Tire and Gearing Question

Meatywand · January 22, 2005

I have a Z71 with a 3" body lift, and a 3 inch custom suspension lift. Right now I'm running 35" Procomp X-terrains on the factory 16" Rims. I have 3.73 gears in the rear. My question is what should I change my gearing to to restore my lost performance, some people have said 4.11 some have said 4.56. I'm not sure which to go with cause I'm afraid the 4.56 will not be good for highway driving.

Also a guy I talked to at the tire shop told me that I could fit 36x13.50 tires on my truck if I went to an aftermarket rim that had a different backspacing from the factory ones and if I went down to a 15" rim, does anyone know if this is true or not? I would appreciate any help

potz1999 · January 22, 2005

First I take it your Z is an OBS (pre-'99). Then yes you could go to a 15" rim. If yours is a NBS (99-05) then no, you CANNOT use a 15" rim. Your tire guy is probably right, but what backspacing does he want to run? Does your suspension lift require a maximum backspacing? I wouldn't run backspacing less that about 3.25" (generally) since that can lead to weird alignment problems.

With the gears, you want to go numerically higher not only to recover lost performance, but it takes stress of the tranny. With the exception of the Allison, most transmissions are fragile and the weak link in a drivetrain. If you go to a 4.10, you will recover most of your stock performance (within maybe 5%). Going to a 4.56 will definately wake up your truck: more performance.

Really your call. The 4.56's and 35's are running at the limits of your 10-bolt. If you don't do hardcore wheelin' you should be fine. As for the highway, are we talking 75mph cruising with the occasional 85mph blast pass? Then you'll like the 4.56's. Consistant 90mph cruising, probably would like the 4.10's better.

Shotgun · January 22, 2005

WOW ,35's with 3.73's! Must be terrible seeing the chevettes drive by you....J/K. You need at least 4.56's with that setup and maybe 4.88's. If your worried about economy lose the 35's and go back to stock. That is the trade off though your engine is definatley not running in an ideal setup now, you will improve your fuel economy going to the 4.56's because you will use way less power to move your truck.I am running 4.56's with 33's and my opinion is that it is the perfect setup for getting the power to the ground.

Meatywand · January 23, 2005

I'm not sure about the backspacing he said he would have to check that out, ok so part 2 of my question whats a good place to order gears from, what exactly should I order? I have a limited slip right now do I need to get limited slip 4.56 gears? or would it be worth my money to buy a detroit locker? Also how much will just the gears (not install) cost me for a set of 4.56s?

Shotgun · January 23, 2005

I wanna say I paid like $1300 for the gears installed. I'm sure this will vary some.If you don't already have a locker this would be the perfect time to add one. Here is a good gear vendor that specializes in gears....Randy's ring & pinion

Jacqson · January 23, 2005

I'm not sure about the backspacing he said he would have to check that out, ok so part 2 of my question whats a good place to order gears from, what exactly should I order? I have a limited slip right now do I need to get limited slip 4.56 gears? or would it be worth my money to buy a detroit locker? Also how much will just the gears (not install) cost me for a set of 4.56s?

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You could also check out (www.macromotive.com). They carry Ring and Pinions by Superior Axle and gear which I have heard are top notch ring and pinions.The prices look good and the shipping is free. You could probably get a set (F & R) for under $500.00. Also you can run about 4.5" to 5" backspacing on your wheels. The stock limited slip in GM trucks is a piece of crap, if you are going to the expense of getting new gears look into a posi from either Eaton or Detroit. They are both very streetable lockers.

Meatywand · January 23, 2005

ok Would you reccomend doing the front and rear, or just the rear? I don't do alot of really hardcore wheeling so would it be better for me to change the rear gears and maybe put a locker in in just the back?Also is motive a good brand?

Shotgun · January 23, 2005

ok Would you reccomend doing the front and rear, or just the rear? I don't do alot of really hardcore wheeling so would it be better for me to change the rear gears and maybe put a locker in in just the back?Also is motive a good brand?

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You cannot just change the rear gears. If you do ,there will be alot of broken pieces falling out when you engage the 4X4.. If you want quality bullet proof gears go with Yukon or Auburn.It's the stuff the pro's use.Motive gears are built and designed for racing and will not last under everyday driving conditions.They are made from softer alloys.

Meatywand · January 23, 2005

aight thanks!

potz1999 · January 27, 2005

ok Would you reccomend doing the front and rear, or just the rear? I don't do alot of really hardcore wheeling so would it be better for me to change the rear gears and maybe put a locker in in just the back?Also is motive a good brand?

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You cannot just change the rear gears. If you do ,there will be alot of broken pieces falling out when you engage the 4X4.. If you want quality bullet proof gears go with Yukon or Auburn.It's the stuff the pro's use.Motive gears are built and designed for racing and will not last under everyday driving conditions.They are made from softer alloys.

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Motive gears are used by OEM's and one of the more popular gears out there. Why would a racing gear be made from softer alloys?

BIGASSZ71 · January 29, 2005

I have 35's on my truck until i get the rest of my lift put on and the 38's are bolted up and i have stock 3.73s and i can spin them over no problem on dry pavement.

min9861 · February 11, 2005

i also need 4.56's for my truck when i get 35's. any recommendations?

how about lockers?

sonicr1 · February 11, 2005

Had a dodge with 35's, stock gearing (3.73) for a year, towing a boat... burned up clutch packs... went to 4.56's... MUCH BETTER!!!! But Dodge's tranny's suck anyway (hence the reason I own a chevy now!!!). With the Chevy, though, the 4L60E, has a decent first gear, so you can get away with stock for a while, but if you tow, you will want to swap out gears asap!!!

My vote is 35's and at least 4.56's!!!

Stryker · February 19, 2005

Hey guys, I'm also looking to get bigger tires. I am currently running 33" with 3.73 gears (i believe). Anyway, my question is would you need to change your shift point after regearing? I believe so, so my next question is where do I turn to get that done. I hear of mod chips and stuff but I am confused as to what to get. How much $$ are we talking too. Thanks.

Shotgun · February 20, 2005

Hey guys, I'm also looking to get bigger tires. I am currently running 33" with 3.73 gears (i believe). Anyway, my question is would you need to change your shift point after regearing? I believe so, so my next question is where do I turn to get that done. I hear of mod chips and stuff but I am confused as to what to get. How much $$ are we talking too. Thanks.

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You would only have to reprogram for the new gears which can be done with a Hypertech programmer. You could probably pick one up on e bay cheap.