Cracked right front brake rotor.

[Guyver]

Ok, so I'm giving the bike (94 ST1100 standard) a once over today, and I spy a small crack in the right front brake rotor, it's about 4mm long, leading from the edge toward the center....
Then I see another, then another, then another, all the way around the rotor about every 10cm is a small crack. The longest one being about an 10mm long, and stops at a rotor vent hole. These cracks are not splits, there is no gap.
The other front and the rear rotors are fine.

Has anyone ever seen this before?
Should I change both?
How big of a risk is this?

 

[Mark]

I wouldn't ride with a cracked rotor...
On the others I'd measure them to see if they are beyond the lower wear limits.

 

[the Ferret]

Someone had this issue before. I thought this was the same thread? Hmmmm

Here it is

https://www.st-owners.com/forums/showthread.php?125376-Broken-front-disc-maybe-fate-!!

 

[Bigmak96]

Not good. You should check with JimSTer, I saw two front rotors hanging on his wall and the 1100 is history.They may be close to toast but may have some life left otherwise why keep them.

 

[Basic]

Seems like you have been doing some serious braking. Google for "cracks in disk rotor" and you will find quite a few examples of similar, though not specifically on ST1100.
Consider yourself very lucky to have found this in time. It seems like some more heavy braking may worsen things rapidly.
When changing front brake pads, it is always advised to do the two sets at once. I can think that for the same reason the disks should both be replaced.

In case you are not the kind of guy that is going very hard on the brakes, you should look for a technical defect causing this thermal stress on your disks.

Rob

 

[Guyver]

Should have said before... The bike is new to me...

 

[Guyver]

Someone had this issue before. I thought this was the same thread? Hmmmm

Here it is

https://www.st-owners.com/forums/showthread.php?125376-Broken-front-disc-maybe-fate-!!

I found that one... It's not the same, his was split and gapped by 2mm, mine have no gap to speak of, just cracked.

A LOT of people on line say this is ok, and they have been riding for quite a while on cracks... I'm not so sure, but new rotors after just shelling out the cash for the bike, is going to set me back.

 

[Basic]

What happens in case of rotor failure does seem to be unpleasant. After seeing some of those pictures, I would play safe.
I can imagine that replacements may be used parts, as long as their condition is ok.

Better be safe than sorry and check your caliper working when replacing the disk. This also because only one of your disks has it.
- A quick visual check of the pads might show uneven wear.
- If you lift the front wheel and try to turn it, resistance is a strong indicator that brake maintenance is needed.
- Taking the calipers off, you should be able to move them freely on the slide pins that center them.

Rob

 

[Guyver]

thanks...

The bike is parked for now.
I'm looking for a use one. The new ones, even those that say OEM, do not look the same, and I'd have to replace both.... OCD at its best.

 

[st1300r]

Small thermal cracks [heat checking] might be ok but I wouldn't want to see them extended to the edge of the rotor or connecting hole to hole.
Hopefully some guys who wrench for a living will chime in.

 

[George]

Wait for IGoFar to chime in, he's most knowledgeable about mechanics for my money.

I have some rotors laying 'round here. STandard or ABS?

 

[Guyver]

Wait for IGoFar to chime in, he's most knowledgeable about mechanics for my money.

I have some rotors laying 'round here. STandard or ABS?

Thank you so much, but I found a used one from a 2000 that looked in decent shape off of eBay....
$40 US.
I'll keep you in mind should this one go bad as well.

 

[George]

No problem, Guyver. $40 is a good price. Thousands of those discs on the road, relatively few with problems. (Other Hondas use the same diameter discs, different holes in the center but the bolt patterns are the same. The single disc from a Hawk GT works, might find it cheaper if ya want a new one. Also, one of the aftermarket brake pad companies has a set,,, STrayCatt has their discs on his 91 black.)

 

[RONST1300]

I am curious as to what type of brake shoes you use. Do you happen to remember if they were OEM or replacement HH.
Ron

 

[George]

I've used about everything, but prefer OEM. Just installing a new set on my 01 ABS.

 

[Guyver]

The pads were just swapped before I bought it, and the cracks appear to have been there for a while. There is no telling when it happened or what kind of pads were used.