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Right Front Wheel Hub Failure at Autocross, Part 2


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Here are the pictures I promised

 

The back of the wheel center, as you can see they aren't flat but there are 2 "rings" that contact the hub, one right at the outer edge and one very close to the center.

Based on the worn paint the rims must be moving a bit and it is apparent that there is contact all the way around both the inner and outer rings.

wheelcenter2.jpg

 

Whats left of the wheel hub

hub8.jpg

 

The parts that broke off

stud1.jpg

stud2.jpg

 

Even though there is contact between the wheel center and the hub there are a few spots where it looks like it may not be completely uniform pressure.

I think its time to stop running these steel wheels and also see if I can talk the machinist at work to milling down my rotor spacers so I can use them with the 280Z hubs I got from Logr.

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I recently bought a similar wheel from Marsh Racing Wheels to use for mock up trying to build steel landspeed wheels for moon discs. When I saw the bolt-up surface I said to myself "I wouldn't put those wheels on my trailer!" Marsh was terrific and let me return it for full refund. I just couldn't bolt that stamped surface up to my car.

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Ken,

It's tough looking at the pictures but it appears that there was some initial cracking  (the shiny areas) and then they just gave way suddenly. You might want to die check the next hub you put on just to be sure there aren't any cracks that are difficult for the naked eye to see.

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The back of the wheel center, as you can see they aren't flat but there are 2 "rings" that contact the hub, one right at the outer edge and one very close to the center.

 

Even though there is contact between the wheel center and the hub there are a few spots where it looks like it may not be completely uniform pressure.

I think its time to stop running these steel wheels and also see if I can talk the machinist at work to milling down my rotor spacers so I can use them with the 280Z hubs I got from Logr.

Looks like the lug nuts are torqued down over an air gap and the rigidity of the flat steel between the two rings is expected to transfer the force to the contact surfaces, maybe even just the outer ring.  Even worse.  But the steel isn't rigid enough.  Probably flexing all over when racing.  Looks like a poor wheel design.  They should pay for your hubs if they're selling those as performance wheels.  Maybe the design is meant for a hub that fits completely inside the outer ring.  Could be the wrong application.

 

Just an opinion, it's not my field.  I just know the basics, and the picture is a little grainy, and two-dimensional.  Looks bad though..

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Maybe the design is meant for a hub that fits completely inside the outer ring.  Could be the wrong application.

 

I think you might be right, or alternately the design was to be used as high offset, like they would on the front wheels of a truck, but then someone decided the design should work flipped for racers who need the low offset...

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Ken, Are you sure the inside ring on the wheel is on the same plane as the outside one? The older Diamonds that I have are not. I wonder if the inside ring is used more for centering than as a mating surface.

I don't know for sure Mike but they look to be in the same plane just eyeballing it.

 

As I said before, the most perplexing part of this whole thing to me is I ran that first front pair of Diamond wheels for almost 7 years without any problems.

The key difference seems to be when I switched to the Hoosier A6s and had Ricky co-drive with me.  I'm not saying Ricky had anything to do with the failures but he has helped me to become faster and he is very fast.  It might be that the combination of the A6s and both he and I pushing the car that much harder is what ultimately lead to the failures.

 

For now my plan is to have my brake rotor spacers machined down so I can run that set of 280Z hubs I got from you and stop running the steel wheels.

I'll then need to find a set of wheels that will clear my brake calipers (Toyota S12+8 for vented rotors) and I can get decently wide Hoosiers for.

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Thanks NewZed but I'm not putting any 240Z hubs back on the car.

 

I'll either go with the 280 hubs I have (they "look" significantly stronger than the 240 units) or I'll switch to 5 lug 300ZX hubs as Logr suggests.

The downside I see for me with the 5 lug swap is sourcing a set of rear stub axles that are configured to work with 300ZX-T CV axles.  MM used to offer billet sets but with them being defunct I don't know where to go to get a set.  The reason this is an issue for me is I had my 240 inner stub axle flanges modified to work with the CV axles by MM instead of switching to 280 stubs as I should have (my cheap nature bites me again).  This limits my options for new stub axles to those that I can get with inner flanges configured for use with the CV axles.

I hope all that makes sense. :) 

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Ken, Just redrill the 240z stubs you are using now for 5 lug.

 

You know you are going to break those and wish you had gone to 280z ones instead.

 

Didn't I send you a spare 240z one? I think I found the other one too.

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  • 2 weeks later...

It's not even fronts but just the right front hub that has broken twice.

Rear stubs were mentioned in the context of converting to 5-lug hubs in the front which would prompt a switch to 5 lug stub axles and associated flanges in the rear.

 

I saw those hubs from TTT but am not comfortable running aluminum hubs considering the issues I've run into with the steel ones.

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