Measuring brake discs (and probably hubs)

[myzomela]

VIDA shows a fancy tool for measuring lateral runout on brake discs:


Rather than buy one of these, I decided to try a crude subsitute.

I bought the dial gauge on ebay (make sure you get one which goes down to 0.001mm) and the timber and nuts and bolts from the local hardware shop and car parts shop. You'll see that the brake disc is held on with the wheel bolts, together with five matching nuts. The original Volvo tool has a ring underneath the five flange bolts, but I skipped that.

The back plate bolts on in place of the brake caliper, and uses bolts with the same thread as the real brake caliper bolts.


The dial gauge slips into a hole in the wooden arm, with a slit cut into it to tighten with a small nut and bolt.


End result: my discs are good for a few more kms yet

If you're in Canberra, you're welcome to borrow it.

[jimmy57]

I have the lateral runout measurement tool shown in VIDA. You made a very good copy.
I get a Sharpie and mark a line on the wheel pilot that sticks past rotor on the hub between a couple of the lug holes. I write the runout in hundredths of a millimeter on the wheel face of rotor indicated by my first line. I move the rotor one lug increment and instal lugs and measure again until I have them all measured and then mount rotor at the lowest runout. You should have one location at no more than .04 mm.