Jason-85944

Everytime I drive my car the damn thing pops off and rattles. Anyone else ever have this problem? What is causing this and how do I fix it?

Thanks,

Jason

unreal_news

I used to know what driving a 951 was like ... anyway, dust cap? to what?

Jason-85944

dust cap for front wheel bearing.

Techno Duck

Are the edges of the cap scored or anything? Worn out? How about the outter portion that it slides onto?

unreal_news

oh O.o The cap or the area its settleing into must be damaged? dunno how that would happen, but somethings not right. And of course its on all the way? Normally, I have a hard damn time just getting it off.

testarossa_td

Just jam some grease on it and pop it back in, the grease should hold it.

Dave in Chicago

They are made of a different material than the hub, expanding at different rates while they heat up. Add to that the hot grease heating up and creating a bit of pressure... Cap pops off!

This is not a normal issue for street cars though. It happens on my track car and I need to whack them on before each run/race.

Check the fit. Should be a tight friction fit. That's good enough for the daily driver stuff. From there one can do the following obnoxious modifications (in order of PITA level).

1) Silicone the edge of the cap on (messy, not fun to clean up at later point, but easy)
2) 1 above + drill 1/8" hole in center of dust cap to relieve pressure
3) Remove hub, drill hole in it also, then safety-wire cap onto hub (lots of work unless you just happen to be dissassmbling the front suspension for another reason)

I have heard of folks pounding "dimples" into the cap with a punch and the like. Word at the track is that it doesn't really work. I suspect this is because one is now relying on 3 dimples as the pressure-fit surface area versus the entire cap rim.

Z-man

I have my wheel bearing dust caps is safety-wired. They stay in place that way.

-Z

Jason-85944

It's good to know that this happens to others as well...my car is basically only driven for autox. I may try the drill and safety wire to keep it on for now.

Thanks,

Jason

Z-man

Trust me - it works like a charm. Many folks who see that at AX or DE's (I take the center caps off at the track and at DE's) say it's not a bad idea.

-Z.

Dales944

Maybe you should take it out a little more often. Get comfortable in it. Maybe then you beat me at the next autox!

xsboost90

mine came out about half way at the last DE, but not off ever. Are your bearings a bit too tight?

APKhaos

Its a basic spare in my trailer box. Probably replaced four in two seasons, one of those after drilling a 1/16 inch breather hole. Its a heat and pressure thing. The safety wire idea is a good one - thanks!

Oddjob

Ive also had them fall out on track cars. The more they are removed to replace/repack wheel bearings, the more likely they will become "loose" and want to fall out. I bought a couple new from a dealer and replaced the worst ones, and the new caps have stayed on well.

Also agree that it is partially due to the heat expansion difference between aluminum hub and steel cap (alum expands more per given temp increase) and also from a pressure build up inside the hub. The more grease in the hub and bearings, the more the cap will want to pop off - and leave a mess on the wheel when it does!

With the safety wiring, do you run into any problems with certain wheels that have little to no hub clearance. Can you post a picture - I would be interested in seeing the technique.

Jason-85944

yea...I'd like to see a picture too if someone has time to snap one.

-Jason