Gearing change

trever1t · November 12, 2005

Right now i'm running 3.42 on 265/70/17 (31.6") and it pulls good but i know a lower gear ratio would improve my take off dramatically and also improve my off-road performance also.

I plan on eventually going up to 285/70/17 (32.7")

Most of my driving is around town with a lot of stop and go, probably 70%, but i'd hate to lose too much economy on the highway.

What gear ratio would you recomend for me and what kind of LSD or Locker should i install while i'm in there? Again, about 70% of my driving is around town, back and forth to work, 29% highway and the rest...

Where is the best site to order parts from?

Should i stick with GM parts?

vhato · November 12, 2005

Right now i'm running 3.42 on 265/70/17 (31.6") and it pulls good but i know a lower gear ratio would improve my take off dramatically and also improve my off-road performance also.
I plan on eventually going up to 285/70/17 (32.7")

Most of my driving is around town with a lot of stop and go, probably 70%, but i'd hate to lose too much economy on the highway.

What gear ratio would you recomend for me and what kind of LSD or Locker should i install while i'm in there? Again, about 70% of my driving is around town, back and forth to work, 29% highway and the rest...

Where is the best site to order parts from?

Should i stick with GM parts?

<{POST_SNAPBACK}>

IMO,

3.73's would be a good choice for 265's. However, after you spent the money having the gears changed you would not notice too much a difference if you noticed at all. I would recommend 4.10's since you are going to 285's in the future. And don't worry, we all know people who say 4.10's drink the gas, but these same people probably never had 4.10's or they had 4.10's in a 3/4 ton truck or new a guy who them once. My point is, the 4.10:1 gear ratio isn't gonna kill your gas mileage. If you do alot of city driving you will notice an increase in economy (assuming you can keep your foot out of it). Worse case highway loss would be 1 MPG. If you get 18 MPG Highway now and upgrade to 4.10's that would equal roughly 22 miles a tank lost (based on when the low fuel comes on at 22 gallons of consumed fuel). But your gain in the city might offset the minor loss on the highway.

When it comes to differentials, I recommend 3. An Auburn Pro LSD, and Eaton Posi LSD or Detroit Locker.

The Auburn Pro LSD and Eaton Posi LSD work the same way, but are mechanically different. Which ever you can get cheaper I guess is the one to get. For a mainly street driven vehicle you will get EXCELLENT traction when you need it and they are always quiet. Decent off-road. The Eaton Posi can be upgraded to near locker like performance for $50 if necessary.

Next up is the Detroit. This unit is ultra strong and won't die. The rear axle as a whole will fail before this will. For the ultimate in *No Excuses* off-road traction

this is it. The main drawback is it is REAL notchy (feels like your truck is being kicked by a horse) when turning on the street and loud when it engages and disengages. Usually for guys with 4x4's that don't like getting stuck.

My old 2000 NBS Z-71 with 9" of lift had 4.88's and an Eaton Posi LSD. My truck was basically a street queen seeing off-road maybe 1% of the time.

trever1t · November 12, 2005

Thanks for the reply with excellent info. I am pretty set on the 4.10 as i believe you are correct that the 3.73 although sufficient leaves no room for larger tires.

Since most of my driving is city street I will opt for a LSD although I like the idea of and ARB or ELocker too!.

Think I 'll go for the Detroit "TrueTrac", was quoted $413.99+tax by 4WP's. Any better source?

Mark_in_Tulsa · November 12, 2005

You are planning on changing the rear and the front right?

I'm only asking because it wasn't mentioned and I noticed you have a Z71

trever1t · November 13, 2005

Yes, of course, front and rear.

Mark_in_Tulsa · November 13, 2005

Yes, of course, front and rear.

<{POST_SNAPBACK}>

lol

I didn't doubt ya but since it wasn't mentioned and you only mentioned one price I was just going to make sure.

I can't wait to hear about your results. Are you going to do it yourself?

trever1t · November 13, 2005

I can't wait to hear about your results. Are you going to do it yourself?

Oh No! I have little patience and usually end up getting hurt

I have a quote from a local rear end specialist for $1000 front and rear plus the cost of the posi. He did my bud's '64 impala and comes recomended. The local speedshop and 4Wp's wanted $2K in labor!

vhato · November 13, 2005

I can't wait to hear about your results. Are you going to do it yourself?

Oh No! I have little patience and usually end up getting hurt

I have a quote from a local rear end specialist for $1000 front and rear plus the cost of the posi. He did my bud's '64 impala and comes recomended. The local speedshop and 4Wp's wanted $2K in labor!

<{POST_SNAPBACK}>

$1,000.00 front/rear+gears+fluid is an accurate price. I didn't mention the Detroit TrueTrac because it is not commonly installed as well as the ARB and E-Locker since they cost significantly more.