Disk brake front rim dimple pattern

Hi all,
I've just bought this Borrani 19 x WM2 rim 40 holes with 3 x 1 dimple pattern,
not a common pattern but I believe I can use it on a 72 disk brake hub?
I found this info on Central Wheel site
https://www.central-wheel.co.uk/cwc-british-chrome-rim-info
Am I right? Any advice?
thanks in advance
Mario

The problem you will have is that the 3 x 1 may be the same but are they drilled at the right angle for a small hub and with the offset for a disc where one side has nearly vertical spokes. The odds of some random rim being the right one is remote.

Any rim/wheel I might be interested to fashion, I document before disassembly with measurements using this drawing.
If I am trying to find suitability for a rims use, I take 4 spokes with nipples and insert them in 4 consecutive holes, (usually adjacent to the valve stem hole). Push them all against the rim to find their natural angle of repose, and write them each down.
This chart is for a commando disc rim. spokes 2-4 are for the disc side which is almost straight as you can see the R angle is very low.

Cool chart and great info!

The original Norton front rims where drilled differently to everything else. The left dimples were used for the rh hub side to give a little bit of "lean" to the rh spokes as they are almost vertical. Thus they get a slight angle from vertical and make the wheel a bit stronger against side loads. Norton knew the shortcoming of their disc front wheel as they specified stronger spokes and two different threads for the front wheel compared to the back wheel. The rims that I got from AN (or Central Wheel) in the last few years were all drilled wrong - i.e. RH dimples for RH spokes - thus making the wheel very weak despite fully tensioned spokes. Dynodaves drawing shows that the two dimples marked "R" go to the left side of the hub - this is exactly as the original wheels were built. So be aware of that when you order rims from AN or elsewhere....
cheers

No from me, but interesting bit of history on the disc wheel.

''Here is the history on the Norton Front Disc wheel.


Norton finished the design of the bike and then came to my father with a hub to build a wheel to fit - due to the fact that they had not considered the wheel in their original design the wheel had to be made with the disc side virtually flat to make it fit the bike - the original wheels were therefore produced with rims with a 1x1 dimple pattern and cross laced to fit and accommodate offset requirement 8 gauge spokes were used on the flat side and 9 gauge on the other for extra strength on the flat side. Later when the disc brake rear hub was introduced both front and rear wheels were built with 3x1 dimple rims meaning that the front wheel then could be laced with a standard lacing pattern, so both 3x1 with standard lacing and 1x1 cross laced can be used for building the front wheel - we believe the 1x1 was original for 2 years - 1972-1973.

Normally, when available we will supply the rims with a 3x1 dimple pattern to keep the lacing pattern standard regardless of the year - but with alloy rims we only stock 1x1 dimple pattern blanks so these would always be supplied for cross laced lacing pattern.''

Madnorton said:

No from me, but interesting bit of history on the disc wheel.

"Later when the disc brake rear hub was introduced both front and rear wheels were built with 3x1 dimple rims"

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Well, that isn't right!

The early 850 Mk3 front rims were apparently the same 1x1 pattern Dunlop MC275 and the later Mk3 rims were MC288, also 1x1 pattern. The Mk3 MC289 rear rim is 3x1.

Madnorton said:

"we believe the 1x1 was original for 2 years - 1972-1973."

Click to expand...

Obviously not correct either!

Would "we" happen to be CWC?

MKIII 33390x, still new, 5 miles, never registered, 1X1 MC288 front rim... laced same as MC275 show in drawing above, however spoke gauge not checked.

Curious to know the original author of ''Here is the history on the Norton Front Disc wheel.
In the past I got MK3 front rim from (BCS) Devon that the spoke pattern angles were not even close for a disc wheel, yet the rear was perfect 3x1 and spoke angles were good.
Last MK3 rim set sourced and specified by Walridge from CW was good/acceptable but supplied as MC275/288 1x1 front 3x1 rear.

CW06-1951 19xWm2 40 Norton Front Disc 3 x 1 Dimple Pattern
They may work OK but I would not buy these.

Been digging, from what I can tell the 06.1951 front MC 275 rim cross laced was used from early 1971 until 1975, it is 1x1. Can't find anything yet to suggest that the front was also supplied as 3x1. Now the rear, there was a 2x1 rear rim (Mar '74) for the MK3 but this seems to have never made it onto the bikes as the 06.6119 3x1 rim was drawn in July '74. I have eyes on a MC 287 3x1 rim here that is laced to MK3 hub. Can't find anything to suggest that the MK3 had a rear 1x1 rim at anytime, not even in the MK3 build book. The MC code should be on the disc side for the front wheel, adjacent to the near upright spokes.

