Thumping Vibaration M1009

[Walrus]

I have searched the forum and have had no luck. I have a '86 M1009 with a thumping vibration that I feel through the drivers seat that seems to increase and decrease with speed. I do not feel it in the steering wheel and it does not seem to be from the engine compartment. It almost feels like a flat spot on a wheel. This is my daily driver and have kept up with maintenance, fuel additive and tire pressure. I always go back to the last thing I did before the new problem arrived. I had a lose alternator bracket, so I tighten and locktight the bolts that seemed to solve the vibration I had at idle when in drive and foot on brake. Now the thumping vibration. I am not a mechanic I am learning as I go. Thank for your time and knowledge.

 

[cucvrus]

U joint or tire that is coming apart internally. Check the rear U joint. Quick diagnosis at best.

 

[richingalveston]

Probably the slip yoke u-joint on t-case. Need to have drive shaft rebuilt

 

[Walrus]

Thanks for the info, now I know were to start looking. Now when it stops raining I can get under it and take a look. Till then back to the TMs to see how to work the U-joints and drive shaft. Will let you know the out come.

 

[Tinstar]

Could have the classic forklift driveshaft damage.
Even the slightest amount will have a big impact

 

[Walrus]

So as I was waiting for the U-joints to arrive from Rock Auto, no real change to the thumping till Saturday. Driving back from helping out at church with my daughter the thumping picked up and got a lot louder. We were able to pull off the road to a parking lot to find that the right side rear tire had gone flat. I guess the tires have more years on them then miles. So now I am off to go get new tires and when the u-joint comes in might as well change it out as well. Thanks again for all the help.

 

[Tinstar]

That would do it too!

 

[NDT]

Yup, light truck tires do not age as well as the ancient non-directionals. I put the Wrangler Authority 31's from Wal Mart on my truck, they look sweet on an '09.

 

[dmetalmiki]

Fortunately that occurred at a low speed and out of harms way. Glad the outcome was minor and easily remedied

 

[cucvrus]

U joint or tire that is coming apart internally. Check the rear U joint. Quick diagnosis at best.

Tire that was coming apart internally. I have been there many times. What is the date code on the tire?

 

[Walrus]

The date code DOT MK60 LRHV 1400 so if I read the web page right the date of this tire is the 14 week of 2000. I monkey math has the tire at 16 years old. I guess they have done their time. New sneakers for my 09 on Monday. Then work on rust removal and rattle can paint.