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Discussion Starter · #1 ·
I've got a '69 Malibu with a mild 461, stock TH400, and 12-bolt open 2.73 rear end. The car is strictly street driven, a daily driver. I'm thinking of upgrading to somekind of posi set up. I want something that will grip the road better as well as still handle acceleration while turning. I'd also like to keep highway-friendly gears. What would be best? Changing the internals to a posi or adding a locker to the existing rear end?

I've read here that Eaton is a much better unit than the Auburn. True? I realize that I'll have to step up to a 3.07 gear, which is not a big deal.

If I go locker, which is the best? Lock Right? Truetrac? Any others? Some opinions are that lockers are noisy and annoying for street use.

Which would be more street-friendly going around corners? Which would be more cost effective? I'd be having the rear-end rebuilt if I went with a locker. Also, I don't have the place or the tools to do it myself and would have to take it to a shop.

I'd appreciate any first-hand advice or insights.
 

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Discussion Starter · #3 ·
Thanks for the heads up.

I've done some deeper reading on this and other sites and have decided the locker isn't for me. It's not because of the noise, but because although lockers let go in a turn, they tighten back up if there's any acceleration in that turn. Could be annoying or dangerous, especially on wet pavement. Correct me if I've misinterpreted.

That leaves the Eaton posi, or the Truetrac, also made by Eaton. Apparently, they're both really good in turns. The posi uses clutches and the Truetrac gears. What are the pros and cons between clutches and gears?
 

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To best understand this you need to go back to the basics, which you probably already know...

The differential allows one wheel to rotate more while the other rotates less, thereby matching wheel rotation to distance travelled. In a corner the outside wheel must cover more distance than the inside wheel.

An open differential does this with a free wheeling set of gears. Maximum cornering traction and tire life are provided. Of course driving force is limited to the lowest traction between the two tires.

A classic posi uses clutches that provide friction and thus lock up one wheel to the other until the break away force is met or exceeded. This actually reduces cornering traction and reduces tire life slightly because some force goes into making the differential action work. Driving force is limited to the lowest traction between the two tires plus the break away torque. So it is not a 100% solution although by playing with springs and weights they can get closer.

Finally there is the spiral gear differential. The first I read about were the "Gleason Torsen" (if I spelled it right) differentials. These use worm gears so that the wheels can spin freely side to side but full driving torque is delivered to both wheels. The magic is in the angles of the gear teeth with differential torque meeting a steep and easy angle and the driving torque meeting a shallow and hard angle. There are no friction devices to wear out. There are no springs. Traction is maximized because there is nil break away force and both wheels receive full driving torque. All in all a good deal.

Of course with a free market economy (and probably more expensive to manufacture gears) the Truetrac and Torsen type differentials are more expensive. So you make your own trade off.
 

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I am getting my Truetrac today and dropping my 3rd member off at the shop today after work. All in all I should have the rear end back in the car this weekend. Since this is a 9" swap, I'm not sure about the drive line, but I should have the car back on the road next week.

The point being, if you want some first hand feedback on the Truetrac, I would be happy to share as early as next weekend.

To add my 2 cents, i went with the Truetrac because I run the car at the track a lot. I didn't want the Locker because of the noise, I drive the car a lot on the street as well. I didn't buy the posi because I also wanted something that would take the power and abuse better.

Corey
 

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I have the Lock-right and love it. But listen to these guys, they are right. I dated a girl and when she rode in the car she didn't like squeling around corners sometimes or when it would bark seconed gear(i was trying too), it probably doesn't help it has a shift kit. If you do lots of in town driving or turning I would go posi. Or if you haul the other half with you difinetly go posi!!!
 
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