when i first got my truck it already came with 4.56 Precision gears turns out my uncle can trade me for some 4.88 yukon gears there going to be installed tomorrow (monday) and all i need to pay for is the differential fluids. what is the best fluid to get royal purple? also wat weight,(kind)?? any help would be greatly appreciated.

 

I don't know much about gears, but I sure would like to see some pics of this truck. Sounds sweet!!

jrbhc8

 

I've always heard that it's not worth it just jump one size but if your only paying for the fluids it shouldn't be too bad. Sorry I don't know what weight...

 

yea of course, i wouldnt do it if i would have to pay for them but sh*t how much could i waste just by buying gear oil? $100 tops? good CHEAP mod imo.

 

Tell him I got another set of 4.56's up for trade to.

 

seriously? i could ask him if you want. hey do u still have those black headlights?

 

Try and hook something up, I wouldn't mind 4.88's

And yes I still have the heads, why? Interested?

 

yea. clear ur PM'S, how much?
ill ask my uncle bout the gears im gonna see him tomorrow.

 

Pm's cleared.

I'm taking off right now, send me a pm and i'll get back to you tonight.

 

You should aim for 5.12's...

But, 4.88's will make the truck a bit peppier.

 

anyone know what gear oil to use?
i dont think 5.13's fit the front diff.

 

any oil is fine. btw, royal purple is cheaper than motorcraft. you dont need 5.13s, 4.88s are fine, unless you plan on putting 40s on.

 

Not sure either... but that's just insane to have that tall of a gear.

The gear oil that needs to be used, according to Ford spec is:

Front diff: 3.7 pints 80W-90
Rear diff:
8.8" & 9.75" Diff: 5.5 pints 75W-140
10.25" Diff: 6.9 pints 75W-140

Add 4 oz of friction modifier if you have a LS or Posi.

 

OK, isnt the front end a 8.8 rev? i know my rear dif is a 9.75.that means im gonna need about 11pints? damn that seems like a lot. does it matter if i use 75w-140 for front and rear?
i dont know if to go with Motocraft or Royal Purple. i wanted to start using royal purple for everything on this truck, but not sure if its worth it.

 

I think because the front is reverse rotation... I think you need the thinner lube.

But I wouldn't see why not... maybe a heat issue?