QC with 35mph vibration

[VIPR PWR]

Horse ---in the old days Mechanics would say, that if you feel it in the steering wheel it was in the front end of the vehicle and if you feel it in the seat it's in the rear of the vehicle.....not sure if this still holds true---but if it does it might help isolate the problem.....Shocks ,springs, bushings,loose parts, Alignment,Tire/wheel balancing,driveshaft and pinion angle, trans and motor mounts......maybe the axle or axles are still not right.....

Scott change your screenname to to Sonar the acoustics man..lol

 

[mauiSRT/10]

This happens because of harmonics. The vibration (like sound) will create harmonics at multiples of itself. So, if it is related to speed, it will happen at 35 then 70 then again at 105 and so on. If you were to get to 140, then show all of the harmonics by strength, you might find that the one at 105 was the strongest, depending on whether the vibration is caused by dynamic imbalance, or something loose (sort of), or even how many spokes are on the wheel. If it is not related to speed, then you will not feel the vibration at these harmonics.



Because sound is vibration, all of this is true for any noise as well.





Sorry, I just went back to my Navy days!!

That's acoustics 101.

Nice clarification dude!!!!:rock:


patrick

 

[horse]

Thanks a bunch guys for all your ideas, ntwork...thats some serious indepth anaylsis going on there....cheers

I have heard of a tool to trace vibration, I will need to find someone here that has one.

I am going to try some more wheels/tires just to make sure....

 

[horse]

Ok guys I have 99% fixed the vibration, turns out the driveshaft was distorted in the front section possibly due to the previous owner doing skids with the 26" wheels. The first driveshaft guy never picked it up.

Another question though as I am still chasing the 1%, are the driveshafts on these trucks slightly offset? I notice when looking from the transmission to the diff that there is an angle there and was wondering if I moved the hanger over it might get rid of the last of the vibration.