[show95stang]

i went about 100mph in 5th at about 3000rpm,is that normal for a 95 mustang gt ,or do you think i have 4:10 gears?

[JONJON]

what tranny and size tires do you have?then I can answer you.

[ryans88gt]

Originally Posted by show95stang i went about 100mph in 5th at about 3000rpm,is that normal for a 95 mustang gt ,or do you think i have 4:10 gears?

Assuming your tach and speedometer are correct (which they aren't) you would have maybe 3.27 gears.

with 4.10 gears you'd only make it to 70 mph at 3000 rpms
with 3.73s maybe 80 mph at 3000 rpms
3.55s ~90 mph

Those are just off the top of my head numbers, but should be approximately right.

[Chris951]

Originally Posted by ryans88gt Assuming your tach and speedometer are correct (which they aren't) you would have maybe 3.27 gears. with 4.10 gears you'd only make it to 70 mph at 3000 rpms with 3.73s maybe 80 mph at 3000 rpms 3.55s ~90 mph Those are just off the top of my head numbers, but should be approximately right.

That's right

[baine21225]

so he prbly has stock gears....

[Stangzilla]

Originally Posted by show95stang i went about 100mph in 5th at about 3000rpm,is that normal for a 95 mustang gt ,or do you think i have 4:10 gears?

Jack up the rear end and have someone slowly turn the tire. Put a mark on the driveshaft and count how many times it spins after one full rotation of the tire..

[show95stang]

i have a t-5 tranny if that helps.how does that tire turning thing work?do you have numbers?

[Chris951]

Originally Posted by show95stang i have a t-5 tranny if that helps.how does that tire turning thing work?do you have numbers?

You have 3.27's.

[Stangzilla]

Originally Posted by Stangzilla Jack up the rear end and have someone slowly turn the tire. Put a mark on the driveshaft and count how many times it spins after one full rotation of the tire..

The tranny does not matter. put it in neutral. If the shaft turns 4.1 times you have 4.10s if it turns 3.73 times you have 3.73s ect ect...

[TENGRAM]

Originally Posted by Stangzilla The tranny does not matter. put it in neutral. If the shaft turns 4.1 times you have 4.10s if it turns 3.73 times you have 3.73s ect ect...

x2. turn the wheel 1 full rotation and count how may rotations the driveshaft makes.

[JONJON]

what tire size, but I think they are 3.27 also.

[TT86]

Originally Posted by Stangzilla Jack up the rear end and have someone slowly turn the tire. Put a mark on the driveshaft and count how many times it spins after one full rotation of the tire..

Just do it! !! BTW I have 4:10s with a T-5 ....and 3K is around 70 mph with a 275/40 17 rear tire....

[ryans88gt]

The size of the tire doesn't matter b/c your speedometer is driven off the trans. The only way the tire size would matter is if you had your speedometer calibrated for the tire size you were actually running...

tire size does change actual speed, but not speedometer speed.

[Drick]

Originally Posted by show95stang i went about 100mph in 5th at about 3000rpm,is that normal for a 95 mustang gt ,or do you think i have 4:10 gears?

No way do you have 4.10's then. at 100 with my 3.73's I go about 4K and 115 im 4800

[shurb125]

I have a set of 3.55's and it's about 3000 rpms at 100mph in 5th.

[Speedstang302]

i have stock gears again and at 2000rpms at 120 in 5th

[1slo5.0]

Originally Posted by ryans88gt The size of the tire doesn't matter b/c your speedometer is driven off the trans. The only way the tire size would matter is if you had your speedometer calibrated for the tire size you were actually running... tire size does change actual speed, but not speedometer speed.

I could be misunderstanding what you are saying here but tire height definitely effects speedometer reading. Anything behind the tailshaft that makes the driveline spin more rpm is going to effect the speedometer reading and anything in front of the tail shaft will not effect it. Going from a 28" tire to a 26" tire is just like changing to a lower gear ratio and causes the driveshaft to spin more revolutions. That is why all of the speedo gear formulas ask for tire height.

7 tooth drive gear (manual trans) with 4.10 gear with 26" tall tire needs a 23 tooth driven gear

7 tooth drive gear (manual trans) with 4.10 gear with 28" tall tire needs a 21 tooth driven gear

[ryans88gt]

Originally Posted by Darrell I could be misunderstanding what you are saying here but tire height definitely effects speedometer reading. Anything behind the tailshaft that makes the driveline spin more rpm is going to effect the speedometer reading and anything in front of the tail shaft will not effect it. Going from a 28" tire to a 26" tire is just like changing to a lower gear ratio and causes the driveshaft to spin more revolutions. That is why all of the speedo gear formulas ask for tire height. 7 tooth drive gear (manual trans) with 4.10 gear with 26" tall tire needs a 23 tooth driven gear 7 tooth drive gear (manual trans) with 4.10 gear with 28" tall tire needs a 21 tooth driven gear

yeah you are misunderstanding me.

Tire height DOES effect your actual speed and the relationship between your actual speed and the speedometer, but it DOES NOT affect the relationship between your speedo and the tach. For example, you could have no tires at all on your car with the car sitting on jack stands and your speedo will still read 100 mph at a given rpm in gear. It wouldn't matter what tires you put on, your speedo will always read the same at that rpm. Your actual speed will change, but the speedo will read the same (and be wrong).

My understanding was that the OP was basing this question on his speedo reading and that reading being correct. If he was talking about trap speeds measured third party, then yeah, tire size makes a difference.

[airforcesvt1]

jack the car up and turn the rear tire and count how many times the driveshaft turns!

[airforcesvt1]

or is it the otherway around lol!!! just do it mang!