lets go racing

Slow going while waiting on parts, but finding some time to work on ancillaries.

Mounting plate for the Girling caliper that arrived

lets go racing
lets go racing
lets go racing


Also fabbed up the bracket for the front engine mount that the frame spring contacts.

Next job is onto making a set of rearset mounting plates. I've been pouring through information on the various rigging that folks have engineered to control lateral play at the rear of the cradle; there's heim joint linkages, aluminium blocks between the cradle plates (Herb Becker), and I've seen slider puck set ups located near the bottom of the cradle. Some folks I've spoken to suggest trying to control the play at or as close to the source as possible (i.e. the swingarm pivot), so I made up these acetal swingarm end caps which are just slightly larger than the swingarm tube, and a pair of aluminium slider "pucks" threaded onto 3/8 rod with an inset hex head. The rearset plates I'll make up next will extend forward approx 1.75" to cover the area adjacent to the swingarm, that's where the alu pucks will thread in and abut the end caps, nipped up with jam nut on both sides. May end up being a case of pissing in the wind, but we'll see if it works out

lets go racing
 
I am very old-fashioned. I always prefer a firm connection between the handle bars and the rear tyre contact patch. Manx Nortons used to have Silentbloc bearings in the swing arm. Apparently, if they were replaced with solid brass, the difference could be felt. I do not know what could be done with a Commando frame which might not cause it to crack. Perhaps the cradle could be forced to rotate around the mount underneath the gearbox ?
 
Trial fitting components with a set of scrap cases, front mount rebuilt with new verniers and with the lower spring bracket installed everything lines up. I spaced the spring bracket based on compressed spring length at approx loaded engine weight, I should have around .125 of adjustment range but we'll see. The RGM vernier kit needed about .015 skimmed off the caps to fit smoothly between the frame tabs, which themselves were in spec

lets go racing
lets go racing
 
acadian said:
Trial fitting components with a set of scrap cases, front mount rebuilt with new verniers and with the lower spring bracket installed everything lines up. I spaced the spring bracket based on compressed spring length at approx loaded engine weight, I should have around .125 of adjustment range but we'll see. The RGM vernier kit needed about .015 skimmed off the caps to fit smoothly between the frame tabs, which themselves were in spec

View attachment 116395View attachment 116396
Click to expand...
Could you have set that spring cup us with threads and an adjustable bolt at the bottom to fine tune it in a similar manner to the top spring (MkIII) setup? (Where the front mount bolt just slides thru cleanly at rest)
 
grandpaul said:
Could you have set that spring cup us with threads and an adjustable bolt at the bottom to fine tune it in a similar manner to the top spring (MkIII) setup? (Where the front mount bolt just slides thru cleanly at rest)
Click to expand...
Yup, that's exactly how it's designed
lets go racing
 
More progress, got around to mocking up and fabricating the rearset plates

IMG_4779.jpeg


IMG_4781.jpeg


IMG_4782.jpeg


Made up spacers for the plates to ensure that lateral control pucks are parallel with the delrin caps on the swingarm, when threaded down they sit nicely up against the caps.

IMG_4783.jpeg


The tank arrived a few weeks back, and the the rims and spokes earlier this week, so next on to wheel building

IMG_4784.jpeg
IMG_4785.jpeg
 
Sweet!!! I see you are using the older oil tank. That's the tank I have on my 70 commando. I don't use the late model oil filter which people mount below the cradle. Instead I use a transmission filter that Jim Comstock suggested, which I mounted in my oil return line. I made a bracket that attaches to the bottom bolts of the oil tank and I just double zip tie the filter and a piece of foam rubber to the bracket so it doesn't bounce around and make noise. I also found a pre-bent hose that has all the right turns for where I mounted the filter to get to it and then from it to the oil tank.... It's a good alternative to adding an oil filter with the extra hoses and the fixture under the cradle which your support spring will probably keep you from mounting...

here's the thread with the pictures of where I mounted the magnafine transmission filter in my oil return line.

https://www.accessnorton.com/Norton...nstall-for-a-70-model-central-oil-tank.28202/
 
Last edited:
I assume you are building the bike to be "legal" per some association's rulebook for a certain class (but we won't tell on you if you are bending the rules a little) Which association and class?
 
nortonmargie said:
I assume you are building the bike to be "legal" per some association's rulebook for a certain class (but we won't tell on you if you are bending the rules a little) Which association and class?
Click to expand...

Yes, building as per VRRA period 2 supervintage rules, hence the solid front disc (no floaters allowed), and I have to lose the adjustable dampers as they're not permitted. The frame and suspension modifications are allowed.

acotrel said:
Does that bolt which passes through the Z plate run through an isolastic mount, or is only the front mount isolastic ?
Click to expand...

