ghezzi tech: the quest for lighter wheels

Now the bullshit starts...

I have a black belt in Origami

On the left is the alloy test piece to check spline cutting etc. - perfect fit.
On the right the hardened 4340, ready for the spline cutting come Monday

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Did a track day on Wed, first time I've ever lacked power ............................ not on the straights. But using all my 76rwhp for the first time in a corner.
Dragging toes or side stand at full throttle and high RPM, hitting rev limiter at 8,300 (no tacho) long before completing exit. Back on the road I tend to ride half throttle mid revs surfing the torque curve.

Trial fit today of axle and hubs etc. axle plate/disc carrier last piece needed.

Here you can see how the axle head fits inside the crown wheel cavity.
4340 axle weighs 845g from 4.4kg stock. It could be a little thinner/lighter but will err on the side of caution.
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Question guys, I want to anodize this outer alloy hub. I prefer red to match the front disc buttons.
The 5 counter sunk allen head screws (not shown) can be either black steel, stainless steel or Titanium to match the axle nut. What say ye?

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T6 alloy hubs at 765g from 4.6kg stock.
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Titanium with clear coat for the screws.
Dunno about the outer alloy cover treatment colour, I'm awestruck with the result of your labours.
Mind keeps wandering between the spline cutting and the materials.
Then there's the wheels themselves. Yum.

Okay, go the RED

Superb stuff Wayne, really looking good.
I'd go for a kind of natural finish with Ti screws but hell it's your bike.

IMHO I would not use Ti bolts on anything under tension or that is not check torqued regularly.
I work in aviation. Boeing covered 2 models of aircraft with Ti bolts.
Boeing found that after time the Ti bolts would stretch and lose their torque value. This unfortunate discovery was made after a 800kg trailing edge flap liberated itself from the aircraft and the part crashed into the ground fortunately with out injury.
The resultant world wide fleet wide modification program. Remove all Ti bolts and install Inconel bolts.

I would only use Ti on a race bike where everything is about weight and constant maint/ disassembly - assembly

I do very much like watching the process of your carbon wheels. Fantastic stuff. Genius as work
I don't want to rain on any ones parade, my vocation is the think mechanical safety...
My 2 cents.

I will be waiting for a hot day (30°+C) to bond the hubs, wrapping the wheel in black plastic to increase inside temp to around 60°C.

At this temp it should cure with a Tensile Bond Strength of 15N/mm2 (over 2000psi).
In reality, the M6 and M8 screws that hold the 2 bonded alloy hubs in place, aren't in danger of stretching and losing torque value. The M33 axle nut will keep everything in compression.

I am more concerned about the shear strength of the screws.
BST use Grade 8 screws and clear lacquer the whole wheel when its finished. I realize this stops corrosive liquids penetrating the hubs at any point ....................... and looks pretty. I may do exactly the same as you can see in above photo that centre carbon needs re-lacquering.

Will take on board any advice, keep it coming.

I'll package yer tank up and get it off this week. I'll need to give it a really good rinse out and leave it in the sun to clear it of vapours so the shipping mob don't have a cow over it. The real 'Chrome over steel' tank actually looks quite nice in a vulgar, rap-singer's neck medallion sort of a way......

Pete

Being the king of fashion that I am Pete, chrome plated crass and vulgar is probably right up my alley.

For me red would be to much, to "poser". black or blanc alu. Looking at the picture, how did the axle fit in the carc? Or did you mill away a part of it? I still don't get the right hub, do you use the 4 original bolts to screw it to the carc? Since you made 8 holes.

Ghezzi, I'm fascinated by your solution to this.
Following up on Paul's question does the shaft act only as a drive mechanism and is not load bearing?

mark111 wrote:

Ghezzi, I'm fascinated by your solution to this.
Following up on Paul's question does the shaft act only as a drive mechanism and is not load bearing?

By my eye it seems to be both.  Looks like there is a plate that bolts to the bevel drive and retains the hub/axle.  A single nut then must hold fast the wheel up against the retainer plate.  If the inboard hub sits flat and flush upon the retaining plate and thus the bevel drive, then the shaft wouldn't have to bear much load. I can't noodle how it would work otherwise, but I'm no mechanical savant.

To answer the question; The axle is both load bearing and provides drive. But not solely, there is also a 15mm thick plate that bolts to the bevel via four M12 bolts (as per stock wheel).


1. The axle has 4 tangs that fit into the cavities in the back of the stock crownwheel. It also has a shoulder for centering as per the stock Guzzi wheel hub.

What is missing at this point is the axle mount plate, the axle will need to be hydraulically pressed into the plate, before mounting to the crownwheel as per stock wheel. It also has six fingers and doubles as the disc carrier.

2. The two alloy hubs are bonded and bolted to the carbon wheel. The right hub is drilled for clearance and weight reduction, the 4 larger holes are counter bored for the flange head bolts that hold the axle plate to the crownwheel.

3. With the wheel in place, a single axle nut will keep it all in compression.

4. Caliper and disc will remain in place when the wheel is removed.

5. A Ducati style single sided axle stand can be utilized for servicing, (but not wheel removal).

I takes me lid off to Pete (my machinist).

Finally, all the pieces of the jigsaw are on hand.

Inside view of the hubs etc.
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Outside view of each part.
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Axle pressed home in mounting plate.
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Recess in hub for bolt heads.
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A Ha!!! now I get it, really impressive can't wait to see it on the bike.
A picture is worth a bzillion words

All parts looking great. So mounted now and testdrive? Or wait for the red on it?

Thus far polishing the alloy looks effective, however I would still like to anodize the alloy for a hard surface coating on the splines ......................... colour is still undecided.

Once hubs are bonded to the carbon its forever. Waiting for a warm day and the big yellow oven in the sky.

I also wanted to take more weight out of the axle, machinist is resisting.

ghezzi wrote:

I also wanted to take more weight out of the axle, machinist is resisting.

Is only unsprung weight, not rotating, well it is but so near to centre that it's unimportant.

My thoughts exactly Paul.
Suspension guru has always been concerned about Guzzi unsprung weight, axle and plate can always be removed and modified later if necessary.

My calculations thus far are of a 4.2kg weight saving with the rear wheel and hub.

What does the scale tell with wheel/tyre/and hub?

Stock wheel with worn 180/55 tyre and TUBE, disc and 4 wheel studs 16kg

BST with tubeless 160/60 tyre and all associated hardware is 11.8kg.

However, I've cheated by removing 350g from the rear disc.
On a lighter note (pun intended) more weight could be removed from my 4340 axle and plate.

Dropped alloy off this morning, hard anodizing will be done Friday week (26th Sept).

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You know Wayne, I know a bloke with an 8V motor sitting around begging for a new home.

I reckon your Bellagio crank and a pair of Argo rods built to spec and we could have a stupendous 8V in that beast..........

Pete

Yeah - more bike porn - would that be a GRiGiO?

STOP IT!

Hey guys, I already suffer badly from OCMD (Obsessive Compulsive Modification Dis-order).
Currently my mad wheels disease has sent me broke ............................ stupid cow.

Pete, will it fit?