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Different Diffs

 
 
 
 
  #1  
Old 08-18-2006, 12:20 AM
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Default Different Diffs

I hual a 3 thousand pound boat and am wondering if putting a different size diff will help in any way. What size will help too?
 
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Old 08-18-2006, 01:11 AM
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Default RE: Different Diffs

First of all, is that a 2wd or 4x4.
If it's a 4 wheel drive you need to change both sets of gears to match. $$$$$$$$$$$$$
I also pull a boat, but it's a lot lighter. I use 2 of my trucks for pulling. The black one has 2:73 gears, which is good for the highway, and it pulls my boat. The orange truck has 4:10 gears in it. With the 4:10 gears I can climb up anything and I don't even notice the boat. My gas milage is terrible with the 4:10 set , but if I wanna haul something heavy, that's a good gear set.
So, it's a tough call, because all my trucks are V8's I have enough engine power to do the job.

I don't know if I've helped at all, but hopefully that's a little more information for you to think about.

I have a set of 3:73 gears for the orange truck, I was thinking about trying out, but with the amount of work involved, I'm in no rush.
I figure the 3:73 set should give me a little better fuel milage and top speed and still pull whatever load I need to, as well as climb all the hills I dare to.
 
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Old 08-18-2006, 08:12 AM
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Default RE: Different Diffs

So Chevy Lover... you OWN a gas station then.. RIGHT?.... if not.. you're buyin' one for someone everytime you hit that fuel dock..... (Just Kiddin') I couldn't resist....:P
 
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Old 08-18-2006, 09:25 AM
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Default RE: Different Diffs

Yeah, you'd have to change both the front and rear gearsets. What does your truck have stock? The RPO code list should tell you this.
 
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Old 08-19-2006, 12:47 AM
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Default RE: Different Diffs

It has stock diffs. I was looking at Summit and they have a lot of choices. I was hoping to get some info in which sizes do what?
 
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Old 08-19-2006, 07:10 AM
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Default RE: Different Diffs

Stock as in what? There are like 4 different axle ratios available... You really need to figure out what you have before attempting to change it...

Here are the RPO Codes pertaining to axle ratio for s-series vehicles:
GT4 Rear Axle: 3.73 Ratio
GT5 Rear Axle: 4.10 Ratio
GU4 Rear Axle: 3.08 Ratio
GU6 Rear Axle: 3.42 Ratio

As well as:
G80 Rear Axle: Positraction, Limited Slip

Now I think that GU6 (3.42) is the most common for blazers. Based on my RPO code listing, my Bravada has 3.73's
 
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Old 08-19-2006, 02:16 PM
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Default RE: Different Diffs

I think he has 4wd.

G/L finding 7.25" pinion ring grear set in a higher ratio. Tranny shift points will be screwed up plus you'll be winding out the motor at highway speeds. I think we can tow up to 7500lbs anyway.

I would save the gear money and put it towards more marine coolers.
 
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Old 08-19-2006, 04:27 PM
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Default RE: Different Diffs

Yeah I know he has a 4wd truck.

Doing a little bit more research, the earlier s-series trucks were available with the 3.08 ratio. Also, it seems that the 4.10 ratio was only available in 2wd trucks. So you've either got the 3.73 or the 3.42.
 
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Old 08-19-2006, 08:10 PM
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Default RE: Different Diffs

there are a TON of gear sets available for the gm 10 bolt rear.

as a general rule:
lower number (2.73... 3.08) = higher top speed, lower rpms on motor (better gas mileage), less low range power
higher number (3.73... 4:10)= lower top speed, higher rpms on motor (worse gas mileage), more low end power


gears are expensive to have installed, and its not a do it yourself job unless you know what youre doing. you have to check the wear pattern, backlash, etc etc. the local place here charges ~$500 or so to do it.
 
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Old 08-20-2006, 07:01 AM
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Default RE: Different Diffs

Thanks lunatic you made it understandable. Is that 500 dollars for both with gears? Or 500 dollars labor only for front and back? Basically I want more toque for my boat. It takes off slow. I believe I read in the owners manual that a blazer maxed out towing @ 4000 thousand pounds. Aint no way in hell my Blazer is hualing 7500 hundred pounds as a matter fact anybodys blazer can do this I like to know! With Hypertech Tuner I can change gear ratio's Low. What do you mean by Marine coolers? Oh now my blazer got the hickups but I will leave that for another thread.
 
 
 
 
 
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