Replacing differential

[ZacUnknown69]

Hello everyone, as you know the Mark VIII came with a 3.08 and I feel like it holds back the power. I want to swap it with 4.10's, now I know virtually nothing about differentials so bare with me. Do I need to replace ALL the gears, or can I just do the ring and pinion? If all I need to change is the ring and pinion, can I do it at home? Or do I need special tools, presses, etc? If it's more complicated than that, could someone kindly direct me to where I can purchase a Ford 8" 4.10 LSD as a whole? Or a suggest a high geared LSD that would work with my car. Also, if you're up to it, giving me a basic run down of what I'd need to do would also be helpful (I have the full shop service manual, so I can connect the dots) Either way, I appreciate the input. Thanks!

 

[Bangster]

I think with the aluminum pumpkin you need a spreader to get out the carrier. It can be done with basic hand tools plus a few specialty tools, but it is pretty technical to setup correctly for noise and proper contact. Going with 4.10s you would also need to add a trac-loc carrier, one wheel peel or traction control would be hard to handle with an open carrier and 4.10s.

Ford used to sell a Cobra center with 3.73s but it is now rare to find one.

Unless I took a week off from work, I wouldn't attempt to do gears and a new carrier, even armed with a previous weeks worth of reading and pictures.

 

[soduka]

In your situation unless you have someone to guide you and a heck of a lot of time for a quality learning experience I would just go to a junk yard and find a 4.10 pumpkin already ready to pop in.

 

[ZacUnknown69]

That's probably what I'll do. I'd imagine it'd be about the same price and take significantly less time. And mechanical LSD's are bulletproof so I could find any used 8". How do I find out the gear ratio?

 

[Bangster]

8.8 inch is the ring gear diameter, not 8 inch.

To find ratio you can count the teeth on the ring gear and the pinion gear and do math (ring gear/pinion gear, 4.10 have 10 teeth on pinion gear and 41 on ring gear, 3.73 have 11 on pinion and 41 on ring gear, etc).