So, just to revive an old thread.
Front brake sorted - easily - standard diameter EBC disc and EBC pads, flush and fill with new DOT4.
Rear. I thought that before just fitting new linings, I should investigate and measure up what I actually had, and to see what the condition of the drum surface was actually like. Visually - Very Glazed.
Next step measure. Tried all my usual suspects for an inside mic that would measure up to around 200mm.
No luck, although, one of them has since tipped up with an internal mic set.
So, looked around at what I had.
I found an inside/outside caliper set.
SAM_9444 by
Dr Nosh, on Flickr
How was I then going to measure the caliper accurately?
SAM_9445 by
Dr Nosh, on Flickr
I have a vernier height gauge with a piece of inspection instrument quality granite that is used as a surface plate. (I used to work for a company that made amongst other things an optical device to measure the height of printed solder paste on a printed circuit board - as printed, before component placement and reflow, and the surface plate just happened to be in the boot of the company car along with other things as well when I had to return the car when made redundant, but thats another story for another day
).
I measured 5 points around the hub, at the spoke locations, and measured minimun diameter 201.10mm, maximum diameter 201.39, so ovality of 0.2mm (or 0.008" in old money). According to the Haynes manual maximum ovality is 0.02mm. My actual ovality was 10 x that
The drum absolutely needs skimming to make it round again.
Could not find anybody locally, so after a bit of searching I came across a Terry Ives at Stotfold Engineering in Biggleswade.
http://www.stotfoldengineers.co.uk/
After some discussion on the phone, I took the wheel minus tyre to Terry ,and he skimmed the drum for me and tuned it round quite quickly. (See what I did there
)
SAM_9534 by
Dr Nosh, on Flickr
Having visited Terry's workshop I found that he could undertake all sort of precision mechanical work mainly all related to motorcycle restorations - turning, milling, metal pressing and fabrication, vapor blasting, brazing/welding, assembly.
He purposely left a trace of a witness after turning, his evidence of the minimun amount of metal removed. This cannot even be felt with the finger nail. Its probably <0.02mm (0.0008")
InkedSAM_9536_LI by
Dr Nosh, on Flickr
Back at my workshop I went through the measuring procedure again.
SAM_9539 by
Dr Nosh, on Flickr
I now measured 201.40mm at all 5 points around the drum. Result.
So thats 0.2mm (0.008") removed and its round. Maximum drum diameter according to Haynes, is 201.50mm.
Plenty of life left. Probably get another 1 or 2 skims out. Considering the drum has done 37K miles in 36 years!
At this point just go back to my first post. All the wide fluctuations on the MOT testers brake effort meter was for 0.2mm. I told him that the meter was greatly magnifying what was actually happening
Reassembled the tyre and the wheel, and now waiting for an opportunity to complete a road test.
At this point I have assembled the Ferodo / Motobins shoes. Will get on order a 'soft' lining from Villiers Services and fit to compare. New lining is 4mm thick.
I'll mention a handy little tool for inserting the tube valve stem into the hole in the rim.
SAM_9541 by
Dr Nosh, on Flickr
I picked this up some while ago from
https://www.24mx.co.uk/_pid-84-2980...pbTzetd61W0t7_Ej_GxoCZk0QAvD_BwE&gclsrc=aw.ds. Thread the brass fitting through the hole in the rim and screw into the valve stem. Pull the valve stem through the rim. Easy. Saves trying to get your hands under the tyre to push the stem through.
Disclaimer. The brakes have been overhauled and are awaiting a test drive before I pronounce them 100%.