TH350 speedo problem
03-06-2009, 09:19 PM
#1
TECH Resident
Thread Starter
iTrader: (11)
Join Date: Sep 2002
Location: Louisiana
Posts: 966
Likes: 0
Received 0 Likes
on
0 Posts
TH350 speedo problem I have a 99 M6 Z28 4.11's that I changed over to a th350 and I am having a problem with speedometer. I spliced into the front drivers wheel sensor and tied it in to the black trans speed sensor. Then I measured the tire (81 inches) and divided 3.14 to get the actual tire height of 25.79 and reflashed the pcm to 2.76 gear ratio. Now it is nowhere near what it should be. I put the gps in the car and at 40mph the speedo is showing about 18-20. What could I have done wrong? Could the wires be backwards or did I forget something?
03-06-2009, 10:31 PM
#6
TECH Resident
Thread Starter
iTrader: (11)
Join Date: Sep 2002
Location: Louisiana
Posts: 966
Likes: 0
Received 0 Likes
on
0 Posts
It's only a 26 inch tire.
I'm using the front driver side wheel sensor. Did I not measure it right? I read that you need to measure around the tire, I did that and came up with 6ft 9inches=81inches then divided by 3.14 and that gave me 25.79 inches for tire height
I'm using the front driver side wheel sensor. Did I not measure it right? I read that you need to measure around the tire, I did that and came up with 6ft 9inches=81inches then divided by 3.14 and that gave me 25.79 inches for tire height
Trending Topics
03-09-2009, 09:10 AM
#11
10 Second Club
iTrader: (14)
Join Date: Jul 2006
Location: brimfield, illinois
Posts: 686
Likes: 0
Received 0 Likes
on
0 Posts
This is what I have in mine. I've got metric radials on the front but I think they are 26" tires. Works well for me and it might only be off by 1 mph at 70.
Mile - 40688
Rev Trans - 40.0
Final drive ratio - 1.17
Trans revolution per mile - 755.0976
Mile - 40688
Rev Trans - 40.0
Final drive ratio - 1.17
Trans revolution per mile - 755.0976
03-09-2009, 09:12 AM
#12
10 Second Club
iTrader: (14)
Join Date: Jul 2006
Location: brimfield, illinois
Posts: 686
Likes: 0
Received 0 Likes
on
0 Posts
There is a writeup on how to measure your tire to figure out your correct ratio but i'm to lazy. This will get you in the ballpark tho. I had to do some adjusting on mine to get it a little closer to my tires.
03-09-2009, 09:25 AM
#13
TECH Resident
Thread Starter
iTrader: (11)
Join Date: Sep 2002
Location: Louisiana
Posts: 966
Likes: 0
Received 0 Likes
on
0 Posts
I figured out what the problem was. I forgot my operating system was updated to an 02 and that was an auto setup. So I had to enter the auto gear ratio and all is well. Thanks for the help
