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Bear with me because I am not an expert. Anyway I have the 2012 Grand Sport with auto. I believe the the rear diff. gear ratio is 2:72s I am highly considering going to the 3:42s My question is at 70 MPH what would my RPM difference be? I checked some gearing sites and do not think I did it right so that is why I ended up making this post.
I seem to be doing something wrong. Tells me that I will be doing 358 MPH in 6th gear @ 7000 RPM I give up. I will call a gear shop in morning. Thank you for help.
Last edited by Proud Owner; Jan 3, 2016 at 10:40 PM.
I seem to be doing something wrong. Tells me that I will be doing 358 MPH in 6th gear @ 7000 RPM I give up. I will call a gear shop in morning. Thank you for help.
It is mathematically correct
Theoretically your car would need probably ten times the power to pull to 7000 rpm in sixth
The short answer is it will wake your car up in the lower gears first to fourth
It is mathematically correct
Theoretically your car would need probably ten times the power to pull to 7000 rpm in sixth
The short answer is it will wake your car up in the lower gears first to fourth
Ah yes now I understand. Thanks. Sorry I am just getting back to ya I took my RAM out and just found out that 4GBs have not been working. It is a 8GB MAC. So back up and running on 4GB.
Originally Posted by switchblade six
ignore the overall speeds just look at the speed difference in the two gear examples
remember 4rth gear is one to one ratio 5 and 6 are overdrive
Originally Posted by maustin195
I calculate 2000@70mph with 3.42 gears and 1700@70 with stock 2.73 gears. On your chart you chose the wrong trans if it is an A6.it is a 6l80e.
So 300 RPM difference. That sounds correct. But at 100 MPH should be more than 300 RPM difference?
Ah yes now I understand. Thanks. Sorry I am just getting back to ya I took my RAM out and just found out that 4GBs have not been working. It is a 8GB MAC. So back up and running on 4GB.
So 300 RPM difference. That sounds correct. But at 100 MPH should be more than 300 RPM difference?
You would see approximately 25% increase in RPM's for any given speed with a gear change from 2.73 to 3.42.
Also to give bench racing math, on the 3.42 gears... .1 sec faster to 60 , .3 faster to 100, same 60 foot, same 1/8 mile, same 1/4 mile, slower 1/2 mile by .1, and same 1 mile.
Last edited by Steve Haefner; Jan 4, 2016 at 08:01 AM.
Also to give bench racing math, on the 3.42 gears... .1 sec faster to 60 , .3 faster to 100, same 60 foot, same 1/8 mile, same 1/4 mile, slower 1/2 mile by .1, and same 1 mile.
Steve, Thanks. By looking at that info. it makes me think of forgetting gears. The only big difference that I see is .3 tenths quicker to 100 mph. I would of thought a half second for sure. We have to take into account that this was done on a track. Same driver? Same conditions? Love the side by side comparison. Side note I thought the GS weighed in at 3250 lbs.
Steve, Thanks. By looking at that info. it makes me think of forgetting gears. The only big difference that I see is .3 tenths quicker to 100 mph. I would of thought a half second for sure. We have to take into account that this was done on a track. Same driver? Same conditions? Love the side by side comparison. Side note I thought the GS weighed in at 3250 lbs.
His image was a simulation. You would notice the gears on your butt dyno when doing city driving more than anything.
His image was a simulation. You would notice the gears on your butt dyno when doing city driving more than anything.
And if that simulation is for a standard Vette then the 1/4 mile times are way off as no standard is gonna run mid 11's in the 1/4......not even the glorious GS....LOL.
And if that simulation is for a standard Vette then the 1/4 mile times are way off as no standard is gonna run mid 11's in the 1/4......not even the glorious GS....LOL.
Yep, not standard. Was based on 417whp, and a A6, This is very subjective of course which is why its call bench racing. so yeah lol
His image was a simulation. You would notice the gears on your butt dyno when doing city driving more than anything.
Yes, I am thinking 3.15s gears instead of the 3.42s Am not looking forward to too many RPMs on the highway.
Originally Posted by windyC6
And if that simulation is for a standard Vette then the 1/4 mile times are way off as no standard is gonna run mid 11's in the 1/4......not even the glorious GS....LOL.
My last car was a low 10 sec car and this GS is no where near that.
Originally Posted by Steve Haefner
Yep, not standard. Was based on 417whp, and a A6, This is very subjective of course which is why its call bench racing. so yeah lol
When I first saw your chart I was like something aint right with it. But a nice conversation piece.
Steve, Thanks. By looking at that info. it makes me think of forgetting gears. The only big difference that I see is .3 tenths quicker to 100 mph. I would of thought a half second for sure. We have to take into account that this was done on a track. Same driver? Same conditions? Love the side by side comparison. Side note I thought the GS weighed in at 3250 lbs.
I seem to be doing something wrong. Tells me that I will be doing 358 MPH in 6th gear @ 7000 RPM I give up. I will call a gear shop in morning. Thank you for help.
That chart still doesn't seem right.
Our 2009 with the performance axle (2.73?) diff upshifts at redline 4th to 5th at about 165 mph.
EDIT:
There have been some very long and very interesting threads in the C6 Tech/Performance section about the effects of changing the diff gears, my general recollection is that it makes the car feel livelier around town but doesn't change the 1/4 mile times much.
Last edited by Gearhead Jim; Jan 5, 2016 at 08:54 PM.
That chart still doesn't seem right.
Our 2009 with the performance axle (2.73?) diff upshifts at redline 4th to 5th at about 165 mph.
EDIT:
There have been some very long and very interesting threads in the C6 Tech/Performance section about the effects of changing the diff gears, my general recollection is that it makes the car feel livelier around town but doesn't change the 1/4 mile times much.
That chart is for a 2.73 gear with a 6 speed stick with 325/30/19 tires. An A6 near 6500 rpm Will shift 4th to 5th near 165 mph.
Rear Diff Swap
I seem to be doing something wrong. Tells me that I will be doing 358 MPH in 6th gear @ 7000 RPM I give up. I will call a gear shop in morning. Thank you for help.
And if that simulation is for a standard Vette then the 1/4 mile times are way off as no standard is gonna run mid 11's in the 1/4......not even the glorious GS....LOL.
