Aluminum front hubs for MGB?

[Moderator]

I'm wrapping up a rear axle / suspension project and thinking about what might come next. How about replacing heavy iron front hubs with lightweight aluminum ones? I think several people may have made them over the years, but they seem to be completely unavailable now.  In another thread I wrote about a business called SendCutSend. Just a couple weeks ago SendCutSend expanded into CNC milling, and they announced lathe services are coming next. I'm thinking of giving that a try.

My motivation is weight reduction. Stock cast iron MGB hubs are heavy.



5 pounds 14.7 ounces (including lugs and bearing cups).



Stock lugs were pressed-in. For aluminum hubs, would it be better to thread in wheel bolts instead?



Stock brake rotors were attached with four bolts. Nuts/washers recessed into pockets in the hub casting.



Aluminum adapter hats could be eliminated. Should I attach Wilwood rotors to my new hub directly?

If you were creating your own billet 6061-T6 hubs, what features would you include?

[Moderator]

It occurred to me that someone might misunderstood what I said about thread-in wheel bolts. I was thinking of bolts that thread through the hub from the back, but are attached to your wheels with regular lug nuts. That's what Strange Engineering does with their rather inspirational design:

https://www.strangeengineering.net/wp-content/uploads/2024/12/BALL-HUB-1.jpg
https://www.strangeengineering.net/wp-content/uploads/2024/12/B4700-HAT-DETAIL-1.jpg
(but sadly, their's won't fit my car)

[Scott Costanzo]

Curtis, very interesting! This question might be be a bit premature, but would you duplicate the dimensions of the original hubs or change them in some way? I'll for sure be following this!

[BlownMGB-V8]

I used a slip-on hat, as I prefer to be able to swap brake rotors without removing the bearings. Pretty sure I used press-in studs rather than screw-in SHCS but can't say for sure. I doubt the alloy and heat treatment are the same. SHCS are probably more brittle but with higher ultimate strength. Back spacing is important, especially if setting up aftermarket calipers. Speedway sells some very nice price conscious and light weight rotors. I haven't found a better source for those. Sometimes you can find the aluminum hats on sale for around $50 each. May not perfectly match your spec though.

Jim

[Moderator]

Great feedback, gentlemen.

To Scott's question: I don't have any particular intent to shift wheels outboard or inboard. A small shift might be fine, but moving outboard as much as 1/2" would likely risk fowling the fenders and would noticeably increase steering effort (due to increased scrub radius). My tire sidewalls already kiss my antisway bars during full-lock parking lot maneuvers.

Good points about being to service rotors w/o bearing removal, Jim. I hadn't thought of that!

I have a bunch more thinking to do. More feedback would be welcome!

[Moderator]

Jim Nichols pointed us to some 64-72 A-body (Chevelle) compatible aluminum hubs in a recent post within the Classified forum:

Carl. these Chevelle hubs are 2 lbs lighter than their cast iron counter parts. Curtis, you could plug and redrill for MGB pattern. The rear seal bore needs to be .040 bigger for the MGB seal.

https://www.opgi.com/brake-systems/drum-brakes/brake-hub-kit-64-72-a-body-aluminum-roller-bearing-drum-CH30250.html

I wondered if there might be off-the-shelf aftermarket hubs that'd require less rework. A quick search led me to Sunbeam Tiger pattern aluminum hubs that Wilwood offers for $180/each. Wilwood says they weigh 3.3# each. Wilwood says they start their hub production with forgings. They also have very nifty threaded-on hubcaps, which are included with no extra charge. Their 4x4.25 lug pattern with 7/16" lugs doesn't suit MGB at all, but drilling a second pattern (4x4.5" with 1/2" holes) should be straightforward.  Wilwood doesn't want to do it, I already asked;)

What else might be required? I continued my investigation:

Tiger spindles are apparently similar to MGB's: 1.25" diameter at the inner bearing cone and 0.75" at the outer cone. The spindles also stick out about the same length. With respect to hubs, outside-of-cone to outside-of-cone distance for Tiger is 3.17". (That's dimension "M" on Wilwood's drawing.) I took a quick-and-dirty measurement on MGB: ~2.97". So, if using MGB's distance-tube and shim method of bearing set-up, it'll probably be necessary to shorten the spacer tube just a little. No problem. Tiger spindles use the very same outer bearings as MGB, but they don't use the same inner bearings. Shouldn't matter as long as you use Tiger bearings and seals. Bottom line: Tiger hubs should fit on MGB spindles just fine.

The big difference is that MGB mounted brake rotors to the back side of the hub, whereas Tiger rotors are sandwiched between hub and wheel. That's cool. As Jim Blackwood pointed out above, it'd be nice not to have to mess with bearings when servicing rotors.

There are a few important things I don't know yet:

Without having parts in hand and taking measurements much more carefully, I don't know how deep a hat would be required, so I don't know yet if a suitable is available.

I do know Wilwood doesn't offer a hat for 4x4.5 that's anywhere near deep enough, so it'll almost certainly be necessary to spec one of their undrilled hats and have it drilled locally. Probably not a showstopper, but I don't know how much this customized hat is gonna cost. Hat pricing varies widely.

