Highter speed speedometer for 90 GM

[over2tonsofFun]

Actually my wife asked. IS there a higher speed speedometer available for our new 90 Grand Marquis. Anyone know if a similar year Crown vic would fit?

Thanks
Tim

[Tiggie]

90-91 Crown Vic Police Car would give to you 140mph in the speedo. It should be a direct fit for a 90 GM. The speedo background color is black instead of silver but functionally the same.

[VicCrownVic]

Yes, I have one in The Scab ('91 MGM). Direct swap. '90-'91 CV only since the CV cluster changed in '90 then changed again in '92.

If you're up for a challenge, I have a '98-'02 P71 cluster in The Ice Car. The wiring is nowhere near a direct swap. I never got around to swapping the backwards oil pressure sender and physical fitment is not great. I modified the bezel by removing the whole section above the cluster.

[Mainemantom]

I have had mine out a few times to replace bad parts. I just finished replacing the old 140mph with a nos 140. Easy swap. Problem is finding a good used one or a nos part. I have a bunch of used pieces. I do not know If you have to change anything at the transmission, as there is not a speedometer cable AT the speedometer head like the old models. Just plug in snap connections. The gas gauge and temperature gauge just plugs in. As mentioned the face plates will be a different color. All of my old units were off on speed calibrations. Some as much as 10 mph. Hopefully my new one will be accurate. I bring my GPS along as it tells me my speed as well as those speed trailers on the side of the road.

[VicCrownVic]

Direct swap, nothing needs to be changed. The '90+ speedometers in panthers all read the VSS electronically. (Unlike Mustangs which were mechanical until '94.) The '90+ VSS is actually identical to the '89- VSS, but with a removable plastic plug to block the mechanical cable port. Removing that plastic plug allows you to use a '90+ VSS in an '89- panther.

The 85MPH and the 140MPH speedometers both measure the same VSS output and report the same measurements. Basically the VSS has no idea what speedo is at the other end. If your old 140MPH unit was off and the new unit is also off, I would look at the gear on the VSS to make sure it has the right number of teeth. If that is correct for your rear gear ratio, and the rear gear ratio is stock for that car, I would make sure the correct tire size is on the car. If that's all good my next question would be if the trans is original to the car. If not, the number of teeth on the trans output shaft might not be right for the car.

Is suppose there is a chance the unit is not calibrated properly, but I've never seen or heard of that happening.

[Mainemantom]

I was wondering about the gear on the VSS. I understand the gears come in different colors for different number of teeth. My car's tires may have affected it. The newer ones are the same size but look different. Trans and gear ratio have not been changed. When I repainted the needle, on one replacement speedo, the speed was off for sure. Did not think that would happen but it did.
Police speedometers have to be calibrated to different standards. They have to be accurate at different speeds with very little error. That is why they have the designation "calibrated" on the speedometer. There are more legal reasons which I won't get into.
Unlike civilian models which have a wider margin of error at a variety of speeds.

[Kodachrome Wolf]

Shouldn't need to swap the VSS gear unless you put some super weird tire size on that's much taller/shorter than stock or swap rear gears.

I've got a '90 police cluster in my '97. Had to reset it one time because the original stepper motor for the needle started sticking. Swapped a stepper motor from a '94 GMQ cluster to the police board, got up to 60 MPH with a GPS, and stabbed the needle correctly (definitely do that on a open, empty road). It was accurate prior to having to swap the stepper motor, but a sticking one does no favors.

[Mainemantom]

I would liked to have seen you stick the needle at 60. Driving with your knees, one eye on the road, the other on the needle.
Can't see anything that might go wrong. As you say, empty road helps.

[Tiggie]

Corners give me +/- 5mph on a 140 speedometer depending on left or right turns. Otherwise it’s spot on. It was that or +5-10mph at 75 MPH on bumpy parts of the interstate on the old 85 unit. Around town. I really prefer the 85. But if you are on a 65+ road frequently, the 140 is the winner.

[Mainemantom]

Drove the car today. From 0-20 mph when the vehicle has initially started up. The needle does not move. From then on perfect. Same thing at the next start up. Seems like a delay in a sensor reading. Unless it is an easy fix, I am not pulling the speedometer again. If it will not damage anything by leaving it alone, I am leaving it alone. It is perfect for its age as far as I am concerned. Speed accuracy is right on once the needle moves.

[over2tonsofFun]

Being in Wide open Wyoming. Our 2 lanes are 70 and the Intestate is up to 80. so yeah a 140 would be beneficial. I have a 140 for the 85 Two door.

T