Factory Limited Slip Questions

[Pearl_Diesel]

Does anybody know anything about a limited slip in a 1986 Ford 3/4 ton HD? Like specs for the lim slip itself or what kind of special additive it takes or anything to do with it at all?

 

[jperecko]

The gear oil you use has to be "LS safe" or you can buy the additive seperate and use regular gear oil. What more do you want to know? on an 86 250HD I am guessing you have a Dana 70. You can check the numbers on the axle to make sure.

 

[Pearl_Diesel]

Thank you, I thought it was either a DANA somethin or other or a Sterling 10.25, and wasn't sure. I haven't taken a real good look at it. Is there much difference between the two?

 

[jperecko]

dana has 10 bolts where the ford 10.25 has 12 I think

I still say check the numbers

 

[Pearl_Diesel]

Thanks, I will. I'm swapping this rearend underneath a 1990 F250HD, is there anything I should be aware of in the process?

 

[jperecko]

I have not done that swap myself but I think, just measure and make sure the springs are the same width apart and the rest should be bolt-up.

 

[Goofyexponent]

Are the rearend gearsets the same ratios? Take your VIN number from the trucks and punch it into this decoder There should be an Axle Code on the tag inside the drivers door. a letter followed by a number or just two numbers. Match it up to this chart to see what the axles are and if the ratios are.

 

[Pearl_Diesel]

No the ratio's are not the same, I'm upgrading from 3.55 to 4.10 or 4.11 so I can get up to highway speed in a reasonable distance with 35" tires, and be able to pull stuff a little better before I get those tires

 

[Pearl_Diesel]

It's easier for me to swap axles than take out the gears and change them over, and the truck that has the axles was free

 

[Goofyexponent]

I would swap the 4.10 housings in as a complete unit like you are doing. They should just bolt in as a simple swap.