Is this rotor ok to run?

Scott Heavin · Posted: Thu Aug 06, 2009 5:55 pm Post subject: Is this rotor ok to run?

Had a little issue with my new rotor. Think it's good for one more race?

LOL! This happened in qualifying - like 3 or 4 laps. Didn't hit anything - just heat. It had to have a defect in it-my pads weren't even cooked and it probably had less than 100 laps on it. Weird thing was it didn't happen on track - I was in the scale house & heard this loud 'PING' and then found it. Oh-and it didn't split across a pinch seam on the carrier - it was between two solid sections.
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Joe Brizzolara · Posted: Thu Aug 06, 2009 6:42 pm Post subject:

I'd say it is good for at least a few more races!

Wow..never saw anything like that on a rotor. Maybe it had a defect that started a crack when it got hot. Then when it started to cool the hub was still hot and expanded and pop.

Dan Haynes · Posted: Thu Aug 06, 2009 6:48 pm Post subject:

nothin' a mig won't fix Laughing

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Jeff Stamper · Posted: Thu Aug 06, 2009 7:22 pm Post subject:

Jeff Field · Posted: Thu Aug 06, 2009 7:27 pm Post subject:

That'll buff right out.

In 2009, no rotors should have holes in them.
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gregg boyce · Posted: Thu Aug 06, 2009 7:43 pm Post subject:

Scott,

That could be from the disk cooling down unevenly. When I raced Barber stuff in '95 (1st year of the Dodge) we had brake issues EVERYWHERE. The rears were inboard and they'd over heat and then over stress the fronts. At the Road America round you'd hear the "ping" you talked about because guys would come in and have to leave their foot on the brake to keep from rolling backwards down pitlane and the disk would warp soo quick it would break "ping". A few times a guy would come in and "ping, ping, ping, ping"...all four rotors gone. Mechanics were lovin' it Rolling Eyes

Now I would come in an hit the kill switch and leave the car in gear to keep from rolling...I thought I was OK. The front left rotor "pinged" and no one heard it. I was going into turn 8 ("Hurry Downs") and right, and I mean right, after I hit the brakes BAM!!! When the pads hit the crack it literally broke the upright in half...this is at about 120mph+...pretty fun ride Wink

...I didn't even go all the way of the road...pitched it sideways and scrubbed it off on entry Wink

. The crew thought I just screwed up at 1st Rolling Eyes

.

Never seen that on a kart though...Looks like the Spec Tag needs a brake upgrade...

That picture could have been of ANY of the rotors from that weekend...thx for the memory bump!!

GB
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gregg boyce · Posted: Thu Aug 06, 2009 7:44 pm Post subject:

Oh yeah, were you still in the kart w/ the brakes on when it happened??
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Scott Heavin · Posted: Fri Aug 07, 2009 2:59 am Post subject:

Chris Reinhardt · Posted: Fri Aug 07, 2009 9:02 am Post subject:

I was told by a Bendix engineer, that when they crack to the outside like that, it has to do with how rigid they are mounted. As everybody knows, when metal gets hot it expands, the rotor needs to float to allow it to do so. If it doesn't, then it will crack....

CR

Scott Heavin · Posted: Fri Aug 07, 2009 9:34 am Post subject:

Jeffory Mott · Posted: Fri Aug 07, 2009 10:42 am Post subject:

Mig? Mig welding is for sissies. This is nothing a little bondo and some spray paint cant fix. Laughing

I think I have bought the exact thing on Ebay. The seller swore it was as good as new.

Chris Reinhardt · Posted: Fri Aug 07, 2009 11:20 am Post subject:

Scott, not just "loose" but the holes need to be large enough to allow for expansion. I would look at the newer style aftermarket "floater" type hubs, that might be the ticket...

CR

Benn Herr · Joined: 18 Jul 2001 Posts: 1580

Scott Heavin · Posted: Tue Aug 11, 2009 11:27 am Post subject:

After doing some research, I found that Shockwave use to make an axle heat sink. I called, and they happened to have one left for a 40mm. Just came in - nice little piece. I'll get it installed and try it this weekend. maybe one day I'll borrow a pyrometer and do some comparisons with and without it.

*The more I thought about this, what would be really cool is a heat sink with fins that act like a fan toward the disk.
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Jim Derrig · Posted: Tue Aug 11, 2009 12:19 pm Post subject:

That picture sure makes a good case for not cross drilling rotors.