4.10s lol

jlds91389

New Member
Feb 1, 2009
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Orange Tx
i just placed the order for a set of 4.10s:nice: i cant wait to get them installed. I have a few concerns. I will be using Rp 75w90 gear oil but what eles do i need? should i have got the rebuild kit or the seal kit? thanks for any help and let me know how your 4.10s perform:nice:
 
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First thing you should do is pour that Royal Poople down the drain and get some Mobil 1 gear oil. Depending on how many miles you have on your car would determine whether or not you should do bearings, seals, and clutches, but I ALWAYS do them when I have the rear end apart like that. I would at least do the clutches if you are using the stock carrier. Also, don't forget the limited slip additive!
 
thanks i was going to go with the mobil 1 bust rp already has the addictive in it. my car has almost 120k on it. i have been using rp in the rear since about 80k miles with no problems.

Take a peek at this. I've never had good luck with Royal Purple holding it's weight after some wear, and it looks to be a common problem.

Gear Oil Study

It's almost cheaper to get Mobil 1 and the additive than two bottles of Royal Purple sometimes.
 
thanks for the link thats pretty good info. If i go with mobil 1 what weight should i get and how much additive and what brand should i get?

The gear oil weight is usually based on what the climate is like where the car is typically driven. The colder the average temperature, the lighter the weight you would want. Since your location says Texas, I would run two quarts of Mobil 1 80w140, and whatever limited slip friction modifier you can find. They should all do the same job. I've even heard that Mobil 1 comes with friction modifier already in it, but haven't checked for myself. It should be 4oz of friction modifier, if you do have to add it.

If you do decide to throw in some new clutch discs in your limited slip (which I would recommend), be sure to soak them for 15 minutes in some gear oil with friction modifier in it first before installing them. Also, if you slip in one of your old discs into the new pack, it really tightens up the slipping action and you end up with a locker for a month or so, then once it breaks in you have a very nice diff for traction's sake.
 
Check Summit Racing for a bearing kit. They have great prices.

I used a Ratech bearing kit with my rebuild, and all is fine. Do yourself a favor and get the axle bearings/seals too.

You can get a limited slip rebuilt kit and friction modifier from them as well for around $40ish if prices haven't gone up.
 
thanks for the link thats pretty good info. If i go with mobil 1 what weight should i get and how much additive and what brand should i get?
just go to ford dealer ask for "friction modifier" addative, and a ford racing posi rebuild kit. rebuild the posi and stuff as many shims in as posible, kinda a pain in the ass but it'll make posi super tight.
you'll need a ring and pinion install kit too(pinion bearing and shims, 2 carrier bearings, couple other things I think)
 
thanks everyone for the info. i got a price from triangle speed shop here in orange texas and its areoun 400 if i supply everything. Has anyone used motive gears? i ordered their 4.10 set and the guy i talked to said the were ok gears but not really what he like to put in the cars. has anyone had good/bad luck with them? i will use the search to find more infor but if someone could help me out that would be awesome.
 
thanks everyone for the info. i got a price from triangle speed shop here in orange texas and its areoun 400 if i supply everything. Has anyone used motive gears? i ordered their 4.10 set and the guy i talked to said the were ok gears but not really what he like to put in the cars. has anyone had good/bad luck with them? i will use the search to find more infor but if someone could help me out that would be awesome.

You pretty much have a guarantee (almost always) that FRPP gears won't whine. Most other gear manufacturers are a little more difficult to set up than Ford gears, and some tend to whine more than others. I have done plenty of Ford gears in the past and they all turned out great. I currently have Motives, and wish I would have done FRPPs in the first place.
 
I try to go FRPP as much as possible, Ive done 8-10 gear swaps with FR, motive and (drawing blank), new and used, they all seem pretty similar to me, as long as properly installed they're all very reliable IMO