Front and rear rotors

I know that the min thickness of both the front and the rear rotors is 4.5mm, however does anyone know the thickness of the brand new rotors for the front and the rear before they go into use?

Just curious to see what the staring pint is.

Also in respects to the rear rotor, does anyone have experience or advice regarding the cheap ones on ebay like this:

http://www.ebay.com/itm/Rear-Brake-Disc-Rotor-BMW-R850GS-1996-2000-R850R-1994-2006-R850RT-1996-2001-C-US-/112421750235?fits=Model%3AR1100RT&hash=item1a2cdbc5db:g:tfEAAOSww9xZKcHM&vxp=mtr

Are rotors for the R1100RT compatible with any other models, asking so I can increase my search radius.

I bought a Chinese rear rotor off eBay last year, and it has worked out just fine.

Re the front rotors, mine were grossly under minimum thickness, and I replace them with a set of EBC rotors with bobbins pre-installed, sourced from Beener Boneyard. ~20,000 miles since which a required more time than swapping out the roors.

Thanks for the info, so I will pull the trigger on a new rear rotor. I didnt quite follow the last sentence can you clarify please.

I know that the min thickness of both the front and the rear rotors is 4.5mm,................

 

Also in respects to the rear rotor, does anyone have experience or advice regarding the cheap ones on ebay like this:

 

A good quality replacement rear rotor on the R1100RT is the EBC MD653. I can't say how the Chinese eBay rotor compares to this, but the EBC rotor is much less than OEM and is good quality.

Front replacements are MD607 (left-Side, Right-Side).

Will have a look at EBC as well, have heard a lot of good things about them.

By any chance do you know the thickness of a new rotor out the box?

BMW repair DVD says a new rear disc is 5.0 mm, new front discs are "4.9...5.1 mm". I find the variation in front thickness a little weird. A result of different suppliers, or maybe model year changes?

Wear limit is 4.5 mm rear, 4.6 mm front.

BMW repair DVD says a new rear disc is 5.0 mm, new front discs are "4.9...5.1 mm". I find the variation in front thickness a little weird. A result of different suppliers, or maybe model year changes?

 

Wear limit is 4.5 mm rear, 4.6 mm front.

Agree with rear rotor new thickness and wear thickness by my manual, front disc by my manual says front new thickness is 5.0 mm, wear thickness is same as indicated by Larry.

BMW repair DVD says a new rear disc is 5.0 mm, new front discs are "4.9...5.1 mm". I find the variation in front thickness a little weird.

Why Weird?

If the item can live with wider manufacturing tolerance it will be cheaper for everyone. If you want an item such as a disc machined to tight tolerance they can, but will be reflected in price.

It is after all, just a disc and it WILL change in size over its lifetime anyway.

Weird because I've never seen such a large variation for a new disc.

0.2 mm difference is a lot. The skinny version would have 33% less usable material than a fat one.

BMW repair DVD says a new rear disc is 5.0 mm, new front discs are "4.9...5.1 mm". I find the variation in front thickness a little weird.

Why Weird?

If the item can live with wider manufacturing tolerance it will be cheaper for everyone. If you want an item such as a disc machined to tight tolerance they can, but will be reflected in price.

It is after all, just a disc and it WILL change in size over its lifetime anyway.

Morning__

My BMW 1100 dealer manual shows the same only in a slightly different way.

5mm nominal ± 0.1mm (0.1969" ± 0.003937") --Or just a little under .008" possible variation. (a standard 3x5 card usually runs about .008" thick.

It's really not much of a problem as a little thicker (ie 5.1mm (.2008") is about a piece of printer paper thicker than nominal & the thinnest is 4.9mm (ie .192963") is only about a piece of printer paper thinner than nominal.

This assumes they float to the extremes. In most cases they will probably mike closer to nominal.

Thanks for all the info all. All three of my rotors are close to min spec. I will give the $30 rear off ebay a shot. Does anyone know of any inexpensive replacements for the front, the floating rotors seam to be big bucks....

Thanks for all the info all. All three of my rotors are close to min spec. I will give the $30 rear off ebay a shot. Does anyone know of any inexpensive replacements for the front, the floating rotors seam to be big bucks....

The fronts should all be floating rotors, so factor in costs of bobbins, washers and E Clips.