If the "hat offset" dimension is close-but-not-perfect, that might not be a deal-breaker. I'm thinking of the spacer that goes on the spindle before hub installation. A thicker spacer there might help things fit together.

Finally, I don't know how much the wheel mounting surface would shift from stock. Based on my super-quick-and-dirty measurements it seems likely the shift will be modest, one way or the other.

What are your thoughts, folks?  Ready to jump in and give it a try?

[mgb260]

Curtis, Sunbeam Tiger is the same as the Alpine inner bearing, 1.125 ID on the bearing and 2.250 OD on the race. MGB is 1.250 ID and 2.328 OD. There is probably enough meat to bore out to MGB size or a conversion bearing with 2.250 OD and 1.250 ID? I think you would need to bore the outer race hole .2 deeper.

Wilwood bearing sizes, last two columns:

https://www.wilwood.com/PDF/DataSheets/ds719.pdf

[BlownMGB-V8]

At $220 for the entire kit including both hubs, all bearings, seals, caps, even nuts, washers and cotter pins that Chevelle kit is hard to beat. Can you just use the Chevelle seal? I don't recall that issue with the Roadmaster which uses the steel hubs. And what about the bore length, does the outer bore have to be sunk another 3/16" like on the steel hubs? For a match to the Jag IRS it's almost perfect. The Tiger hubs might be better for the 4 lug.

Jim

[mgb260]

You have to bore the hub .040 for the MGB seal or turn down the spacer .156. MGB seal is 2.441 OD and 1.89 ID. Chevelle seal is 2.400 OD and 1.734 ID. The Sunbeam Tiger seal is smaller yet at 2.047 OD and 1.574 ID. Wildwood chart shows bore spacing the same as MGB, Hub # 270-8769. The one right above the Sunbeam Tiger, 270-11539 is Mopar A body and coincidentally has the same specs as Chevelle but wheel mounting face is about 1" out. Sunbeam Tiger wheel mounting face is about 1/4" out more than Chevelle.

[MGBV8]

My tire sidewalls already kiss my antisway bars during full-lock parking lot maneuvers.

What front sway bar are you using, Curtis?  Wondering if it has the normal amount of bend for tire clearance.

Many years ago I ordered a 7/8" bar from ADDCO that was supposed to fit.  Nice, well made bar.  I had to return it, as it did not have the tire clearance bend.

[BlownMGB-V8]

You can bend those if you have to, just takes a hydraulic press and a setup that will not move (spread out) under the bar.

Seems it'd be easier to turn down the stub spacer than to cut the bore, and easily replaced if needed. Don't forget to add the hat thickness into your track/offset calculations.

Jim

[mgb260]

Stock car racing rotor hats come undrilled and different offsets. You may be able to space caliper brackets as needed too. Wilwood has quite a few with different offsets too:

https://www.wilwood.com/Hats/HatList?appl=&rtBC=&offset=&hatBC=Blank&mtStyle=

[mstemp]

Curtis,

Here is my alloy hubs from Bill G for a comparison. Brg cups installed, wheel studs are a bit long, so might be a slight further weight savings. My question would be is~ 2.5 lb savings worth the effort? (Ignore the gap on the wheel studs, machine shops attempt to correct the 4x100mm mess up. Studs are tight on back side)

[mgb260]

The Chevelle hubs bolt pattern is 5x4.75. Does anyone have a pic of the S10 5 lug rear axle redrilled for 4x4.5? Looks like Bill may have used the Chevelle hub.

[waterbucket]

I went with the Chevelle hubs, I don't remember the source, maybe Speedway. IIRC they are almost exactly a pound less than the MGB hubs, at the rear I went with MGC WW hubs. I went this route partly because there are some nice old BMW wheels that fit (120mm vs 220.6mm PCD). I now have 284mm vented discs with RX7 callipers (a bit more weight saved). In the end I am going with some Z4 rims that came with almost new Continental tyres which happened to be the correct size for my wife's car. One minor benefit is that it reduces the scrub radius by about 3/4".

[mgb260]

Phil, you used the iron version. The aluminum ones are even 2.5 lbs lighter than yours. I found a picture of Hank Ronish's axles drilled from 5x4.75 to 4x4.5 in the thread below. Looks like no conflict with the holes.


https://www.britishv8.org/MG/HankRonish.htm

[BlownMGB-V8]

For the money I don't think you can go wrong on those Chevelle alloy hubs. I had probably $200 just in material to turn my billet hubs from and those are forged so at least as good and already machined. Cutting the outer race 3/16" deeper is no big deal, maybe 1/2 hr of lathe time for both. As mentioned I'd cut down the inner spacer to match the seal if that's needed. Not the solution for 4 lug of course.

Jim

[mgb260]

Jim B, You don't have to bore those, The drum hub spacing is the same as MGB. The disc brake hub is the one you have to bore 3/16". You do have to modify the seal. It will work for 4 lug if redrilled as shown on Hank's axle pics in link above.

[BlownMGB-V8]

Even Better! Nothing like an affordable off-the-shelf part!

Jim