i picked up a set of FRPP 4.10's on ebay for 75 bucks, how awesome is that? anyway, they have about 2500 miles on them according to the seller. so here are my questions. 1) do i need to break them in (i'm guessing no)? and 2) what kind of gear oil? i know a lot of u guys like royal purple, but i'd like to know about some other brands too. also where do i find gear oil, how much do i needand how much is it typically? thanks

 

I would still break in for your car. Motorcraft is great as long as it is full syn as they already use it in there (I think). Get some friction modifier and as far as prices check your local auto parts store. I think the rears on our cars take a little over 2 quarts. Check the capacities section in your owners manual that might help as well.

 

thank you gt500. btw, what is friction modifier?

 

friction modifier is for the Limited Slip Differential. Helps it work better and keeps it from making noise

 

1+

 

thanks fellas

 

Oh man, I hate to be a downer, but I'd be very suspicious of 4.10s that were used for 2,500 miles and removed.

 

+1....I bought some 3.73s for my old 90 that had only gone a single 1320 session on a twin turbo GT that needed a taller gear...when I explained all that to the shop, they got really uneasy about the job... just spend the $220 at summitracing.com; the extra $$ is worth the peace of mind.
p.s. kind of ironic that I'm posting this but bought a used off-road x (3 hours used to be exact), but exhaust is different...

 

I would be weary also.....i would also buy new for something like that....you got them cheap cause most people know better and spend the extra dough!

 

Once a set of gears has been used there will be a wear pattern on the gear surfaces, If you put them in another car the chances of them being quiet are pretty slim. It's almost impossible to set up used gears and get the same wear pattern in a different housing. Used gears that need to be set up in a complete different housing are not usually a bargain at any price. I would expect them to be noisy.