My new to me truck has a front end hop at 60mph. I've read a little about this and it seems like the critical speed for this to happen.

I drove the truck home 200 miles from the dealer and did not notice any hop. The front tires were 90% worn and the rears about 75% so I rotated them rear to front. All my other diesels wore the fronts faster.

Now it has a vibration on the left (driver's side) at 60, pretty noticable.

Had the Left front balanced, no change.

Had the Left front road force balanced and they got it within 10lbs with 15 being the limit. Still vibrates.

Swapped the fronts side to side and very little change, still mostly the left side but definitely a difference.

I ran the vehicle on stands in 4WD and the wheels and tires spin very round and true.

When I swapped front sides I looked at the rotors and calipers and they seemed very good. Truck has 60k on it.

I can shake the front driveshaft up and down at the transfer case, the cardan joint has no play, it is the transfercase yoke. Although this is a wheel speed vibration not a driveshaft vibration I am thinking of disconnecting the front driveshaft and going on a test ride. Not sure how much play is acceptable on this yoke but it will move up and down noticably. 4wd is electric shift and works great.

HELP! ANY OTHER IDEAS??

Thanks,
Doug

 

Bump. Need some help here!

 

I know you said that you had it up on stands to check the tires but while it was up there did you check to see if the rim was bent?

 

who ever did the road force balance should have checked the rim.

 

Yes the rims look pretty good. I trust the tire shop so far. they have solved issues with a Porsche and a Mercedes and declined work they knew they could not do it so I appreciate their honesty.

Actually the rims looked perfect running on the stands and the tires were quite good despite the overall wear. There is not much balance weight on any of the tires either. I held a screwdriver close as it was running and noticed zero movement of the rims and very slight on the tires.

I have been doing a lot of homework on this board and there is a thread or two addressing a switch to a one piece driveshaft on the rear that addresses a 60 mph vibration. I won't rule that out but this is definetly a wheel speed problem and not a higher frequency driveshaft problem. But if the truck has a natural shake at 60 then many things could drive the vibration, I suppose.

I might try one more rotation back to the original as purchased positions and drive it again as I did not initially notice anything on a long test drive or the 4 hr drive home.

 

Ok. Tonight I moved all the tires back to their original positions. Now the vibration is all but gone. I really have to hunt around 60 to convince myself it is there?? Hmmm... Guess I'll leave the worn down tires on the front and the better ones on the rear. See what happens. So much for balancing and rotating..