Racing hubs or alternatives for rear?
07-17-2007, 12:11 PM
#1
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Racing hubs or alternatives for rear?
Hi guys,
I've just been informed that the rear hubs will crack and break when racing with big, sticky tires. I tried searching and didn't find answers so...Are there racing/upgraded hubs out there? Who sells them? What do LGM or other pro racers use?
Thanks!
Steve
I've just been informed that the rear hubs will crack and break when racing with big, sticky tires. I tried searching and didn't find answers so...Are there racing/upgraded hubs out there? Who sells them? What do LGM or other pro racers use?
Thanks!
Steve
07-17-2007, 12:26 PM
#2
Le Mans Master
I am anxiously awaiting the replies to this thread, too. Just an FYI and correction to what I wrote you yesterday, I don't recall breaking any of the rear hubs myself off-hand, but I do regularly break the front hubs on both my Z06s.
The actual wheel bearings can actually cook-off and fail from the heat generated by the brakes as I understand, although I have never personally had this happen, probably because I replace them regularly now.
Oli
07-17-2007, 12:30 PM
#3
Melting Slicks
I dont think there is any readily available solution for the stock suspension setup. I am curious to see what the speed gt guys run, but if its different than ours, I bet its a drastically different setup.
07-17-2007, 02:14 PM
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I just spoke with Dan Kellermeyer, who has been very helpful and was recommended by one of the guys on here. They actually have a C5 with 55000 race miles, and never experienced a hub cracking or failure. The point he brought up was to ask if these failures happened with the factory GM wheel bearings or aftermarket bearings? Do you guys know?
Apparently there are some aftermarket bearings touted as the actual GM bearings, but at $100 less in cost. Possibly they're not really the same, and he thought possibly there could be a relationship to them and failures? Just trying to figure in out.
Steve
Apparently there are some aftermarket bearings touted as the actual GM bearings, but at $100 less in cost. Possibly they're not really the same, and he thought possibly there could be a relationship to them and failures? Just trying to figure in out.
Steve
07-17-2007, 02:22 PM
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The corvette wheel bearing is made by Timken. and you can get that bearing from Autozone in a Timken Box, for much less then in a GM Box.
Stock corvette Timken bearing can take quite a beating. and if it does go bad, they are cheap and easy to change.
Stock corvette Timken bearing can take quite a beating. and if it does go bad, they are cheap and easy to change.
07-17-2007, 03:01 PM
#8
Le Mans Master
I have broken and cracked both the ones from GM and ones from other sources. I agree, they all appear to be made by Timken and identical from what I can tell.
I know Chris Ingle just broke a front hub at a race at Roebling a couple weeks back. So they do break and there is no doubt about it.
I know Chris Ingle just broke a front hub at a race at Roebling a couple weeks back. So they do break and there is no doubt about it.
07-17-2007, 04:21 PM
#9
Drifting
I am in the middle of building a purpose built track car using C5 suspension pieces. I would be really interested in seeing the failure. Can someone post pics of a failed bearing unit? When the bearing fails, do you also see damage in the upright? Are these catastrophic failures, or does it start with a grinding noise and get progressively worse?
Thanks
Ken
Thanks
Ken
07-17-2007, 04:27 PM
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Mine just wobbles. I caught it before it failed completely. My CV joint boot got a cut in at the same time and slung grease everywhere, which got me looking for problems. I don't know if one was related to the other or if I just got lucky.
07-17-2007, 04:31 PM
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Dan had certainly mentioned that I will have to keep an eye out for the bearings in the rear, as they will go out, especially if you run over the curbs regularly. That is a regular check item for them.
Oli, so have you heard of others have many failures of the rear hubs? or is it just the fronts?
Various experiences so far, but no upgraded parts...hmm...just how common is this? Is there a market for it?
s
Oli, so have you heard of others have many failures of the rear hubs? or is it just the fronts?
