ghezzi tech: the quest for lighter wheels

Pete, the crank can stay, with some work you can get an alternator on it. Has been done before. The german guys from guzziladen do it to put the 8v in a tonti, and I think millepercento too.

Wayne, the holes on the side of the disc don't look good, I would get a new disc and make some smaller holes.

That's my version of Swiss cheese ..................................................... without the cheese. It's light.

I also want to reduce rear brake power so it needs more foot pressure before lock up. Will also modify pads for better feel.
If it works don't fix it.
If it warps, breaks or just plain dun work, I'll design my own off road style disc and have it custom made.

Rear disc looks sexy but.......... I expect failure soon.

Why?

It looks to me, that the heat generated would crack or warp the disc in the areas where the metal is thinnest between the holes and from the outermost hole to the outer circumference.
Sorry man, I love what you're doing but myself, I wouldn't personally use that disc. The thought of a chunk of it breaking off, jamming in the caliper and possibly ruining all of the other great work would have me buying another disc.
Just my opinion of course.

Someone has to be on the bleeding edge. Good on you Wayne

Basically, the brake I use the most is the big internal disc (flywheel), followed by my potent front end set up.
Rear brakes main use is when I'm parked at traffic lights or when death is imminent. So it never gets much heat
When I get a chance for another track day I'll punish it severely, reason being, if it all goes wrong the Ambo is only 500 meters away.

Looks are deceiving in the photo, the gap (or metal bridge) between each hole is 2.0mm wide but also 4.5mm deep, and from the outer hole to the perimeter is 3.5mm wide.
Most people look at the thin bridges and think too little metal to handle too much heat. I look at the two adjacent holes and think of the greater cooling in that location.

If I had used a mill drill on a rotary table I would have made all three holes into one long slot. Therefore even less metal on the face but it would look better without the thin bridges.

If anybody can find a light weight replacement for the stocker, let me know. None of that wavy fashion bullshit, I want an off road mudchucker.
Something like this - more air than metal. (less is more)
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It its for weight, use smaller holes and drill an extra number of holes. And not all holes have to be same size. Before you made the center you had the chance to choose another disc, now there is no choice. Or it must be that guzzi used a bmw part, as they did for the caliper rear.

Paul, I designed the carrier to utilize the OEM disc, in case others want the same wheels.
BMW discs are 5 bolt and attach to spokes of wheel, not compatible.

Also, Guzzi 6 disc bolts trigger the speed sensor.

ghezzi wrote:

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.

HI Wayne, rather than wait for a hot day (although predicted soon), why not make an oven using a cardboard box and a small fan heater, just cut a hole in the bottom of the box big enough to fit the front of the heater in, I always put a little shelf in the box to sit the item on (2 bricks and a plank), put the wheel (or what ever it is) seal the box up and turn it on, you can also regulate the heat.

Just a thought.

Also Im still holding those rollers for you, do you still want them.

Cheers

Stephen

I could have used bonding as an excuse to buy a very big BBQ, however I do have some large cardboard boxes and a fan heater that's never been used (in Qld).
Means I can bond overnight, mmmmm. [You must be registered and logged in to see this image.]

I was just thinking it looks like too much of the disc was drilled away.
Yes, I'm an arm chair engineer (which means I do NOT have a degree).

DM

Wheel is on but I can't test ride, no headlight.

First I started with the fan forced oven as was suggested by Steve on the Gold Coast.
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My coffee temp gauge came in handy, an hour at 60 and she was well done.
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Looks the business!

Looking great, you had it on the tire balancer after gluing in the center?

Looks good.

Not balanced yet Paul. I glued in one of the s/s thread inserts that came loose in the original dis-assembly process, and clear lacquered the centre carbon we had lightly machined. Then baked in my cardboard oven.

In my initial research and seeking of advice from the alloy merchant, I failed to ensure he understood all I wanted to achieve. He sold me 2011 T6, machine bar that has been heat treated. Turns out its composition (possibly too much copper) means it cannot be hard anodised, and the colour finish is different as well as soft and very easily marked.

I am more concerned about the splines than cosmetics, so I have elected to only bolt (and not bond) the hubs to see if there are any detrimental effects. I will know in a few weeks.

Can you do a Vickers / Brinell test on it? Might give you some idea whether the splines will hold or not.

Better still, cane the piss out of it over the Lions Rd TT Oct long weekend.
Then inspect for wear, I don't expect any really, would have more confidence though if it were over engineered.

Meanwhile, been for a 70k city ride.
Just a light front wheel made a huge difference, expected that as it's connected to the handlebars and very little effort is required to turn.

Adding a lighter rear wheel has increased the responsiveness, it feels like the bike takes a tighter radius every corner. Even though I was taking it easy on a brand new rear tyre, there is evidence that the entire surface has been scrubbed in. Didn't think I was trying to lean it over.

Remember, I have dropped from a 180/55 to a 160/60 on a 5" rim ............................... loving round-a-bouts.

To increase the agility in the flip-flop considerably. (Bruno Saturno)
That was my goal and this I have achieved.

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Suspension guru, whoever you are. Rear end seems harsher now, what do I do?

Less compression and less rebound?

most likely you do not need more compression on the low speed circuit but do need more on the high speed circuit. and you will need more rebound to have the same feel you lost sprung mass. Sorry had a new third job start, and been ill at the same time so been very busy and felling like hit by a truck as well no time to visit here last week.

for 5"rim 170 is correct wide I think


4.5 = 160
5= 170
5.5 = 180
6= 190

thats what tyre co's recon you match so the rounding from the tyre is what they thought.

Thanks Uzi, I always get it arse about with suspension.

Paul, for some reason there is a limited choice in 170 tyres, I wanted to try one on my stock 5.5" rim.
At the moment it all feels good. Give me 6 hours and I'll try and tell more.

Ok, Been for a ride up to O'Reilly's with a mate on his Wilber's equipped ST2 Ducati. It has a 170/60 rear tyre.
Previously with only the front C/F wheel, both bikes felt similar for steering input and responsiveness.
Now with both C/F wheels I let John go for a squirt, On his return "F-Truck" was his first word. "I kept turning in too far, too early". That is the reason I declined a ride on his Ducati, I didn't want to go straight on, .............................. into orbit.

Definitely no tyre issues. Track day with the 180/55 side stand was scraping, a little mod near the pivot point and it tucks up further. Now with the 160/60 I am using the whole tyre, but I'm also at the edge of my comfort zone, not the bikes limit. Front tyre chicken strip may indicate some more rear ride height is needed.

Best description I can give is, it may be a big bike but it feels more like a 250 to throw around.

Update/edit 1st Oct - After this ride I pulled it all apart to check bolt tensions and especially the alloy hub splines for wear.
The anodizing hasn't been marked/worn on the splines so its back on and test some more 4th - 6th Oct over the Lions road and Mt Lindsey H'way.

Uzi - added 1 more click of High Speed Comp, was already running a lot of rebound, tried more and moved it back. [You must be registered and logged in to see this image.]