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Old 07-14-2020, 09:21 AM   #1
Dleslie212
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Help choosing rear end parts

Good morning everyone. I took apart my rear end conpletely yesterday except for the pinion. I want to go ahead and rebuild the entire thing, but Iíve never done this before and was hoping for a bit of feedback. Hereís what I have

77 K10
12 bolt
30 spline axles
11 pinion teeth, 41 ring gear teeth (3.73 ratio, correct?)


It currently has the G80 locker, but Iíd like to install an actual locker on it. The ring gear has a few small chips on the ends of of a few teeth, but nothing major. I donít mind replacing the ring and pinion, but Iím pretty intimidated by that. At the same time, Iíd love to be able to say that everything in the rear has been replaced. What does everyone here think about installing a new carrier, but keeping the old ring and pinion? Should I be pretty safe reusing the old axle shafts instead of getting replacements?

Also, what kind of locker should I go for? I do a bit of off roading, but never anything hardcore. Most light or medium stuff, and lots of sand. Iíd say 75 percent of my driving would be on the road, mostly just picking up the kid from school, or cruising around
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Old 07-14-2020, 09:41 AM   #2
Matt Man
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Re: Help choosing rear end parts

Quote:
Originally Posted by Dleslie212 View Post
Good morning everyone. I took apart my rear end conpletely yesterday except for the pinion. I want to go ahead and rebuild the entire thing, but Iíve never done this before and was hoping for a bit of feedback. Hereís what I have

77 K10
12 bolt
30 spline axles
11 pinion teeth, 41 ring gear teeth (3.73 ratio, correct?)


It currently has the G80 locker, but Iíd like to install an actual locker on it. The ring gear has a few small chips on the ends of of a few teeth, but nothing major. I donít mind replacing the ring and pinion, but Iím pretty intimidated by that. At the same time, Iíd love to be able to say that everything in the rear has been replaced. What does everyone here think about installing a new carrier, but keeping the old ring and pinion? Should I be pretty safe reusing the old axle shafts instead of getting replacements?

Also, what kind of locker should I go for? I do a bit of off roading, but never anything hardcore. Most light or medium stuff, and lots of sand. Iíd say 75 percent of my driving would be on the road, mostly just picking up the kid from school, or cruising around
I would rebuild the entire axle with a new ring and pinion and a master rebuild kit which includes new bearings and seals. 11 pinion teeth and 41 ring gear teeth is a 3.73 gear. As far as axle shafts go, I would pull them and look at the splines for damage or if they are twisted up. Also check your outer axle bearings and replace the seals while you are there.

For the kind of driving you do, I would strongly recommend a Eaton TrueTrac limited slip. This is a excellent posi that does not have clutch packs to wear out and you run just regular gear oil with no additives for the clutch packs found in other limited slip units. The TrueTrack uses a helical gear design. The g80 was marginal at best even when new I would ditch it. I have a TrueTrac in the front 10 bolt in my 81 k10 and it has been flawless and I wish I put one in the rear of my truck instead of the Detroit locker.

Rebuilding a rear end is not a task for beginners as you do need some specialty tools such as a dial indicator. I would strongly recommend you take the axle or truck to a shop to do the work. It is possible to do yourself but like I said not for a novice mechanic or beginner.
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Old 07-14-2020, 09:47 AM   #3
Dleslie212
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Re: Help choosing rear end parts

Quote:
Originally Posted by Matt Man View Post
I would rebuild the entire axle with a new ring and pinion and a master rebuild kit which includes new bearings and seals. 11 pinion teeth and 41 ring gear teeth is a 3.73 gear. As far as axle shafts go, I would pull them and look at the splines for damage or if they are twisted up. Also check your outer axle bearings and replace the seals while you are there.

For the kind of driving you do, I would strongly recommend a Eaton TrueTrac limited slip. This is a excellent posi that does not have clutch packs to wear out and you run just regular gear oil with no additives for the clutch packs found in other limited slip units. The TrueTrack uses a helical gear design. The g80 was marginal at best even when new I would ditch it. I have a TrueTrac in the front 10 bolt in my 81 k10 and it has been flawless and I wish I put one in the rear of my truck instead of the Detroit locker.