Various experiences so far, but no upgraded parts...hmm...just how common is this? Is there a market for it?
s
07-17-2007, 05:21 PM
#12
Le Mans Master
BTW. I finally got to reading the latest Velocity. There is a good picture of your BSR car in there.
All of my failures that I can recall have been on the fronts, so maybe the rears are not much of a problem. But when I started breaking hubs, I change them all regularly now.
I also recall a thread somewhere. The guy was talking about machining a billet hub to solve this problem....
Here is a video link that Ingle did showing his broken hub.
http://www.youtube.com/watch?v=sZtPPhkSKyw
I have one in my trailer still that I broke at Miller Motorsports recently. That one not only cracked, it was completely separated. It was only held on by my caliper as the broken flange spun around the round center. It broke at the end of the 140 MPH Miller front straight going into turn one. My car pitched into some over-steer, but I saved it. At first I thought I screwed up my trail-braking, but I soon as I straightened out and loaded the left front, where the break was located, as I turned into turn two, I could hear the grinding noise.
Sometimes you can hear, or more of a feel, a big snap from the hub as it starts to crack, but is not completely broken. Imagine someone plucking a long piece of rebar pulled tight somewhere in your car. That is the feeling it transmits if cracked, but not yet fully broken.
Fastest regards,
Oli
All of my failures that I can recall have been on the fronts, so maybe the rears are not much of a problem. But when I started breaking hubs, I change them all regularly now.
I also recall a thread somewhere. The guy was talking about machining a billet hub to solve this problem....
Here is a video link that Ingle did showing his broken hub.
http://www.youtube.com/watch?v=sZtPPhkSKyw
I have one in my trailer still that I broke at Miller Motorsports recently. That one not only cracked, it was completely separated. It was only held on by my caliper as the broken flange spun around the round center. It broke at the end of the 140 MPH Miller front straight going into turn one. My car pitched into some over-steer, but I saved it. At first I thought I screwed up my trail-braking, but I soon as I straightened out and loaded the left front, where the break was located, as I turned into turn two, I could hear the grinding noise.
Sometimes you can hear, or more of a feel, a big snap from the hub as it starts to crack, but is not completely broken. Imagine someone plucking a long piece of rebar pulled tight somewhere in your car. That is the feeling it transmits if cracked, but not yet fully broken.
Fastest regards,
Oli
07-17-2007, 09:58 PM
#13
Race Director
they do break, but rarely. GM Racing sells a set with tighter packing (they last longer before getting sloppy) but doesn't improve the metal any. They don't sell them to the public either.
In my 9 years of tracking and racing C5's and C6's, I've never broken one the way you describe (but have had the bearings and speed sensors wear out), but know a few people that have. It is rare, and should just be checked regularly for cracks.
In my 9 years of tracking and racing C5's and C6's, I've never broken one the way you describe (but have had the bearings and speed sensors wear out), but know a few people that have. It is rare, and should just be checked regularly for cracks.
07-17-2007, 10:09 PM
#14
Le Mans Master
they do break, but rarely. GM Racing sells a set with tighter packing (they last longer before getting sloppy) but doesn't improve the metal any. They don't sell them to the public either.
In my 9 years of tracking and racing C5's and C6's, I've never broken one the way you describe (but have had the bearings and speed sensors wear out), but know a few people that have. It is rare, and should just be checked regularly for cracks.
In my 9 years of tracking and racing C5's and C6's, I've never broken one the way you describe (but have had the bearings and speed sensors wear out), but know a few people that have. It is rare, and should just be checked regularly for cracks.
I have cracked several fronts. Just a couple weeks back I did toast a speed sensor as you point out. The consequence is that ABS shuts down. No big deal, but I can't brake mindlessly like when I have ABS. For me the metal fatigue is the problem and not the bearings.
Checking for cracks on the flanges is part of every one of my pre-race inspections. Pull the wheel, pull the rotors and look for cracks. When in doubt, swap is my routine.
07-18-2007, 05:30 AM
#15
Le Mans Master
same here, was swapping out the rotors and noticed it, so I caught a lucky brake.
