Brake disc grinding - TrueDisk LLC

Rob

Rob

Hero member
Location
Midlands, UK
Astute chap, that Keith Nairn of Laverda Scozia.  He was inspecting my spaceframe wheels with their brand new stainless steel discs and confirmed 7 thou runout.  He had already milled the hub and disc carrier faces perfectly flat and showed me that the runout was caused by inconsistent disc thickness around the disc face. He went on to observe 'anyone can make a disc these days, but not everyone can make 'em flat and parallel'!

The only way to fix the problem was by grinding - Keith explained that refacing on a lathe would be fraught with difficulty.  There has been previous comment and mixed experience on the forum with refacing of brake discs.  I found the True Disk website (www.truedisk.net) and a quick exchange of emails with Tom Tokarz convinced me that he knew what he was doing, based on the comments from Keith. 

So I shipped off my 3 discs (mounted on their carriers) to Tom on Monday.  UPS got 'em there on Wednesday and Tom turned them round on Thursday and posted them back (very securely packed) on Friday after I paid the princely sum of $45 per disc plus shipping via PayPal. 

Tom confirmed that my discs were quite a mess but had got them to within half a thou (.0005") of flat, without taking off any more material than necessary.  I thought this sounded all too good to be true, but after checking the remounted discs back home I'm absolutely delighted with the results.

TrueDisk (note the spelling) provide the same service for cast iron discs too.  Based on my experience, their service is highly recommended!
 

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Rob said:
brand new stainless steel discs
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Hi Rob

Can you tell us where the disks came from, or is that fraught with risk of litigation (a disk risk?)

Cam

PS: A note on spelling. I've always defaulted to "disk" for anything other than a compact disc, but it I just did a little googling and while there doesn't seem to be any recognised convention, it appears that "disc" is also the most often used spelling for brake rotors.
 
I would put a warrenty claim against them - they scratched the surface massively!!!  :o

:D

And btw: it is a feature that the discs are not straight and/or differ in thickness: the pads are getting pushed off the disc when you release the lever. Now they stay at the disc and overheat them...  :o

(just kidding...  :LOL:)

looking good, thanks for sharing!!
 
Can you tell us where the disks came from, or is that fraught with risk of litigation (a disk risk?)
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Given that they weren't from a commercial enterprise, and he isn't supplying them any more AFAIK - Jim Bushman.  I would say that Spub reported being delighted with his, so I may have been unlucky.  Apparently Wolfgang took some too.  I know Jim put quite a bit of research into material, hardness etc and they are an excellent copy of the drilled Brembo rotor. http://www.laverdaforum.com/forum/index.php/topic,81825.30.html

TrueDisk are based in Michigan, USA.  Contact details are on their website www.truedisk.net - 1620 West Newburg Rd, Carleton, Michigan, 48117, USA
Contact is Tom  Tokarz  Phone  (734)625-0290  Email  tokarz48117@hotmail.com
 
  I made a pair of cast iron discs from a couple of billets I had saved from when we had discs made ages ago. I had some issues with turning them on the lathe as there was some resonance when machining the outer edges that lead to a slight amount of chatter. I'm going to see how they perform - and if they are not Ok - I can have them ground locally or maybe even try a C.I recommended stone in my toolpost grinder. I wouldn't be so keen to machine the stainless discs and a grind would be almost obligatory.  Good recommendation Rob - but I expect delivery charges make it a tad expensive for non US owners. - Regards - Phil
 

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Maybe if enough units come together, it would make sense to get a re-production done by a known source (EBC, Spiegler or the likes)?

I did a re-production of SFC1000 Disks, with 13 pairs (26 discs), they came down to 175? each (complete Disc; Rotors for sure would be cheaper).
 
Metal gear in Australia make those rotors (in Stainless steel only).  Not particularly cheap, but a nice product and great to deal with.

http://metalgear.com.au/mgear-brake-disc-front-leftrightrear-p-7511.html

Yes, they are 'sided' so you end up with one spiral pattern going forwards and one going back.  But at least some (and perhaps all) bikes were like this from new.  If you look at the 81 Jota brochure for example (here: http://www.breganzane.com/archives/brochures.php) the spirals are opposed, and a couple of 1-owner bikes I know have them thus also.
When (if?) I ever get around to the rebuild on my 79 Jota I'll be asking them about some solid versions as per the earlier disks.

 
Also Stein Dinse do them in Stainless for 149 Euro's, not sure but they might fit either way so the spiral hole pattern is correct:

47201001

http://www.stein-dinse.biz/Complete-partlist/Laverda/Lav-brake-disc-1000-fro-back-280mm-Va-perforated::10776.html
 
breganzane said:
Metal gear in Australia make those rotors (in Stainless steel only).  Not particularly cheap, but a nice product and great to deal with.

http://metalgear.com.au/mgear-brake-disc-front-leftrightrear-p-7511.html
When (if?) I ever get around to the rebuild on my 79 Jota I'll be asking them about some solid versions as per the earlier disks.
Click to expand...

MetalGear don't do a solid un-drilled version yet, although I have suggested it.
DAM Racing is an agent for MetalGear discs and pads. It costs nothing to ask for a price :) Can ship worldwide.
BTW I've had to fit a couple of Lav wheels in the lathe to true up the hubs and disc carriers before fitting the new discs. Especially after the cast wheels have been dry sandblasted and repainted/powdercoated. http://www.thedam.com.au/The_DAM/DAM_Laverda_Discs.html
 
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