Set up tips for aluminum case 9"?

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peejay
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Set up tips for aluminum case 9"?

Post by peejay » Wed Mar 30, 2016 7:45 pm

Finally got all the pieces together for my car's new rearend. Bought a Yukon through bolt style case, aluminum pinion support, and the fancy bearing races to put my 31 spline Locker in a 3.25" case.

It occurs to me that I have had good luck setting up iron cased rears but I've never touched anything all aluminum like this. Never done a 9" Ford either, although I can't say that I will miss having to press the pinion bearings off and on getting the depth right.

Any pointers? My gut feeling is to set it up a little tight on the backlash and a hair too deep with the pinion with a little extra bearing preload so when everything gets hot and things flex everything will be happy. Bad idea?

Car is ~2600lb, maybe 270hp (maybe 240, maybe 300, depends on whose math you believe), going to be running 5.43 gears. Mostly used for 200-1000+mi trips punctuated by a few minutes of balls out running on rough dirt/clay. Have been running 4.78 gears in a 7" rearend with no real issues as far as R&P go, I'd just set it up with around .004" backlash (spec is .004-.007 for that rear) and a little extra bearing preload and it never gave me grief. Lots of twisted and bent axles and housings which is why I got the 9" now. I'm hoping that with all the aluminum in the dropout and the light brakes I will get close to the same unsprung weight as the old setup I had.

Coloradoracer
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Re: Set up tips for aluminum case 9"?

Post by Coloradoracer » Thu Mar 31, 2016 9:51 am

Last one I ran I set up exactly the same as the iron one I run now.......Ring and pinion looked brand new after almost 200 passes down the 1/4 mile.......
Mark Goulette
Owner/Driver of the Livin' The Dream rear engine dragster
Speed kills but it's better than going slow!
http://www.livinthedreamracing.com
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