[madskater905]

I have a question...I want to get a 140 speedo from a '90 gt. i already have 3.73's. I figuered id just get the speedo correction tranny gear for a '90 with 3.73's and put that in for a correct 140 speedo in an '88. i dont see why it wouldnt work i just wanted some feed back to make sure it would work. if it wont please tell me what i would have to do. thx ahead of time!

[lxarlo]

supposedly only 89 140 clusters work with the 88s if that 90 is an early production, it will probably work too. as for the gears all you need is the red 21 tooth speedo driven gear, that goes on the trans end of the cable.

[mustang5.0-1982]

i was just wondering whey i dont have a 140 speedo i have a 90gt ?

[FoxChassis]

All early '89 (Oct. '88) and later V8 Mustangs had a 140 MPH speedometer as original equipment. Special Service Mustangs ('82-'93) had 140 MPH speedometers through '89. ('90+ SSPs had 160 MPH speedometers.)

If you want to put a 140 MPH speedometer in your '87-'89 Mustang, source one from a late '89 GT or LX 5.0 (non SSP) or an '87-'89 SSP. Mustangs with airbags ('90+) had a differently shaped cluster and gauges. Later speedometers will work in earlier clusters but it's not a simple plug-n-play fit.

Using the correct speedometer driven gear is a separate matter from the speedometer. Changing speedometers does not change the calibration of the speedometer drive and driven gears. Speedometers are calibrated internally.

An '88 V8 Mustang transmission had a 7 tooth speedometer drive gear...

Speedometer Drive Gear x Rear Gear x Tire RPM¹ / 1000 = Speedometer Drive Gear

¹Factory Mustang tires had an RPM of around 800.