ABS as Tom said. Here is the ugly info. On the meritor setup I could NOT find a way to access the ABS sensor without removing the hub. It is totally hidden deep inside the rotor hat. It is a standard bendix sensor. On later coaches with the SB7 discs on the tag the sensor is still hidden but a new one can be installed without removing the rotor
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home )
As far as I can tell, the ABS sensor is just a transducer that “senses” the toothed part of the hub. Although the tolerance between the sensor and the teeth is critical….the electrical conveyance to the ABS controller is not. So….if you splice in a wire to cover the broken part….its probably gonna work.
The reason that you have not noticed the ABS light on the dash is because 1) the PO took the bulb out or 2) the bulb burned out. The ABS light on the dash turns on for a few seconds when you turn the ignition key to the first position.
In for a penny, in for a pound. That's the way it always starts, right?
I'm changing brakes pads on my TAG axle. I have one side done, and I'm working on the other... but this rotor has to be changed. I've never changed one on something this heavy, and closest job I've ever done is probably changing bearings on a boat trailer. However, I'm not deterred, even if I should be.
I do have a tractor I can put a fork on and hold/lift the rotor, so this isn't a problem. Here are my questions:
1. It appears I need two 8-sided sockets to remove this. My micrometer tells me they are 3 1/4" and 3 7/8". Does this sound about right? I can't find a parts explosion for this anywhere that shows me these nut sizes. (I searched for Meritor 1560)
2. It also appears there is some kind of locking ring between the two afore mentioned nuts. And this locking ring requires its' own socket like thing, but I have no idea what specs are on this. Any idea exactly what tool this would be? (I have seen these sockets with teeth, in different sizes, so I know about what it looks like.)
3. I don't suppose there are places that rent heavy duty tools like this? This is probably a one-time deal for me, so I don't like buying one and done tools unless I have to. (But I'm thinking this isn't an Auto-zone tool loaner type of situation).
4. This final question maybe should have been my first question. I have not been able to find anything that actually tells me specifically how to remove and reinstall the rotor. The Meritor manual just says to "remove the rotor from the spindle." So now I'm guessing this must be documented in some other manual (maybe an axle manual), but I don't know where. Hopefully this would tell give me the steps, tools needed, and torquing specs.
Napa has the tools for sale in most locations. They are not horribly expensive. You only need the inner one, you can get a large pair of channel locks on the outer. When you get the outer off, you will see the lock ring between the two nuts has indicator holes that match with the inner nut. The lock ring slides in and out. It is not threaded. That prevents it from coming out of adjustment. Once you have the two nuts loose, it will slide straight off just like the boat trailer wheel.
Take a very hard look at the bearings and races for any pitting or scoring. The tag axle bearings take a beating when turning. By all means replace the seal with a new one. Be careful when going back together not to cut the seal. I used my all purpose lift table from HF for the job.
The only trick is reassembly torque of the nut. Get all snug, spin the rotor, and torque to 200 ft lbs, spin some more, back off the nut, retorque to 200 and spin, rinse and repeat a third time. You’re not done, the torquing and spinning was just to get the parts snug. Now mount a dial indicator on the hub with the pointer on the axle stub. You want to adjust the inner nut until you have 0.002 to .005 end play. If you don’t do this the bearing will run hot. I have data on this.
Oh yeah one more thing, if you are replacing because of cracks, warpage, or thickness then by all means. But the rotor is asymmetrical in thickness. One side is much thicker than the other. When i first saw mine I mistakenly thought i had a huge problem only to discover they were made that way
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home )
I had previously used a cross referenced non OEM pad. It fit just fine, but after a few years of use, the pad was not sitting in the correct location in the caliper. When I got the Meritor branded part, I saw why. There were very small differences in the Meritor pad that prevent it from “sinking” in the caliper and contacting the rotor in the wrong place.
If you used my info to source those pads, I suggest you inspect the hub where it joins the rotor to ensure the brake pad backing is not riding on the hub. If it is you will see a shiny spot that shouldn’t be there. I am sorry if I provided bad info.
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home )
Our coach came a lot of questions, working on the tag axle I've found have one new hub on the drivers side with new disk brake pads, after installing new studs I moved to the passenger side and found an old hub with worn brakes not totally worn but I have a set of new disk brakes for the tag axle that was not installed for what ever reason. I have them ready to replace but have one question, how do you retract the puck back into the caliper. The PDF file that is under the tag axle post is for drum brakes.
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