somewhat of an answer to my gearing ?

[jeffs89gt]

today on my way to the track i paced my friend in his gto and we were dead even next to each other and when i was in 5th at 2grand and my speedo said 80, his speedo said about 68.then when mine said 90 his said about 73. he has an 05 gto so my guess is that his speedo is accurate. im assuming that i have the rear from a different car..... what do u guys think the chances are that my car ended up comin out of the factory with 3.27s.... i guess ill never know for sure

 

[HISSIN50]

someone probably swapped gears (not necessarily the entire rear) and did not get the speedo dialed in right.

3.27's were reportedly an option on Autos.

Good luck.

 

[jeffs89gt]

my rear has the diff tag for 3.27s. it says 3SL27. i got the car from the original owner and he said nothing was ever modified in the driveline. the only mod the car had was no mufflers, if u consider that a mod. and black tail light lenses and a system from like 5 years ago. he didnt seem like the kind of perosn that would do somethin like that to the car. my thinking is that it was warrenteed because the rear mad noise and went bad or somethin and they threw that in instead.

 

[Doc GTO]

The GTOs speedo is pretty accurate. He should even had a digital speedo in his DIC center. It could be gears, tire size or maybe a distributor issue where the speedo pickup is.

 

[vristang]

The GTOs speedo is pretty accurate. He should even had a digital speedo in his DIC center. It could be gears, tire size or maybe a distributor issue where the speedo pickup is.

Interesting to think that the Goat may have gears, or another problem. I think everyone had assumed the Mustang to be at fault.

I ran some numbers using my tire diameter. Let me know yours and I will be able to get more accurate numbers.

Speed (mph) ______68 ____68 ____68 ____80 ____80 _____80

Tire Diameter (in) __25.25 __25.25 __25.25 __25.25 __25.25 __25.25

Rear Gear Ratio ___2.73 ___3.08 ___3.27 ___2.73 ___3.08 ___3.27

Fifth Gear Ratio ___0.68 ___0.68 ___0.68 ___0.68 ___0.68 ___0.68

Engine rpm ______1679 ___1895___2012___1976___2229___2367

Sorry for the formatting, Excel didn't seem to want to paste in here.

 

[jeffs89gt]

The GTOs speedo is pretty accurate. He should even had a digital speedo in his DIC center. It could be gears, tire size or maybe a distributor issue where the speedo pickup is.

what do u run wiht ur gto... and how many miles are on it.... my friend still cant get into the 13s with his 05.... hes got 2800 on it. our other friend with a 05 with the sport apperance package with 3250 on it ran a 13.5 after we did the the pcm relearn. he couldnt get better than 14.0 and we pulled hte fuse and reset the computer and then his next run he was 1/2 a sec faster, and he launced and shifted the same. ill give u the link to the pcm relearn instructions if u want it