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Right front wheel hub failure at autocross


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Here's a youtube link to a video of an autocross run where the right front wheel hub on my car failed at the end of the run.

 

http://youtu.be/PEOFEHu8H0c

 

The car is a 73 240Z, the hub was the 41 year old original, I was running 10" wide sticky new Hoosier A6s and the car is making somewhere around 400hp at the crank.

 

Not sure there is a moral to the story, I had pulled the front hubs this last winter and they "looked" fine, the lugs were torqued correctly and I'm not running wheel spacers in the front.

 

Does anyone manufacture new hubs that are stronger than the originals?

Are the 260 or 280 hubs stronger and are they compatible with the 240Z spindle?

 

I know there's a thread that shows the different shapes (I believe it's one of the brake threads) but I don't remember anything about one hub style being stronger than the others.

 

I have no desire to switch to a 240SX strut arrangement so please don't waste time suggesting that. I have way too much money and time invested in these struts to make a switch.

 

Wheelman (Ken Wheeler)

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Must suck to see your wheel pass you.  :-)

 

There's really not a significant strength difference between the 240 and 280 front hubs.  For years I shipped steering 280Z racks, front crossmembers, stub axles, companion flanges, and rear LCAs to Star Motorsports in the UK for their rally 240Z builds.  I asked about the front hubs and they said there was no difference from their experience.

 

Buy replacement hubs and put them on a crack testing schedule - at least once per year.

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So what actually failed? Did the outer portion of the hub (where the wheels sits against) break off the bearing section? Or was it something else?

 

Some pictures of the failed part(s) might help determine what happened and possible ways to keep it from happening again.

 

At first I didn't know what you meant by hub failure, until I saw the wheel passing you on the left, I had to watch it again, to see when it failed. I'm not trying to be disrespectful, but that is pretty funny to watch. To have your wheel come up past you, especially on the opposite side of where it came from.

 

Was there much other damage? It looks like the fender took a hit, how is the bottom of the strut/suspension? It didn't sound like it scraped for long, so I would hope that it should be ok that way.

 

At 59 seconds into the video is that a bump in the track or that when the hub actually failed? It looks like the car gets jolted around at that point.

Edited by Six_Shooter
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What about 300zx hubs Ken. I know they bolt on but don't remember if they made them in 4 lug, thinking they did but not sure.

 

I have the five lug ones on my Z.

 

The offset is not that different and with your flares..........

 

I have one here(5 lug) and I have 2 extra flares as well as a Z hub if you do end up needing it. Is Ricky coming up this weekend? I can load up his trunk.

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Six_Shooter,

The jolt at ~59 seconds is a transition from the banked oval part of the track to the "flatter" infield where the timing lights were located.  There's also a drain right there that creates a dip I was on the very edge of with my left tire.

 

As for what failed, the hub "ears" the lug studs are pressed into broke away from the center of the hub, I'll post some pictures tonight.

The point in the run where the failure occurred was also a transition from one asphalt section to another, there's a seam and the grip level is different between the two plus the car was sliding sideways.

 

Don't worry about offending me, it is humorous to see the tire roll by on the wrong side of the car, at least it didn't hit a cone so my run was clean. :) One person at the event almost got punched after the incident though, he was being an ass (as usual) saying things like we have to break at least one mod car per season.  Logr will know who I'm referring to (his initials are LD).  

 

Logr,

I'll talk to Ricky to make sure but I remember him mentioning something about finding a co-drive for your upcoming event.  If he's going up I'd sure be interested in at least one of those flairs and will take both if that's the only way you'll sell them (are they from MSA?).  I'm interested in the Z hub as well but if you don't know it's history it'll only be used to get the car off the trailer and into the garage.  Dan Smith has a 2+2 280Z with a good right fender and both hubs that only has 50,000 miles on it. 

 

I'm pretty sure the Z31 300ZX hubs were 4-lug for a while, I'm running 300ZX 4 lug brake rotors front and rear right now.   

I don't want to convert to 5-lug so not interested in the 300ZX hub you have.

 

OH, I have an answer for Brian's seemingly miraculous 42 second run that day, he was following me in grid, got red flagged when my car broke and a course worker ran through the lights on the way to help me but timing didn't delete the time.  The timing folks need to fix the official times but I did win my class and was within .026s of Ricky.