07-18-2007, 09:54 AM
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Here's what the deal is:
As you know, I'm working on a non-stock replacement for our bearings.
http://forums.corvetteforum.com/show....php?t=1552590
But a lot of Corvette drivers have to run the stock unit. So, I decided to find out why the stock wheel bearing are so bad. Especially when taking a car to the track. I took one apart, and look what I found.
Single lip seals, which melt at track temperatures, and can't hold the pressure of the gas created when the grease heats up. The failure lets the gas pressure out, but more importantly they fail again when they cool down letting not just gas in but contaminants, and PLASTIC wheel bearing cages?!?!? Of course as soon as they melt the ball bearings grind against each other, and the bearing is toast.
Well that's the bad news, the good news is that the seals are easy enough to get, but you destroy the plastic cage in the process of taking it apart.
So, if I can find a replacement bearing that fits, preferably with a steel cage. We can turn them into something that's rebuildable. Fortunately I've got a friend who's been a race engineer for years, has plenty of sources, and has gone through this already with BMW cassette bearings. ( same design style )
If owners replace their seals after every event, which we should be doing but can't currently. These bearings, despite being placed to close together, should last a long time.
BTW Way cheaper than a new one, or my heavy duty design. I'll save that for people who can afford the custom pieces.
http://forums.corvetteforum.com/show....php?t=1552590
But a lot of Corvette drivers have to run the stock unit. So, I decided to find out why the stock wheel bearing are so bad. Especially when taking a car to the track. I took one apart, and look what I found.
Single lip seals, which melt at track temperatures, and can't hold the pressure of the gas created when the grease heats up. The failure lets the gas pressure out, but more importantly they fail again when they cool down letting not just gas in but contaminants, and PLASTIC wheel bearing cages?!?!? Of course as soon as they melt the ball bearings grind against each other, and the bearing is toast.
Well that's the bad news, the good news is that the seals are easy enough to get, but you destroy the plastic cage in the process of taking it apart.
So, if I can find a replacement bearing that fits, preferably with a steel cage. We can turn them into something that's rebuildable. Fortunately I've got a friend who's been a race engineer for years, has plenty of sources, and has gone through this already with BMW cassette bearings. ( same design style )
If owners replace their seals after every event, which we should be doing but can't currently. These bearings, despite being placed to close together, should last a long time.
BTW Way cheaper than a new one, or my heavy duty design. I'll save that for people who can afford the custom pieces.
07-18-2007, 12:35 PM
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Brian,
Thanks for all your efforts on this matter and for linking us to your previous thread. So did you find the cost for the 1 piece forging? Where did this project end up?
Thanks,
Steve
ps - I have a racing friend here who has a shop with ridiculous toys (cnc machines, water jet cutter, etc.), and is an excellent, accomplished manufacturer. If you like, I can present him with something of yours to get some quotes if he'll do it. He might also have some good input.
Thanks for all your efforts on this matter and for linking us to your previous thread. So did you find the cost for the 1 piece forging? Where did this project end up?
Thanks,
Steve
ps - I have a racing friend here who has a shop with ridiculous toys (cnc machines, water jet cutter, etc.), and is an excellent, accomplished manufacturer. If you like, I can present him with something of yours to get some quotes if he'll do it. He might also have some good input.
07-18-2007, 12:45 PM
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Most people seem to want something that "passes for stock"
I could still do the custom forging if there's enough interest.
The alternate would be to run C3 rear spindles up front.
I could still do the custom forging if there's enough interest.
The alternate would be to run C3 rear spindles up front.
07-18-2007, 01:22 PM
#19
Drifting
Also, from the video posted above, and the written description, it looks like the flange is failing from bending fatigue. Do you think is caused by the bearing itself failing?
Ken
07-18-2007, 01:39 PM
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I replaced my front bearings in march '06 w/ Timkens and after my last VIR event a month ago my RR is howling... replacing the rears now w/ Timkens.