Its just what it says. It stiffens everything up in those old rears, the wheels almost lock up to turn equal amounts acting like a spool. They also used to make spider gears with flat sides on them to lock them up too.
a 12 bolt moroso brute strength posi does almost the same effect. The way its set up is why its not rec to be used on the street it doesnt give much on turns. A buddy of mine does this to his rearend setups all the time.
basically it's using your spider gears shims as the clutches in your 'real' posi. They will slip a bit in the turns and allow you to drive it on the street as apposed to a fully locked spool or welded spider gears. the drawback it that it is metal on metal slipping past eachother and while polished they slip OK with al the oil, they have no means to get oil to the inside of the shim area so will wear and get hot and be damaged after some use, depending on the tightness of how they shimmed it and your driving habits. i had thi sdone way bak in the day on my driver 68 camaro that had a 9in in it, worked for years.
basically it's using your spider gears shims as the clutches in your 'real' posi. They will slip a bit in the turns and allow you to drive it on the street as apposed to a fully locked spool or welded spider gears. the drawback it that it is metal on metal slipping past eachother and while polished they slip OK with al the oil, they have no means to get oil to the inside of the shim area so will wear and get hot and be damaged after some use, depending on the tightness of how they shimmed it and your driving habits. i had thi sdone way bak in the day on my driver 68 camaro that had a 9in in it, worked for years.
Get the dish shaped washers/shims in different thicknesses. Take out the spiders. Reassemble; use assembly lube on shims and spider gears, putting the shims in place first with pin hole lined up, then tap the spider in with brass hammer until hole is lined up and put the pin in. Play with tightness until you are happy with the performance.
The Jalopy Journal
