX
Thanks for the advice, I stayed with the 3:73 since a performance hotrod setup is what I’m looking for, will look to get the tuning adjusted on the shifting.
@JCart I’m running a modified stock turbo with .84 turbine housing, has the KCTurbos S300 turbine with a GTP38R backing and ported compressor housing 4” inlet with a 67/88/93mm 6-6 billet wheel
 

JCart

Member
Joined
Jun 9, 2011
Messages
509
Reaction score
2
Location
Kamloops, British Columbia Canada
Thanks for the advice, I stayed with the 3:73 since a performance hotrod setup is what I’m looking for, will look to get the tuning adjusted on the shifting.
@JCart I’m running a modified stock turbo with .84 turbine housing, has the KCTurbos S300 turbine with a GTP38R backing and ported compressor housing 4” inlet with a 67/88/93mm 6-6 billet wheel

Cool cool, I’m thinking either way you’d be ok for gearing and by staying with what you’ve got you can always adjust wheel/tire diameter to dial in gearing to optimum for your needs.
j
 

Latest posts

Members online

Top