Another speedo (gear) thread

Bill Cool

Previously 87MustangGT

Founding Member

Nov 18, 1999

1,268

3

39

Seymour, CT

Nov 17, 2010

#1

• Nov 17, 2010

• #1

I've got an 87, with 3.55's out back, and just installed a T-5z tranny whose case was from an unknown year Mustang. How can I tell whether I have a 7 or 8 tooth gear in the tranny? I need to know that to know what the correct speedo gear is, right? After the tranny was installed, the speedo bounced until ~60mph... And after I swapped my stock H for an off-road pipe after an emissions test, the speedo doesn't work at all. Perhaps the gear was wrong, and the teeth have gotten chewed off?

 

87coupe50

Member

Feb 10, 2008

105

1

16

WAYNESBORO, PA

Nov 17, 2010

#2

• Nov 17, 2010

• #2

check out this site: Mustang Speedometer and Transmission Gears

you can look into the speedo gear hole to see what color trans gear you have, or even count the number of teeth.

Most likely the speedo gear teeth got chewed or you snapped the wire all together

 

Bill Cool

Previously 87MustangGT

Founding Member

Nov 18, 1999

1,268

3

39

Seymour, CT

Dec 5, 2013

#3

• Dec 5, 2013

• #3

Blast from the past... I can't see the drive gear (but I'm waiting to hear back from my tranny guy as to what gear is in there). Driven gear is the white one.

Just installed a new speedo cable. Took several miles, but the cable seems to have broken in a bit (I still have to lube it). The speedo is still pretty jumpy... And still not reading accurately vs. my GPS. Speedo @ 55, GPS reads 60...speedo @ 72, GPS reads 79. I still have the T-5z, and 255/40/17's.

 

Grabbin' Asphalt

10 Year Member

Jun 10, 2013

2,029

310

124

Atlanta, Ga

Dec 5, 2013

#4

• Dec 5, 2013

• #4

I need to do this, I've waited too long.

Jarrod@latemodel

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,347

18,081

224

Massachusetts

Dec 6, 2013

#5

• Dec 6, 2013

• #5

T-5Z is usually the 8-tooth drive gear.

6-tooth is black
7-tooth is yellow
8-tooth is green

You can pull he speedo cable, shine a flashlight inside and see the color and ID it that way.

The clip that secures the gear to the mainshaft usually fails. It snaps and the speedo drive gear walks down the shaft and your speedo stops working. Usually happens after a rebuild which is why i suggest to use a NEW clip anytime you must remove it. Stretching it to take it off usually causes it to break