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Auburn / Truetrac FRONT LOCKER QUESTIONS

8.6 didn't come out till 99

In all of our squares the 10 bolts are 8.5s.

89 is a changeover to 30 spline from 28 spline

See Ethan carrier bearing difference. The 8.6 uses 8.5 gears. It's the larger bearing.

Still not clear on the difference on the 556 to 557 though
 
the 8.6 is 30 spline only and can be used in front or rear same unit. This is per Detroit site.
 
frankin5 said:
the 8.6 is 30 spline only and can be used in front or rear same unit. This is per Detroit site.
Click to expand...

The question Ethan has is that Summit has 2 different part numbers, one listed as front, one as rear, both 28 spline.

The last three of the part numbers is 556 and 557. On summits website one is more expensive, everywhere else I've looked they are the same price. Both being 28 spline they should be able to swap for each other. But it doesn't specify.

@campfire I'm staying that correctly right?
 
blazinzuk said:
The question Ethan has is that Summit has 2 different part numbers, one listed as front, one as rear, both 28 spline.

The last three of the part numbers is 556 and 557. On summits website one is more expensive, everywhere else I've looked they are the same price. Both being 28 spline they should be able to swap for each other. But it doesn't specify.

@campfire I'm staying that correctly right?
Click to expand...

Yes. They look identical aside from the following description differences:

TT70P10509 (557) says "For axles with small bearing bores."
and

TT70P10508 (556) says "Designed for 1998 and earlier applications with 28-spline axles. Must use special large carrier bearings with 1.781 in. I.D. and 2.891 in. O.D. race (See Suggested Parts tab). For use with 2.73 and numerically higher gear ratios. "

But they're both 28 spline somehow. :dunno: :confused:
 
the 556 is an 8.6 and is specifying the special bearing the adapts a 8.6 into an 8.5 housing
the 557 is the standard 8.5(small bore) bearing. This is my interpolation of the the above information
 
frankin5 said:
the 556 is an 8.6 and is specifying the special bearing the adapts a 8.6 into an 8.5 housing
the 557 is the standard 8.5(small bore) bearing. This is my interpolation of the the above information
Click to expand...

Ok. So...if the "normal" 8.5" version is $100 more than the "big bore" 8.6" version...why wouldn't I just buy the special bearings and ignore the extra surcharge? And am I right in saying that front/rear has nothing to do with the distinction? :dunno:
 
I am using the 8.6 Detroit's in my 8.5 axles. I am using the 30 spline as I have Warn Full Float rear and have new 30 spline front axles. Reusing the the my outer axles as they are the same. Bearing cost not a factor, bearings and races are about $20 per set on Amazon. Detroit site say they work front or rear same unit.
 
I love my tru-trac in the front of my K5. It's very predictable off road. No torque steer if I leave it in 4wd on pavement for a short time. It provides the pull needed to get through off road climbs. If you do hang a wheel in the air, all you got to do is drag a little brake to hold the wheel hanging and power gets tossed to the opposite wheel.

I'll put it to you this way, you can send enough power to one side you can break a stub axle with one. Ask me how I know.
 
Not to hijack but what about a cheap gov-lock in the front? If you hang a wheel in the air with a limited slip you still need to ride the brakes to send power back to the other wheel not unlike a gov-lock. So why not save the money and put one of those in your front axle?
 
I would think the gov-lok would need to be spun pretty fast in free wheel ,before it would lock up with a bang,possibly busting an axle u-joint or shaft,stub shaft..
 
Supposedly it's 150 rpm difference to make them lockup... But if you pulling good up a hill and one tire comes up suddenly I bet you could get some good breakage going on.

I thought Auburn's had the conical clutch mechanism. ... Whichever one does is supposed to have the most force applied to both wheels.
If you can get that one used for say 200, and throw a rebuild kit in it'll still be loads better than an open diff for around $300. Another $100 or so would get you a truetrac and a LOT stronger carrier though.
 
Chevy305 said:
Not to hijack but what about a cheap gov-lock in the front? If you hang a wheel in the air with a limited slip you still need to ride the brakes to send power back to the other wheel not unlike a gov-lock. So why not save the money and put one of those in your front axle?
Click to expand...

I don't have one of those lying around. But even if I did, I have not been impressed with them. 2/3rds of my trucks blew their rear G80s, and the third one came with open axles. :rolleyes:

The blue truck has been on verified light commuter duty since about 1990. No mods, no off-roading, not even a bunch of miles. The gov-lock still didn't survive. Front duty might be different. I'm just guessing here, but I'd think that the abrupt locking jolt will not be nice to stub shafts.

It sounds to me like a recipe for front axle failure.
 
shady said:
If you can get that one used for say 200, and throw a rebuild kit in it'll still be loads better than an open diff for around $300. Another $100 or so would get you a truetrac and a LOT stronger carrier though.
Click to expand...

Given that it's not actually an Auburn, and it retails new for $260, I'm money ahead to skip the craigslist gamble. I assume he'd drop the price since I don't want the 2.56:1 ring and pinion he's including. Though it's a good clue as to what this carrier may have been used for in its former life.
 
There have been some threads about front G80 over the years, with a few guys actually doing it. IIRC, none of them liked it.
 
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