 

 

Wheelman (Ken Wheeler)

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Ken,

Sounds like you don't really need that wheel to do well. Just stick and channel iron skid in there and go for it!

Don't know if you noticed on the other forums but that funny noise I was having in my car was the rear differential mount. Both the nuts holding the diff to the mustache bar were loose. could have been really interesting if the studs had slipped out of the mustache bar. :-(

Bill

Edited by Phantom
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I am very interested to see the pictures of the failed hub for several reasons: 

I am running 275/35/15 Hoosier A6 wheels on 10 inch wheels (like you).

I have the 4-lug hubs (like you).

I am running about 400 rwhp (like you).

 

I don't want my wheel to pass me on track (unlike you). :rolleyes:

 

I hope you didn't mess the car up very much.

Edited by 74_5.0L_Z
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Ok, here are the promised pictures:

The hub, or what's left of it anyway:

hub1.jpg

 

The wheel with the parts of the hub still attached:

wheel1.jpg

 

A couple of shots of the fender damage:

fender1.jpg

 

fender2.jpg

 

74_5.0L_Z,

We are running almost identical parameters, the only difference is my tires are 275/45-16 while your's are 275/35-15.

 

I appologize for the large pictures, I don't know how to shrink them.

 

Wheelman (Ken Wheeler)

Edited by wheelman
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Maybe it's just the photos, but it looks like the mounting faces of your wheel and hub were not mating flat and flush.  The area on the wheel at the inner bore and  the area of the hub adjacent to the bearing housing are both shiny as if you had a very narrow area of contact.  If this is true, then when you were torquing the wheel you were also putting the ears of the hub in bending. 

 

It may just be the pictures though.

Edited by 74_5.0L_Z
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I'm going to replace the left side hub when I put eveything back together, I'll take a look at it and post the results.

 

I noticed that shiny ring in the picture as well, maybe thats the root cause of this failure. 

I never noticed it when ever I had the wheel off the car but that doesn't mean the wheel was mating flat to the hub.

Edited by wheelman
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Ken,

Those hubs obviously are castings. If you seriously want some3thing stronger then I'd have the part machined from billet 4140 steel. It will be significantly less likely to fail. It may bend but it won't fracture like a casting will. Who knows - maybe you could get a "group buy" going on them. :-)

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I knew who you meant without the initials. Heck, I had to tell him not to bring his car back to our event if he didn't fix the oil leak and then he is talking about mod cars. This is the guy that mounted the calipers on upside down and couldn't figure out why the air wouldn't come out with the bleeder screws on the bottom. At least he quit trying to drive a mod car, now he just talks about them.

 

I sure suspect the wheel not bolting flat.

 

I know the history on my hubs. They came off a Z car. :lol:

 

I will check where the flares came from but I don't really need one. I put extra wide ones on the front of that last sx and have these left from the set.

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Yeah, I went out and looked closer at the wheel and hub, I agree, it really looks like the wheel wasn't bolting flat.  This means the left side hub is definitely being replaced as I've swapped the tires left to right several times over the years.  It also means that rim and possibly both fronts will be replaced, gets more and more expensive by the minute.  I suppose these situations teach lessons that aren't forgotten, really glad nobody was hurt when it failed.

 

All this is making me seriously consider installing a roll-bar.

 

Logr,

So, how much do you want for those flares?  I'll get back to you about the hubs once I talk to Dan Smith, depending on what he wants for the pair he's got I may take the one you have and possibly 2 if you have that many to sell. 

 

Bill, 

That's not a bad idea, would hubs machined from billet aluminum be strong enough?  The ones Techno Toy Tuning sells are machined from 6061 Aluminum, they are sure proud of them, $450.00 a pair for pieces that look to be easy to machine.

 

Wheelman (Ken Wheeler)

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What wheel is that? Bassett?

Nope, Diamond Racing.

I've had them for about 7 years but they've been strictly used for autocross so not many miles.

I got them used from Braap, he might be able to give some history prior to when I bought them.

 

What I find strange is there was never a hint of vibration from them.

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I have never seen that or heard of that occuring. I did have a 1966 Ford F100 that pulled/wallowed the studs through the hub. I had never seen or heard of that either. I felt something stopped and the wheel fell off with all the studs and lug nuts still attached to the wheel.

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