Brake Rotor Cracks

[Bob_Roller]

I took the rotors form the LS to work yesterday, to drill off the rivets, and remove the rotor from the hub .

I'm sending the hubs to Spiegler to have a stainless, semi-floating upgrade done .

I started looking at the old rotors, the original owner had the rotors machined in 1989, to remove the grooving , that is so common on these rotors .

According to the maintenance log that came with the bike, the rotors were machined to .160 in., the minimum thickness is .180, according to the BMW manual, and the numbers stamped into the rotors .

The rotors have 91,000 miles on them, and the deepest grooves on the rotor face, are .050 in. deep, so the rotors are .060 in. thick at these points .

After looking at the rotor under a magnifier, I found 7 cracks on the left rotor, and 11 cracks on the right rotor, all following the grooves in the rotor face, between the drilled holes  .

Confirmed this by using a dye penetrant, didn't even have to use any 'developer', the red penetrant came through to the other side !!

[Bengt_Phorqs]

Good catch Bob!  What's the tariff on new rotors from Spiegler?

[Bob_Roller]

They are $240 each, plus shipping .

I think that's a bit less than OEM rotors.

[montmil]

It's my understanding that the rotors are not to be surfaced machined for groove removal. PO obviously may have gone against the BMW recommendations. You're quite lucky you did not have a rotor fail on you at speed.

A word to the wise and others not so... do not machine the rotors.

Monte  

[Bob_Roller]

I have not ridden the bike, or started the engine since taking ownership of it about 3 months ago .

That was one of the glaring problems I saw in the maintenance log I got with the bike, even if there were no grooves, it was machined to below limits to begin with .

[Rob Valdez 79 R65]

And the Spiegler option is less expensive than EBC rotors at regular price?

[Bob_Roller]

EBC rotors are around $260, unless you can find them on sale .

Semper Gumby, had his EBC rotors go bad at 45,000 miles, parts got galled and loose, and they can't be repaired .

So I thought this may be an alternative to EBC rotors .

Spiegler has replacement parts for semi-floating rotors on their website, I'm calling them tomorrow to get all of the information from them before I send the hubs into them .

[Bob_Roller]

Contacted Spiegler today, and the semi-floating upgrade, is rebuild-able, all of the parts that keep the rotor on the hub can be purchased and replaced as necessary .

Rotors will be dropped of at a FedEx Ground facility today .

Should be no more than one week turn around time .

[nhmaf]

When you get the rotors and if you are pleased with them, I'd suggest putting something on these in the FAQ for easy finding later on - at some point many of us will be in the same boat of needing new rotors.

[Bob_Roller]

I just checked the price of an OEM front disc, $435US each !!!!!

Even with a 20% discount at Chicago BMW, that's still $348US each .

[Bob_Roller]

Received a call from Spiegler Performance Parts this morning, they have the rotor hubs, they've been cleaned and inspected, no cracks or other damage found .

They will start their rebuild process today, they don't start working on the rotors, until payment is secured by credit card .

Should have them headed back my way,  by Friday this week, and I should have them the middle of next week .

If your order is over $500, no shipping charges back to you .

It's $240 for each rotor, and $145 for the three stainless flex lines for the front brakes .