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post #1 of (permalink) Old 08-15-2001, 04:42 PM Thread Starter
 
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Gearing?

Gentlemen,
I recently sold my old Toyota 4X4, and stepped up with a 96 Chevy extended cab Z71. I shopped around for ever and finally got exactly what I wanted. This baby is bad ass, 6" Dick Cepek lift on 35's. I bought the truck for a few reasons, one of which to tow my 19' jet boat out to the river, but's there's a problem. I'm hoping this can be remedied with some new gearing, and that the transmission is not going out. The truck runs great, but has no balls when trying to accellerate up a grade. It's an automatic transmission with overdrive and the truck has only 70k on it. As i begin to gas it to maintain speed the transmission will kick down, and you can still feel it pulling. This is reving between 2000-3000 rpm's. If i continue to accellerate, the tranny will shift even lower, raising the rpm's, but it will actually begin to lose speed. There's no way in hell I can pull my boat up some grades around here as is, I'm hoping this is a common problem with lifted trucks and this will go away with some new gears. Any ideas? Much appreciated boys!

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post #2 of (permalink) Old 08-15-2001, 04:54 PM
 
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Re: Gearing?

<font color=blue>Well the first question should be, Did you or the last owner change the gears from stock? If not then it's no wonder you find yourself lacking power! With that auto tranny, And the fact that you tow I'd go with some 4:56 gears, That is the lowest you can go with the IFS front, And it's just about perfect with 35's and the overdrive. If the gears are stock, You can look in the glove box for the option sheet, Look for one of these codes, They'll tell you what came with your truck, The most common gearing seems to be 3:73's. Anyway here are the codes.
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42
GT4 - 3.73
GT5 - 4.10
HC4 - 4.56
G80 - Posi, limited slip rear end
Hope this helps.</font color=blue>


<font color=blue>Come on Come on listen to the 40's talk!</font color=blue>
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post #3 of (permalink) Old 08-15-2001, 05:29 PM
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Re: Gearing?

4.56s my friend.

[img]/wwwthreads_images/icons/wink.gif[/img]Somebody once said "Go Big" . . . Well we're goin' Full Size[img]/wwwthreads_images/icons/wink.gif[/img]
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post #4 of (permalink) Old 08-15-2001, 05:47 PM
 
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Re: Gearing?

Actually most the guy's on here wish they had 3.73's I bet it came with 3.42's.
And it now has 35"s lets see 3.42's, and auto tranny, and 35" tires [img]/wwwthreads_images/icons/blush.gif[/img] and you say it dosnt have any towing power [img]/wwwthreads_images/icons/shocked.gif[/img] yeah thats right!
4.56's all the way bud !!! don't let anybody talk you into 4.10's nether[img]/wwwthreads_images/icons/frown.gif[/img] with 4.56's you will have low end , off the line Balls[img]/wwwthreads_images/icons/smile.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img](hey look, smily balls) Plus you will be able to use your "Overdrive" on the freeway!!!

Side note: if your truck does not already have an external tranny cooler, buy and install one immediatly! it is the best $50 you will ever spend, and it could end up saving you $$$$$$

Scooby Dooby Doo !!!
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post #5 of (permalink) Old 08-15-2001, 06:18 PM
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Re: Gearing?

ther is also a kit that is sold by b&m that lets you change youre shift points with a dash mounted switch this may help you as well . its about 60 bucks through summit and is about a 20 to 30 min install .

when in doubt, let er feed
post #6 of (permalink) Old 08-16-2001, 11:35 AM Thread Starter
 
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Re: Gearing?

Thanks for the words of wisdom gentlemen, sounds like 4:56 is the way to go. Let's say I went to a smaller tire, like a 33...perish the though. Would those gears still work, or would I want the 4:10 instead. Thanks for your help boys, I'll get a picture up of the new rig soon.

'96 Chevy Z71 extended cab, 6" Dick Cepek lift on 35's
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post #7 of (permalink) Old 08-16-2001, 11:44 AM
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Re: Gearing?

Rule of thumb for an auto is 35"=4:56,33"=4:10's or maybe 3:73's and most 265's/285's run great with 3:73's. I am running 285's with 3:42's and its a little slugish.

If you are looking for good millage on the highway though and don't do alot of offroading you could go with 4:10's with the 35's there for keeping your RPM lower and still have tons of torque when in LOW to pull that boat out of the water.

RYan

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post #8 of (permalink) Old 08-16-2001, 11:52 AM
 
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Re: Gearing?

I think you have to take into consideration OVERDRIVE not just that it is an auto, if it were just a 3spd auto (TH350,TH400) I would say 4.10's would be OK but cosidering that he has a OD he can easily get the 4.56's and not loose any hiway mileage

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post #9 of (permalink) Old 08-16-2001, 12:41 PM
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Re: Gearing?

your gear ratio in your trans is:
1rst 3.06
2nd 1.62
3rd 1.00
4th(od) .70 <----this is what scoobydoo means by you can easily use 4.56s and be okay on highway.

DJ(dude)

post #10 of (permalink) Old 08-16-2001, 05:25 PM
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Re: Gearing?

Scoby- I was condsidering OD. Its just that even with 4:10's he will still have enough torque to do the job. With 4:56's he would be just above stock level there for giving him a tad worse mpg even in OD. Now if he wants to go with 4:10's because he doesn't do that much off-roading he could. The 4;10's will give him a tad more mpg but will hurt his out of the whole but not by much. I look at it by the 1st gear!!! I know my Sport was a 5-speed but because it had a lower first gear than the auto's I could have went to 3:73's instead of 4:10's but I was wanting more torque down low for off-roading with my 35's. Where the 3:73's would have given me enough torque to haul out the boat and also would have gave me more mpg on the high way in OD.

Not sure if any of that makes sense....Either one is going to work and both gears have pro's and con's but either one will do what you want you just have to decied what you want to do[img]/wwwthreads_images/icons/wink.gif[/img]

Ryan

93 GMC Yukon
Chevy SuperStock 4x4 Truck Puller
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