Low speed rear vibration

[Alec]

Hey guys. I'm gonna do a full inspection tomorrow, but wanted to get some ideas first. I recently took my truck in for a fair amount of service (60k service) and when I got it back I had a lot of low speed/low speed turning vibrations. I've now noticed it's due to the rear wheels vibrating. At low speeds, and esp when turning, the rear wheels stutter repeatedly. It doesn't happen faster than 5-8 mph. I don't think it's my posi cause it doesn't lock up abnormally at other times, and the lugs seemed tight. Any other suggestions? Parking brake, axles, gear problems? At all other times, the truck runs great and I have no vibrations, even at 100 mph. Thanks!

 

[zensius]

At the service did they rotate your tires?

 

[Alec]

supposedly. I'll examine the wheel weights tomorrow and see if I remember where they used to be. Let me say that previously I really trusted this shop and they've worked on all my family's vehicles for almost 20 years. They even gave me a free wash and wax after my long road trip

 

[zensius]

I'm not saying they did anything wrong. But the tires may have 'seated' themselves in their original positions. Then when they were moved they vibrated. Just a guess.

 

[Alec]

I just looked at the bill and it didn't have the rotation on there. I just told them to do it if they thought they needed it, so they might not have. If they did it for free it wouldn't still been on the bill, but not charged. So I guess they didn't.

Dunno if this matters, they did change the rearend fluid.

 

[Harry5150]

Did they put friction modifier in with the diff fluid?

 

[Alec]

Honestly I don't know. I don't know if my Eaton posi needs it, and he said he'd put in whatever he had to put in

Fluids aren't my specialty

 

[Alec]

Well, I decided to take the truck in to my Austin mechanic tomorrow morning and have him take a look. (The work was done by my Houston mechanic.) Lol, I know it sounds crazy, but I like in both cities

Any more input would be much appreciated though

 

[Alec]

Yup, the Houston shop just had a major brain fart.

The rear diff didn't have friction modifier in it and was a qt low on fluid. The tranny also had the wrong fluid in it, it had merc 3 and needs merc 5.

Also replaced the TPS today and the truck runs like a champ.

 

[Jason_25]

Alec your rear axle shouldn't require friction modifier with the eaton posi.

 

[Alec]

Well, should or shouldn't, it does. It already feels sooooo much better.

The thing that ticks me off is that the shop in Houston drove my truck for a few miles after they finished the work to go get it washed and waxed. Even if they would've driven it only 10 feet they would have noticed.