Do I need to replace this rotor?

I bought my Seca 900 about two weeks ago and only today I had both time left and warm enough temp to go look at it. It is in a winter storage close to my place. THis is a nice storage, with lots of camp-trailers and sport cars. But this is not a place where I could wrench a lot.
So I went there today with a very specific task in mind: to measure the thickness of my brake rotors. Here are the numbers:
-front 0.283" right side, 0.290" right side, specs are 0.280 minimum
-rear 0.305" specs are 0.320 minimum.

Pads seem to be OK becuase the wear tabs are far from the disks surface.

So , do I have to change my rear rotor in a hurry? I won't be able to ride before two or three months (snow all around) buit I'd like to beready when the spring comes.
I don't plan to ride a lot, maybe 2000 to 3000 kms this year. We all know that most of the braking power is in the front anyhow. So would it be safe to ride it a bit and feel if they work well before changing the rotor?

 

If the Rotor miked 0.0305 ... not 0.305 ... you can run it but you can't have it machined.

If it looks like it needs to be cut, ... replace it.

 

Sorry, my measurement is right at 0.305" but I wrote the spec wrong at 0.032, in fact it is 0.320. I just edited my text.

So I understand that I could ride the bike as is, after a good inspection of the other components of the braking system and a short test ride including lots a brake-testing. If the brakes feel soft, I'll look for new lines.

Of course, if I feel any significant drag at the rear wheel or vibration when braking because the rotor is a bit warp, I'll replace it.

 

quebecois59

You are translating French,right ??

If the brakes

work smoothly and dont grab, they will be OK

Please list your miles.

 

I'm not translating French, I always write English like this, lol!

By "please list your miles", do you mean that I should take a record of my mileage when I'll change the brakes, or the pads or anything else (oil, brake fluid, air filter, etc)?

 

Nah, he means 'tell us how many mile/kilometers are on the odometer.

I wouldn't bother with measuring rotors, replacing rotors, etc..... unless there's pulsing and grabbing when you apply the brakes. If the brakes work well and smoothly, I'd leave 'em alone. When I have the pulsing show up, it has always turned out to be the time for replacing pads, and the pulsing has always gone away with the new pads. I've only ever had to replace one bad rotor.......it was on my Intruder 1500--slightly bent when it was totalled. When I built the bike, that was something I didn't see at the time, and took a long time to figure out the weird braking issue that I was having. A new rotor solved that problem.

Dave Fox

 

OK, bike has 76,683 kilometers on the counter.

I think I wouldn't have bother with measuring the rotors if I had a chance to ride the bike and feel the brakes, but the weather doesn't allow me to do so.

 

I suggest moving to a warmer climate.

 

REPLACE THE LINES, seals, and the pads.

Not because of wear, because of age. Original brake lines were rated to last 4 years. Look at the date code printed on or molded into the lines.

Original caliper and master cylinder seals were to have been replaced every TWO years.

Thirty year old brakes are dangerous. Period.

***addendum: out of curiosity, I sliced open an old brake line, one that was in fine shape from the outside. The inner line, the one that does the work, is cracked and/or crumbling. Pics coming soon***

 

Replacing the lines and the seals is obviously a part of my plans, but I need to ride the bike at least once to see if any rotor has to be changed, so I could order all the parts I need at the same time.

As for the pads, the bike has been ridden regularly for three years, the pads look thick enough and I can't see a reason why they should be replaced. These pads are not 30 years old. Please explain that one.

 

If the pads are relatively new, as they may be, then you may be able to reuse them. On most of the XJ's (not the 900 like yours) there was a drum rear brake that would de-laminate over time. That is one of the things that all new owners need to check. With the Master Cylinders, calipers and lines. I agree totally with what Fitz is saying. I just rebuilt my caliper and master Cylinder and the only thing that was going through my head the whole time was, "how did this thing ever stop like this?" The main boot on the MC was in 2 pieces which made for a ton of corrostion in the master cylinder, the caliper dust boot and seals were in many pieces, and the build up of bad brake fluid was obvious. Now they are all cleaned up and looking good, just need new lines and hopefully I will have good brakes.

Fitz, glad someone is putting up pictures of that. I was planning on cutting mine up as soon as I got them off for that very reason.

 

@osprey1000
I want to make it clear first that I DO NOT question in any manner Fitz's expertise. If i want to ride the bike first before I make my mind, it is only because i'd like to order all brake stuff I need at the same time.
I can easily understand that 30 years old rubber parts need to be replaced, and that tires and brakes are vital parts for our safety, a lot more than shocks or gauges.
I've already rebuilt MC and caliper on a nearly 35 years old Yamaha, I know what you mean.

 

Nah, go ahead and question him, somebody should

 

If you're absolutely 100% sure of that; and equally sure they're less than about 10 years old, then by all means, "use them up."

If you have no "hard evidence" and can can only guess at their age based on degree of wear, I wouldn't bet my life on them.

 

All right, you probaly didn't notice or you don't remember that this bike has close to 77 000 kms on the counter. Do you think they made pads that good 30 years ago?
Is there any story of pad desintegrating or delaminating I should be aware of?

 

Pads that are old enough to have "acquired" moisture from the air can and often do start to crumble once put back into service.

I don't for one minute doubt that they've been replaced at least once; but even though they are likely replacements, are you willing to bet your bike and your life on them still being viable after (???) years?

If YOU had put the 77K on it, then you'd know. My point was; if you don't know, then don't take the chance. Or at least I wouldn't. (New brake pads are quite a bit less expensive than a hospital stay.)

 

The only thing I know for sure is that the pads are more than three years old, because the PO has own the bike for three years and he didn't change them.

It is a fact that pads aren't expensive and I'll put them in my order for sure.

But you didn't answer my question: have you ever heard a story about pads desintegrating and falling in seconds, causing the wheel to lock or the braking power to drop to zero, and resulting in an accident? Not me, but I'm a bit younger, lol!
My bet is if they start to crumble as you said, chances that the three of them do so all at the same time are pretty close to zero, and one would experience fading brakes for several days before shit happens
But I may be wrong, it happens all the time.