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Discussion Starter #1
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.


Tony
 

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I've got their gears on my car and am very happy with them. Setup was trouble free, pattern was very good, and they are nice and quiet.

Most of the top names in the industry sell and use their stuff.
 

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hAVE HEARD NOTHING BUT GOOD THINGS ABOUT THEM. to my disappointment couldnt get a 3.90 gear from them for my 8.8. 3.90 ARE ONE OF MY FAVORITE GEARS.
 

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Discussion Starter #4
When did you check to see if they have a 3:90 gear? I called them last week had an extensive chat with them (very nice BTW and spent time and answered all my questions), they currently don't have the gear and will have to produce some and to get the treatment on it I am looking at about 6 months time.


I'm not in a hurry to get the gear so I'll probably order the gear soon and wait out the time for it to arrive and arrange for the install next year sometime.


BTW, they sell direct to the end user online https://www.offhighwayplus.com/


part # for 3:90 gear is 07-888390 and with the treatment it's 07-888390ISF
 

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8.8 rears US gear dosent make 3.90 gears. Years ago they advertised them for a 8.8 but earlier this year contacted them about a 3.90 they said they decided not to. As I STATED ONE OF MY FAVORITE GEAR RATIOS SINCE THE LATE 60S. Did go with Motive gears had one hell of an issue getting a gear pattern took me about a month to get a pattern that dosent look too bad. Havent installed the rear in the vehicle yet. My pinion depth guage was of no use. Just Hd to stART WITH A .055 PINION SHIM dropped .004 at a time on pinion shim thk untill the best pattern ending up with a .011 shim. Have set up 9" rears in a day. If you do go with 3.90 gears from motive best bet in the "Italian" made ones not India or china produced ones. Richmond may have them but were bought up by Motive.
 

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Discussion Starter #6
I'm gonna pull the trigger on the gear set. Their online site shows the Lightning Series gear sets for 9" Ford and other axle assemblies. 8.8 is still special order but it shows up so it will be avail.

Any other parts I should consider getting to support the install of the gear set?
 
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