Z06Vette.com - Corvette Z06 Forum - Broken C5 Hubs on the track - Add this check to your pre-race safety check

Olitho · 07-20-2007, 07:08 AM

OK, folks, I put togehter a short video of one of my broken hubs.

It shows fairly clearly where the metal fatigue induced fractures occur when running your car frequently on the track with big wide sticky race tires.

The front and rear hubs are the same. While I have broken or cracked several front hubs, I don't clearly recall breaking any on the rear. I might of had one rear hub that was starting to show signs of cracking. Anyway, here is a three minute documentary showing you how they break and what to look for in terms of cracks before they completely break.

http://video.google.com/videoplay?do...05136519594980

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**Stry** · 07-20-2007, 07:24 AM

Yikes !!!

Thanks for the info...

Ray B · 07-20-2007, 08:27 AM

Olithio: Thanks for the heads up. Very good info. Ray B

WB6HRO · 07-20-2007, 09:06 AM

I definitely have that on my check list. I think every time you change brake pads a good hub inspection would be prudent!

Oli what tires are you running? I've been running Kuhmo V710 F 275-17 R 315-18. I get the feeling that you might be running wider tires which would obviously accelerate the hub failures.

Wonder if the Phoenix preped cars use something different..Brad?

Olitho · 07-20-2007, 09:55 AM

Hi Joe:

My car is a Phoenix built car, too.

I am running the 315x17 set-up on all four corners per the SCCA T1 rule book. I have used mostly the Kumho V710s, but when this particular hub broke at MMP I was running Hoosier A6s.

Fastest regards,

Oli

WB6HRO · 07-20-2007, 10:28 AM

Yea the A6's are softer than the R6's.

I have to got to a 305 rear tire when I run NASA Time Trials to keep me in "TTA" Class.

2MchFun · 07-20-2007, 01:42 PM

Does anyone make a stronger-than-stock replacement?

No Doubt · 07-20-2007, 02:37 PM

Not currently although it's being worked on...

http://forums.corvetteforum.com/show....php?t=1552590

GM (I should say Timken*) does make a 'racing' version of the stock hub but they're not readily available to the public. They're the same basic design but have tighter packing, although they still fail in the same manner as the stock parts do and hence are not really any better.

*The OEM hubs are also made by Timken and you can buy them at many auto part stores for less than the otherwise identical GM part.

froggy47 · 07-20-2007, 03:26 PM

Thanks, I'm always swapping practice wheels to comp wheels & back depending on the event, so an easy thing to add to the list.

I make it a practice to wash the wheels each time I swap & my neighbors think I'm getting ready for a car show. In reality I'm checking for cracks in the wheels.

So just to be 100% clear that is one cast/forged/machined whatever piece. No weld or any other mfg process that makes two parts into one, right?

Noob question.

No Doubt · 07-20-2007, 04:08 PM

Correct, the hub flange is one piece. You will have to remove the rotor in order to inspect it, which also requires removing the wheel as well as the brake caliper.

froggy47 · 07-20-2007, 04:26 PM

Good timing, got 4 new rotors & pads going in.

Subdriver · 07-22-2007, 12:56 PM

Oli,
That's ugly... thanks for sharing the video. I did have wheel hub replacement on my annual checklist, but mostly due to rapidly increasing slop in the bearing, not actual failure of the hub.

I wonder if its time to start considering a spec tire in T1. These cars just weren't designed to run the sustained G's capable with the current generation of DOT track tires. I'd like to see us all have to run something like the Toyo RA1 or Nitto's.

Olitho · 07-22-2007, 05:30 PM

Quote:

Originally Posted by Subdriver

Oli,
That's ugly... thanks for sharing the video. I did have wheel hub replacement on my annual checklist, but mostly due to rapidly increasing slop in the bearing, not actual failure of the hub.

I wonder if its time to start considering a spec tire in T1. These cars just weren't designed to run the sustained G's capable with the current generation of DOT track tires. I'd like to see us all have to run something like the Toyo RA1 or Nitto's.

I totally agree Brad. A spec tire would make sense. I think it would bring the tire budget down and tend to equalize the cars even more. Yes, the new tires are so big and sticky I think it just tends to put a lot more energy through those poor hubs than what they were designed for.

Another reason I may be going through more than most folks is Buttonwillow raceway and Streets of Willow Springs. Unlike other tracks around here, Willow Springs International, Cal Speedway and the like, both of those tracks have fast esses with curbing, especially BW. The fastest way through the esses at BW is about 100 MPH bouncing off of the curbing. If you learn how to do it, I can bounce right off of those things just right so I barely have to steer. They just sort of pitch the car for the next ess. It is hard on the suspension, and the hubs too I suppose, but it is a fast way through there when someone is on your a$$.

In addition to the spec tire, allowing a stronger aftermarket hub would be a huge safety benefit. It won't make the car any faster so we are not messing with the carefully managed competition adjustments, but the car will be much safer.

I sure don't want to find out about a hub failure entering bank oval turn one at Cal Speedway or doing 130+ into the turn eight and nine combo at WSIR.

No Doubt · 07-22-2007, 07:24 PM

I agree with the spec tire for the reasons mentioned, assuming one is competing in a given class, but the need for an adequate aftermarket hub would not be necessary if the OEM hub itself was adequate in the first place. It's clearly a design weakness, possibly a cost saving measure. One of many I'm afraid.

WB6HRO · 07-23-2007, 08:21 AM

It's economics and a compromise, Tadge (New Vette Chief Engineer) gave a talk at Spring Mountain. A big point was that how many people acutally push the car as hard as we do at the track......probably 2% of the cars sold.

So from the production point it's a valid compromise.