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Gear Change 9.5" 12 bolt


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So the rear Ring and Pinion set is the same part number from the old gear sets all the way back to late 97-current.

 

RT

 

Yes that is what everyone has been using. And that is because all GM has made so far is 3.08 and 3.42 for the 9.5" 12 bolt.

 

IMHO don't get wrapped around the gears being "direct fit". As far as for going to 3.73's, all you need to convert is the new $107 yoke. Everything else; install kits and new pinion seal is stuff you would have to buy anyway.

 

Read this: http://eastcoastgearsupply.com/files/PDF%20Files/gm9-5-12-bolt.pdf

 

They state that you must replace the carrier. That may be true for 4.10 or 4.56 gears but I know I didn't have to buy a new one.

 

As far as "trusting" the G80? I have had two friends have theirs explode on trucks that had only slight engine mods. One was running 34" bias TSL's and one was running 35" KO's. Both had 350 engines. However both axles were 10 bolts. I personally have never heard of another G80 going out. Not saying it hasn't happened but I haven't seen it.

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Good info here...I have been setting up ring and pinion's for 20+ years I just haven't recieved any dimentional specifications (until now) or taken any measurements on these rear axle assemblies. I'm definitley going with a better carrier as I have seen thousands of exploded G80's in both modded and non-modded axles. Thanks for the information.

 

RT

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DO NOT... FEAR... THE GEAR. Always go bigger. If i had it to do over again with the 5.3 I would do 4.88 or 5.13. 4.56 was just OK. And ditch the G-80 unless you want problems down the road; especially if you work the truck every now and then.

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44Bogger, why did you replace the front carrier? Was my understanding those are interchangeable for any of the 8.25" front axle gear sets. Rest of the info is spot on from what Tate at Randy's R/P told me also. Only thing I would do different is swap the rear crush sleeve to a solid pinion spacer, couple extra in/outs of the pinion to set preload, then it's a done deal.

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44Bogger, why did you replace the front carrier? Was my understanding those are interchangeable for any of the 8.25" front axle gear sets. Rest of the info is spot on from what Tate at Randy's R/P told me also. Only thing I would do different is swap the rear crush sleeve to a solid pinion spacer, couple extra in/outs of the pinion to set preload, then it's a done deal.

Yes, same differential. 3.08 and higher use a different carrier. So if your ride has 3.42's, you use same carrier.

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  • 2 years later...

I know this is an old post but is there any updates for a direct swap for the 9.5 12 bolt? Looking for 3.73s

 

What stock ratio does have your truck have? Yukon makes 9.5 12 Bolt gears now. Direct swap if you have 3.42's. If truck had 3.08's you need to ether replace the carrier or use a spacer. Same applies for the front axle, 3.42's use same carrier, 3.08 need to replace the carrier.

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What stock ratio does have your truck have? Yukon makes 9.5 12 Bolt gears now. Direct swap if you have 3.42's. If truck had 3.08's you need to ether replace the carrier or use a spacer. Same applies for the front axle, 3.42's use same carrier, 3.08 need to replace the carrier.

I have 3.42 and want 3.73. So this sounds good to me. I'll look into it. Thank you. Also I'm just 2wd.

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  • 2 weeks later...
  • 11 months later...

Guys that have a bunch of miles on your East Coast Gear Supply setups, any premature ring & pinion wear?  My local driveline shop who I highly trust (he does dozens of gear swaps every week and also does custom rears with shortened tubes and any custom build you can think of) says that he has had premature R&P wear with the ECGS ring gear spacers when installing Duragrip or Eaton TruTracs and different gear ratios. 

 

I currently have a 3.42 gear 9.5 12-bolt and I want to keep the current 3.42 gears, but install a TruTrac.

 

https://eastcoastgearsupply.com/i-23993370-gm-9-5-semi-float-detroit-true-trac.html

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  • 3 weeks later...

I did my own gear swap on my 2015 1500 5.3 just take your time. I made set up bearings to get everything right. Just in case I needed to switch pinion depth shims. I also used a magnetic dial indicator tool for my backlash. Cam, Stall Tune, Full exhaust with long tube headers.  Now the  Geared to compliment all these mods. My SILVERADO is very fun to drive now

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