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Cannot see any reason why it should not work then. For people worried about sleeving, we had done the rear spindles on a friends' EP70 Starlet Turbo about 8 years back like this, using a high-temp anaerobic retaining compound between the sleeve and the spindle just in case. Never had a single issue.
They run the high quality OEM hubs cause they work, they also run the same wheels and tires as we do. I haven't found an aftermarket bearing that wasn't just OEM that's been blueprinted. 6UL, Jongbloed, ect all make a BMW specific offset. So regardless of ultimate G loads they are producing the same grip, just that the heavier cars result in less peak G's.
Just screwing around with a freebie cad program, these aren't the actual dimensions but just a rough design to get an idea of pricing. Looking pretty good so far.
Final product would look like this made from 6061 aluminum
Spindle spacer and washer would be 304 stainless just because I don't want to mess with zinc coatings and risk the chance of this stuff rusting to the spindle.
You guys didn't think I'd be turning 20 of these out on my little hobby lathe did you?
Looks good! Before start machining away, you might want to take a look on what's already available. That hubcentric spacer looks like it could be purchased and maybe modified to work, a tube might have dimensions really close to the sleeve, etc. Eager to see these tested!
So that's exactly what I did for my prototypes I posted pictures of, that was DOM tubing I machined into the spindle sleeve, chunk of steel rod for the washer and hubcentric spacer was a bolt on adapter that I modified so that's why it had the extra holes, I couldn't find a slip on spacer as thick as I needed, it was really close but I had to start wtih a 1/2" spacer and cut down from there.
I'll let the cat out of the bag, I've used e-machine shop for small batches of stuff that I don't have the means to do myself and their prices are pretty darn close to what getting the raw materials and finding a local shop to make them would cost, lead times just suck at ~4 weeks. I don't mind making stuff for my own consumption, I actually rather be able to say I did it myself, but if there is enough interest I would farm all this out except for the bearing modification and just be the packager.
I'm just a dude trying to go fast for a hobby, I have a full time job and a family so i don't get a lot of time in the garage and I certainly don't want to spend it all on production of parts, my time is worth more to me than that. Once I have the proof of concept running around and I can verify all the dimensions are correct I'll either make another set myself for testing or just have e-machine shop do it at a higher cost. Third step would be to set pricing which would be based on volume and at that point we can talk turkey here and I can get setup as a vendor. I'm not going to get rich off of this, but if I can buy some go fast parts off of my research time then great. Pricing is going to be much less than the tapered roller bearing setups you've seen recently. I don't think folks will want to go this route unless I can get the kit put together with a set of bearings for less than $500 a pair. That's my goal anyway.
I'll test them for you. Shaky Dog Racing is a WRL team. One of our cars, Moose, has been testing and destroying the new MAZDASPEED hubs at an alarming rate. We think we might have a solution for them that we will start testing tomorrow. I have a test at Hallett setup this weekend and a full test day later this month. We also have two 8 hours races in mid-October and possibly a COTA race and VIR race in December.
Send them and we will put them through the grinder.
While its not obvious the E30 bearings are better (rolling elements, races, seals, …), the little we can see about the E30 hub does appear to be stronger (thicker flange, generous radius on the inside side). So, its likely worth testing to destruction or at least long enough to know it is better than available off the shelf Miata hubs.
I believe the best solution will use “unmodified / off the shelf BMW hubs”. The rational for this is the hub/bearing is a wear item and should be readily available from multiple manufactures at common local auto parts stores. Other items to make it all work like special sleeves, spacers, washers, etc. are NOT wear items and can be custom parts as needed.
The people that will benefit most from stronger hubs and better bearings are those on track, generating high G cornering on 275 slicks, jumping over race curbing and sliding off track onto gravel or grass (it happens). These same racers use non-standard wheels and brakes, etc. so, keeping the stock Miata Hub OD/Rotor ID and Hub OD/Wheel ID is likely not as critical as for a road car user. (but road cars with lower cornering loads likely don’t need such an improvement anyway).
