Interested in installing a Spartan locker in my 76 Cutlass, Running 3;23 in an open diff with a 455.
Pros and cons ? Realworld experience....thankx

 

Same design as the old Powertrax units.

They are positive locking, which can be noisy or harsh on sharp turns or when parking.
Personally I'm not a fan, the locking / unlocking action can be erratic on wet roads.
You will feel it engage, which I found annoying in a car, but less pronounced in a heavy truck.

I have installed a few for people but would never put one in my own vehicle.

A good limited slip carrier is not much more money, although slightly more installation work.

My first choice would be a Torsen gear unit over a clutch type posi, which would have been the factory style unit.

 

I've got a Nitro Gear Gear and Axle version in my car. It's been installed for over a year with about 5000 miles and a few hole shots on it. They are very simple to install (following instructions) and work fine, however as said you can hear them ratcheting when turning.
My project thread:
This winters project, rear suspension and locker install - ClassicOldsmobile.com
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I've run the Detroit and Powertrax versions as said, a bit noisy and clunky. I can tell you, they break under abuse, especially the 7.5" version. When you break the pins off, it becomes a spool and parking becomes a violent affair😁.

 

We had a powertrax version in an 82 G Body Regal and I can say that You will regret installing one of these lockers vs. a clutch style posi or the torsen style.

Our powertrax unit broke after about 10,000 clunky and scary street and strip miles behind both a mild 455 and a mild 403, and we installed a rebuilt factory clutch style posi unit.

We could have saved money and hassle in the long run by going to the factory style posi unit...... It was much smoother and more enjoyable to drive with the posi.


Your 76 model Cutlass should have a corporate 8.5" 10 bolt and likely won't have c-clips (it will have bolt on axle retainer flanges) if it is like the 76 Monte Carlo rearend I had.

 

I had one in a Monza for YEARS and YEARS...Never an issue.
If you have a Lunch box, spartan power trax lock right maxx trax locker installed correctly they should only make a tapping sound in turns.
THAT is the BIGGEST issue.
If you do not install these things correctly and keep that center gap correct on install. THEY can be a terror.
I think the gap is in the .130 - .154 range ...So if you install them in a worn out case or forget the thrust washers when they are suppose to be used, it will violently clunk or not unlock at all.
All in all they are pretty strong on the straight hard accel. We cal,l them weekend warrior posis....

Jim
Just another opinion on the item
JD Race