Madnorton said:

Been digging, from what I can tell the 06.1951 front MC 275 rim cross laced was used from early 1971 until 1975, it is 1x1.

Click to expand...

MC275 is the front disc brake rim so 1972 - early 1975.
The front and rear drum brake rims were MB41 except for some 850 Mk2/2As that had MB286 rear. Also some Jones (rear?) rims appear to have been fitted to Mk2/2A.

https://www.accessnorton.com/NortonCommando/dunlop-mc286-rim.10110/

Madnorton said:

I have eyes on a MC 287 3x1 rim here that is laced to MK3 hub.

Click to expand...

MC287 has been mentioned for Mk3 rear.

https://www.accessnorton.com/NortonCommando/mkiii-rear-rim-pattern.9769/#post-130173

Don’t know if this is helpful
1/75 MKIII
Front MC 275
Rear MC 287
Pete

Deets55 said:

View attachment 7160 View attachment 7159
Don’t know if this is helpful
1/75 MKIII
Front MC 275
Rear MC 287
Pete

Click to expand...

Has that rear wheel been rebuilt? The spokes look bent near the nipples and the rim also looks as if it could be fitted the wrong way around as the three dimples would normally be on the sprocket side and single on the disc side?

Les,
That’s the way I got them about 27 years ago. I’ve since rebuilt with flanged Excel rims and SS spokes using the same layout.
Pete

http://vintagebikemagazine.com/technical-articles/lacing-norton-front-disc-rim-06-1951/
may be usefull........??

L.A.B. said:

the three dimples would normally be on the sprocket side and single on the disc side?

Click to expand...

+1
That's how my two rear wheels are built, and no bent spokes...

marinatlas said:

http://vintagebikemagazine.com/technical-articles/lacing-norton-front-disc-rim-06-1951/
may be usefull........??

Click to expand...

edit=useless

One problem with the article.....using a CWC rim for the article, and the credit "Text and Pictures Copyright John Healy 1998-2015" His article does not match historical evidence of hundreds of bikes that came from the norton factory.
So far, since 1988, I do not recall ever seeing in north america an unrestored pre MKIII commando with a 3x1 rim.

If there actually is an original norton factory (not AN) 3x1 commando rim then they must be quite rare and an exception rather than the rule.

dynodave said:

One problem with the article.....using a CWC rim for the article, and the credit "Text and Pictures Copyright John Healy 1998-2015" His article does not match historical evidence of hundreds of bikes that came from the norton factory.
So far, since 1988, I do not recall ever seeing in north america an unrestored pre MKIII commando with a 3x1 rim.

Click to expand...

He does know, so he should have mentioned it.

http://www.britbike.com/forums/ubbt...tern-disk-brake-norton-front-wheel#Post355431

John Healy

"This 3x1 pattern never came stock on the Norton front wheel.
Central Wheel, and others, have started to use the 3x1 dimpling as their standard for the Norton front wheel in just the last couple of years.

Click to expand...

I don't do many rim lacing jobs any more, I now mostly just teach classes and have club guys do their own wheels here in my shop. Very entertaining....LOL
Here was one of my favorite lacing jobs. A Rickman front disc brake hub and Borrani rim for my 68 Dunstall Atlas. CWC made up my stainless spoke set.

Les,
Thinking back I had Buchanan label the rims front/rear, direction of rotation and disc side. I followed the same lacing pattern but did not realize the dimple issue. Guess I got lucky because everything lined up naturally and no bent spokes/nipples.
I’m still not sure what you mean by “3 dimples on the sprocket side an one on the disc”.
Thanks,
Pete

Your rim is flipped over from normal. That is not good.
Why so? The sprocket side spokes are apart by the thickness of the hub flange, almost 1/4". They easily pass by each other going down to the rim.
However...
The disc side spokes are (inner spoke) runs in a groove, and the outer spoke is on the hub surface and is smack adjacent to the inner spoke. They would easily and likely interfere with each other on the way down to the rim especially if the wrong dimples are used. Such is the case with yours currently being in the row of 3 dimples on the right.
Therefore:
The disc side outer spoke needs the 1 dimple on the right side of the rim to allow clearance for the inner spoke (in the groove) which then would go to one of the left side 3 dimples. They will then not rub each other in passing.

Even correctly assembled, they do all touch a little and/or come very close. It's a matter of how much they interfere with each other. 3 on left and 1 on right gives best clearance for all spokes.