GMC Truck Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
2,078 Posts
Discussion Starter #1
What are the stock gears for the V6 motors? Just wondering so I can compare.
Since most of my travel is Highway, and I want both rear tires going at the same time (I'm hating 1-wheel-peels), what are the choices of gears that I will need to put in?
 

·
Registered
Joined
·
303 Posts
you are talking about getting a limited slip. Gears and are completely different from a differential.

Right now you have an open differential meaning "one tire fire."

If you are serious about performance then buy a detroit tru trac. That will cost about $400 plus install

If you want gears then I'd get nothing taller than 3.90's. You have 3.42's stock. Your highway mileage will suffer by about 1-2 mpg but the performance will be definantly noticeable.

All in all, expect to pay about $1000 for gears, limited slip, install. That price could change based on the price you're quote for install but the parts should cost about $600
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #3
Hm...I dunno now. I'm just researchin' a bit. I'm not that serious on the performance though. Which gears are good for the Highway? The 3.90's, right?
 

·
EMBRACE WHAT'S LEFT
Joined
·
3,487 Posts
Hm...I dunno now. I'm just researchin' a bit. I'm not that serious on the performance though. Which gears are good for the Highway? The 3.90s, right?
4l60 trans you have sucks. Do you ever plan on running larger tires?

If not do either 3.90 or 4.10 gears and a detroit true trac and labor will be about 300 to install
 

·
Registered
Joined
·
303 Posts
Hm...I dunno now. I'm just researchin' a bit. I'm not that serious on the performance though. Which gears are good for the Highway?
Let me put it this way. I've never heard of people "gearing up" to increase gas mileage. It just doesn't make sense. You are going to waste your money by spending $500 on gears for maybe 1-2 mpg.

3.23 gears are gonna be best for highway, but like I said, you'd have to have your truck for 10 years before they paid for themselves, and you are going to hate how slow your truck is.
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #6
v6offroad said:
4l60 trans you have sucks. Do you ever plan on running larger tires?

If not do either 3.90 or 4.10 gears and a detroit true trac and labor will be about 300 to install
I plan on running 265/60HR18's when I get my wheels I want...But for now, I'm just running the 255/70r16's, and will be for a long time until I get my new wheels (whenver that is)

lowgreen01 said:
Let me put it this way. I've never heard of people "gearing up" to increase gas mileage. It just doesn't make sense. You are going to waste your money by spending $500 on gears for maybe 1-2 mpg.

3.23 gears are gonna be best for highway, but like I said, you'd have to have your truck for 10 years before they paid for themselves, and you are going to hate how slow your truck is.
So, if I change to different gears, my MPG will go down eitherway, right? Ok, so it doesn't matter much.

3.90's are good for the driving I'm going to be doing, correct? Which is mainly highway driving.
 

·
Registered
Joined
·
303 Posts
So, if I change to different gears, my MPG will go down eitherway, right? Ok, so it doesn't matter much.

3.90's are good for the driving I'm going to be doing, correct? Which is mainly highway driving.
Ok man this is a little frustrating, but I know you're new to this so I'll try and break it down a little easier.

You know what gears do right?

Right now you have 3.42 gears. That means at 75 mph you're probably at 2000 rpms. 3.42 gears aren't good for performance at all, but you get pretty good highway gas mileage with them

3.90 gears will probably make you turn about 2150 rpms at 75 mph. These will make your gas mileage suffer, but performance will be much greater and your city gas mileage will get better.

If you went with something like 3.23's, your gas mileage would improve on the highway, but only by 1-1.5 mpg(if at all). These would be the best to maximize gas mileage, but it isn't worth it since you'll have to pay $500 for a gear install.

If you're that worried about your highway gas mileage, just stick with your 3.42's. If you want better performance and better city gas mileage then get 3.90's or 4.10's. I have 4.10's in my room waiting to go in and I'll be running 255/70/16's like you.
 

·
Registered
Joined
·
1,292 Posts
A 265/60HR18 tire according to my calculator is about 29.63" tall.

Uswing 29.63" tire, 0.70:1 OD ratio for the 60e trans and a 70 mph cruise.

