lets go racing

acadian said:

my version of the valve spring/engine support bracket, this has a 7/16-20 bolt threading into a valve cup from the bottom

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I am intrigued by your build! I guess you positioned the bracket on the frame/engine centerline, and intend to use an asymmetric bridge at the cradle to transmit engine weight onto the spring?

Bracket and valve cup need to be parallel to the lower frame rails, which are horizontal, so the valve cup could just as well have been integral with the bracket. One bolt less to loose, and a little bit of weight shed, but a bolted solution gives you some positioning freedom of course.

- Knut

acadian said:

SA and cradle reinforced, new verniers installed

View attachment 115056

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Interesting mod. Has this been tried by others? I guess the design intent is preventing the cradle plate in compression to buckle / bend out of plane? It is possible to take this one step further, by installing a solid plate between S/A tube and cradle tube, effectively creating a H-beam section. This however opens up a new direct load path for transverse forces, which will load one of the existing rear frame lugs additionally (they may subsequently fracture due to bending).

- Knut

lcrken said:

I used the 5 hole conversion carrier to fit the Norvil rotor to a Mk3 Commando front end, along with the stock hub and Norvil slider. It was pretty straight forward., and works quite well.

View attachment 115748

View attachment 115749

View attachment 115750

Ken

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Can't locate this carrier on RGM's site, so I've emailed Norvil to enquire about availability and part #

mdt-son said:

I am intrigued by your build! I guess you positioned the bracket on the frame/engine centerline, and intend to use an asymmetric bridge at the cradle to transmit engine weight onto the spring?

- Knut

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Correct, I discovered this by browsing the frame modification threads on this site, Jim Comstock pioneered it I believe, though I intend to use it in addition to front cradle rubbers rather than as a replacement, the other reinforcements I've done (engine cradle etc.) are fairly standard for a commando framed race bike IMO, though the real work will be around reinforcing the stock 750 cases, I'm consulting with Herb on that, but in addition to fabricating a gearbox outrigger, I'll be making a shrink fit plate for the drive side case and gussets for the case-cradle lugs, the trick will be avoiding the need to weld as much as possible (Herb used to bolt his drive side reinforcing plates to the face of the case). Anyway, will be looking to the forum for advice as I move forward

Great project! I noticed on the previous page that you are going with the Landsdowne dampers. I don't know for sure, but I recall someone saying that a certain vintage class of racing required that no damper controls be visible. I could be wrong, but I thought that's why Cosentino Engineering make a removable fork cap cover that hides the controls on their dampers. You might want to look at the rules of the class you are going to race in to check my "baloney"

o0norton0o said:

Great project! I noticed on the previous page that you are going with the Landsdowne dampers. I don't know for sure, but I recall someone saying that a certain vintage class of racing required that no damper controls be visible. I could be wrong, but I thought that's why Cosentino Engineering make a removable fork cap cover that hides the controls on their dampers. You might want to look at the rules of the class you are going to race in to check my "baloney"

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Thanks for the head's up, looks like you're right, from tech rules:

"4i FORKS must be of a type available during the period. Post period anti-dive devices are not
permitted. Maximum stanchion diameter is 38mm, unless the motorcycle was originally equipped
with stanchions of a larger diameter. Aftermarket fork braces of any type and style, similar to those
available in the period, are acceptable."

F'in great

Looks like I'll have to figure out a way to make the adjusters inconspicuous

acadian said:

Thanks for the head's up, looks like you're right, from tech rules:

"4i FORKS must be of a type available during the period. Post period anti-dive devices are not
permitted. Maximum stanchion diameter is 38mm, unless the motorcycle was originally equipped
with stanchions of a larger diameter. Aftermarket fork braces of any type and style, similar to those
available in the period, are acceptable."

F'in great

Looks like I'll have to figure out a way to make the adjusters inconspicuous

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There is no mention there of visible damping adjusters being illegal ?

Fast Eddie said:

There is no mention there of visible damping adjusters being illegal ?

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I assume the phrase "forks available during the period" includes dampers, don't you? Were externally adjustable dampers available in the 60's or whatever period the class rules refer to?

- Knut

mdt-son said:

I assume the phrase "forks available during the period" includes dampers, don't you? Were externally adjustable dampers available in the 60's or whatever period the class rules refer to?

- Knut

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That’s an interpretation that needs clarifying. Different clubs will allow, or not, such mods to period forks.

