I have the rear end vibration that several people have posted on various sites. It starts around about 50mph and gets pretty bad at 65 or so. I feel this vibration in my seat, on the floor, but not in the steering wheel. It seems to be coming from the rear. I needed to replace my tires so all 4 were replaced. I then took a file and very lightly dressed the mating surfaces of the wheels to the truck. I then torqued everything with a torque wrench. The vibration was exactly the same. I unbolted the front of the drive shaft and rotated it 180 degrees. Still a vibration. I replaced both u-joints on the main drive shaft and the vibration only got sharper. I then had a drive line shop remove my drive shaft and straighten it. Turns out it was 40 thousandths (.004) out, which though not much, they straightened it anyway. (I never take my truck off road by the way). The vibration remained unchanged. It was also discovered that I had metal in my rear end on the magnet of the drain plug. The mechanic said he thought the limited slip clutches were locked up and causing a shudder. He took the cover off the rear and everything looked good. Replaced the oil and lifted the truck and placed a block of wood under each rear wheel separately and lowered the truck onto the wood to force each side to turn independently of the other. This seemed to free up the clutches. Again, no change to vibration. Drove the truck a thousand miles and now I have metal on the drain plug magnet again. I'm thinking the pinion bearing might be bad, but the metal makes me think the ring gear and pinion would need to be replaced if that were where it came from. Since I'm no expert, I wondered about just swapping out the rear assembly for a late model Superduty truck at a salvage yard. Does anyone know where I can get info on interchangeability for my Excursion?
Thanks.

2000 Excursion
3.73 Limited Slip
7.3L A/T 4WD

Tim

 

All gears are interchangable between the SINGLE rear wheels F-250, F-350 and Excursion. Hope new gears solves your problem. Sounds like you've exhausted a lot of avenues.

 

Check out Car dash parts dot com
That might help find what you need , By the way your pinion bearing is bad more than likely. May be an axle bearing, but more than likely it is the pinion bearing.
Don

 

If it's my pinion bearing and I have metal, wouldn't that mean probably new gears are needed also?

 

Another good source would be from one of the Ford dealer's here on the site that are sponsors. They have very good prices if you want to stay OEM.

 

No not necessarily. I have been lucky when the front pinion brg. went out and just changed one bearing. If the bearing is causing vibration and you pull it down before catastrophic failure you should be able to use the gears again. I would measure the backlash in the gears before disassembly, check to specs, then do visual inspection for tooth damage. If it is ok here I would re-use it.

Now since you have a Posi-/ limit slip clutch pack differential have you added the Ford required additive for this differential. If the additive isn't in the oil you will have noise issues from the clutch pack.

If you don't have the additive, add it,, then warm the truck up and do some figure 8's in a parking lot to exercise the clutch pack. If this doesn't help you could have a bearing issue. Axle brg's will roar with wheel rotation speed. Differential pinion will be higher.

Good luck.. Jim

 

This is the info I needed. I will replace the pinion bearing and go from there. I do have the required Ford additive in the rear and I do know what bearing roar sounds like. The metal shavings are what concerns me. Maybe if I'm lucky they are from the pinion bearing.

 

A pinion roar is relatively consistant,, a bearing wheel or carrier will be at axle rpm's. Jim

 

I don't have a roar at all...just vibration...then again, that diesel is quite loud...

 

Pinion, bearings , there are 2 of them 1 frt. at the yoke & 1 at the gear it's self . If thay are bad clean & check all the bearing's . I always replace all bearing's even the axle bearing's,flush it out , tourqe to specs. & check back lash !!! Install proper fluid & go !! It's uncommon that this happen's but it will .

Don

 

Special tools required for replacement or should I take it somewhere?

 

If you pull the carrier out to remove the pinion the correct way is to use proper measuring tools to set the depth of pinion for gear meshing and gear tooth mesh for ring gear position.

It is possible using identical bearings and putting shims back in the exact location to open it up change bearing re-use gears and be successful w/o measuring.

1. The backlash at the yoke will tell you if the side to side on the ring gear is correct.
2. Gear mesh pattern with prussion blue will tell you if depth of pinion is correct.
3. Torque in inch pounds at the yoke will tell you if you have the preload correct.

Jim

 

Thanks, I think I'll take it to a shop.

 

Make sure the shop sets all the "stuff" as I mentioned. If you are paying they should do "ALL THE DETAIL". Ask questions about how much backlash and what preload are they setting on the pinion. Make sure they do a good set up. If not it will have gear noise or clunking. Jim

 

Okay, good point.