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Help - front bearing dust caps falling off

Old 11-07-14, 07:16 PM
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Help - front bearing dust caps falling off

I have an FC.

I have lost 2 front wheel bearing dust caps at the track. Is the hot air in the hub pushing out the caps? If this is the problem I will drill a small hole in the caps as a vent.

Or are the hubs heating up and letting the dust caps fall out?

Any tips or tricks to keep them in?
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Old 11-08-14, 05:56 AM
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Drill a small hole in them. They get hot and build up pressure and pop off.
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Old 11-08-14, 06:35 AM
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Doesn't that then defeat the purpose of a dust cap? Also, where are you buying your new caps? I tried some 1.78" trailer caps but they aren't quite big enough.
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Old 11-08-14, 08:58 AM
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Originally Posted by Lavitzlegend View Post
Doesn't that then defeat the purpose of a dust cap? Also, where are you buying your new caps? I tried some 1.78" trailer caps but they aren't quite big enough.

We are talking a 1/16" hole here. I'd rather have a very small hole in the cap than have them fall off completely since they aren't made anymore.

I don't know where to get new ones. I bought a set off a member to have as spares.

I have 4 spares now, after replacing the lost one I will have 3 spares. I did not want to drill them if that was not the problem.
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Old 11-10-14, 12:36 PM
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In my experience a small 1/16 - 1/8" hole does the trick. After that mine never came off in a club race again. This is a pretty common fix for most racecars not just RX7's
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Old 11-10-14, 04:08 PM
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I drilled them with a 1/16 hole in the center. No issues yesterday at the track.
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Old 11-10-14, 04:42 PM
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Originally Posted by LargeOrangeFont View Post
I don't know where to get new ones. .
a couple of the japanese tuners make aluminum caps, $$ though
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Old 11-10-14, 05:08 PM
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Originally Posted by j9fd3s View Post
a couple of the japanese tuners make aluminum caps, $$ though

The 4 lug guys parting out cars seem to be a good source for spare caps. I got one set with a set of 5 lug hubs I got as spares, then another set from a 4 lug guy stripping the car. And I have 1 NIB one from Mazdatrix.

I've lost 2 in a couple years of tracking the car. I've caught them a handful of times half way out. Drilling them seems to be the ticket.
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Old 11-12-14, 10:19 AM
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Actually a .050" hole will work just fine. In addition, if you are worried about dust/dirt, find a small aircraft rivet that fits in the hole with clearance and use that.
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Old 11-12-14, 12:03 PM
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I guess I was referring more to the possibility of trapping water inside if you were to wash it with a pressure washer. I guess I could find something to cover them for washing.

Does anyone have a good measurement for 5 lug front hubs so we could possibly find a different vehicle that would use the same sized dust cap? There has to be something out there that would fit. None of the junk yards in my area (southern Kansas) have any 2nd gen rx7s...
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Old 11-12-14, 12:57 PM
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Originally Posted by Lavitzlegend View Post
I guess I was referring more to the possibility of trapping water inside if you were to wash it with a pressure washer. I guess I could find something to cover them for washing.

Does anyone have a good measurement for 5 lug front hubs so we could possibly find a different vehicle that would use the same sized dust cap? There has to be something out there that would fit. None of the junk yards in my area (southern Kansas) have any 2nd gen rx7s...
A small piece of double sided tape or duct tape over the hole should cover you if you are going to spray the hubs. The bearings are coated with grease, they wont rust even if a little water gets in. With some driving any trapped water is going to evaporate. We are talking a very small hole here.

It takes a lot of heat to get them to pop out.
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Old 11-14-14, 01:03 PM
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Yeah I already had one fall off at my last track day. I brake pretty hard. Trying to source another set of them so I can replace that one and also have a backup. Was wondering if some other old cars would be the same size dust cap and maybe they are still being produced.
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Old 11-14-14, 03:39 PM
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I have been racing my FC since 1997. I have gotten the front brakes hot enough to crack rotors and melt seals out of the calipers, but I have never had a cap pop off. Either I am really fortunate or I am not using as aggressive a pad as you guys. Also, do you think it could be grease related? I have always used premium greases that don't melt out. I wonder if the type of grease and the vapours it releases could be a cause.

Eric
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Old 11-14-14, 03:44 PM
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What exact brand and formula of grease do you use?
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Old 11-14-14, 04:08 PM
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I had one fall out once only because the fit was not very tight. I ordered new ones from mazda and it never happened again.
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Old 11-14-14, 09:46 PM
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Yes I'm sure fresh caps fit great. Slightly flaring the outer diameter of used caps may help keep them tight as well. Also I have heard using a punch on the ID to put a small dimple in the cap every 90 degrees will add a little more resistance.

I'm using redline grease, it is holding up fine.
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Old 11-16-14, 02:49 PM
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Originally Posted by LargeOrangeFont View Post

I'm using redline grease, it is holding up fine.
i used that stuff on everything, i love it
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Old 02-05-15, 08:06 AM
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So what's the the size of he oe cap . I have no center caps on my wheel combo and my grease caps are kinda dented up a lil . I work in a shop so I have multi parts houses at my finger Niger tips .thanks guys
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