Careful study and clarification of the rules, in order to build the most competitive machine, is all part of racing.

No issues with external fork adjusters in the UK at least.
My F1 didn't have them from the factory but I was OK'd by the CRMC to have them on mine.

Surely the law of omission applies - if they're not specifically excluded they're not illegal.

The obvious answer is to ask

B+Bogus said:

No issues with external fork adjusters in the UK at least.
My F1 didn't have them from the factory but I was OK'd by the CRMC to have them on mine.

Surely the law of omission applies - if they're not specifically excluded they're not illegal.

The obvious answer is to ask

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And if all else fails… duct tape over them…!

I will enquire, I just assumed "anti dive device" would include adjustable dampers

acadian said:

I will enquire, I just assumed "anti dive device" would include adjustable dampers

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Entirely different things. See what your enquiry yields.

I agree an anti dive device is a mechanical set up with linkages from the 80s. The principal was sound but I never liked their appearances .
If we are wrong use Triumph fork oil stickers the perfect cover up.

When I pit crewed for dirt cars, other racers could pay for an inspection by the officials of any car competing in a race after a race was over. If the person refused to allow the inspection, he was disqualified from the race. It was a way of keeping guys from having illegal parts inside their engines when their class required stock parts. It also applied to displacement measurements for the class and things like tire stagger, tire sizes too. Maybe if you know someone racing in the class you belong in, they can give you an idea of what sort of inspection you can expect, and what sort of enforcement is used.

One year, a racer at our track won the last race of the year to become the class champion and his runner up for the class championship paid for his inspection after that last race. The racer in question gave up the win of the last race of the year and gave up the class championship because he refused to let the officials tear down his engine... My Pit chief loved that because he said the guy was known to have cheated before by all his competitors. So there is that kind of thing to consider when you are racing... So if it's illegal to use those landsdownes.....you might want to know in advance.

Similar but different - a very successful sidecar racer was challenged under the same rule by a competitor who'd spent a fortune on his engine but still couldn't beat him, and put up the required £100.
The engine was stripped and found to be 100% legal, so he got to keep the money.
He then held up the £100 and asked for the other guy to do the same.
The other guy refused, loaded up, drove off and got a ban instead!

Got a quote for the Norvil homologated disc with 5 bolt carrier... $650, so I think I'll put that on hold for the moment, saving my pennies for the Molnar crank. In the meantime I got the rear hub assembly finished, judicious lightening of the various bits, also made up a set of axle adjusters that fit around the axle nuts. Just waiting on rims and spokes

Fast Eddie said:

That’s an interpretation that needs clarifying. Different clubs will allow, or not, such mods to period forks.

Careful study and clarification of the rules, in order to build the most competitive machine, is all part of racing.

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Those rules are a reason many people do not race. If a bike has a single, twin or four cylinder air cooled four-stroke motor of similar capacity to my own, I am happy to race against it. I do not care if it is fuel injected, or even runs nitro. If I want to race again, I need to apply for a log book from Motorcycling Australia, and pay a fee. Then join another club and pay a fee. Then enter for a race and pay a fee. Then have a ride at a practice day and pay a fee. - What is the common factor ? - Money-making bureaucracy bullshit ! Some people are paranoid about getting beaten, that is why we have rules. You will find the rules only suit certain bikes - who writes the rules ?
In Australia, most classic bikes are extremely over-bored. It does not make any difference.
I think the only bike which would give me a real problem would be a VT1000 Suzuki.

One of my achievements is - in Australia, our industrial safety laws are now risk-based instead of prescriptive in every jurisdiction. Motor race circuits have been deemed by our courts as not being workplaces. But when controls are risk-based, they might be better. What do prescriptive rules do for classic racing ?
All I have ever wanted out of road racing is to develop a certain TYPE of motorcycle and have fun. They can hang Christmas trees all over them for all I care.

Chris said:

I agree an anti dive device is a mechanical set up with linkages from the 80s. The principal was sound but I never liked their appearances .
If we are wrong use Triumph fork oil stickers the perfect cover up.

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First rule of production racing - don't get behind on rule bending.
Second rule - don't get too far ahead either

Adjustable anti-dive might change the way the bike behaves when the front brake is used - or not ? Race organisers should be more pointed towards getting entries than stopping modifications which do almost nothing but provide a psychological advantage. Agostini crash helmets should be banned - everybody might go home, rather than race.
Guys who have tyre-warmers frighten me.