Speedometer replacement

[89OctaneStang]

Well, I just replaced my 85 MPH speedo with a 140 MPH speedo. But now I'm having problems getting it to read right. I changed my original 18 tooth gear set to a 23 tooth gear set and it didn't fix the problem. And when I took the 23 tooth gear out today, the gear teeth had been broken while inside the trany during that short period of time. Has anyone worked on their speedo before and experienced something similar to this and found the fix to the problem? Cause I'm clueless at this point....

 

[white 89 GT]

For now put in a 20 or a 21. the 21 may not last long also.
Basically im saying put the highest count gear in that will last till you can change some internals (7 tooth output shaft) then save your dollars for some trans upgrades like the ones I did to mine.

 

[04MystiCobra]

Theres no other way other than to go into the tranny? Just doesnt sound right. There are so many out there that have done this swap (not me) and I havent read that. I dont see many foks willing to do this if you gotta go in the tranny.

 

[white 89 GT]

I think someone makes a add on speedo correct gadget.
PAT performance automatic trans. look it up on the web

 

[89OctaneStang]

Well, I just went to the guys house I bought the 140 from and got my 85 from him off his bench. Checked the back of the needle and seen that there is a weight there that I dont have on the 140 speedo. So tomorrow after work I'm going to tear apart my dash again and put the needle from my 85 onto the 140 and see if it makes any difference. And then I'm going to put the 18 tooth gear set back on since that worked perfectly for the car and see where that leaves me.. I'll keep you all informed of what progress I find through doing this.

 

[white 89 GT]

Check my previous post

 

[89OctaneStang]

Do I need that part???

If so, where can I get one????????

 

[white 89 GT]

Do I need that part???

If so, where can I get one????????

I think it will help correct your speedo and can be found at PATC AOD trans, then look around till you find speedo adaptors and click on the link and scroll down to aod adaptors.