The inside bearing is behind the mounting flange so the body could be made much larger for a larger bearing. That's how the GM metric chassis is setup, inside bearing is easily twice the size of the out board bearing. Spreading the bearings apart also helps as well.

 

The alternate hubs were tested last year, and held up well. “The hubs have undergone testing at multiple events, on different cars, with different drivers and multiple locations and tracks throughout the U.S. over the last year,” says Sean Hedrick, who is not only the owner of MiataCage.com, but is also a member of SCCA’s Spec Miata Advisory Committee and was involved in the testing process of these alternate hubs. “The final test was the 25 Hours [of Thunderhill] in December. Each set of hubs on the 25 hour cars had over 30 hours each on them prior to taking them off of the cars and sending them back to the manufacturer for visual and microscopic inspection.”

That's not good, well atleast you can rebuild it with a new bearing, and seal which should be easy enough to get from an auto parts store. I was hoping the teething problems would be minor after testing on them as per the above statement. I sealed my caps with rtv. I haven't benn on track with mine yet but well be the 13th, so well keep a close eye on them and report back.It's usually the outer that gives up also.

 

Update on the new hubs, Mazdaspeed has no replacement bearings available. The bearings do not appear to be a popular size and therefore not readily available. I called NSK, the manufacturer of the bearings supplied with the hubs, and they said they might be able to get some out of South America. I finally found some in Europe made by Koyo of the same size. They have a 28mm bore, 68mm cup diameter and a total stack height of 19.75mm.

I also called Mark and asked him what grease he has been using during testing. He said they have been using Mobil 1 Monolith 460. Anyone here ever use it?

 

No wonder i couldn't find them last week when i was trying to decide if i wanted them.

What a cluster.

 

Idiotic. The whole point was to have a maintainable hub. WTF?!?

 

I'm using Amsoil dominator grease and haven't had any issues. I agree on the bearing issue, I too talked to some engineer at NSK and he says he thinks it is a knockoff bearing since he can't find that nbr with a 'J" in any of their master engineering paper work.

 

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I'd be ok with a not-forever service life and rebuilding a couple times a year if it was with an easy to find and affordable bearing, personally.

If the bearings are unobtanium or expensive, then what's the point?

 

Read above post, these were tested last yr extensively. As for reliability, these are going to have to be adjusted right, they are not preadjusted. So far [knock on wood] mine are doing fine. I would like to be able to get some spare bearings though and after talking to the NSK engineer it does have me wondering a little. STM says right now all are being used to build new hubs which they are selling all they can make. I don't quite understand as they surely knew that there would be replacement issues. Other then the brg supply issue I am happy so far and mine get used hard. Mark is on vacation at STM so well try to find out more when he gets back.

 

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The widest tires I've fit on the Catfish were Hoosier 275's on 6UL 11" rims. At 949 Racing. Lots of room in back, and a good amount of room up front. I'll bet a 305 rear could fit and be staggered if the horsepower went WAY up. I'm just not sure what that horsepower figure might be.

 

I found that the bearing number is HR303/28 this should help others search.

 

Yes, that is the bearing number but be careful because there are bearings that use that number with are MUCH larger.

Really you need to know the dimensions and specs of the bearing as well as the number to be certain you are getting the correct one as a replacement.

 

Man. Overall, I think Mazda is really good to us in keeping our 10-15-20 year old cars running in race conditions. But this tapered roller bearing hub release is just a cluster ****. All the way around. Not what I would have expected from Mazda Motorsports.

 

AIUI, Mazda didn't make this hub/bearing, they're just reselling it.

--Ian

 

Well right, I understand that. But they put their name on it. They put it front page on the email blast. They heralded it as The Solution for racers rebuilding hubs after every weekend. It may not be their direct product, but issues of availability, for all of the rebuildable parts, that are the reason for the hub existing in the first place, not doing any due diligence on the actual availability of those parts surprises me. Not planning to have those parts on hand in stock surprises me. Not being prepared for what I assume was a pretty high pent up demand for this product surprises me.

I understand supply chain management is a thing, and it costs. Having a warehouse full of inventory is a cost. But .... there's just a big bucket of fail in the preparation for actual supply and delivery of this item.

 

I've only ever bought OEM parts from Mazdaspeed. Mazda supply chain is first rate. Aftermarket parts, well, that's a cottage industry.

 

i agree,
any chance you could make another set of the rotor centering rings?

thanks

 

These rings are really thin. As posted above he had to press on thicker rings and then mill them down as they only need to be .020" thick. Just go down to your local hardware store and buy 2 of the brass strips 12" x 1/4" x .016" . Bend them around the cap until they meet and cut to length. Mark said they ran them as is with OEM rotors in all the race cars, but I have the big brake kit and the Mini rotors have much bigger stud holes so I did this and it has worked fine. Once the wheel is tight the rotors aren't moving .

 

Just got off the phone with STM powersports and for anyone that has ruined a brg they can supply some. They plan to have them available in stock to Mazda in a few weeks along with seals. They also have made new caps with the step machined in for the rotor. just waiting for a PO from Mazda.