There are lots of stronger units out there, but installing an aftermarket posi requires setting up the gears again which runs around $200 at a shop. You can rebuild your stock trac lok with an extra clutch disc in it to get a little more pre-load. When you rebuild it, just re-use one of the old discs. I believe you can also use the stiffer spring out of a ford truck trac lok (I may be wrong here). Try doing a search in the windsor or drag racing forum for more specific instructions.
Yeah you can add one of the old clutches when you have it rebuilt. That's what I did. I had it rebuilt really tight and added 3.73's.
Or you can go to an aftermarket unit. (which is what I should have done... oh well next time, along w/ some 4.10's )
Eatons are really good, because they have a much thicker case and the clutches they give you are made of some sort of carbon fiber. Plus they are rebuildable which most of the aftermarket units are not. They go for about 350 bucks. Check them out......
Truck spring and extra clutch disc only make the preload stronger, but does not make the unit itself any stronger. It will be stiffer though and will work for the amjority of street cars out there(even helps on the drag strip too.) Don't me wrong, I did the two myself on my car. The only problem is with the truck spring you have to grind down the ends of the axles to get it in, and even then it is a b**ch.
If you have the money, the trick set-up is a torsion rear end.
You do not have to grind down the axle ends to fit an F-150 S-spring in. It is more difficult to get in but grinding is not necessary.
Go to www.oldwestracing.com under articles for information about the alternate clutch packing method and the F-150 S-spring. I have done both to my car and it is worth the trouble. As was said, it will not make it stronger, but does lock up quicker.
Interesting. I know I had to grind down the ends of my axles. I know two or three other people who had to do the same thing. I originally got this info on how to do this on corner-carvers.com from Msquared, who had his car done at Houston Performance. Maybe you:
1) Got lucky,
2) Got the wrong spring, or
3) have alot of end play in your axles.
It's not that big of a deal. I guess some people don't have to do it. But from what I have seen and done, they need to be ground. Again, it is not alot you have to take off, just don't be worried if somebody does try this and it won't fit.
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