Okay, first off I've done a fair amount on vehicles over many years, but I've never messed with differentials. Everything from the flywheel back I've left to someone else when I could.

So I need to put new spider gears in an 8.8 L/S... and have been given LOTS of free advise. BTW, this is a 2003 FX4 4.0 so it SHOULD be a 31 spline. Haven't had a chance to measure the tube diameter to verify.

So I've had three versions of what to do to replace the spider gears.

1. Remove the axles completely before even thinking about starting.

2. Slide the passenger axle out an inch or so to give the clearance to drop the side spider gears out between the axle tips.

3. Leave the axles in place and slide the side gears in to let them drop out.

This will be a driveway on jack stands operation so the less I have to do the better. Had the back cover off to do a quick inspection and the L/S is totally gone ( but not missed ). But in rotating the axles independently the outer gears move up and down the pin NOTICEABLY. Like a quarter of an inch or so and they are nice and shiny. The truck has around 285,000 on it. It also had a healthy rear vibration over 70 mph, so I'm thinking spider gears as the pinion and differential bearing are nice and tight.

Am I correct that the L/S clutch is a part of the left ( drivers side ) gear and that I could get the L/S functional by replacing the clutches when I replace the spider gears?

Thanks for all the help in advance.

 

OKAY WTF!

I was looking at replacement videos on u-tube, and realized that there is no center S spring in my L/S.

Got a buddy to put it up on the lift quick to check the bearings, and neither one of us realized that there was no center S spring...

My way of thinking is that's part of the L/S and without it there is no pressure for the L/S clutches.

Looks like somebody did some work in the past and couldn't and didn't put the s spring back.

Could that be part of my highway vibration?

 

If you have not done this type of work, I suggest you replace the entire rear end with a known good assembly. it will cost less to do and you will have less of a chance to screw it up.

 

I'm wondering if my problem is the missing S Spring. Was thinking of picking one up and popping it in.

 

The spider gears that have a 1/4 inch of play in it means you have a lot of metal shavings grinding up all the bearings and gears in the rear end.

It sounds like you may have multiple problems, I doubt if you replace the entire rear end that will fix all your issues.

You need a qualified mechanic to inspect the entire drive line of the truck to diagnose the problem.

You could have worn u-joints, carrier bearings slip yoke issues not to mention the front axle and drive shaft, motor mounts, trans mounts etc

 

We've went through the drive shaft, the transmission was just repaired from a broke sprag, the transfer case was inspected by the transmission shop and seems to be solid. No play in any of the rear end bearings, no noise or grinding. The only thing is the missing S spring and the vibration over 70. I know the rear cover has been off several times, fresh RTV and the ID tag has a bit of a twist making reading the numbers very difficult. The buddy that put it up on the rack is a drag race mechanic and we couldn't find anything wrong with the rear end. Bearings all tight and smooth.

At this point I'm thinking somewhere in the past who ever had it did some work on the rear end and either forgot the S spring until he had it all back together, or gave up trying to get it back in place. From what I'm seeing getting it back in on a 4.10 is difficult if you don't know to compress it in the vice and then use needle nose vice grips to get it started.