99 pumpkin with 4.10 gears too tight?

[AvalancheSVT]

Hey guys, so I've got this whole rear axle setup from a 99 cobra in really god condition for its age.
However, when I turn the pinion flange its pretty difficult to turn with my hand. Like, impossible if its slick.

The fluid that came out of it was black as night and it has 4.10 gears and it came out of a road race car.

Do you guys think it could be improperly shimmed or the pinion preload could be too right or something? I have the cover off and it sitting on my bench right now, I'm gonna try adding some fresh oil to the bearings tonight to see if that helps it out a bit but I would think it should spin without any real effort.

What do you guys think? I'm doing all new bushings and new clutches but I'm wondering if I should do a full rebuild.

 

[Hoytster]

They usually have some resistance, but you should be able to turn it fairly easily by hand with nothing connected to it. I have an 03' unit in my garage with a fresh rebuilt 4.10 setup I can check in an hour or so and let you know what my pre-load is.

 

[Hoytster]

So my pinion preload on this fresh rebuild is around 18 in/lbs, which appears to be in spec. I'm showing a used pinion preload should be 8-14 in/lbs. So yes, you should be able to spin it by hand fairly easily. Personally, I would rebuild it anyways if you have it out.

 

[AvalancheSVT]

I suspect it may just be shimmed improperly. I'm going to pull the diff and see what the pinion gear feels like by itself. I really don't want to have to mess with pinion preload if I don't have to. thanks!

 

[AvalancheSVT]

The pinion preload or outside bearing was the problem. OVER 25 INCH LBS of resistance to make it turn. way passed spec.

looks like she's gonna get a full rebuild. one of the carrier bearings fell apart when I took it out. This little unit was definitely beat to hell lol

gears are 4.10 and have ford stamps, so that's awesome

 

[Hoytster]

Wow, no wonder you had a hard time turning it by hand! That's good your rebuilding it, those things usually get beat up on road race cars without a cooling system.

 

[AvalancheSVT]

So, the gears that came out of this thing don't have pinion depth markings on the face which might explain why it was set up improperly.
My instinct is to buy a new set of ford racing gears from AM and just make sure I have all the right stuff going forward.

What do you guys think? its 175 bucks for knowing I have the right gears and it means I don't have to guess at pinion depth.