Rebuilding a rear end is not a task for beginners as you do need some specialty tools such as a dial indicator. I would strongly recommend you take the axle or truck to a shop to do the work. It is possible to do yourself but like I said not for a novice mechanic or beginner.
The TeueTrac is actually one I had been looking at already, and I think you just solidified it for me.


https://www.summitracing.com/parts/dtl-913a315

Does the above look correct for my application?

As far as taking it to a shop, I really want to do this myself. The whole point of buying this truck last year was for the learning experience. I’m fairly mechanically inclined, so I’m confident I can get it done. Although it will probably take me waaaay too long to finish it correctly
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Old 07-14-2020, 09:56 AM   #4
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Re: Help choosing rear end parts

If you do take it to a shop make sure he specializes in rear ends. I took mine to a shop where I thought he was good ,had a little howl on coast which he said it would break in and the pinion bearing went in a year. Do a lot of asking around and you will find one shop pops up more than others
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Old 07-14-2020, 10:00 AM   #5
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Re: Help choosing rear end parts

Quote:
Originally Posted by Dleslie212 View Post
The TeueTrac is actually one I had been looking at already, and I think you just solidified it for me.


https://www.summitracing.com/parts/dtl-913a315

Does the above look correct for my application?

As far as taking it to a shop, I really want to do this myself. The whole point of buying this truck last year was for the learning experience. Iím fairly mechanically inclined, so Iím confident I can get it done. Although it will probably take me waaaay too long to finish it correctly
Yes that is the correct unit for the TRUCK 12 bolt. Don't buy any parts for the 12 bolt car axle as they're different. In my opinion the hardest part is setting the pinion preload and dealing with the crush sleeve. See if you can buy a crush sleeve eliminator kit and look up videos on youtube on how to do it. Good luck and keep us updated lots of good help on this forum. Go slow and make sure the specifications are right on backlash, pinion rotational drag and teeth mesh. As you probably know, if you do not set up all these items correctly your rear end will eat itself alive.
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2020 Silverado Double Cab LT Z71 5.3 8 speed Daily Driver

K10 build http://67-72chevytrucks.com/vboard/s...d.php?t=671934

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Old 07-14-2020, 10:14 AM   #6
Dleslie212
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Re: Help choosing rear end parts

Here is what Iíve picked out so far. Iím hoping somebody wouldnít mind going through this list and telling me if I have all the correct parts, or if thereís anything Iím missing


Differential -
https://www.summitracing.com/parts/dtl-913a315

Ring and Pinion -
https://www.summitracing.com/parts/mgr-gm12-373

Ring and Pinion Install Kit -
https://www.summitracing.com/parts/rat-3005k

C-Clips -
https://www.summitracing.com/parts/yga-33083

Crush Sleeve Eliminator Kit -
https://www.summitracing.com/parts/yga-55046

Carrier Bearing Kit -
https://www.summitracing.com/parts/yga-57010
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Old 07-14-2020, 10:17 AM   #7
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Re: Help choosing rear end parts

Looks good. Nice selection of parts.
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86 c30 crew cab dually 454/400 4/6 drop SOLD 1-8-11
1981 chevy K10 short Bed Scottsdale SOLD 10-26-2020
67 GMC Stepside Straight six/3 on the tree "The Peach"
2020 Silverado Double Cab LT Z71 5.3 8 speed Daily Driver

K10 build http://67-72chevytrucks.com/vboard/s...d.php?t=671934

The Peach build http://67-72chevytrucks.com/vboard/s...d.php?t=733903



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Old 07-30-2020, 10:39 PM   #8
Dleslie212
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Re: Help choosing rear end parts

I’m a week or two away from pulling the trigger on ordering these parts, but now I’m having doubts about the 3.73 gears. I’d rather not have to regear the front, but I also want to do the rear correctly the first time

I running a 350, 700r4 and 35” tires. I’ve read that I should be using a higher gear ratio... anybody have any thoughts on what I should do?
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Old 07-30-2020, 11:15 PM   #9
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Re: Help choosing rear end parts

I def wouldnt go any higher..with 35s and od, 3.73s would be as high as I would go...
With 3.73s, 35s, and a .7 od, your only turning 1629rpm at 65...
4.11s will get you 1795rpm....if I was gonna change that's more what I'd look at....

