9 Inch carrier Aluminum or N case?

[Cdog]

I'll be buying one soon for my LD rear end. Was looking at the aluminum over the steel housing. Strange or Yukon? 370 gear with the Detroit track lock. Will the aluminum carrier live under autocross and road race conditions? Is the 15 pound weight savings with the aluminum carrier worth the extra $100?

Any recommendations?

[big gear head]

I usually don't recommend an aluminum case for street or road race use because of heat expansion, but that is probably not an issue. I know that many street cars have aluminum cases, such as all of the Corvettes made from '80 and up, along with Ford Explorers and several others. The aluminum 9 inch Ford cases were designed for drag racing in lighter cars, but many people have used them in heavier cars without problems. I guess if you want to spend the extra money to save a few pounds then it should be fine. I think Mark Williams might have one of the stronger aluminum cases. I'm a Moser dealer, but I have not had my hands on a Moser aluminum case, so I can't give an opinion on that one. The Strange aluminum cases that I have built had die cast caps on them and they didn't seem very strong, but I don't know of any that have broke. I built a few for a Mustang that is running 200 MPH in the 1/4 mile and he hasn't broke one yet.

[funcars]

Aluminum is not as stiff (about 1/3 the modulus) as steel/iron given the same cross sections. So aluminum will deflect more under max loads than steel will. The stickier the tires and the higher the torque going through the driveshaft to the rear end the greater the deflections will be. A common result is that R&P gears don't last as long as with a nodular iron case, but it obviously depends on several factors. I'd call the manufacturers you are considering using and ask them.