ConeBoss

Anyone installed these in your Boss? Wondering what your impressions are for difference in acceleration. Also, what your 2nd gear tops out at MPH wise?

Brandon302

I would love to know this also.

kn7671

The differences between 3.73 going down to 3.55 would be fairly minor and not very noticeable. What are you hoping to gain from a potential gear change, better street driveability, better track gear/rev matching, fuel mileage, better top speed, more usable 1st gear, etc...?

Here are the mph differences between 3.73, 3.55, and 3.31 gears using the 26.9" tall factory rear tire for calculations:

@7500 rpm with 3.73's
1st = 44 mph
2nd = 66 mph
3rd = 95 mph
4th = 122 mph
5th = 161 mph
6th @ 60mph = 1825 rpm
6th @ 80mph = 2425 rpm

@7500 rpm with 3.55's
1st = 46 mph
2nd = 69 mph
3rd = 100 mph
4th = 128 mph
5th = 169 mph
6th @ 60mph = 1750 rpm
6th @ 80mph = 2325 rpm

@7500 rpm with 3.31's
1st = 49 mph
2nd = 75 mph
3rd = 107 mph
4th = 137 mph
5th = 181 mph
6th @ 60mph = 1625 rpm
6th @ 80mph = 2150 rpm

Cobra 2997

Going from 3.73's to 3.55's wouldn't make any noticeable difference as stated above. Would be a waste of time and money in my opinion.

ConeBoss

My goal is to get a little more top end out of 2nd gear. The car is primarily my Auto-X car and 2nd gear is king. If going to 3.55 ratio will net me a bit more top end w/o reducing grunt out of corners and off the line I would consider it worth while...maybe 3.31 is a better choice, though I wonder if it would start to effect acceleration at that point.

kn7671

Are you using a different size/diameter tire, as that will affect the overall effective gear ratio as well.

If we are only talking 2nd and 3rd gear, 3.31's would probably be a better choice if you are having to barely shift to 3rd, or maybe move to 4.10's or 4.56's would make 3rd a more usable gear at the tracks you run at, as you would be better off have a good 1-2 or 3-4 shift instead of 2-3.

Seeing how we are dealing with tuning the gear ratio's to the track, here are the 3.73's, 4.10's, 4.56's, plus 3.08, and 3.15's:

@7500 rpm with 3.73's
1st = 44 mph
2nd = 66 mph
3rd = 95 mph
4th = 122 mph
5th = 161 mph
6th @ 60mph = 1825 rpm
6th @ 80mph = 2425 rpm

@7500 rpm with 4.10's
1st = 40 mph
2nd = 60 mph
3rd = 87 mph
4th = 111 mph
5th = 146 mph
6th @ 60mph = 2000 rpm
6th @ 80mph = 2675 rpm

@7500 rpm with 4.56's
1st = 36 mph
2nd = 54 mph
3rd = 78 mph
4th = 100 mph
5th = 132 mph
6th @ 60mph = 2225 rpm
6th @ 80mph = 2975 rpm

@7500 rpm with 3.08's
1st = 53 mph
2nd = 80 mph
3rd = 115 mph
4th = 148 mph
5th = 194 mph
6th @ 60mph = 1500 rpm
6th @ 80mph = 2000 rpm

@7500 rpm with 3.15's
1st = 52 mph
2nd = 78 mph
3rd = 113 mph
4th = 144 mph
5th = 191 mph
6th @ 60mph = 1550 rpm
6th @ 80mph = 2050 rpm