924Board.org

[daniel]

Hi All
I have had a little trouble with brake rotors and wheel bearings. Heres the story:
The race weekend before last during the last race I started to notice a vibration in the drivers front wheel, over the course of 1 lap the vibration became worse to the point that I lost control and the car came to rest off the track. When I had a close look, the hub part of the front rotor had been smashed to pieces along with the inner and outer wheel bearings.
The bearings and rotors were about 5 race weekends old and the passengers rotor and bearings were fine.

So I replaced both rotors and all front wheel bearings and entered the next meeting.

During the last race of the next meeting the same vibration returned, so I immediatly pulled over. Upon dissasembling the drivers side wheel assembly, this is what I found:














So now I suspect some issue with the stub axle, perhaps a micro crack that grows with heat and causes a vibration. Regardless the stub axle is now damaged and requires replacement.

My question is this: Have any of you with race cars that have used 4 lug rotors experienced anything like this? Or does anyone have any theories as to what is happening here?

I will say this though, please dont suggest that I should upgrade brakes,that is not possible due to my class rules.

Thanks

Daniel
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

[Cedric]

This looks mad..I have done both many many track days and endurance racing with the stock setup (although nice pads, fluid and lines). I have never seen anything like it.

Although I had a bad bearing which self destruct within a trackday or two. Got a new one that time from the seller, SKF, so nice quality. It have worked since then.

Do you tighten the bearing according to the manual?
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1980 924 Turbo
www.instagram.com/garagecedric/

[daniel]

Hi cedric, i dont know what the manual says about tightening the bearings. I thighten them while the wheel is spinning until it stops. Then i back it off a bit but not too much.as to cause pad knock off.
_________________
Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

[!tom]

I had an issue with my car eating front wheel bearings which I concluded was due to a bent spindle. I didn't race the car though.

My 5-lug upgrade fixed that.

Too bad a 5-lug conversion isn't allowed for you, even though they were available that way from the factory.
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78 924 NA
5-lug

[masterslamma]

my brakes glow highly red after driving threw the alps. the had about 8-900 degrees is guess, but thats no problem at all . I run ate powerdiscs, ferodo pads and ate blue racing fluid.

that is definitely not normal
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My other car is a Porsche,
but today i am in a hurry!