I went with 4.56s on mine...I wanted around 2000rpm at 65 with my LS/v4500
Heres a rpm calc thatll help you determine things...just fill in blanks at bottom of page...

http://www.csgnetwork.com/multirpmcalc.html
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Last edited by mongocanfly; 07-30-2020 at 11:26 PM.
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Old 07-30-2020, 11:18 PM   #10
Dleslie212
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Re: Help choosing rear end parts

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Originally Posted by mongocanfly View Post
I def wouldnt go any higher..with 35s and od, 3.73s would be as high as I would go...
Maybe I meant lower. I get confused with the terminology
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Old 07-30-2020, 11:33 PM   #11
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Re: Help choosing rear end parts

Gotcha...yeah higher means lower...haha....higher numerical = lower ratio....

Matt's covered it pretty good...building a diff isnt for the faint of heart...
can be very frustrating and requires some specialized tools as well
You'll need dial indicators, calipers, torque wrenches...both ft/lbs and in/lb...
A dial in/lbs torque wrench to check rotational torque..
A good press, bearing separators , setup bearings.. a case spreader is nice to have
And a lot of time and patience...

I agree with the tru-trac...but I like Yukon gears and kits...
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Old 07-30-2020, 11:37 PM   #12
Dleslie212
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Re: Help choosing rear end parts

Quote:
Originally Posted by mongocanfly View Post
Gotcha...yeah higher means lower...haha....higher numerical = lower ratio....

Matt's covered it pretty good...building a diff isnt for the faint of heart...
can be very frustrating and requires some specialized tools as well
You'll need dial indicators, calipers, torque wrenches...both ft/lbs and in/lb...
A dial in/lbs torque wrench to check rotational torque..
A good press, bearing separators , setup bearings.. a case spreader is nice to have
And a lot of time and patience...
I bought all the tools needed this past week besides a press. Thereís a machine shop near me that i can swing things by to have pressed if heating the bearings in the oven doesnít work. Iím planning on ordering a second pinion bearing to sacrifice as a setup bearing as well. And it doesnít mean much, but the past month I think Iíve watched almost every single YouTube video possible related to ring and pinion installs.

Anyway... whatís the deciding factor on if I should go with LOWER gearing in the rear? It drove down the freeway fine before. It didnít feel like it had much oomph when stomping the gas, but Iím not going to be racing it or anything
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Old 07-30-2020, 11:48 PM   #13
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Re: Help choosing rear end parts

That no oompfff means you really need a lower gear...
If your riding around at 55 or less in od, your engine is just barely above a idle...like barely 1300rpm..
It all boils down to what you want...
thing is, if your going to the trouble and expense to do all the work, then optimizing your setup would be a good thing....my opinion
Off roading will be much more enjoyable with lower gears...
I've done quite a few riffs, and I still watch the vids ...its one of those things that if you dont do it every day it's easy to forget the little things..
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Old 07-30-2020, 11:54 PM   #14
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Re: Help choosing rear end parts

In your list of parts you have carrier bearings listed seperate...those are included in the kit..
I've not used ratech...I think it uses koyo bearings..
I'd highly recommend the Yukon kit...it comes with timken bearings..and the Yukon gears instead of motive
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1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
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Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Last edited by mongocanfly; 07-31-2020 at 12:01 AM.
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Old 07-30-2020, 11:55 PM   #15
Dleslie212
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Re: Help choosing rear end parts

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Originally Posted by mongocanfly View Post
In your list of parts you have carrier bearings listed seperate...those are included on the Yukon kit..
Good catch... thanks
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