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Lost...Positraction and Open Carriers

Operator238

Operator238

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So, my 1985 K5 is an open carrier truck. There is no G80 designation in the glovebox and now that I have the rear end on jack stands, I need to make a decision.

I don't understand why GM would not put a limited slip in a truck like this, much less a 4WD vehicle??

If I just keep the open carrier, what capability will the truck have? If I go to the beach, will I be doing one wheel rooster tails?

I called a driveline shop, and their pricing was outrageous. They want $750 labor only to tear down and rebuild a rear end, not including a new carrier, bearings, etc.

I have changed axles and bearings etc.. Even built engines and degreed cams, etc...... However, I have never set the backlash for a new carrier assembly.

What should I do? I have considered lunch box lockers, but I have grown concerned; I don't want to take off around a corner and have another wheel engage and end up in an accident etc.

What would you do? Leave it Open or something else? I have access to G80 axles, but their condition and function is unknown.

UPDATE- based on everyone’s recommendation I went ahead and ordered a TrueTrac
 
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No way would I want a G80 in place of an open 10 bolt, the 10b G80 is junk. What are your intended uses of the truck. Lunch box lockers take a little getting used to but by no means should cause you to crash….you could always do a selectable locker. Keep in mind that locking a 10b in any form is kind of a time bomb.
 
I wouldn't ever install a G80. There are much better options.

For mostly street use with some sand and mild offroad, I would always go for a Truetrac. I have one behind a big block in my '70 K10. Works very well.
My son has 2 of them, one behind a Dmax, one behind a 5.3 in a 2wd.

I have built a couple of axles and so setting the backlash is not a worry for me. I would guess that you could do it no problem as well, however you may not have the tools.

A drop in, or lunch box locker usually behaves fine on the street. Some may make a little noise.
 
I'd have to second the True-Trac for not hardcore offroad stuff.

I like the G80 *in the larger axles*. But going those routes adds a lot more things you'll have to address, and again, with light usage, probably not worth the tradeoffs.
 
You could do a lunchbox locker in back and then you wouldn't have to do a gear set-up. This is not a particularly strong combination, but cheap and easy. EDIT: I re-read and see that you're afraid of lockers. I think some of the newer ones are softer engaging. I think you'd get used to it and I'm assuming Houston doesn't usually get snow and ice.

Have you had the axle open to confirm what's in there? A G-80 acts like an open diff on the jackstands.
 
Operator238 said:
What would you do? Leave it Open or something else? I have access to G80 axles, but their condition and function is unknown.
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Haven't you been reading on this site? The right process is bigger axles, engine swap, transmission swap, bigger tires, cut the fenders, new drivelines and have it on jackstands till 2050.
 
If you did go with the Eaton true trac. You would need to adjust for back lash and check the pattern. Since you would be reusing you ring and pinion. The pinion can remain untouched in the housing.
A daily indicator with magnetic base will be needed.
A case spreader would be handy but expensive for a single use.
 
Wes Harden said:
If you did go with the Eaton true trac. You would need to adjust for back lash and check the pattern. Since you would be reusing you ring and pinion. The pinion can remain untouched in the housing.
A daily indicator with magnetic base will be needed.
A case spreader would be handy but expensive for a single use.
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So are there any carrier options where I wouldn’t have to deal with pattern and back lash if I’m reusing the same ring+pinnion?
 
Operator238 said:
So are there any carrier options where I wouldn’t have to deal with pattern and back lash if I’m reusing the same ring+pinnion?
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Nope. If the carrier is replaced you need to recheck backlash and gear pattern.

I’m another fan of the tru-trac. But it will require setup. Read up on the process. Everyone thinks it’s voodoo science or something. It’s not. Get a dial indicator and some gear marking compound. Take your time and get a pattern and measure your backlash. Post up the results. Any number of guys here will guide you through the adjustment that needs to be made.

As far as your original question why would gm build them without a limited slip or locker? Because the G80 gov loc was an optional part. Not everyone needed that. From an off-road standpoint it’s insane to think they would builds them without, but I’d bet a higher percentage of these trucks never got driven on anything harder than a dirt road and having G80 standard would have been overkill.


I’d say if you have the skills to build an engine and degree a camshaft you have the skills to swap a carrier. Don’t sell yourself short. Use it as an opportunity to buy a new tool (dial indicator) and save $750 that you would have paid some schmuck to do it for you.
 
Doing a rear end isn't that difficult, other than doing it in truck.
I did my first because I wanted a limited slip and a gear change in my old 2wd truck.
Your just changing the carrier, should be easy peasy. Don't rush, or get impatient. Just take your time and it'll be fine.
 
ZooMad75 said:
Nope. If the carrier is replaced you need to recheck backlash and gear pattern.

I’m another fan of the tru-trac. But it will require setup. Read up on the process. Everyone thinks it’s voodoo science or something. It’s not. Get a dial indicator and some gear marking compound. Take your time and get a pattern and measure your backlash. Post up the results. Any number of guys here will guide you through the adjustment that needs to be made.

As far as your original question why would gm build them without a limited slip or locker? Because the G80 gov loc was an optional part. Not everyone needed that. From an off-road standpoint it’s insane to think they would builds them without, but I’d bet a higher percentage of these trucks never got driven on anything harder than a dirt road and having G80 standard would have been overkill.


I’d say if you have the skills to build an engine and degree a camshaft you have the skills to swap a carrier. Don’t sell yourself short. Use it as an opportunity to buy a new tool (dial indicator) and save $750 that you would have paid some schmuck to do it for you.
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I have a magnetic dial indicator already. I have heard bad things about true trac (via search). I was looking at Summit Racings unit or Yukon but I think they’re clutch pack units. Already re did my front end but that’s where u should have shoved a lunchbox unit.
 
What did you hear bad about the true-trac?

The ONLY downsides I've seen of them are that you may break front axleshafts if you put one in the front, they are not a true locker, and cost.

For a light off-road truck, personally I wouldn't consider anything other than a true-trac or G80 (in the 9.5" or 10.5" axles only). For me an E-locker is pretty cool, but not being able to engage it on the fly isn't appealing.
 
dyeager535 said:
What did you hear bad about the true-trac?

The ONLY downsides I've seen of them are that you may break front axleshafts if you put one in the front, they are not a true locker, and cost.

For a light off-road truck, personally I wouldn't consider anything other than a true-trac or G80 (in the 9.5" or 10.5" axles only). For me an E-locker is pretty cool, but not being able to engage it on the fly isn't appealing.
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You can engage an elocker or air locker at any speed. Just not when you have one wheel spinning.
 
I am not an expert, but I didn't bother to check the pattern when we did just a carrier swap. Checked the backlash in 3 spots, and got as close as we could upon reassembly. The pinion didn't get removed, so the depth didn't change, so I didn't see a need to look at the pattern.

Without a housing spreader, I use a deadblow hammer to install the carrier because when new bearings come into it, the carrier preload will make it too difficult to just shove it in, once some preload is added.
You could use the dial indicator to check for side to side end play in the carrier bearings before you pull it apart. This would give you an idea about the extent of wear, since they get some preload when originally built, which may eliminate most of the endplay for those bearings. There is still endplay when using a prybar, just less than with worn bearings.

If you decide to buy a new carrier, I would suggest that you examine your axle shaft splines and wheel bearing surfaces for wear. If they show much, now would be the time to buy new and go with 30 spline, like the '89-'91 axles had. It's a tiny upgrade.
 
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