Loose front Disc

Yesterday I was cleaning my bike and noticed that my front disc has some play in it. I looked and it is straight and it is very tight where it is bolted on the wheel. It has a very small amount of play where the actual disc is attached to the part that bolts on. There are little round circular pieces that you cannot adjust or tighten where the play is. I hope ya'll can understand where I am talking about. Anway, it doesn't seem to affect the riding I just don't think it should have any play in it at all. BTW, the play is from front to back and it is maybe .5 cm or so. Is this normal or should I do something about it? Or can anything be done about it?

thx

well you must be equipped with WR 450, wich received a brake blessing, called floating disc

this is normal behaveour for such disc and is ment to eliminate any vibration occuring for diffrent reasons

well you must be equipped with WR 450, wich received a brake blessing, called floating disc

this is normal behaveour for such disc and is ment to eliminate any vibration occuring for diffrent reasons

Actually it is the WR426, but hey I guess it is the same thing. I guess I learn something new everyday :) Well, isn't that ccol :)

BTW, the play is from front to back and it is maybe .5 cm or so. Is this normal or should I do something about it?

You mean .5mm, not .5cm, right?

Umm, isn't .5 cm the same as 5mm? :)

No, I mean 1/2 a mm, not 1/2 a cm... 5 mm seems like a rather large amount of play for a floating disk, especially if it's in the rotational axis, & not side to side. When I got the Berringer setup for my KTM supermoto, it was the loosest floating disk I had ever seen, & it didn't wiggle that much. :)

i think (but not know) it should have somewhat 2-3 mm of play

its hard to measure with eye

That sounds about right for side-to-side, but I'd think about 1mm front & rear (rotationally) would be about as much as you'd want... :)

The actual purpose of floating the rotor is to allow it to absorb heat without turning into something that looks like it came from a Pringles can. Floating it frees it from being rigidly bound by the bolts fastening it to the hub. Check how tight it is after you've ridden a while. But wear gloves!

It may not be 5mm, it may be less than that. I will check when I get home. It just seemed like a lot. I guess it doesn't really matter because there is no way to adjust it or tighten it anyway. And it really doesn't move from side to side at all, just front to back.

I'll have a look at mine when I get home tonight too, just to see, but in my experience (which is fairly limited in the Dirt Bike area, I used to be a "street guy") most of the play was supposed to br from side to side.

Class! Reports due in the morning! :)

Well heck, I don't know. I will look again tonight at both my bikes. I looked last night at my R1 and it didn't move at all in any direction. But I will look again at the WR tonight to see how much and if it is side to side at all.

Normal, this is a floating disc. The 426 came stock with these as did the 450. Not sure on the 400's

Normal, this is a floating disc. The 426 came stock with these as did the 450. Not sure on the 400's

This I understand, I'm just curious as to how much it moves. It seems to me that if the disc moves 5mm (1/2 cm) front to back (not side to side) it might be a bit worn & need replaced, as that seems like a ton of movement for the rotational direction of a floating disc.

This I understand, I'm just curious as to how much it moves. It seems to me that if the disc moves 5mm (1/2 cm) front to back (not side to side) it might be a bit worn & need replaced, as that seems like a ton of movement for the rotational direction of a floating disc.

Yeah, I am curious of that too. My bike only has about 800 miles on it but if it is too much movement and is worn I will be looking to change it soon.

Ok,looks like I am in good shape. I looked just now and it only has a couple mm's of play in it. Shew, glad I got that taken care of. lol.

The actual purpose of floating the rotor is to allow it to absorb heat without turning into something that looks like it came from a Pringles can. Floating it frees it from being rigidly bound by the bolts fastening it to the hub. Check how tight it is after you've ridden a while. But wear gloves!

Isn't the point of a floating rotor so that the braking surface can be of one material that is better for braking while the material that attaches it to the hub can be a stronger material that may not be as good for brake friction?

I'm not saying that grayracer is wrong, but I just understood it differently.

My WR400 came with a solid front brake rotor, it's a 1999.

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