It Shakes when we drive

[fabric8r]

I have a 98 Monaco Diplomat with 80K miles. I have had this shake since the day i purchased the RV. It has a shake in the steering/front end at lower speeds, but increases when you are over 55mph. It's hard for me to isoloate where the shake is, but I notice it in the front of the RV and steering wheel the most, but the entire coach shakes also. Last year I put 6 new tires on, a steering stabilizer on the front end, and had it aligned at the Freightliner shop. It is better but it still hasn't solved the problem. Also, it has a very rough ride and takes bumps like a Model A. If anyone could give me some assistance it would be greatly appreciated. Thank you!

[riverruby]

How about a bent or warped rim from improper torque. Lower the jacks to raise the front tires and spin tires to check. Tire shops do not care about equal torque as most have one compressor trying to keep up with have a dozen workers.

[Diplomat Don]

I would check the rims first as riverruby stated. Next would be a set of shocks and then an alignment.

[safari1]

Are you positive the tires are good? I thought mine were good as they only had 3k miles on them. The alignment shop spun the wheels and tires on the chassis, tires were bad, vibrating the whole truck.
Maybe have them jack the front up and spin them on the chassis. I also installed Centramatic Automatic Wheel Balancers, they work great.

[riverruby]

I too now have a front end wobble at about 50-60 mph after having new tires installed. Afterward I purchased new bolt on wheel liners and when removing the lug nuts I found out on some of the nuts I had to use a 33:1 lug nut reducer tool and some turned off easy. I have a F53 Super Duty which has 16" rims with beefed up axles and 10 lug nuts. Does anybody know the correct torque for this setup? I plan on purchasing a 3/4 drive torque wrench because it has a 33" length handle and goes up to 300 ft lbs. I will torque to 100 ft lbs( I know that some of the big rigs have 300-500 ft lbs) till I find out the correct torque. Mine also rides like a stage coach and I have the tire air preasure set at max 90 lbs which is also what Damon reccommends. I am going to drop back about 5-10 lbs for next trip. The new Bilstein shocks and sway bar bushings did not help a bit. Next trip may not happen till this fall as I have found a wonderful spot in the mountains(cooler) with water, elect ,sewer for $200 monthly. How can I resist this? Update on F53 lug nut torque: online research shows maybe should be 150-165 ft lbs and there is is TSB on this for front end wobble.

[fabric8r]

Thanks everyone for the information. I am taking to the Freighliner shop and have them check to front rims, then install 8 Koni FSD's, followed by an alignment. Lets hope for the best

[Caemlyn]

have the tires checked for roundness... had this same issue and found the tires seriously out of round. 4 of 6 were so far out of spec I don't know how they got off the production line. Took a whole lot of effort to get the issue resolved - Goodyear tried blaming me, the shop, and everything else under the sun for their poor manufacturing

[fabric8r]

Thank you. I just got off the phone with Jim at Source Engineering and he has pointed me in the same direction. I am going to check the run out on each of the front tires and see if they are in tolerance. This was my first time contacting Source and they have been more than helpful, even though I am not purchasing anything from them at this time. He has volunteered to take me through a number of checks and adjustments over the phone. Best customer service I have received from any company that I have had contact with about RV parts and information.

[Mike Canter]

I might add here that front end alignment being out does not cause a wobble or shake. A wobble or a shake at a specific speed range is normally caused by a tire or wheel being out of round or out of balance. There are tire machines with a computer that map the rim and map the tire and then tells you to turn the tire on the rim to a set point to make the tire and rim as one. Some tire shops are good enough to do this by the eye. Steel wheels are a pain because they are hardly ever true.

[safari1]

Mike is right, front end alignment does not cause vibration. 90% of the time it is Tires, balancing, or bad wheels (bent or warped).

[fabric8r]

I checked the run-out on both front tires and found that on the drivers front I have .045", but on the passenger front I have a WHOPPING .125". I understand that 1/8" is way out of tolerance, but what is an acceptable tolerance, and what might cause this much run-out>