1995 C2500- Open Diff to Posi Swap

[df2x4]

You got it!

That's why I suggested buying something new. If you want a posi, I'd look into an Eaton TrueTrac. If you want a real locker, I'd look at the Eaton Detroit Locker.

 

[Tavi]

From my understanding, the G80 in the larger differential is less likely to explode. However the design flaws in operation are still there. And since you replacing an open anyway. I would go with one of the options @df2x4 recommended.

 

[JCribb]

Put it like this, I have probably double the factory horsepower in my truck and it has finished off every weak link GM made. Those are the NV3500 light duty 5 speed and the gov bomb factory 10 bolt I had.

Don’t get me wrong the gov lock worked in mine, but I had pinion noise and play and leaks. I wound up trading out my 10 for a 14 bolt 9.5” axle, and sadly it was an open differential. I tried a powertrax lock right locker which is supposed to be a spring based limited slip. I broke it the first day turning a corner and it went back to being an open diff. I speculate that I broke a spring or something simple, and I have not opened my diff to find out as there’s no noise or anything strange going on, so I left things alone.

Detroit is the way to go, and they are pricey, but worth it. Once I get enough money rounded up this is the road I’m traveling.

 

[Urambo Tauro]

Yeah, I was looking at those "Lock Right" things, and they look kind of similar to the Detroit Lockers, but something about them doesn't look quite as strong.

But I'm not really sure I want a true locker. The Eaton DL looks tough, but it looks like it'd be noisy and rough.

The TrueTrac is interesting. Looking at its gears makes my head hurt though. If I had to guess, I'd say that it has something to do with the way a worm gear (or in this case, helical) turns (but can't be turned by) the other gear.

What about Positraction? I was kinda throwing around the term "Posi" earlier, but Positraction is actually a particular type of LSD, isn't it? ...the spring & clutch type? Or is it just a marketing term that GM slaps onto any LSD/"LGD"?

 

[JCribb]

Yeah, I was looking at those "Lock Right" things, and they look kind of similar to the Detroit Lockers, but something about them doesn't look quite as strong.

But I'm not really sure I want a true locker. The Eaton DL looks tough, but it looks like it'd be noisy and rough.

The TrueTrac is interesting. Looking at its gears makes my head hurt though. If I had to guess, I'd say that it has something to do with the way a worm gear (or in this case, helical) turns (but can't be turned by) the other gear.

What about Positraction? I was kinda throwing around the term "Posi" earlier, but Positraction is actually a particular type of LSD, isn't it? ...the spring & clutch type? Or is it just a marketing term that GM slaps onto any LSD/"LGD"?

Yes you are correct it is a worm gear driving the trutrac. I had a 4x4 shop tell me all about it after I told him what all I had done to my truck, and he said you need a Detroit, and he said they’re pricey but worth every penny. I stopped by and saw the guy in person and he’s near 70 or maybe older, but still playing with hot rods, and very knowledgeable.

I haven’t seen a good posi trac like I have in the Ford 8.8 rear end.

 

[df2x4]

What about Positraction? I was kinda throwing around the term "Posi" earlier, but Positraction is actually a particular type of LSD, isn't it? ...the spring & clutch type? Or is it just a marketing term that GM slaps onto any LSD/"LGD"?

Yup, you've got it right. Typically people are referring to the clutch type LSD when they say posi-traction. Eaton also offers that type of LSD for a little cheaper than the TrueTrac.

The TrueTrac is basically a bullet-proof LSD that functions the same as a clutch posi but using helical gears instead of clutch packs. They are super smooth, quiet, and durable. I have one in the 12 bolt in my 1970 Monte Carlo and love it.

The Detroit Locker might be a little more violent and loud under normal driving conditions, but I would choose one over a LSD in a truck every time. (Except maybe in a street only lowered application.) The reason being is that with most LSDs (including the TrueTrac) if you get one wheel completely off the ground, all torque will be sent to that wheel and you won't go anywhere without feathering the brake a little to create some resistance on that free-spinning wheel. With a real locker like the Detroit you can have one wheel off the ground and the other will still be engaged and pushing. If and when I ever get around to swapping a 14 bolt into my red truck, it will get a Detroit Locker.

 

[JCribb]

@df2x4 thanks for the extra information. That double seals the thought that I was headed for.

I have had to upgrade everything in my drivetrain because of how my engine is built (towing and play) so I have gobs of torque that I have a hell of a time trying to harness with my one tire fryer I have going on. Thank goodness I have the deep reduction NV4500 first gear that I can use to slowly take off with. Living on a dirt road makes it hard for me right now.

 

[df2x4]

You're welcome! I've done a lot of research in the interest of doing better donuts.

 

[Tavi]

The positrack is the factory name GM gave the LSD. It used clutches to hold the side gear position in the carrier until outside force can overcome the springs tension. It will eventually need to be rebuilt as the clutches wear out.

The torque bias true track allows for open differential operation under normal driving. When torque is applied at all ends it will lock it up tighter (when going around a corner and you stab the gas, it will act like a locker both wheels turning at the same speed). When on wheel is off the ground, it can spin freely. Applying the brakes will simulate the torque at all end scenario required for it to start locking up.

The Detroit locker has springs that push the side gear into the spider. Gears are square cut. The unit remains in the locked position until outside force overcomes the spring tension. Each side gear functions as an on off switch. A tire is either receiving power or it isn’t. But only until the next tooth on the gear. I have heard reports of the units being noisy. But have never heard a noisy one myself.

My personal opinion is the true track is the most versatile. And the best choice unless you start getting into serious off-roading. The clutch style units are good and work well. But the clutches wear out. The true track should outlive the truck before it even needs a rebuild.

 

[Rock Hard Concrete]

Powertrax No-Slip (the more expensive, non-noisy model than the lock-rite) works better than advertised and requires no removal of the carrier and is installed easily. I have one and have had 0 issues I will never use a clutch pack style diff in a truck.

*EDIT* and if you are a fan of burnouts or drifting better than subarus in the snow it is the locker for you.