Moon disc fasteners

[Dynoroom]

Ditto what Rich said.  I've got Moons on my pickup -- and the screw-on type wouldn't stay put.  They'd loosen just enough that I'd hear click-click, then in the mirror I'd see a disc pulling out to pass me.  I kept tightening them -- that didn't help enough, either.

The button-type I've got on the pickup now stayed quiet -- and stayed on -- all last summer without a whimper.  I can check air pressure easier, too -- just like he said.  Pretty soon it'll be warm up here, the salt on the roads and the snow in the driveways will be gone, and I can put the Moons back on the truck.  Of course there's one potential hassle -- when I had the winter tires put on the rims they bent the mounting tabs in a bit -- now I've gotta figure out how much to pull them out before I can make the buttons fit.  Life is rough in the Great White North. 

We went snowshoeing off our deck yesterday. I betcha not many of you can say that (yeah, I know, you don't want to be able to say that, either...).

Some of the cars I have seen using "Dzus" or button fasteners only have 3 per wheel, Is there some allowance for these to use 3 instead of 6 per wheel? Is there someone that markets ready made tabs to weld onto my steel wheels? Thanks for your help in this.

The 2009 SCTA rule book 2.G page 20 last paragraph "full wheel discs " " " if secuely fastened to the wheels with 6 or more machine screws or 3 Dzus-type fastners.

[gearheadeh]

Thanks:Dynoroom, Mil.Midget, Dr. Googles, Int. Bystander, I found what each of you said helpfull. About the 6 vs. 3 fasteners, I was thinking of what I had read in an older rule book, Thanks for the clarification.

[DallasV]

I picked a disk off the course at WF this year of a corvette that used screws, he lost both rear disks. We use 3 dzus' and have never had a problem.

[Rex Schimmer]

The Dzus fastener was designed back in WWII to hold on engine cowling panels and such on airplanes and being able to stay latched while experiencing heavy vibration was one of the major design parameters. To me it looks like the only option worth considering. There have been some new aero quick release fastners design mainly because of strength but the old Dzus is a pretty good fastner for our applications.

Rex

[SPARKY]

our experience---definitely go with the DZUS

[manta22]

Putting Loctite on the screws should fasten the Moon discs securely-- not as quick to get them off as with Dzus fasteners, though.

Regards, Neil  Tucson, AZ

[Seldom Seen Slim]

Screw-into-the-rim:  Lasted a few months on the pickup, eventually worked loose and sent the discs sailing along the interstates.

Dzus -- installed with the Moon jig, and only three per wheel:  Have been on the pickup, without any incidents or losses, for two full racing seasons.  Each season includes 10-20,000 miles of driving including not only interstates but also gravel washboard roads.  Never once have I had one work loose, much less fail.  I recommend cleaning the spring wire at the end of and beginning of each season, though -- they wire will corrode and make installation and removal of the button difficult.  By the way, I don't run the discs during our winters since the salt and other crud will harm the aluminum.  I use factory steel wheels during winter -- which also means I don't have to mount or remount winter and summer tires on the wheels.  Doing that is difficult with the welded-on tabs -- most tire mounting machines want to bend the tabs inward during the mounting process.

later -- it's almost winter and I need to attend to removing the Moon discs from the pickup.

[Cajun Kid]

The  3 Dzus set up from Moon is the way to go.  You can get the jig from them for $50.....when you send it back they will credit you the $50 back to the charge card you used.


Simple and effective.

Charles

[Seldom Seen Slim]

Back to moon discs for my '09 GMC pickup that's got 17" aluminum wheels.  Here's today's update and a new question:

First of all, it turns out that the spare tire/wheel that comes with the truck -- is a 16", not a 17".  So -- did GM give me a non-usable spare, or will the 16" fit after all (the shops have all told me that the 16" won't fit because of interference with the calipers).  So the other evening I dismounted the 17" and put first the old 16", from my '04 pickup, and then the 16" spare from the '09, on the right rear.  There's less than an eighth of an inch clearance with the factory 16" '09, and a tiny bit less (hard to get a feeler in there to get a real measurement) with the old wheel.  But -- both fit.  I've got a full set of the old 16" wheels and would like to use those instead of buying all new 16" '09 wheels, of course.

