274 replies to this topic

[Parity]

Finally remembered to take closer pics while I was at the track.  (Images are much larger than what the forum resizes them to.  Just click on them.)

 

 

That's an interesting looking hub. It looks like the stud holes are not counter bored. Hard to tell from the picture but are the faces machined where the stud flange seat?  

[Todd Green]

That's an interesting looking hub. It looks like the stud holes are not counter bored. Hard to tell from the picture but are the faces machined where the stud flange seat?  

 

No idea.  It is a stock hub from Mazda Motorsports (other than the stud swap) purchased last year.

[Parity]

If the raised bosses are cast then the stud flange faces would not sit completely flush which would cause higher stress points where contact is made. However, it looks like it may have faced of in a turning operation. If so, the remaining  fillet radius as a result of the machining becomes critical since it can give way to stress risers. This particular failure looks like something different that the recent ones.

[SaulSpeedwell]

Looks like the Beck/Arnley part with unmarked races ....

 

http://www.rockauto....BA0516034-1.jpg

[Brandon]

Others can confirm/chime-in on what transpired but I heard there might have been another two failures this weekend at WGI.

I saw a picture posted on FB showing the inside of the wheel/rotor/caliper and someone commenting about there '...being a couple of those 3-wheelers coming in on the flatbed...'

[Parity]

Brandon, who is your contact at Mazda? I spoke with them today and so far they believe they only have 2 failures. The first one was determined to be under torqued but the second did have a cracked ball which they replaced. As far as they know, the only other complaint is shortened bearing life (4-6 events).

 

Any chance moderators can consolidate "Hub Failure" threads?

[Brandon]

Paul, there are two distinct failures that have been documented: bearing/race failure & "hub" failure.

 

The pictures posted above are what I deem a hub failure and result in a catastrophic (for the car & possibly driver) situation.

These failures appear to be more associated with the type of hub (casting), any heat treatment applied by the factory (yes/no) and/or installation of longer stud w/o the proper radius at their base (expansion of the pre-cast hole causing microfractures; my summation and not a technical statement).

 

My particular failure (and Mike Lo's) was a bearing failure.

 

Our two failures would be the ones that MSP has been notified of.

I heard secondhand there was possibly another pair that failed at the 12-hour but that's not been corroborated at this point and would be up to the purchaser to pursue anything w/MSP.

 

Anyway...that's what the other thread I started was for - Failure of MSP enduro hub (or something like that).

[DrDomm]

I had to change a hub this weekend at the Glen because of wobble.  I'm not sure that qualifies as "failure".  There was no noise from it.  I haven't dissected it yet.  It was a brand new SKF ABS hub that I repacked.  

 

I did 4 days at the Road Atlanta Major in SM and STL, as well as a track day at Watkins Glen with it on the left front.  It was fine after that.  I removed it, repacked it, and put it on the right front.  It wobbled after 2 sessions.

[Parity]

Domm, would you be able to send it to me for inspection? I'll inspect the end play, radial play, report my findings and I'll return them to you. Also, where did you buy them?

[Bench Racer]

Brandon, did you ever ask MSP or I think you mentioned ProParts, if the original design parameter was to have the inner ends of the inner races touch when properly torqued. Or when the inner ends of the inner races touch is that when the tolerances all stack up in a failure direction and the 12-6 grap of the wheel shows wobble with no ball, cage or outer race failure.

 

If you provide the exact number, I'll make the call and ask the question. If they have no answer I'll ask them for their manufactures number and call them. NTN never responded when I e-mail asked them the question. From my reading of many threads/posts no one knows the answer of by design should the inner ends of the inner races touch.

 

Any of you hub re-sellers know the answer???

[DrDomm]

Domm, would you be able to send it to me for inspection? I'll inspect the end play, radial play, report my findings and I'll return them to you. Also, where did you buy them?

 

Sure.  PM me an address.  I'll send it.

 

I bought 2 SKF hubs from some random vendor on eBay(don't judge) in March.  They came in the SKF boxes.  They had the "heat treat ring". I knocked the ABS rings off, and re-packed them.  They were torqued at 125 ft-lbs.

[Parity]

PM sent

[Parity]

Bench, MSP has a request in with MAZDA, Japan concerning NTN contact info. Should hear back in a week or so.

[Brandon]

Dom, judging from what others have stated I'd say you were under-torqued by about 15 ft/lb (by my minimum; 140 ft/lb) and 35 ft/lb per MSP/ProParts (160 ft/lb).

I'll be installing mine to the MSP/ProParts spec of 160...the new/replacement one (LF) and the existing (RF).

 

Bench, I never inquired about that particular detail but others have commented it would be a loss of pre-load on the balls to have the inner races touching leading to premature failure fairly quickly and easily considering the loads be place on them.

 

Like I said earlier, I've experienced a different failure from what others have experienced: my wheel has never decided to voluntarily run for the Armco at the most inopportune moment.

[Bench Racer]

 

Bench, I never inquired about that particular detail but others have commented it would be a loss of pre-load on the balls to have the inner races touching leading to premature failure fairly quickly and easily considering the loads be place on them.

I hear you and understand you and what others are saying. Were doing a lot of guessing. I for one want to know the exact design parameter relative to touching or no touching.

Thanks Paul, looking forward to the info. 

[DrDomm]

Dom, judging from what others have stated I'd say you were under-torqued by about 15 ft/lb (by my minimum; 140 ft/lb) and 35 ft/lb per MSP/ProParts (160 ft/lb).

I'll be installing mine to the MSP/ProParts spec of 160...the new/replacement one (LF) and the existing (RF).

 

Maybe, but I'm not sure it will matter.  I was told the outer race/hub is the weak link.  I'm not sure the torque on the nut/inner races is as important as some think...but it's worth a try I guess.

[Johnny D]

^^^ I think it does, crank it up and best of luck, if that doesn't work your(SCCA) is looking at a smaller tire or custom hub, not the way to go, IMO.

J~

[john mueller]

^^^ I think it does, crank it up and best of luck, if that doesn't work your(SCCA) is looking at a smaller tire or custom hub, not the way to go, IMO.

J~

 

Without knowing the details it's safe to say that Custom hubs will be a no-go in NASA.

[RazerX]

If the hub/outer race is in fact 'bellmouthing' the extra torque should yeild no positive effect.  In some deductive ways if torquing to 160 results in the same or faster rate of failure in the hubs without any noticeable effect on the  inner race, then the finger continues to point towards the hub/outer race material and fabrication.

[Brandon]

I've updated my "MSP Hub failure" thread with new details.