Right now i have an 85mph speedo from 1985 TA and it is very annoying that it only goes up to 85. I would like to switch it to 140mph, I already have the 140 from 1991 Firebird. They are both 305 V8 one is a TPI one is a TBI. Can I make this work without too much cutting of my dash apart? Is the 85 mechanical or not, I have heard different things. Anyone ever do this swap?

 

The 85 is mechanical and the 140 is electirc, what you will need is the buffer box from the 91 and the VSS that goes inside the tranny to send the signal. There is a write up, but don't remember the thread that had the link in it off hand but someone may remember.

 

you see thats funny, b/c i have read posts that have said 82-84 is mechanical and the 85-92 is electric. I guess i need to find that thread on how to change it over i would really like to have the better speedo, It is so hard to do a sucessful search on here, I get so many threads that have nothing to do with what i want.

 

Here's the link I was referring to

http://www.hioutput.com/tech/speedo.html

The electric speedo started late 86, my '86 was mechanical, but I bought an 86 cluster from a V8 car for the lens and it was electric, but it was also from a Canadian car.

 

My 85 TA has a mechanical speedo. If you want to be sure, look under the car on the drivers side. Near the rear of the transmission, look to see if you have an electrical connector (electronic speedo) or a heavy cable with a screw on connector (mechanical). Seeing is believing.

 

I have the same problem as u with the 85 in my 85TA.... iv been lookin into swaping to a 140mph speedo out of the 82-84 TA's but cant get a strait answer on if it will work and fit right.... I hear that hawks does a overlay service for the 85mph speedos to go to 140mph but havent found prices are anything on it