the flyin' scotsman

Just got my new rear rotors (thx Roger) which have the cast in holes; question of the day, whats the correct rotation pattern ie. whats left or right?

I'm thinkin' this is the left rear:

Charley B

"cast in holes"?

the flyin' scotsman

I added a pic

Bill Ball

Look between the rotor plates at the ventilation vanes. The vanes should be oriented AWAY from the direction of rotation.

Charley B

I didn't think rear rotor's had the curved internal vents. External venting usually goes toward the direction of travel as in Bill's picture above.
Even tho that cross drilling looks like a directional pattern I'm not sure it matters which way they roll.
The idea of cross drilling is to assist the gasses in escaping. That should work either way.

the flyin' scotsman

Thx Bill............I do recall that pic but when looking at the rotors I don't see any curvature to the vents............the rotors are Zimmermans.

You may be right Charlie...............there is some lettering on the outer edge but I can only comprehend the min thickness and that they're made in Germany

deutschmick

"Drilled" or "cross-drilled" is pretty much a misnomer these days and you are correct in saying they are cast-in holes.

I think you have the correct orientation as that looks like the LR rotor. Put a pencil in a slot between the rotor halves; IIRC if it points rearward you have the proper orientation. The retainer screws that attach the rotor to the hub will also line up correctly.

I have "big reds" on the RF and LF and of course they are directional. I have Zimmerman for RR and LR and I don't think they're directional vanes.

I like yours better!

FBIII

Read the title of your post and thought you were rotating your rotors like a set of tires. Thought I was about to read a first.

docmirror

I can't see the arc of the vanes, but this looks like a right side rotor to me. If the arc of the vanes matches the arc of the holes, then it is for the right side.

Charley B

Rear rotors do not need or use curved vent cooling. Vents should be perpendicular to the hub.

the flyin' scotsman

I can't see any arc to the vanes but the arc of the holes does suggest right.

I'm not replacing them tonight but probably tomorrow then I'll see where the retainer screws align.

thx for all the input.

ROG100

The rear rotors are not handed like the fronts so will only fit one way.
They are the same part number.

Charley B

If they're the same part number, wouldn't they fit either way? Left or Right?

Lizard928

That is what he is saying yes,

Rears are the same left and right, doesnt matter which side they go on.

ROG100

That's the point I am making Charley - it makes no difference.
The fronts have a left and right and providing you keep the part numbers seperate you can figure what goes where.
If not you revert to the info as given by Bill for correct rotation.
Rears you have no choice.
Maybe I am wrong 8>)