RV-12; Matco Wheel Nut Adjustment

I was talking with Marty about the wheel nut adjustment and he told me I better read the instructions. (What ? Me be wrong ) Seems these are tapered wheel bearings and they require a different loading / large nut torquing than I'm used to on other RV's axles.

They want you to rock the wheel back and tighten the nut as tight as you can get it by hand. (So far so good.) Then tighten to the NEXT hole. This is different than what I've been told to do in the past, which is to back off to the next hole provided there is no lateral (side to side) movement. Also, make sure the washer is centered on the nut to correctly put pressure on the seal.

Just a heads up for anyone else who has worked on RV wheels before. Please read the instructions as there are other parts on these wheels (specifically, the lock washer(s) orientation) that are not on other RV's I've worked on. Nuf said, carry on.

Oh, I almost forget...Thanks Marty!

Geico266 said:

They want you to rock the wheel back and tighten the nut as tight as you can get it by hand. (So far so good.) Then tighten to the NEXT hole.

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That goes against any tapered bearing that I have ever set........ Good luck you RV12 guys.........


Remember, Matco brought you the FLIP IT OVER nose wheel...

Wheel Bearing adjustment

This has been discussed before. See my post dated 06-03-2009:
http://www.vansairforce.com/community/showthread.php?t=43450&highlight=tapered+roller+bearings
I have always tightened bearing finger tight too. But Matco is the manufacturer and they want them tighter.
Joe

Seal design issue

The seal can create so much drag, it can spin the bearing with it on the axle. ( not good ) They had to overcome the seal drag by tightening the bearings more to keep the seal in the center as much as possible. In most cases these wheels actually don't turn much, so the bearing can take it likely. Not normal bearing procedures, but their design.

John Bender

Mich48041 said:

This has been discussed before. See my post dated 06-03-2009:
http://www.vansairforce.com/community/showthread.php?t=43450&highlight=tapered+roller+bearings
I have always tightened bearing finger tight too. But Matco is the manufacturer and they want them tighter.
Joe

Click to expand...

This is Miches post...... http://www.vansairforce.com/community/showpost.php?p=331000&postcount=20

There was never a problem with the old felt seal used by cleveland for the past 50 + years. Matco just took a cheap way to build a wheel that does not need a retaining ring and a groove to set it in.

The plus is that the tight bearings will decrease your landing roll.....

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I tightened the axle nut by hand while turning the wheel in the same direction until the nut would not turn anymore. But the big washer and seal were still turning. It is not good for the washer to be rubbing against the nut. So I tightened the nut some more with channel locks until the next notch in the nut lined up with the hole. Now the washer and seal do not turn with the wheel, just like Matco specifies. But the wheel sure seems to turn hard now. Matco's website says that it should take between 18-26 inch pounds of torque to turn the wheel. (Although Matco's instruction booklet says 10 inch pounds) I decided to measure the torque using a fish scale. I wrapped twine around the tire and pulled it into a groove in the tire tread so that it would not slip and attached the fish scale and pulled. The scale read 4 pounds. Multiplying 4 pounds times 6 inches (tire radius) gives 24 inch-pounds, which is within specs given on the website. A more accurate scale would give more accurate results. Regardless, I tightened the nut until the seal stopped turning just as Matco's specifies.
Joe

Taper roller bearings always require a tiny amount of preload. tighten them till they zero lash then a bump for final tightening. If more than 1/2 a flat is need for cotter pin/locking device placement then go the other way. This is fact not my daddy showed me this when I was a boy. ball bearings require free play taper do not. to be more specific if you were assembling a case that trapped two taper roller bearings in it you would want the case .002 NARROWER THAN THE OVERALL THICKNESS OF THE BEARING. YOU DO THIS WITH A SOLDER CRUSH TEST. measure the solder after test assembly and use a shim .002 thicker than the solder to achieve the proper pre-load. now having said that tapper bearings are VERY forgiving of free up to about .010 play and just a touch too much preload and they will fail fairly quickly. easier to overdo it than under do it.. but that is why all the tighten em up and back off scenarios work..but with wheel shimmy I would recommend running them as required by the manufacturer. used bearings require less drag torque than new ones. If your rear axle on your car (which has tappered roller bearings) had even .002 end play it would scream like ray charles when you let off the gas.

Note: finger tight will never leave you stranded but on new bearings you will need to readjust them soon.