speedometer 120 to a 140

do you guys know if the 120 mph speedometer is actually different than the 140 mph speedometer? or is it just a differrent gear in the transmission? 120 is on a 64 cat, 140 came out of a 64 riv.

 

ttt

 

They are the same unit.

 

Tom
If They Are The Saame Unit Then I Need To Use A Different Gear In My Tranny?
John

 

there was a company in California that rebuilds speedometers.
in my 85 Monte Carlo I upgraded from the 85MPH to 140MPH speedo.

He asked me what transmisison I had.. which was a '75 TH350... and.... it worked perfect. I guess he calibrated it to that trans.

 

do you know the name of the co?

 

In one word, No.

 

http://www.speedometerplus.com/



I shipped them to my uncle who lives in CA and let him walk in there and negotiate the price down with the guy.. (my uncle is a real pain in the ass).. so I saved $40 off the price I was quoted.. but anyway.. that's the site. Good luck!

 

Tom

I'm Still Not Clear What Your Saying About Them Being The Same Unit?
Do They Just Have A Different Face Or What Please Clear Up Your Answer

 

A speedometer needle has no actual contact with any of the mechanical parts of the speedometer system. The only contact is through a magnetic field with a rotating magnet & a round piece of metal which is connected to the speedo needle. Inside the speedo head there are NO mechanical connections made, only magnitizum.

 

Ok But There Has Got To Be Some Kind Of Difference In The 120 Vs The 140

Or I Could Just Change The Glass On The Front And It Would Bee A 140 Speedo

So Is It The Gear Ratio Or What?

 

NO!!!! You need to change the WHOLE speedo assembly, not just the "Glass"

 

SEE HERE YOU SAY THEY ARE THE SAME UNIT NOW I AM CONFUSED. WHAT IS THE DIFFERENCE IN THE TWO?

 

John, I think what Tom is saying is that you can swap the 140mph speedo assembly in without making any other changes. You would only need to change the speedo gear in the trans IF you changed your differential ratio.

As far as actual differences between the two units, I can only speculate. I'd assume the 120mph face/needle is calibrated to itself and the 140mph face/needle is calibrated to itself. You can change out the speedo units as a whole without problems but you can't just take the face off one and put it on another.

 

Thats What Im Trying To Get At?what Is The Physical Difference Between The Two?

It Sounds Like Maybe I Can Recalibrate It Using The Service Lised Above If I Cant Actually Find The Guts Or A Whole New 140 Speedo

 

You said 120 is out of the cat & the 140 is out of a '64 Riv. One would naturally "Assume" you would be using the speedo assembly from the '64 Riv. They are a bolt-in swap using also the face,140MPH. You CAN'T recalibrate your speedo. It would be cost prohibitive. Just swap out the speedo & face, that's it. Or can't you get the 140????

 

I think I paid $120 or so for my 85 MPH to 140 MPH job.
not sure what they did, but when i got it back it was accurate.....

but what tom is saying makes sense
why dont u take the entire thing out of that riv and swap it?

 

I Guess You Guys Misunderstood My ? I Wanted To Know The Difference In The Two?


All I Have Is The 120 Speedo And A 140 Piece Of Glass

So I Gues The Answer To My Question Is Yes They Are Different I Do Need To Buy A 140 Speedo To Make It All Work Or Recalibrate My 120 And Use The 140 Glass

 

ahhh


well, call that speedometer shop and ask them what they can do for you, man! :idea2:

a phone call doesn't cost anything! not these days at least

 

NOW I UNDERSTAND!!!!! You made it sound like you ALREADY had the 140 speedo. Now that you explained all you have is the glass it all makes sense. No wonder all the questions with no positive answers. Need a 140 speedo also????? Solves alot of problems.