So the question is:  Is there an absolute minimum of clearance that is REQUIRED between wheel and the stationary parts in the system -- or is "it doesn't rub" good enough?  I can't imagine there's any flexing of the wheel while in use, so the biggest problem I can see is the potential for buildup of crud.  And the turning wheel would clean itself, I should think.

If I don't hear one of you telling me not to try it I'll mount all four of the old wheels on the truck and drive it down the road for a few miles to see what happens.  The tires on them are too small and therefore will be replaced by bigger ones -- but I don't want to spring for a new set and then (and only then) discover that the wheels just won't work.

Any comments?

[tedgram]

 If they don't rub they should be fine. Most trucks come standard with 16" wheels 17" are the upgrade option.

Back to moon discs for my '09 GMC pickup that's got 17" aluminum wheels.  Here's today's update and a new question:

First of all, it turns out that the spare tire/wheel that comes with the truck -- is a 16", not a 17".  So -- did GM give me a non-usable spare, or will the 16" fit after all (the shops have all told me that the 16" won't fit because of interference with the calipers).  So the other evening I dismounted the 17" and put first the old 16", from my '04 pickup, and then the 16" spare from the '09, on the right rear.  There's less than an eighth of an inch clearance with the factory 16" '09, and a tiny bit less (hard to get a feeler in there to get a real measurement) with the old wheel.  But -- both fit.  I've got a full set of the old 16" wheels and would like to use those instead of buying all new 16" '09 wheels, of course.

So the question is:  Is there an absolute minimum of clearance that is REQUIRED between wheel and the stationary parts in the system -- or is "it doesn't rub" good enough?  I can't imagine there's any flexing of the wheel while in use, so the biggest problem I can see is the potential for buildup of crud.  And the turning wheel would clean itself, I should think.

If I don't hear one of you telling me not to try it I'll mount all four of the old wheels on the truck and drive it down the road for a few miles to see what happens.  The tires on them are too small and therefore will be replaced by bigger ones -- but I don't want to spring for a new set and then (and only then) discover that the wheels just won't work.

Any comments?

[Seldom Seen Slim]

Not this truck, though.  The 17" is standard -- 16 not available.  but, I did find -- the 3/4 and 1-ton vans come with 16" -- and so either GM has two different brake arrangements for the trucks and the vans -- or the 16's will fit.

By the way -- there's a very small, but discernible, difference in the inside of the wheels -- a section on the "new" 16s is just a tad lower than on the "old" ones -- giving about one RCH more clearance.  But like I said, there appears to be no rubbing.  I'll take your word (but'll listen for other comments) and then put the old ones on the truck and go for a ride, then remove and look for scrapes and shiny spots.

[754]

Put a few layers of masking tape on, then look for rub through or hitting..

[Seldom Seen Slim]

Another good idea.  I'll put it on the calipers -- the wheels are pretty-well corroded up from having gone to the Salt for a few years.  Thanks.

[Seldom Seen Slim]

Well, yesterday it was a fine, 45F day -- so I spent a little while and swapped the factory 17" wheels/tires for the old 16" ones I've got -- the ones that already have the Dzus tabs mounted. 

And all is fine.  the fit, don't scrape or even go "ching, ching, ching" as I drive down the road.

So the next question is about the absolute minimum required clearance -- and why it is required.  What is likely to happen that'd make the wheels and calipers interfere with one another?  Will the calipers move far enough towards the wheel "spokes" to rub?  I don't think so -- there's lots of room.  Will the calipers grow with heat and move outwards, towards the inside of the rim?  I doubt it, but maybe.  How much is the absolute minimum clearance, or how much growth might I expect?  Are there other issues I haven't thought about that I'll need to consider?

I'll visit the dealership where the service manager and service writer both said that the swap wouldn't work.  I expect they're going to give me the "factory" line on why I shouldn't do it.  I'd like your comments to offer on why I (we) think it'll be okay to have such-and-such clearance -- or maybe you'll convince me that if it clears now -- it's good enough.

Okay, the floor is open to you all.  Let's hear from you.

[Stan Back]

Gee -- If the 16's won't work -- why the 16" spare?

And if they taper in a little where the clearance is tight -- how about a 1/4-inch spacer to set them out a little.

And if the calipers are red-hot and expanding that much, they're probably not much good on the rotors, either, and you may want them interfering with the wheels!

Stand Back!