Front end shake or shimmy

tommy g wrote:

352 wrote:

wolfe10 wrote:

tommy g wrote:

wolfe10 wrote:
On the older F53's there was no track bar/panhard rod as fit on newer F53 chassis.

This allows wobble between axle and chassis (side to side motion). Particularly if hitting a transverse bump, like RV tracks at an angle to coach direction, it could cause what was known as "death wobble". If encountered, must slow down until harmonic wobble quits.

Yes, it can be loose wheel bearing, out of round or balance tire, bent rim, worn steering component, etc, but if the basics checkout, add a track bar.

Would this wobble be consistent? Mine does it every time at same speed.

No. If consistent at speed, start with the tires.

And while you have it off the ground take a bar

Check for run-out first (any good tire store will have a run-out gauge. Takes less than 2 minutes per tire. Check both fronts. Even a perfectly balanced "egg" will wobble. If more than .035" fix it (rotate tire on wheel, wheel on hub, etc).

You can even check run-out yourself. Jack up a front wheel. Use a 4x4" or other piece of wood. Move it closer and closer to the tire until it just touches the tire at the tire's "high point". Rotate for maximum gap and measure it. Not as precise as a run-out gauge, but you will get close.

Next, spin balance the tire ON THE COACH. You want all rotating masses in balance, not just the wheel and tire. The brake rotor and hub also must considered so on the rig does that.

And while you have it off the ground, take that same 4x4 and put it under the tire and lift up on the end of the 4x4. If you have play up and down movement the ball joints are shot.

We did this to check ball joints and king pins.

352 wrote:

wolfe10 wrote:

tommy g wrote:

wolfe10 wrote:
On the older F53's there was no track bar/panhard rod as fit on newer F53 chassis.

This allows wobble between axle and chassis (side to side motion). Particularly if hitting a transverse bump, like RV tracks at an angle to coach direction, it could cause what was known as "death wobble". If encountered, must slow down until harmonic wobble quits.

Yes, it can be loose wheel bearing, out of round or balance tire, bent rim, worn steering component, etc, but if the basics checkout, add a track bar.

Would this wobble be consistent? Mine does it every time at same speed.

No. If consistent at speed, start with the tires.

And while you have it off the ground take a bar

Check for run-out first (any good tire store will have a run-out gauge. Takes less than 2 minutes per tire. Check both fronts. Even a perfectly balanced "egg" will wobble. If more than .035" fix it (rotate tire on wheel, wheel on hub, etc).

You can even check run-out yourself. Jack up a front wheel. Use a 4x4" or other piece of wood. Move it closer and closer to the tire until it just touches the tire at the tire's "high point". Rotate for maximum gap and measure it. Not as precise as a run-out gauge, but you will get close.

Next, spin balance the tire ON THE COACH. You want all rotating masses in balance, not just the wheel and tire. The brake rotor and hub also must considered so on the rig does that.

And while you have it off the ground, take that same 4x4 and put it under the tire and lift up on the end of the 4x4. If you have play up and down movement the ball joints are shot.

tommy g wrote:

352 wrote:
How the the old front tires were wearing will give you an indication of any problems you have now.

The old fronts were wearing on both outside edges and in the center. I thought that strange as well. 45k on 2008yr date tires.

wolfe10 wrote:

tommy g wrote:

wolfe10 wrote:
On the older F53's there was no track bar/panhard rod as fit on newer F53 chassis.

This allows wobble between axle and chassis (side to side motion). Particularly if hitting a transverse bump, like RV tracks at an angle to coach direction, it could cause what was known as "death wobble". If encountered, must slow down until harmonic wobble quits.

Yes, it can be loose wheel bearing, out of round or balance tire, bent rim, worn steering component, etc, but if the basics checkout, add a track bar.

Would this wobble be consistent? Mine does it every time at same speed.

No. If consistent at speed, start with the tires.
The tires have all been replaced and changed around. I figured that if one or two were the cause then the symptom would at least change somewhat. No change was obvious.
Check for run-out first (any good tire store will have a run-out gauge. Takes less than 2 minutes per tire. Check both fronts. Even a perfectly balanced "egg" will wobble. If more than .035" fix it (rotate tire on wheel, wheel on hub, etc).

You can even check run-out yourself. Jack up a front wheel. Use a 4x4" or other piece of wood. Move it closer and closer to the tire until it just touches the tire at the tire's "high point". Rotate for maximum gap and measure it. Not as precise as a run-out gauge, but you will get close.

Next, spin balance the tire ON THE COACH. You want all rotating masses in balance, not just the wheel and tire. The brake rotor and hub also must considered so on the rig does that.

wolfe10 wrote:

tommy g wrote:

wolfe10 wrote:
On the older F53's there was no track bar/panhard rod as fit on newer F53 chassis.

This allows wobble between axle and chassis (side to side motion). Particularly if hitting a transverse bump, like RV tracks at an angle to coach direction, it could cause what was known as "death wobble". If encountered, must slow down until harmonic wobble quits.

Yes, it can be loose wheel bearing, out of round or balance tire, bent rim, worn steering component, etc, but if the basics checkout, add a track bar.

Would this wobble be consistent? Mine does it every time at same speed.

No. If consistent at speed, start with the tires.

And while you have it off the ground take a bar

Check for run-out first (any good tire store will have a run-out gauge. Takes less than 2 minutes per tire. Check both fronts. Even a perfectly balanced "egg" will wobble. If more than .035" fix it (rotate tire on wheel, wheel on hub, etc).

You can even check run-out yourself. Jack up a front wheel. Use a 4x4" or other piece of wood. Move it closer and closer to the tire until it just touches the tire at the tire's "high point". Rotate for maximum gap and measure it. Not as precise as a run-out gauge, but you will get close.

Next, spin balance the tire ON THE COACH. You want all rotating masses in balance, not just the wheel and tire. The brake rotor and hub also must considered so on the rig does that.

352 wrote:
How the the old front tires were wearing will give you an indication of any problems you have now.

tommy g wrote:

wolfe10 wrote:
On the older F53's there was no track bar/panhard rod as fit on newer F53 chassis.

This allows wobble between axle and chassis (side to side motion). Particularly if hitting a transverse bump, like RV tracks at an angle to coach direction, it could cause what was known as "death wobble". If encountered, must slow down until harmonic wobble quits.

Yes, it can be loose wheel bearing, out of round or balance tire, bent rim, worn steering component, etc, but if the basics checkout, add a track bar.

Would this wobble be consistent? Mine does it every time at same speed.

rgatijnet1 wrote:
Did they actually check the run-out(wheel wobble) on your front end with the tires mounted? Since you said it started after driving over a rough road, it sort of indicates something was bent. I guess if the bump was hard enough a front spindle could be bent but I would have thought that alignment would have picked that up. Most alignments are done with the front tires still on the ground. Perhaps you need to see how the wheel spins when raised off of the ground to see if there is any wobble. A low tech way is to lift a front tire off of the ground and put something next to the coach that just barely misses the front rim(not the tire). Then you rotate the tire and see if the gap changes. Anything more than a 1/16" could cause a shimmy.