Rupes backing plate screw

[SR99]

When I removed the 6" backing plate (with the washer mod) I noticed the plate must have shifted during operation since the edges of the washer where the sides are flattened have dug into the backing plate a bit, on opposite sides of the backing plate (see photos).

I had the backing plate tightened as much as the small allen wrench that comes with it can reasonably get it, considering you also have to hold the backing plate while tightening it, but it seems it needs to be tightened more than that. Probably the only way to be sure it's tight enough is to use a torque wrench.

Does anyone know the factory torque specification for the backing plate allen screw?

I know some people have said the screw was impossibly tight from the factory, so I guess it really needs to be that tight.

If anyone has a "factory fresh" machine and a torque wrench with a 5mm allen key I guess you could reverse engineer what the factory torque is(?)

As an unintended consequence of this, the washer is now frozen in its current location shown in the photo and I cannot pry it out.

 

[jrs1418]

This happened to me as well. I think its because the washer shifted prior to being tightened down all the way causing us to tighten it in the wrong position and damaging the backing plate.

I spent about 20 minutes re-aligning the washer and backing plate to perfection before tightening down and now have left my 5" backing plate on there. I have a GG6 that I use for 6" pads, but have found that the Rupes with 5" works best for me anyways.

 

[swanicyouth]

I could be wrong, but I think what happened there is the washer wasn't seated all the way initially. I say this because it happened to me. I filed a washer enough so I thought it fit. I started tightening the BP slowly and it started to wobble when I spun it. So, I took it apart again.

I thought the washer was "bottomed out" in the BP, but it wasn't. More filing ensued. I think that is why yours may be "stuck", because it wasn't bottomed out all the way - and tightening it wedged it in there. Once it's tight, I can't see how using it would move the washer since the BP doesn't shift around on it's rotational axis.

I didn't even try to use that little Allen key. I used a socket and a long 3/8" ratchet - It broke free no problemo. I tightened it as tight as I could get it with the same combo. You can likely remove that washer with some patience and some 90° picks.

 

[SR99]

Thanks guys. That makes sense.
I was able to pry the washer out.

Hmmm...I wonder if you can magnetize the washer so it holds in place against the spindle (both the washer and the spindle nut are magnetic) so it doesn't shift when you put the backing plate on. I think I'll try it.

 

[SR99]

Hmmm...I wonder if you can magnetize the washer so it holds in place against the spindle (both the washer and the spindle nut are magnetic) so it doesn't shift when you put the backing plate on. I think I'll try it.

I tried to magnetize the washer by setting in on a magnet, but didn't have any luck magnetizing it. Seems like it could work to keep the washer in place though.

While we're talking backing plates, I used the 5" backing plate without the washer, and note in the photo below that the friction from rubbing on the housing leaves a black film. If you don't use the washer mod, it might be a good idea to take the backing plate off every now and then to clean the black stuff off, since I imagine after a while it might build up and sling out while you're polishing.

The other thing I noticed is there's some sort of grease on the recessed ring on the housing (the part with all the holes around the circumference):

Does anyone know the purpose of that grease, and whether you are supposed to periodically refresh it? It doesn't seem like it was accidental grease left from the manufacturing, so I assume you shouldn't remove it.

Another thing I noticed is the reddish colored stuff around the spindle. It comes back if you wipe it off. Anyone know what that is?

 

[swanicyouth]

To me it made sense to do it the opposite way others do it. Instead of putting the polisher upside down, laying the washer on the spindle, and CAREFULLY trying to put the BP on strait; I placed my filed washer in the BP (aligned) and held my polisher facing the floor.

With my 3rd arm and 1 foot, I somehow got the Allen bolt started and snug. All while the polisher was facing and perpendicular to the floor. That way gravity was aiding holding the washer in place.

 

[arisking]

I put a bit of grease on my washer I made and it stuck in place no problem.

You could really super glue the washer in perfect position and then it won't move during install I'd think.

 

[SR99]

I might have found an answer about the grease (see post #2)
anyone know how to regrease your rupes? - Autopia Forums - Auto Detailing & Car Care Discussion Forum
He says it's there to reduce friction (without the washer mod), which I suppose could be true if the grease migrates to the area of contact. Maybe you're suppose to manually rub some grease along the rim every now and then.


PS the 1st post in that thread, with the before/after videos of some other grease change, is interesting too. Too bad there's no other info on what was done.