Hey everyone, I've pretty well made a decision to change out the rear end ratio on my 13 Shelby. The ratio it has is pathetic (3:31).
After figuring out what I really use the car for (recreation driving, a bit of drag racing and lapping days on road courses) I figured that a 3:90 ratio would be the best one to go with.
Since Ford Racing doesn't make one that ratio (they go from 3:73 to 4:10) I had to look at other companies for the 3:90 ratio. 3:73 to me isn't enough of a change from 3:31's accounting for the time and amount I need to spend on the change and 4:10's would be too short for the road course I run the most at and limit my top speed down the main straight.
I originally looked at Motive and Richmond for the gear I wanted but have heard some bad issues with their quality, especially the gear sets they offer that are made overseas (in the 3:90 ratio they only offer their economy line, their top line gear sets are US made and avail in the more popular 3:73 and 4:10 ratios and have better reviews that I've read).
Then I found US gear. They claim all their gear sets are US made (even the 3:90 ratio I want) and they even offer their gear sets in a new Lightning Series where they coat the gears in a special coating like what NASCAR teams now use.
I would probably want that coating on the gear set I buy, would like to know how the company is with regards to their ring and pinion products. I think they make decent stuff but most guys that want to swap gears usually do Ford Racing or Richmond/Motive.
Here's their webpage on the Lightning Series:
Aftermarket Surface Finishing Ring and Pinion Sets for Racing Enthusiasts
Check the flyer on the bottom of the page
Of course this gear set is for a Ford 8.8" axle and my car comes from Ford with the Torsion diff.