Brake discs for GSXR wheels

Hi Piet
Yes I've noticed some models use 320mm as opposed to 310mm.

Sounds like you got a good combination on your bike. I'm glad you mentioned the bolts, I've yet to get to that point, I'll measure them up soon, supposed to be 10.5 but that's probably a nominal figure.

I'm preparing another set of wheels for my 18" race tyres, that's the continental 3cr road legal and the Bridgestone CR11 which are sadly not.

The only other 18" are Metzeler racetec ( not available ATM.

Rob
 
Sorry for the slow reply but have been away on ride to watch the warbirds flying at Tocumwal with the Victorian Laverda crew, great planes and a great weekend 😂👍🍺🍺 Front end is a mixture of two sets of Paoli forks. One set came from a Bimota sb6 and the other set were an aftermarket set for a Harley. Reason I had to mix and match was I needed the longer for tubes from the Harley set to suit the laverda. Lovely action on the forks with hardly any stiction and quite a lot of rebound and compression adjustment, as well as spring preload. Fork yokes are Suzuki sv1000 with a custom alloy steering stem. Offset is 32mm as opposed to to the Laverda’s 45mm offset. All works good as the steering head angle has been reduced to 26 degrees.

Now I need to go and find a track day to use it again😂
Tom
 
The next upgrade to the Motodd will be a new front end. The 38mm Marzos are now the weak point of a fantastic handling frame.
Still need a fair bit of offset as the frame tubes are quite wide at the lower yoke.
 
motoddrob said:
The next upgrade to the Motodd will be a new front end. The 38mm Marzos are now the weak point of a fantastic handling frame.
Still need a fair bit of offset as the frame tubes are quite wide at the lower yoke.
Click to expand...
Just remember that offset = trail. And that greater offset = less trail.
 
What determines the off set on my Motodd is the clearance between the frame down tubes and bottom yoke.
With the current set up, standard Ceriani yokes with 1.5deg offset the bike handles fantastic, just need stiffer legs
 
I’ve never heard of offset being expressed in degrees. I’m only familiar with mm or inches back in the old days, the same with trail. The only thing I know that is measured in degrees on the front is the rake. How is it being measured?
 
I'm referring to the Ceriani yokes Laverda fitted until they changed to Marzos. the steering stem isn't parallel to the stanchions.
IIRC it's 1.5deg. to the steering head, increasing trail. If you look on the underside of the bottom yoke you'll see the steering stem isn't centred to the casting.
The SFC750 used parallel yokes as did the 3ce that Slater Bros fitted them to. As far as I know all the Ceriani fork Laverda used on their production bikes used those offset yokes.
 
You clearly see the difference between the SFC and the yokes fitted to my Motodd
 

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So the rake is increased by 1.5* over the angle of the stem. Gotcha, it was the reference to offset that was throwing me off. Essentially you have less offset on the bottom clamp than on the top. Along with angle bored stem holes.

We did something similar when we built cheater GSXRs: we raised the rear so much to get the correct swingarm angle that the rake became too steep and trail just went away. To fix the front we used smaller steering head bearings and a smaller stem and had our machinist make new bearing cups with an angle in them.

The factory Suzuki team didn’t dare to do this for fear of getting caught so all season Matt Mladin raced with his handlebars violently shaking under braking. Eventually we just pulled the rake out to have stock front geometry when the back was dramatically raised and this became standard for privateers. This was a lot easier and cheaper.
 
You used to be able to buy adjustable triple trees with inserts that allowed adjustments to change the trail figers and offset. Apparently, fitting SFC parallel triple trees improves stability over the non-parallel ones for high-speed use, that must increase the trail dimension, I guess. Late model Ducatis had factory available longer Magnesium swingarms that required triple tree adjustments to get optimal geometry, for racing, and all the cool kids wanted that. There are places in Oz that make custom trees. Batto was heading there years back, I think his Blue RGA got the only set he was offering sets till I think the workload became too much. Finding any frontends that come close to working also hits a bit of a dead end. I was amazed at how much flex reduction happened after I swapped my old Husky 35mm forks to 43mm forks off a 125cc Kawasaki MX bike; the disc brake helped as well.
 
Vince said:
You used to be able to buy adjustable triple trees with inserts that allowed adjustments to change the trail figers and offset. Apparently, fitting SFC parallel triple trees improves stability over the non-parallel ones for high-speed use, that must increase the trail dimension, I guess. Late model Ducatis had factory available longer Magnesium swingarms that required triple tree adjustments to get optimal geometry, for racing, and all the cool kids wanted that. There are places in Oz that make custom trees. Batto was heading there years back, I think his Blue RGA got the only set he was offering sets till I think the workload became too much. Finding any frontends that come close to working also hits a bit of a dead end. I was amazed at how much flex reduction happened after I swapped my old Husky 35mm forks to 43mm forks off a 125cc Kawasaki MX bike; the disc brake helped as well.
Click to expand...
we machined our own triple clamps on our race bikes Vince, is not rocket science
 
I guess all it comes to is 2 alloy plates with a few holes in them. I have some hole saws and a 5-inch grinder. I start tomorrow. Maybe not. Arriving at a design that works for an improvement over std and fits the frame and tank would take some clever figuring. It's a bit academic to me these days, no chance I will be overpowering my 38mm Cers.
 
Making your own is the easiest way to incorporate modern suspension (with all its benefits of adjustability and low stiction) on an old bike, ie, one with long rake figures. Simply fitting a complete front end from a modern bike - which will usually have shallow offset matched to relatively steep rake - gives you trail figures so way out that no amount of fiddling with settings will ever produce workable steering.

So you either cut the head tube off and replace it at a steeper angle - and use the shallow offset clamps, or use triple clamps with more offset ... which usually means making your own, because the ones that came with the forks are matched to a completely different frame geometry.
 
Pretty much what happened when I fitted a later disc brake frontend to my XT500 Yamaha: I went to the local Motolinner place, and they were everywhere in the 1980s. They had them heat and push my frame headstock out to 27 degrees—knowing nothing except what the Chopper blokes did back then. Years later, I read Tony Forles' book and found out so much more. I lucked out, and that XT handles and steers really well.
www.google.com.au

Motorcycle Handling and Chassis Design

Provides a thorough explanation of the structure and performance of motorcycle frames and other chassis components.
www.google.com.au
 
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