Ok a few questions....

The first few are in regards to recalibrating it:

1st) My car has 76k original miles on it. Not bad for a '91. I believe the 140speedo has around 55k. Obviously I want to have it the exact same mileage because my car is so low.

2nd) The 140mph has the same circumfrance as the 120mph. Obviously, I can't just slap it in w/o a 5-6 mph difference.

3rd) I plan on gears in the next few months (3.73's most likely)

What is the cheapest/best tool I can buy to recalibrate all this on my own? Is it easy to do?

What are the things I might run into when swapping speedos? I believe the 140 is from an '89 formula. (It's actually from a 5spd car, so the redline is about 500rpms higher...kinda cool!) So I should be ok because both should be electrically driven, correct?

What other things might I run into?

Thanks!

-Kevin

 

As long as you swap the entire speedo assembly (gauge,circuit card) it will work fine. I did this swap on my Formula and had no troubles. As for the odometer,just carefully take the gauge apart and swap the odometer portion from the 120 into the 140. I also did this as well to keep my mileage correct. As for the gear swap,you'll just need to swap the two gears in the tailshaft of the tranny. I believe you can still get them from SLP and GM. Check the FAQ section for the speedo gear list for the correct ones. As for it being from a 5 speed car that will make no difference. Just make sure you swap the circuit car when you swap the gauge. It's in the cluster mounted with the speedo.

 

that's some helpful advise. i was also thinking about switching my 120 cluster for a 140. i'm assuming that it will work the same for a 88 firebird cluster to a formula cluster around the same year....'86+.

 

So what is the gauge circuit card look like? Is it external from the cluster? Because all I have is the cluster.

Short of taking the dash apart and swapping them out, it sounds pretty simple. Plug-n-play right? So no calibration necessary to go from 120-140?

 

i believe that the circuit card that he's refering to is the green plastic-like, paper thin layer that's on the back of the gauge cluster....of course, i could be wrong.

 

It has the circuitry and all that jazz? Then yes I have that. So it's plug-n-play? Please say it is, please say it is!!!!

I am only free time away from installing it now!!

 

The circuit card in question is mounted above and behind the speedo head, inside the cluster (white part the gauges mount to), cant miss it.
The 'green plastic-like, paper thin layer' one on the rear is the printed circuit for the cluster itself.

If you have the entire cluser from the donor car, yank the old out of yours, plug in the 'new', reassemble and call it a day.

 

Deadbird is right. You didn't say if you had the entire cluster so I went with you just swapping the single gauge. It is a plug and play deal as long as your car came with an electronic speedo in the first place.

 

Sorry about that missing detail. Yes, I do have the whole cluster. Now here's the details, I took it apart last night and getting the odometer off the 140speedo, looks impossible. There's gears, and things...how do I remove the odometer?

That's the only thing stopping me now.

 

When I swapped my 140MPH cluster in, I just spun the little numbers on the odometer. There is a little cam that holds them all in place and spins the next number when one turns a complete revolution. You can slide one of the cam ends out just a hair and raise it off of the numbers to adjust them quickly. It can be a task to keep the numbers lined up exactly when locking the cam back in, but it is possible. I chose this as the easiest way to change my odometer reading to match my car. I think I went from 140k miles or so on the swapped-in guage cluster to the 82k or so that my car had at the time (don't remember at what mileage I swapped it into my car).

 

Thanks, I shall try that. All those gear and cams make me want to scream.

 

I changed the mileage. But I was hoping to just swap my odometer with the 140's odo.

Will it change something that will raise a red flag some day? Because my car has pretty low miles for a 15yr old car, I don't want to have someone question it if it throws a "secret code".

 

Done and done. Install went smooth. However it's kinda dark in the gas gauge corner. I might have to dig in there some day and switch out the bulb. 140mph looks so much better than 120mph. I just wish we got a 155mph speedo.

 

i put my new 140 speedo in and now its like 10mph off. what went wrong

 

Did you remove the needle at one point? I actually need to have my bro or girlfriend pace me with their cars. But so far it seems pretty accurate. But 10mph off sounds bad. Did you go from 85-140?

 

yes, idid. i just moved it a lil while ago and it seems better but idk for sure.no i went from a 120.

 

yes, idid. i just moved it a lil while ago and it seems better but idk for sure.no i went from a 120. actually i think it was only like 5 mph off. the car i sued to begin with to pace me has problems

 

I know mine is correct because last night I was going 70mph, threw it in 3rd gear (auto) and watched the rpms hit about 2700rpms. So that shows that my car has 2.73 gears.