gear and install kit question

[Mikes73]

Hello everyone, I am getting ready to buy a richmond ring and pinion set for my mustang that has a 9" open rear end under it. I am thinking a 3.50 ratio would be a good compromise because the car use is 95% street-5% highway. My question is does anyone know if I need the 2.891" or 3.062" carrier bearing kit? currently the car has 2.75 gears in it so I think the jump to 3.50's would be a decent upgrade.I have set up several 8.8 rear ends but this will be my first 9 inch. Any input will be greatly appreciated, thanks.

 

[TommyK]

Hello everyone, I am getting ready to buy a richmond ring and pinion set for my mustang that has a 9" open rear end under it. I am thinking a 3.50 ratio would be a good compromise because the car use is 95% street-5% highway. My question is does anyone know if I need the 2.891" or 3.062" carrier bearing kit? currently the car has 2.75 gears in it so I think the jump to 3.50's would be a decent upgrade.I have set up several 8.8 rear ends but this will be my first 9 inch. Any input will be greatly appreciated, thanks.

If it is the original open carrier for the car it should be 2.891.

The 3.50 looks like a good choice based on your intended usage.

 

[Mikes73]

Thanks tommy for diving in on this one, I will order the 2.891" install kit when I order the gears. Is it safe to assume the fmx automatic transmission will shift correctly after the gear swap? also I am thinking maybe a 21 tooth speedometer gear will correct the speedometer readings after the swap from the 2.75's.

 

[TommyK]

Thanks tommy for diving in on this one, I will order the 2.891" install kit when I order the gears. Is it safe to assume the fmx automatic transmission will shift correctly after the gear swap? also I am thinking maybe a 21 tooth speedometer gear will correct the speedometer readings after the swap from the 2.75's.

I briefly ran a 3.70 with an FMX and didn't have any issues. Might want to consider a shift kit at some point.

Assuming a 26" tire the 21 tooth is as close as you can get.

http://www.classic-cougar.com/tools/speedocalc/speedocalc.php

 

[Mikes73]

Thanks again tommy, I will post a follow up after the install.

 

[InjectedMach]

I would suggest you use a solid spacer kit(20$) instead of a crush sleeve which gives you 1 try to get right.