What rear gear set does it seem like I have installed? ---

[alwayscode390]

I was going through receipts from my recently purchased 2001 GTS ... one said "gear install" ... I am AROUND 1450rpm at 60 in 6th.

If there is a better gear and mph to check at , please let me know.

Seems like somewhere around a 3.42 (chevy numbers is what I am familiar with, lol).

What does it seem like to you?

Thanks ---

 

[alwayscode390]

Is it looking like 3.55? ---

 

[hou99gts]

What size rear tire are you running?

 

[Steve-Indy]

While I don't have my chart handy...I would say that you are correct on the 3.55. Our stock 2001 runs about 1350 rpm in 6th @ 70 mph. It is yellolw...so naturally, it could be faster !!!

 

[alwayscode390]

I am running 345-25-20 Nittos ---

 

[Steve-Indy]

Wonder if you have a 3.73 ??

 

[DanielR]

I am running 345-25-20 Nittos ---

With that tire size, you are probably not at 60 mph when you take your tachometer reading, even though your speedometer reads 60 mph. Unless of course you can verify that you have a Unitrax, yellowbox, or some other speedometer correction device installed and properly calibrated.

 

[hou99gts]

With that tire size, you are probably not at 60 mph when you take your tachometer reading, even though your speedometer reads 60 mph. Unless of course you can verify that you have a Unitrax, yellowbox, or some other speedometer correction device installed and properly calibrated.

x2, we will need more info to help you.

 

[Jack B]

Check it in a lower gear, say 2000 rpm in fourth.

 

[alwayscode390]

How do I verify that my speedo is correct?

On the 2000 mile trip home all the worksite radars were saying I was going 62 when my speedo said I was going 60. Its pretty close.

I found a receipt for a "$400" computer mod ... I was thinking that was a dyno tune/speedo calibration?

Where do I look to see if it has a unitrax or yellow box?

I will check tonight to see what MPH I am at in 4th at 2000rpm.

Next step is trying to call the old owner on the 6 year old phone number I have from a receipt, lol!!!

Thanks ---

 

[alwayscode390]

Check it in a lower gear, say 2000 rpm in fourth.

At 2000 rpm in 4th the speedo showed 42mph ---

 

[hou99gts]

It looks like you have 3.73's to me.

 

[alwayscode390]

Dang, that would explain the rocket takeoff LOL ... I'm starting to think the same way as you ---

 

[vancouver-gts]

You have 4:10 gears!. Just checked again yesterday on the road, I'm turning 1500rpm's at 60 mph in 6th with 4:10 gears in my 99 GTS, 18" wheels and tires. I got the Unitrax speedo calibration box.And yes, take off is rocket like,hehe

 

[Jack B]

What size tires. I also have the unitrax box and the 3.33 box they gave me was a 3.55

 

[alwayscode390]

You have 4:10 gears!. Just checked again yesterday on the road, I'm turning 1500rpm's at 60 mph in 6th with 4:10 gears in my 99 GTS, 18" wheels and tires. I got the Unitrax speedo calibration box.And yes, take off is rocket like,hehe

WOW, the gears are REALLY quiet, I am impressed.

What MPH are you at in 4th at 2000 rpm? Next time you are in your car cruising check it out for me.

What Tires are you running ... I want to see if we are the same overall diameter ... THANKS ---

 

[vancouver-gts]

I have new BFgoodrich KDW G-Force tires, OEM size. Checked the calibration of the box with handheld GPS and it was spot on
the speedometer. I'll have the car out Sunday again and will check the rpm/speed in 4th where the ratio is 1:1 in the tranny to give most accurate info. I've also checked the ratio on the hoist checking driveshaft/wheel rotation. I've got Mopar gearset and it's quiet.

 

[vancouver-gts]

took the car out today, so here it goes.@2000 rpm in 4th gear, speed is 41mph with 4.10 gears.

 

[alwayscode390]

I really DO have 4.10 gears ... thank you very much for your help ---

 

[vancouver-gts]

My speed was actually closer to 40 mph @2000 rpm's in 4th gear. If you went 42 mph @2000rpm's in 4th ,you may have 3.73 gears in case your speedo isn't in calibration. 3.73 gears should result 43.5 mph @2000 in 4th gear,providing you have OEM size tires. Best way to check for sure is to take your car to a garage with a pit, raise the rear wheels off the ground.Make a chalk mark on the drive shaft and turn the wheel one full turn, counting the rotations of the shaft.

 

[hou99gts]

He lists 345/25/20 rear tires above, that is why I said he has 3.73's, ya'll are running different tire heights.

 

[alwayscode390]

Oh dang, I forgot to calculate my tire size vs stock height tires.

The 345/25/20 I am running has an overall diameter of 26.8"
The 335/30/18 Stock has an overall diameter of 25.9"

Difference of .9" more on my setup.

I actually just found an online calculator that allowed me to put in 2000rpm, 4th gear viper spec t-56, 42mph and tire size

It came back 3.73 ... you were right!!!

I will have it checked the next time the car is on a lift ... but this is good info for now

Thanks for the help guys!!! ---

 

[hou99gts]

Now you've got it.

Glad I could help.

 

[Stonep185]

” I actually just found an online calculator that allowed me to put in 2000rpm, 4th gear viper spec t-56, 42mph and tire size”

What website did you go to for that? I would be interested to calculate mine as well.

 

[alwayscode390]

Its a mustang site, lol ... but here you go ---

http://www.corral.net/tech/gearcalc.html

 

[Stonep185]

Awesome, did you use the 4.6 or 5.0 t56 calculation? Or does it not make a difference? I guess I'll find out when I try it...

 

[alwayscode390]

I used the "4.6 VIPER SPEC" one since it mentioned it being a viper t56 ratio transmission ---

 

[Stonep185]

Oh duh! It was too obvious for me to grasp...