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Joe, If the slack adjusters and the rod going to the S cam have been lubed that is likely rotating freely and probably doesn't have much wear.
But the rollers on the end of the shoes riding on the S cam are dry as is the S cam. If they aren't rolling freely, either in the end of the shoes or on the cam that is the area most likely to be the culprit. At least that's the way I read Hector's post.
Not being setup to remove wheels at the house I hope I can get to them b y turning the wheels L and R.
I have bottomed out once or twice. My front axle is heavier than I like with both the generator and 8 4D's and three 3000 Watt inverter in the second bay across. I'll watch it on our next trip.
Thanks GregM
Greg,
What does you steer axle weigh? I have put on 100,000+ on our bus and have never bottomed out. Did you have less then normal pressure in the air bags? I can't imagine your bus hitting bottom. I would think that would pop the air bags.
Question how do you check the air pressure in the bags? I am close to 14K on the front axle.
GregM
While it is possible to check air bag pressure by adding a bunch of fittings and an air pressure gauge none of us has any ability to influence or alter the air bag inflation pressures.
The ride height valves are a mechanical device which admits air or exhausts air from the air bags depending on the position of the lever arm. When the ride height valve lever arm is positioned so air will flow into the air bag the increase in air pressure inside the air bag raises the coach body until the arm is in the neutral position. At that location air neither enters or exhausts from the air bag.
Our ride heights are determined solely by the amount of air pressure in each air bag, but only to the extent that the pressure increases or decreases the height of the air bag to move the arm to the neutral position.
At one time in the early 90s some converters were exceeding the Prevost front axle weight limits, and as a result the air bags that were installed were not large enough to raise the front of the bus. Remember that the bus is raised by the air pressure inside the air bag, and to increase the lifting ability the air bag needs an increase in diameter. More surface area equals more lift at the same pressure. As a result Prevost retro fitted some coaches with larger air bags.
This has nothing to do with brake noise.
DaleJ
Did you remove on set of shocks and if so did it change the ride?
GregM
Greg,
No, I haven't done anything to the bus, It's been sitting since October. I will pull two shocks off the front and add the enviro-cool filter to the cooling system before we leave the end of January. I will let you know how it rides.
Joe, gmc, did you guys check the rollers? Any updates to this? I just experienced this when doing my montly run, had to stop hard for a light that changed sooner than expected, kinda freaked me out. I would love to know if it's this or not.
Geoff
It probably is. An actively driven vehicle is constantly exercising the rollers that ride on the "S" cam. That keeps the roller and the "axle" for the roller free of corrosion and binding. There are no bearings in there, nor is there any provision for lubing beyond what Hector described. When you hit the brakes hard after periods of inactivity I think the bang is the result of exactly what Hector described. On a front axle, turning the wheel gives limited access to the "S" cam and the pair of rollers riding on them. You likely need a small mirror and something to reach into the rollers. The quick, but not necessarily good way to lube them might be to give a shot of oil to the roller axles, but at best it is a bandaid. The whole assembly of parts needs to be wire brushed clean and lubed as described. If you want a quick answer, daub some grease on the rollers and "S" cam so they slide. The roller will not turn, which it should, but the bang should go away for a while. That is NOT a fix.
Doesn't look like we are going to make our trip South to warm weather. So the bus is under it's cover. Too cold here in Oregon to crawl around under it outside.
GregM