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Z1000 Disc Thickness?

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750steve
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Z1000 Disc Thickness?

#1 PostAuthor: 750steve » Tue Mar 06, 2012 2:51 pm

Can amyone tell me what thickness the OE discs were please for the following models, they all used the same disc.

Drilled/Ventilated
KZ1000-A3 (KZ1000) (1979)
KZ1000-A3A (KZ1000) (1979)
KZ1000-A4 (KZ1000) (1980)
KZ1000-B3 (KZ1000 LTD) (1979)
KZ1000-B4 (LTD) (1980)
KZ1000-C2 (Police 1000) (1979)
KZ1000-C3 (Police 1000) (1980)
KZ1000-C4 (Police 1000) (1981)
KZ1000-D3 (Z1R) (1980)
KZ1000-G1 (Classic) (1980)
KZ650-E1 (LTD) (1980)
KZ650-F1 (1980)
KZ750-G1 (LTD II) (1980)


Non - Drilled (same disc with no holes
KZ1000-B1 (KZ1000 LTD) (1977)
KZ1000-B2 (KZ1000 LTD) (1978)
KZ1000-C1 (Police 1000) (1978)
KZ1000-C1A (Police 1000) (1978)
KZ900-B1 (LTD) (1976)

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CAT3
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#2 PostAuthor: CAT3 » Tue Mar 06, 2012 3:28 pm

UK 1976 Z900-A4 twin discs were 5mm thick & un-drilled.

The UK & US single discs 1972-75 were 7mm thick & un-drilled.
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750steve
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#3 PostAuthor: 750steve » Tue Mar 06, 2012 4:23 pm

Cheers dude, thats exaxtly what i needed to know, i need to get 2 of the 7mm discs machined down to 5mm (off a '77 Z750 B2 Twin & a '76 Z650 B1). Being used as an upgrade for the 750 brakes, cant find Z1000 Discs in good enough shape & these will be like new when finished.

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CAT3
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#4 PostAuthor: CAT3 » Tue Mar 06, 2012 5:14 pm

Would the thicker discs not fit in your calipers without machining ?
If you are going to reduce the thickness of a disc it would be better to have it surface ground rather than machined on a lathe/miller or similar. This would also entail removing the actual disc from the carrier & then reattaching it after grinding.
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750steve
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#5 PostAuthor: 750steve » Tue Mar 06, 2012 7:01 pm

No, the thicker discs won't fit in, i've tried.

Just been told by my local machine shop that he can't machine bike brake discs as they're made from 318 Stainless...........now i don't know if that means HE cant machine them or they cant be machined at all.

I'm a bit inexperienced at this stuff but i've never heard of having the surface ground, taking the discs off the carrier sounds like a rite PITA, if i done that i may as wekk get some new discs laser cut.

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#6 PostAuthor: CAT3 » Tue Mar 06, 2012 8:15 pm

Any material can be machined with the correct equipment & there's no reason why 318 Stainless cannot be machined.
It's unlikely, if the discs are original Japanese ones, that they are made from 318 Stainless anyway. The Japanese make a special steel for motorcycle discs & it's very hard to get hold of outside Japan, purely cost reasons I think.
A suitable alternative is 410 Stainless, but again cost is the main factor & suppliers are unwilling to supply small quantities. The metal would need laser cutting, heat treating & then surface grinding to produce a flat, un-warped disc. one thing to bear in mind is that for surface grinding the material needs to be magnetic as it's held in place on the machine using a magnetic chuck. Some Stainless steels are non-magnetic & some are. Also the person doing the surface grinding needs to know what they are doing & be willing to do the job properly. The disc would need shimming on the chuck so that when the first side is surface ground it remains flat when the chuck is switched off. Then it's turned over & the other side is then surface ground. Now when the process is finished you know the disc will remain flat when removed from the chuck. All this sort of work costs money.
You can get discs made using various other grades of Stainless or even other metals, without heat treating, but they will not be as good as doing the job properly.
Removing some thicker discs from their carriers & getting them ground down to your required thickness would be the way to go for a good job.
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#7 PostAuthor: Garn 1 » Wed Mar 07, 2012 6:11 am

Steve, when you reduce the 7mm discs by, say, 2 mm you will have trouble with the machinist, as the disc carrier usually have stamped/ embossed... Min thickness 6.5mm ,whereas, on the thiner disc has embossed Min thickness 4.5 mm. The machinist is reluctant to go below these limits, albeit, they would be safe in this day and age.
RegardZ.
Garn (Sydney) Z1, Z1A, Z1B and Z900-A4


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