115 to 145 gauge swap

Im ordering white face gauges for my car, and i was wondering if it is hard to convert your car from 115 to 145 mph gauge. I knw you probably have to replace the tranmission speedometer motor, but is that it?

I'm not sure you have to replace anything. The speed sensor is calibrated to the gearing of you trans and rear end, not the speedometer.

i dont know. i was just looking for gauges last night online and i say some sites that specifically said you cant just order gauges with a higher mph and put them on youre car with a lower mph. i dont know why this is, but thats what it said. id like to get new gauges for my car also. im stuck wieh a 110 speedo and id like to upgrade to the 145 one.

All you do is swap out the gauge cluster, nothing else. On 1982-1989 the speedo sensor (VSS) is on the back of the gauge cluster, where as on the 1990-1992 it is intergrated with the speedo gear in the transmission. You don't have to change any of this. The speedo itself is calibrated to convert the rpms from the trans to what ever the speedo should display. Now if you were to change out the differential gear, then you would need to swap out the driven/drive gears in the trans to match the new gear set out back. :cool:

ok now try this one. the drivetrain in my car will be not even close to stock. 1997 lt1, 1997 t56, ford 9 inch 3.89 gears. so how do i get the speedo right? because i didnt even think about the change in rear gear ratio.

I want to get mine done too, I think you can take it to a shop and they will calibrate it for you for a reasonable price. Cause I have 3.73 rear, built tranny so I dont know if the gears are the same or not and I have huge rear tires and Ive heard that can affect it.

Are you telling me that all I have to do is put the new gauges in my car and that is it ? I already had my speedo redone for my 3.73 and my 28" tall tire.

Originally posted by 3GLT16speed
ok now try this one. the drivetrain in my car will be not even close to stock. 1997 lt1, 1997 t56, ford 9 inch 3.89 gears. so how do i get the speedo right? because i didnt even think about the change in rear gear ratio.

You need to modify the LT1 computer, either with a Hypertech adapter or with custom programming.

I thought about doing this to my 86 roc because it only reads to 85 mph but of course it goes much faster than that. My dad brought up a good point though. it will take away from the stock original look if my car came with that cluster it should keep it. I dunno i just thought he had a valid point with keepin the look of the car as original as possible

You make a good point !For myself it's a little too late for that.

A 145 MPH speedo did come stock in some later 86 IROC's, so you're ok there. Besides, who cares about stock? I dont. My car is for high performance, not to look pretty and be slow.

I just want the look to be stock, performance wise ima do everything my wallet will allow me 2.