With 3.08's you get 1700rpm.
With 3.23's you get 1800 rpm
With 3.42's you get 1900rpm
With 3.73's you get 2075 rpm.
With 4.10's you get 2300rpm.
With 4.56's you get 2500 rpm.

If you do mostly highway I would go with 3.42-3.73 gears.
If you do 50% highway, I would go 3.73-4.10.

If you do mostly city driving I would go with the 4.10 gears.

I ran 4.10 gears with 28" tires in my 97 4l60e truck and I got 70mph out of 2400 rpm engine revs. It was a little revvy on the highway if I was cruising too fast. I owuld go through teh traps of teh 1/4 mile revving 4800-4900 rpm with the converter unlocked.

Then to provide power to BOTh tires, I would go Eaton Carbon Clutch type limited slip, or the Tractech Detroit Truetrac gear type locker.

Here is the Eaton Carbon Clutch LSD
http://www.reiderracing.com/eatonposi.htm

Here is the Truetrac
http://www.reiderracing.com/truetrac.htm

There are many more traction devices listed on teh left side of teh 2 links I posted above.

Take care

peace
PAuly
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #9
Okay. I understand these things now, lol. Will those gears (3.42 or 3.73) fit in the one or both of the above said Limited slips? I want to make sure everything fits.

So, if I keep my gears, and want to provide power to both wheels, just picking up a limited slip is all I need, right?
 

·
Registered
Joined
·
303 Posts
Okay. I understand these things now, lol. Will those gears (3.42 or 3.73) fit in the one or both of the above said Limited slips? I want to make sure everything fits.

So, if I keep my gears, and want to provide power to both wheels, just picking up a limited slip is all I need, right?
YES, they will work just make sure you buy stuff that will work with an 8.6" 10 bolt and not just an 8.5" 10 bolt.
 

·
EMBRACE WHAT'S LEFT
Joined
·
3,487 Posts
Okay. I understand these things now, lol. Will those gears (3.42 or 3.73) fit in the one or both of the above said Limited slips? I want to make sure everything fits.

So, if I keep my gears, and want to provide power to both wheels, just picking up a limited slip is all I need, right?
yep just pick up a true trac or something, i can give you ebay links to get em cheaper

Im not sure if youll have to setup gears again


btw i will be jealous that you have a locker:D
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #12
Okay. Thanks for baring with me on my lack of mechanical knowledge of automobiles, lol.
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #13
Alright. Thanks guys. How much am I going to have to fork out when I do the LSD (Eaton or Detroit, plus your best guess at labor costs)?
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #15
Please read man, I broke down the costs for you already as well as v6offroad
I have read, and re-read, and re-read everything. I won't be changing gears. Just the Limited slip differential and the labor for moving the gears out of the stock differential to the new one.

Never mind...I'll just have to go hunting for prices of an Eaton or a TrueTrac again.
 

·
Registered
Joined
·
303 Posts
I have read, and re-read, and re-read everything. I won't be changing gears. Just the Limited slip differential and the labor for moving the gears out of the stock differential to the new one.

Never mind...I'll just have to go hunting for prices of an Eaton or a TrueTrac again.
$400 for the actual differential. $125-ish for the install.

Why do you need a limited slip? I doubt you can even break your tire loose as it is with your 4.3L and 3.42's
 

·
EMBRACE WHAT'S LEFT
Joined
·
3,487 Posts
$400 for the actual differential. $125-ish for the install.

Why do you need a limited slip? I doubt you can even break your tire loose as it is with your 4.3L and 3.42's
I could break the tires on my tbi with stock tires in a straight line of course that has alot to do with it being a rcsb
 

·
Registered
Joined
·
2,078 Posts
Discussion Starter #18
$400 for the actual differential. $125-ish for the install.

Why do you need a limited slip? I doubt you can even break your tire loose as it is with your 4.3L and 3.42's
Ok. So I can expect to see something around that range. Thanks.

Break loose?
 

·
EMBRACE WHAT'S LEFT
Joined
·
3,487 Posts
make the tires spin without power braking
 
1 - 19 of 19 Posts
Top