shim out rear brake disc - what can go wrong?

[02GF74]

righty ho, did some measurements on my rear disc (Z1000 A1) and run out is 0.5 mm (Haynes say 0.3 mm max) and it is dished, gotta be close to 1 mm between inner and outer surface

anyways, got a replacement, run out is 0.18 mm and no dishing to note ..... but when fitted, the disc is not central in the brake caliper slot - it is too close to the inner side. (original disc was too close to the outer )

To get round this, I can put in a 0.5 or 0.7 mm shim between the hub and disc. I cannot see any issues with this as the disc carrier will still have lots of overlap over the raised hub section to be centralised plus the disc will be clamped up tight as before.

So what do the Z1 owners collective brain think?

The alternatvie is to true the rear caliper or replace it in the hope that a replacement fits.

Any other suggestions????

[02GF74]

.. oh, forgot - one of the pistons appear to be seized argghhhh so looks like I'm gonna have to take it apart AGAIN!!!!!

What paint to people use - satin black? not looking for 100% originality but don't want it to look wank either.

[tlc]

Always used the PJ1 satin VHT before.

Good colour

[Pigford]

OK.. so my first choice would be to remove the offending item & bin it

But, a nice little shim is just the job for this sort of adjustment. As long as it fits nice & snug to ensure heat transfer is good

[DAVE LEWIS]

Hi All I had a front brake disc on my A4 that was so concaved it was obviously scrap, but a friend of mine said he could fix it as he worked for a shot peening company.

Well he hit it with ball bearings and the disc is perfectly true and has been now for 6 years so there are ways round these things so don't just chuck them in the bin.

(Although dose help if you have a mate who works for a shot peening company)

Dave L

[Taffus]

OK.. so my first choice would be to remove the offending item & bin it

But, a nice little shim is just the job for this sort of adjustment. As long as it fits nice & snug to ensure heat transfer is good

Only one brake on the back, so if you remove that.......... Don't think you'll get spanners for that solution

[02GF74]

OK.. so my first choice would be to remove the offending item & bin it

But, a nice little shim is just the job for this sort of adjustment. As long as it fits nice & snug to ensure heat transfer is good

yeah, but it is not as if you can buy rear calipers readily, certainly don't have them in my local Tescos ... and then there is the price.

good point about heat trasnfer although rear disc isn't gonna get as hot as front but using aluminium and a smear of thermal past should sort it.

I will have a go at hitting the caliper to see if I can persuade it a bit over but suspect tht isn't gonna get me far.

[02GF74]

I will have a go at hitting the caliper to see if I can persuade it a bit over but suspect tht isn't gonna get me far.

... surprisingly that did help; block of wood, big hammer a big few whacks has mooved it in maybe 1 mm at most. Not sure if alloy has a "memory" but will see in a couple of days if it sprtings back.

[paul doran]

OK.. so my first choice would be to remove the offending item & bin it

But, a nice little shim is just the job for this sort of adjustment. As long as it fits nice & snug to ensure heat transfer is good

yeah well We have all seen Your effort's when it comes to brakes

[Rich]

Isn't it twin opposing piston on the back? 0.5mm off centre shouldn't make that much difference. If it does shim / skim the spacer / check the bearings are located correctly.

[02GF74]

yes it is.

all back together and all is good, no drag like before.

charging up the battery as I write to fire it up .......