3.89 or 4.11 gears?
 

Hi guys, I'm looking at a strange 31 spline tru track 3rd member and wondering which gears would be best for me. I'm running 26.7" rear tires and plan on using a t56 6 speed trans . I have read that strange is the best 3rd members to go with. Plan on street driving with a little autocross. Thx

I would go with 3.89. I am assuming the T56 1st gear is 2.66?

I'm guessing this is a 12 bolt due to gears listed? If it was a 9" I'm considering selling my 3rd member to buy an aluminum with the gears I want (3.50)

There are about 5 ZILLION gear calculators on the internet.... You put in the tranny - the tire diameter - and whatever else they ask for and hit the button. You can find the right gear by what Cruise speed you want to run at and what RPM's you'd like to see there... or any number of other calcs.


http://www.richmondgear.com/2.html


http://www.ringpinion.com/Calculators/Calculators.aspx

thanks everyone. It is for a ford 9" irs that I am doing. I don't have any experience driving anything with either one of those gear setups. Infact the only muscle car i have had, I am pretty sure it had low 300's for the gear ratio. I bought it and sold it a few years later. So according to tremecs website the overdrive ratio is .62 so with 4.11's @ 80mph i would be at 2565 rpm. That sounds decent plus it would give me a little more "get up and go" . Am i looking at that right? Just wanted to check. Anyone driven both 3.89 and 4.11 gears? Any noticeable difference?

Thanks for this. I wasn't aware of these. Pretty cool!

I made a choice to go the other way this year. I have a shorter tire (315/30/18), and I went from a 3.89 to a 3.64. I liked the drop of RPM for the highway driving, but move significantly, it gave me more RPM range in 1st and 2nd gear during my autocross driving.

2565 seems high for a highway target. I was around that before, and I dropped to 2250-2350 now, and that seems better...

I'm running a 9" with 3.89 gears, 26.5" tall tires, T56 with the .80 and .65 OD gears. This ratio is perfect IMO. I can cruise the two lane back roads in 5th gear at 65mph and 2500rpm. Or I can get out on the interstate and run 75 at the same 2500rpm. I think a 4.11 would be too low. I previously had a 3.64 and I felt it was too tall for my taste, I never used 6th gear.

You might also take a look at Roush Used Racing parts. They sell all manor of surplus NASCAR parts including 9" center sections.
http://www.sriperformance.com/Used-R...rain-s/428.htm

I have 4.11 gears, T56 with 26.7" tires. This works fine, but I feel first is too short.

I would go with 3.89

If you decide you want a 4.10. Maybe we can work a deal. I have a DSE rearend with no miles. It's 31 spline trutrac also.