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H: Hubs, Wheels and Tyres Rear Drum Runout - what is an acceptable figure?

Spqreddie

Well Known and Active Website User
VOC Member
Hello!
I am finishing rebuilding my rear wheel.
Unfortunately I didn't check the individual components before to start.... (Hub faces and drum faces and holes), but mounted all the parts as they were.

I have the following reading now. Are these acceptable?

Side 1:
  • Side movement ( measured on the external diameter - Drum flange) = 18 cent of a mm (7 Thou if I got the conversion right!)
  • Vertical (measured in the internal diameter of the drum) = 7 cent of a mm (2,7 thou)

Side 2:
  • Side movement ( measured on the external diameter - Drum flange) =12 cent of mm (4,7 thou)
  • Vertical (measured in the internal diameter of the drum) = 13 cent of mm (5,1 thou)
  • Chain Sprocket mounded on drum on side 2= 38 cent of a mm (15 thou)

Rear Hub Allignment.jpeg
 

Spqreddie

Well Known and Active Website User
VOC Member
Thank you Greg,
I think it sit square, but as mentioned unfortunately I didn't measure before to assembly... so it's a visual assumption.

Now before, to take everything apart again, given the drum doesn't seems to be much out of line, I would like to know if the runout I have measured, is considered acceptable.

Thank you all!
Edmondo
 

Gene Nehring

Well Known and Active Website User
VOC Member
Thank you Greg,
I think it sit square, but as mentioned unfortunately I didn't measure before to assembly... so it's a visual assumption.

Now before, to take everything apart again, given the drum doesn't seems to be much out of line, I would like to know if the runout I have measured, is considered acceptable.

Thank you all!
Edmondo
I think given the build up I was happy with under 5 thou on the faces of the drums after all the build up. I believe mine were at about 3 thou.
 

Simon Dinsdale

VOC Machine Registrar
VOC Member
VOC Forum Moderator
Yes generally there is a difference between the cheaper cast drums and those machined from a solid billet
Cast v solid billet has nothing to do with it. The critical surfaces are machined on both type and so both type could be machined right or wrong.

I find that if the drums has paint on the area where it contacts the spoke flange then the paint can built up around the edges and cause problems. Same with spoke flanges as the factory originals were cadnium plated so no paint build up, but if you have rusty originals and then blast and paint them then the paint on the contact face can cause problems.

Simon
 

Black Flash

Well Known and Active Website User
VOC Member
Good point Bruce.
It is a common disbelief that the screws will take the shearing force in the Vincent wheel.
As any engineer will know the flange is holding its position solely by the clamping force through the nuts and bolts. That why all the faces must be meticulously cleaned, all edges deburred, especially the holes of the spoke flanges and in the hubs. I have seen really badly undeburred items for sale from various sources.
Regarding the spoke problem, Always try to pull an A4 sheet of paper between the spoke heads and the assembled drum. If it catches and tears, you are likely to have a problem with the rear of the drum touching the spokes and introducing a tumble of the drum.
Bernd
 

Spqreddie

Well Known and Active Website User
VOC Member
I think given the build up I was happy with under 5 thou on the faces of the drums after all the build up. I believe mine were at about 3 thou.
Thank you, my figures seems close to yours, so i hope to be ok too..
Would the issue of spoke bends touching the drum be happening here? Peter Barker used to offer washers to space things out, maybe the VOCSC does now.

Edit; They have a ring for the purpose PN H66
Hello Bruce, no there is enough clearance thanks!
Good point Bruce.
It is a common disbelief that the screws will take the shearing force in the Vincent wheel.
As any engineer will know the flange is holding its position solely by the clamping force through the nuts and bolts. That why all the faces must be meticulously cleaned, all edges deburred, especially the holes of the spoke flanges and in the hubs. I have seen really badly undeburred items for sale from various sources.
Regarding the spoke problem, Always try to pull an A4 sheet of paper between the spoke heads and the assembled drum. If it catches and tears, you are likely to have a problem with the rear of the drum touching the spokes and introducing a tumble of the drum.
Bernd
Thanks Bernd, enough cleareance. And good point about the clamping force indeed.

Any other advice? it my "wobbling" acceptable?
 

Michael Vane-Hunt

Well Known and Active Website User
VOC Member
Hello!
I am finishing rebuilding my rear wheel.
Unfortunately I didn't check the individual components before to start.... (Hub faces and drum faces and holes), but mounted all the parts as they were.

I have the following reading now. Are these acceptable?

Side 1:
  • Side movement ( measured on the external diameter - Drum flange) = 18 cent of a mm (7 Thou if I got the conversion right!)
  • Vertical (measured in the internal diameter of the drum) = 7 cent of a mm (2,7 thou)

Side 2:
  • Side movement ( measured on the external diameter - Drum flange) =12 cent of mm (4,7 thou)
  • Vertical (measured in the internal diameter of the drum) = 13 cent of mm (5,1 thou)
  • Chain Sprocket mounded on drum on side 2= 38 cent of a mm (15 thou)

View attachment 41210
It is hard to see but it looks like the spoke flange is painted also the one nut i can see is not tight.
 

Spqreddie

Well Known and Active Website User
VOC Member
Hello Michael, yes, spoke flanges are painted. and indeed, I had finished rebuild the wheel when this photo was taken, but measurements were taken with all tight and in place.
 

Old Bill

Well Known and Active Website User
VOC Member
From experience of both club solid billet drums and cast items l have found the following; club drums are machined on the inside ie spoke side and l have never found them foul the spoke bends either with cad plated or stainless flanges, they also have the drain hole drillings absent from cast items. Also when used with Spares co linings the brakes give a vastly improved performance over the cast offerings which l have also found to be inclined to crack around the mounting bolt holes. One other point worth mentioning is that hubs machined from solid billets are superior to cast items despite cast items being machined post production. Just my experience, but l have fitted quite a few drums/ hubs/ flanges etc over the years......
 

Vincent Brake

Well Known and Active Website User
VOC Member
I have found that radial play can be up to 0,1mm without so much intermittent brakeing, that is with a 2x2 LS set up. axial wobble is to no problems at all. execpt for the sight of it....
i guess for standard set up even 0,2mm radial is OK, as the unstiff set up forgives a lote here...

note hovever that the MOSTimportant is the flat surface of the HUB, The SPOKE flange DRUM. mostly i had to re-machine, also with NEW parts, i alwas say I buy 90% and the other 10% in quality i do myself. it works V.v. timewise though. if not flat, one gets cracks in the drum, same with the spokes, just grind a bit away on the spot, when interferring.

if bolts dont fit, i have a hand reamer 8 mm (oh sorry Mr Bananaman 5/16") this has a conical part. (use it in a drill press for perpendiculair reasons) But first try and find the position of parts, so most bolts fit.
Und der Berndie hat recht, but if a bit of radial play is there no problem, it cant go far, and braking force in Nm is not that much, it will hold on friction even mountain down.
All in all its just comon engineering.
 

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