Rallye wheel center cap screw mount holes

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St.C Pinball

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Hello! Dumb question here but looking for some advice. Just bought 4 of the later style large center caps part number 3461458 for my 75 dart. They are Mopar performance parts from summit. I think these caps need 5 small screws to mount them to the rim which is fine. They have 5 screw holes in the back but they are not threaded. All 4 of the caps are like this in every hole. Do the screws self tap when you put them in or do I need to tap these holes for a machine screw thread. (They did not come with any mounting hardware. Any advice is welcome. Thanks!

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Should use 1/4-20 self tapping screws. I always tapped them myself and used stainless steel bolts. Make sure the head does not stick out so the rim sits flush with the drum or disc.
 
Self tapping screws and I don't think I have ever seen more than 3 used. And like 66FS mentioned make sure they aren't too long.
 
Agree, always have only seen 3 holes used. Probably so if in the future a hole gets stripped, you just go to the next hole.
 
Typical bean counter stuff, in 1970-971 they used all 5. Later wheels only had 3 holes drilled.

I’d like to use a 1/4-20 tap on them to cut nice threads and get the shavings out of there before installation. Then use non tapping bolts so they are removing metal every time they turn.
 
3 bolts is balanced close enough. A little balance discrepancy so close to center of wheel wouldn't be noticed. 1 missing lug nut or the one larger locking lug nut would prove it. I doubt these cast centers were balanced.
 
3 bolts is balanced close enough........
An example which would also include the weight of the omitted screw bosses........
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FWIW, The old rally centers I've had in the past always had 5 screws. One had to check that the new tire mounter reinstalled them all and didn't break any off.

This outfit may have the correct screws available in the "Hex Washer Head Screws & Bolts (Sheet Metal)" pdf........
Mr. G's Enterprises - Auto Fasteners (mrgusa.com)
 
I believe that all the Mopar replacement caps were not threaded and came with thread cutting - not self tapping - screws. If you buy a set of real replacement screws and are careful using them the first time, and before you put them on a wheel, all will be fine. This practice stayed until at least 1984 - I bought a set of NOS caps for my 1984 Dodge Rampage with factory rallye wheels at Carlisle 2 years ago and sure enough, no threads tapped ... alternative is to run a tap through them first
 
The factory screws (bolts?) have a slight taper and an angled groove cut at the tip (for threading).

They also have a larger hex head than a "standard" 14-20 bolt or screw.

I've never used any type of thread locker on any of the screws I've found and had to use in place of the factory ones, or on those.


I believe a 5th Ave uses the same screws to hold on the part that the wire wheel covers secure to...but only 3 per wheel.

I still see 3-5 5th Ave's in my local u-pull yards every year.

That must be a testament to how many they sold and how well they held up.
 
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Hmm....I was wondering why the 2 or 3 different screws I tried to tighten up that one squeaky center cap didnt seem to be catching any threads.....:)
Serves me right for not taking the center cap entirely off! I hope those "official" ones I ordered from Classic Industries do the trick
 
Fyi, stainless into aluminum is a problem. Use anti-sieze or as mentioned earlier locktite. This prevents galling. Maybe not such a problem with coarse thread, but fine thread for sure will lock solid.
 
Fyi, stainless into aluminum is a problem. Use anti-sieze or as mentioned earlier locktite. This prevents galling. Maybe not such a problem with coarse thread, but fine thread for sure will lock solid.
I recently ran into this issue replacing spark plugs in wifes 2011 RAV4 2.5 ltr. 4 cyl.. Lucky me did have the metric tap to clean up one bolt hole that held their coil pack/plug wire in place. I dont know what plating they put on the bolts but all of them got some anti-seize going back.
 
Fyi, stainless into aluminum is a problem. Use anti-sieze or as mentioned earlier locktite. This prevents galling. Maybe not such a problem with coarse thread, but fine thread for sure will lock solid.

Never had a problem with stainless and aluminum. Stainless and stainless now that is a problem. I work on underwater stuff, so anti-seize goes on everything and blue grease coats all non threaded part interfaces.
 
Never had a problem with stainless and aluminum. Stainless and stainless now that is a problem. I work on underwater stuff, so anti-seize goes on everything and blue grease coats all non threaded part interfaces.
Buddy was putting a lwer unit on an outboard motor,refused to follow instructions to anti-sieze or threadlock the studs. One didnt thread in all the way before it locked up. Anti-siezed the rest and they went in fine.
 
Buddy was putting a lwer unit on an outboard motor,refused to follow instructions to anti-sieze or threadlock the studs. One didnt thread in all the way before it locked up. Anti-siezed the rest and they went in fine.

RTFM (Read The F______ Manual, maybe he learned his lesson on following instructions. Not sure why it would lock up, maybe an interference fit that needed that lubrication. No matter what fastener material, you should use anti-seize on any threads into aluminum.
 
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