The bigger issue was parts availability combined with the reluctance of mechanics to replace the bad ABS valve (the valve had an internal leak which took the air down from 120 to 30-40 overnight). However, to be fair that coach also had a big CAT engine and Jake brake which would put the coach nose down if deployed on high. For 5 years prior to buying this rig I drove an older Vogue which had neither ABS nor disk brakes and had no trouble stopping that heavier coach. To embellish on the statement that I made in the OP's reference I, frankly, wasn't (and still am not) particularly worried about the ABS. Not intending to insult or embarrass or second guess any of our members - I'm just curious about the real value of ABS on big motorhomes. Have any members with ABS equipped coaches ever actually used the anti-lock feature? Is there any indication to the driver that the anti-lock is activated? What was the situation that required ABS? Did it prevent a crash? Could it have been avoided? However, I also realize that many Forum members have a great deal more time than I behind the (coach) wheel. It just seems to me, based solely on my almost 60 years of driving experience, that most emergency braking scenarios could be avoided by defensive driving techniques. Perhaps we are just lucky drivers, or we don't ever drive in the kind of traffic that requires "panic" stops that would lock the front wheels. Slight shudder through the brake pedal and a surprisingly abrupt stop - but that's it. In fact, I took it out in a parking lot one time and purposely locked up the brakes, just to see what it felt like. Our car has ABS, and in the 8 years we have owned it, I have never felt the ABS activate because I have never braked hard enough to need it. Our non-ABS coach has (in my opinion) excellent brakes, but I very seldom ever need to utilize their full stopping power. That was coming down a small hill, on rain-slick muddy pavement, in a camp ground, when we were going about 5 MPH. In the 5 years we have owned our coach, I have only felt the front wheels "skid" one time. But whenever I hear about "ABS" on a 15 ton motorhome, I always wonder how often such a feature is ever actually activated. I completely understand the frustration BillO must feel - being forced to disable a OEM safety feature on his coach because it can't be fixed. After posting here, beating the bushes, and calling every source I could find I had to replace that valve with an old style non-ABS version and disable ABS completely.I'm well aware of the "unobtainable ABS valve" problem from previous posts on the Forum. At least discuss this with customer to prevent unnecessary surprise repairs in the future and prevent the dreaded “It never did this before you worked on it” conversation.Quote from: BillO - September 10, 2018, 09:23:07 pm With my 1997 (along with another owner I'm aware of) I've had to disable the ABS because Haldex obsoleted the front relay valve with no replacement. The ABS system is activating as designed so no warning light will be illuminated in most cases. If WSS is integral and not serviceable, replacing the hub bearings in pairs may be the only answer. Again, the difference in signal from side to side may be enough to trigger false activation. The new bearing will have little to no play, the remaining hub has acceptable play but can still affect signal strength. ![]() ![]() Another possible issue is play in the bearing causing sine wave frequency change and or AC voltage variation. The rust build up actually lifts the WSS from the bearing, increasing the air gap and weakening the signal. ![]() In many cases, removing the WSS from the other side, if possible, and cleaning mounting surface may repair problem. ![]() The problem is usually associated with air gap difference or wiring and/or connector integrity. This is due to the difference in signal strength from the wheel speed sensors (WSS) side to side. The pulsation comes from the ABS valves cycling the supposedly locked up wheel. False activation is usually described as a pulse in the brake pedal when not expected.
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