Yes, that's the rear isolastic mount bolt, the threaded pucks below abut the delrin swingarm caps to prevent lateral movement
 
acadian said:
Yes, building as per VRRA period 2 supervintage rules, hence the solid front disc (no floaters allowed), and I have to lose the adjustable dampers as they're not permitted. The frame and suspension modifications are allowed.



Yes, that's the rear isolastic mount bolt, the threaded pucks below abut the delrin swingarm caps to prevent lateral movement
Click to expand...
Are you not allowed to use the dampers or are they not allowed to be visible? Worth checking the rules properly.

FWIW I did not get one with Lansdowne dampers on the track anyway.
 
acotrel said:
Does that bolt which passes through the Z plate run through an isolastic mount, or is only the front mount isolastic ?
Click to expand...
that is the rear swing arm, now with added lateral delrin abutment. The isolastic mount is out of shot, above it, as on all Commandos.
 
Fast Eddie said:
Are you not allowed to use the dampers or are they not allowed to be visible? Worth checking the rules properly.

FWIW I did not get one with Lansdowne dampers on the track anyway.
Click to expand...
The response I got re: can they be hidden was "don't try it"
 
acadian said:
The response I got re: can they be hidden was "don't try it"
Click to expand...
Seriously ?

I assume from their answer that all adjustable dampers are illegal and they interpreted your questions as asking if it’s possible to cheat!

Thats just wrong !

It’s a genuine question appertaining to actually trying to understand the rules.

IE:

Are adjustable dampers illegal ?

Or

Is it illegal to have visible adjustment for dampers ?
 
Fast Eddie said:
Seriously ?

I assume from their answer that all adjustable dampers are illegal and they interpreted your questions as asking if it’s possible to cheat!

Thats just wrong !

It’s a genuine question appertaining to actually trying to understand the rules.

IE:

Are adjustable dampers illegal ?

Or

Is it illegal to have visible adjustment for dampers ?
Click to expand...
It's very frustrating, I have spoken with a builder who ran in the same class and was told that he's "gotten by" inspection, but also gotten caught. In his opinion it's a crap shoot depending on who is performing the inspection. But in terms of actual legality, adjustable fork dampers are not permitted.

What's more aggravating is that lack of harmonization in rules between VRRA (canada) and AHRMA (usa), many guys race on both sides of the border and, in fact, a VRRA licence (obtained in Canada) fully qualifies you for AHRMA... so it's clear that they want cross border competitors.

I'm not sure what guys do... I mean, do they pre prep their bikes for two set ups (i.e. dampers, floating discs) and then swap on either side of the border??

edit: another example in carbs - VRRA smoothbore size limit = 31mm, AHRMA = 34mm
 
Last edited:
In theory, unless you really are searching for every last tenth of a second, you don’t really need easily adjustable dampers, set them for your weight and the bikes weight and you should good. Good damping doesn’t have to mean easily adjustable damping. I say ‘easily adjustable coz if you think about it ALL damping is adjustable !!

Taking that one step further, with better bushes available, and the ability to experiment with different oils, you will probably find that the standard set up works fine. I was pretty amazed to see in the video about Fred Warmsley restoring the Barry Sheene Manx that he claims to only ever use standard fork internals, and Fred builds some quick bikes !
 
Last edited:
With any sort of classic racing, there is always a conflict between conservation and development. I dislike seeing genuine race bikes lose their originality. In about 1973, I was offered an Ex-Ginger Molloy 1961 500cc Manx for $1300. I did not buy it because I would never try to make it better. With me development is a key issue. I would rather race in a open class than in an historic class. 'Cheating' is bullshit. Back when Manx Nortons were the go, everybody used methanol fuel. Dean Jesser had a 730cc Triton which Ken Blake rode. The fuel was 30% each of methanol, nitro and toluene. So effectively Ken was riding a bomb in A Grade races. When the bike spread it's guts at Mallala, four riders went down the road. Nobody complained - it was all part of the fun.
If I race, I do not care what the other guys ride. There are parts of Winton Raceway and Mount Gambier Raceway where I am always quicker. My interest is always in making the bike faster, and that involves a lot more than just increasing horsepower.
I always doubted the 850 Commando motor - however it surprised me - it is good enough.
 

Similar threads

acotrel
Nortons and classic road racing
Replies
5
Views
211
concours
concours
C
Clutch for racing
Replies
10
Views
461
acotrel
acotrel
storm42
Racing 2023
Replies
12
Views
682
storm42
storm42
acotrel
Road Racing
Replies
11
Views
963
acotrel
acotrel
SteveA
When to quit racing and track riding?
2 3 4 5 6 7
Replies
132
Views
8,075
acotrel
acotrel
Back
Top