A 1996 Ranger Super Cab with 4.0 engine and automatic transmission has a vibration at 67 mph. I've owned it since new and this vibration started a few months back.

1. Tires have been balance twice.
2. I replaced each tire with the spare, and did 4 test drives to id an offending tire. Vibration was always there.
3. A reputable driveline shop rebuilt the drive shaft including a new carrier bearing. They spent some time trying to find the poblem including checking the shafts on their lathe. Vibration is still there, maybe worse. Prior to this work the shaft had never been removed from the pickup, so I don't think improper installation is the problem.
4. Steering wheel has no vibration.
5. Vibration is best felt by putting hand on rear window.
6. I've checked for parts that might be fluttering in the wind and even tied off some brake cables that were contacting something.
7. Checked exhaust for contact. Shook it around. It's not close to anything.
8. No visible play in tail shaft out of transmission. No oil leaks.

Any suggestions?

Don

 

Check all ujoints and the carrier bearing that holds the driveshaft up near the rear of the cab. There is 3 ujoints and 1 carrier bearing. Lots of time the carrier bearing gets play in it and needs to be replaced. It's easy to replace..and if u replace that you might as well replace the ujoints at the same time. That might be the problem. also check the trans mount..easiest way is to grab the exhaust pipe near the rear of the trans and wiggle on it to see if the trans moves...the exhaust pipe connects by a small tab to the one bolt on the trans mount. I've just replaced all this on my Ranger to get rid of the annoying vibration.

 

Welcome to FTE .

Sounds like you've done all the right stuff so far. But I can't help but wonder is you've got an out of round tire or a seperation; a balance can be done yet when you drive with one of these conditions you get a vibration.

I'd jack up the rear and support the truck from the frame in back. Don't point the truck at another car or building. Now have a helper get it up to 67mph and from a safe position, look at the tires and driveline and see if you can notice the vibration. If you're lucky, a tire will be bobbling around a bit and you will have found the problem. While it's in the air and with the rear tires at 67 MPH, feel to see if the vibration is present.

 

I just finished testing at 67 mph with the rear up on jack stands. Even with the rear wheels removed there's still the same vib. So with the front wheels not rolling, and the rear wheels removed, I think we can rule out wheels and tires. I also held a long stick to the rear of the trans, the frame member that holds the carrier bearing, and to the differential. The only place I could feel anything was the differential, but that was not much.

When doing this test with the rear wheels mounted, the right rear had about 3/16" side to side runout. With the wheel off there appears to be a slight runout on the right axel/brake drum, so a bent axel is a possibility. The vibration frequency seems higher than a wheel would cause, and the guy who rebuilt the drive shaft said it did not feel like a wheel to him. I'm now thinking it's something in the differential.

Think I'm going to give up and take it to the local garage.

Thanks for the ideas

Don

 

Good work Don.

Remembering back the few months to when this vibration began, what EVENT preceeded this happening????

This might further help you isolate your search.

The runout on the RR wheel sounds suspicious though, did an "event" happen there, like maybe it got "curbed" or "chuckholed" while carrying a load????

 

If you do not have a $20.00 sirometer that can measure vibration frequencies(which can be purchased through Briggs and Straton) or chasis ears. I would suggest looking in an area that I have'nt yet seen discussed in your replys. Check the Pinion bearing for play. There are actually two pinion bearings. The pinion gear is the inline gear that mates with your ring gear in your differential.you have your drive shaft final u-joint then a flange and then the pinion. If its bad enough you can wiggle the rearmost part of the drive shaft and will detect play. There should be no vertical or horizontal play in the pinion and only slight play when turning the pinion (which is called backlash and is a desired measurment when setting up a rear end) If it is determined that you have pinion play you will want to check the rear end for bearing wear and will most likely need a rear end re-bearing job., All the bearings will need to be replaced if there is bearing metal in the rear end. Hope that helps!!! ,,gmentum

 

It was the drive shaft. Seems the drive shaft shop that rebuilt the 3 joints did not or could not check the balance. The second shop decided to have it checked before going into the differential. The shaft was slightly bent and out of balance. The vibration is now gone, but I still have a noise that sounds like the differential. Only hums over 70mph, and under high load like up a hill or head wind. Anyone had a noisy limited slip differential? Are they difficult to rebuild? I'm wondering if it would be better to buy a used unit.

 

first thing that comes to mind with the noisy ls differential is the diff fluid. have you checked the fluid level, if so was there a lot of metal on the magnet? have you changed the fluid lately, if so did you add the friction modifier? if you have to, get a used rear end, they are not easy to rebuild and you need special tools. check the fluid first and change if necessary.

 

el conquistador is correct in that limited slip differentials are difficult to rebuild. However limited slip differentials usually only make noises (at first and this will continue for a LONG time before driving in a straight line will give symptoms) when cornering,not in a straight line.