For example, 6UL wheels the hub hole (67.1 mm) is larger than both the Miata hub diameter (54.1 mm) and BMW E30 (57.1 mm). So, one could bolt on 6UL wheels using no hub rings Or, using 6UL to BMW hub rings (see 949 Racing site).
Also, if one selects BMW hub compatible aluminum top hat and rotor (from an E30 BBK), then the rotor will be correctly located radially on the hub (selecting the top hat offset may have to be adjusted for the rotor to be positioned correctly on the Miata spindle).
So the solution now requires NO E30 hub machining and 2 of each of: sleeve for the sub axle, spacers for the reduced bearing thickness, a simple flat wheel spacer of the appropriate thickness (4 stud holes, 1 hub hole), and a BMW BBK top hat (and rotor) for the Miata BBK. If one uses a radial mount BBK caliper mounts and calipers one could make fine adjustments for the new rotor offset with radial mounts. Not being a fan of wheel bolts, I’d include a BMW wheel stud conversion kit also.
Non miata hub bore requiring aftermarket wheels with BMW hub bore or larger
Modified bearing
Nothing else needed it just works
All miata wheels fit
All miata brakes fit
I get the idea of modifying the bearing sucks, but it’s really a simple process that can be rough as hell and function just the same. I’m of course going to make the bearing available for purchase but I’m also going to make a delrin plug that fits inside the hub bore that protects the bearing from debris during the “machining” process. At that point use any kind of metal removing tool you have around to grind, saw or sand the nub flush with the plug. It would take all of 5 min with an angle grinder, or if you want it pretty have a machinist chuck it up in a lathe and take 2 min to cut it down.
Faced with the alternative of needing to keep custom brake hardware around which will be changed out probably 4 or 5 times as often as the bearing I really do see the modified bearing as being the better solution. If you’re willing to buy one of the tapered roller bearing solutions out there then you’re already shackled with keeping a custom bearing on the shelf and simply ordering a modified bearing from me or having a local machinist modify one for you won’t be any worse.
I haven’t made much progress as life has gotten busy. I did get my stud conversion kit yesterday so this would be part of the kit.
I’m hoping to get back to finalizing my machinist drawings and getting a few sets on order. I have an endurance team that has offered to break them for me, so if I can get them here soon enough there may be some race use testing before the end of the year. I’ll get my prototype installed this weekend and begin street testing on the 20$ bearing, might even get a few auto-x events in but honestly there isn’t much to prove with my use right now. In my mind hub breakage will be eliminated, just no way they are going to break when compared to the miata hubs. At this point the testing would prove out the bearing life as installed on a miata in contrast to the E30.
The BMW tone ring is really close to the same diameter as the Miata ring so it might actually work for megasquirt users looking for a speed off the front wheel. The diameters work out that the Miata tone ring could be machine and pressed into the BMW bearing. It's on my list of things to work out.
Correct, Miata abs ring could be made to work on the BMW bearing, it will be a custom thing though. Once you have a pair of machined rings you would just continue to press them onto your new BMW bearings.
So the prototype covered it's first mile.... Yup it's a wheel bearing.
Install directions:
Pull your old crack prone crap off
Install bearing sleeve
Install bearing
Slide on heavy washer before torquing nut.
Slide on spacer
Install brakes and dust cap as normal.
Rotor spacing looks dead nuts, bad pic sorry.
Nothing to see here with the wheel on
I'll be street and auto x testing the prototypes with Uber cheap 22$ wheel bearings just to see how they do. I've reached out to a couple of machine shops to see about a small run of test pieces, I wasn't happy with the pricing from e machine shop for 3 sets, gets more reasonable at around 10 to 12 sets.
Send me files, I have a good mill guy that will be waayyyyyy cheaper than emachine shop. FWIW emachine shop has always quoted me outrageous prices. PM me if interested, or you probably know our email.
09-11-2017, 09:11 AM
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