Hi everyone. Changed my rear end over the winter as the old one was noisy. My car is a 96 4.6 GT Manual, and the replacement axle came off a 95 5.0 Auto. Just got the car back on the road tonight and found my speedo is reading 10mph BELOW the speed i'm actually travelling at. I thought they were the same ratio but obviously they aren't. Just wondering how I correct the speedo and also does that mean that my gears are longer or shorter than they used to be? Thanks Chris
If stock auto rear end will always have lower ratio than manual, because there is one less gear to work with (at least in our years). Anyway you need to buy a speedo gear for the transmission to correct the speedometer reading. Or you can swap out the gears back to what you were at.
Or you can buy a speedcal, best thing ever. [MENTION=18797]blackdemon007[/MENTION], you can't get 2.73's with a Auto Mustang? Mine came with 3.27's. The difference between those two ratios is close to 10 mph around 1800 rpm in 5th gear.....
The plastic gear on the VSS should be all you'll need unless you go over 3:55 ratio. But you need to find out what's in the old and new rear end.
Thanks for the replies everyone. Right, so I think I've worked out what's going on. My old diff tag looks like it says "3L27" at the start of the bottom line. My door jamb says "Axle - E". So by my reckoning, my old gears were 3:27's? The new axle from the 95 5.0 Auto, says "2L73", so 2:73's right? I know you guys all like the shorter gears but the car feels plenty quick to me (my daily car is a 1.6 Fiesta!) and with fuel prices over here in England (about $9 per gallon) I'm thinking I might appreciate the better economy! Does anyone know what speedo gear I need to correct it based on the info I've just given? Also, am I going to struggle to find the right gear because I'm now using an Auto ratio axle with a T45 manual? Anyway, as things stand, here's what I'm showing on speedo vs sat nav. [Speedo] [Actual (Satnav)] 30mph - 36mph 40mph - 48mph 50mph - 59mph
http://www.latemodelrestoration.com/products/Mustang-Speedometer-Gear-Calculator http://www.latemodelrestoration.com/item/LRS-17271I-K/83-95-Mustang-17-Tooth-Speedo-Gear-Kit-Manual I think thats what ya need.....
