I just bought 2007 GT with the 3:55 rear end option. I have had a 2000 and 2005 GT's in the past all with 5-speeds Transmissions. Both the 2000 & 2005 would indicate 68 mph at 2000rpm both having the stock 3:27 rear end. The 2007 with the 3:55 rear end seam to indicat the same about 68 mph at 2000rpm. I thought that I would see a difference maybe 65 or 66mph at 2000rpm. Has anyone else noticed this or would know why I am not running a higher rpm at 68mph?
Don't understand!
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The original 2000 Mustang GT had 16" tires(17" on the mid-year and later models). So if it had a 3.27 gear like you say, then that would translate to an approx. 3.47 gear with 17" tires. And that would make the rpm's at 68 mph very close to the 2007 GT with 3.55 gears(assuming it has 17" tires).
I was told GPS is much more accurate, and I have noticed that even though my speedometer shows I am doing the speed limit, everyone is still passing me or tailgating me.
Haha well if you are doing the speed limit, I would be passing or tailgating you as well.
It seems to me like GPS wouldn't be accurate enough for speeds in cars because of any slight delay or tranmission errors in communicating with the satelittes. Seems like the most accurate measure would be from the tires that touch the road, but that also requires the correct calibration. Don't know...just rambling.
My Garmin GPS claims an accuracy of +- .05 meters/second. That's pretty accurate. I use it all the time on the highway and hiking.
Interesting. What sort of Garmin? My girlfriend has one of the cheaper models that is designed to sit on a car windshield. I don't know what accuracy it claims, but just in watching it, I figured it wasn't that useful. Seemed to update too infrequently and seemed sporadic.
I agree. I have used my Garmin on many road trips and I am convinced it is very accurate. Just my 2 cents.
GPS Map 60CS. We wander into the hinterland so we needed a way to find our car again. Works great as a companion mounted on the window during long trips although the screen is pretty small. It also has a habit of picking roads that no longer exist for a route....
mustangmike6996
Member
THE 2005 MUSTANG GT HAS A 5TH GEAR RATIO OF 0.68:1 WITH THE 3.55:1 WITH
THE 3650. THE GT'S WITH THE 3.31 HAVE A 5 RATIO OF .71:1
THE 2000 MUSTANG GT HAD A REAR GEAR RATIO OF 3.27:1 WITH .67:1 5TH RATIO
SOME SIMPLE MATH AND THE 2000 MUSTANG GT HAS A LOWER DRIVING RPM AT THE SAME SPEED IN 5TH
THE 3650. THE GT'S WITH THE 3.31 HAVE A 5 RATIO OF .71:1
THE 2000 MUSTANG GT HAD A REAR GEAR RATIO OF 3.27:1 WITH .67:1 5TH RATIO
SOME SIMPLE MATH AND THE 2000 MUSTANG GT HAS A LOWER DRIVING RPM AT THE SAME SPEED IN 5TH
No need to shout.
If the 2000 GT was a mid-year or later model, then it had 17" tires, and I agree with you.
But if it was made in the 1st half of the model year and thus had 16" tires, then it would have the same rpm at the same speed.
SlideWRX
Member
Er, the 2000 mustang had 16" wheels, while the mid year had 17", but the tire diameters were likely identical.
What were the tire specs for those?And when my speedo reads 70, I'm doing ~68 mph. pretty common, you won't find cars that read exactly right from the factory. They all indicate a bit higher.
Tom
Whoops, you're right. However, the end result is the same.Er, the 2000 mustang had 16" wheels, while the mid year had 17", but the tire diameters were likely identical.
And when my speedo reads 70, I'm doing ~68 mph. pretty common, you won't find cars that read exactly right from the factory. They all indicate a bit higher.
Tom
The 2000 GT has either 225/55-16 or 245/45-17 tires with a 25.7" OD, and the 2007 GT has either 235/55-17 or 235/50-18 with a 27.1" OD.
That would make the 2000 GT's 3.27 gear into an equivalent 3.45, or an almost unnoticeable difference of approx. 50 rpm's at 68 mph.
In addition, 2 tires with the same specs from different manufacturers can have different rev/mile numbers, which in turn can make the engine rpm's for these 2 cars identical at the same speed.
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