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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: TimTyler on December 21, 2015, 05:36:37 PM

Title: Buying Used Brake Rotors ?
Post by: TimTyler on December 21, 2015, 05:36:37 PM
My front rotors are below spec.

I'm considering replacing them with a used very-low-mileage OEM pair I found online. Apparently nearly new. Identified as "spares". I've asked for measurements and they do indeed spec out very well.

This set will cost half of the cost of a brand new set of EBC rotors.

Advice?
Title: Re: Buying Used Brake Rotors ?
Post by: M.Brane on December 21, 2015, 05:44:13 PM
 Make sure you clean 'em really good. Different brake material compounds often don't play nice together. It also helps if they've been marked L/R since running them the other way can cause problems too. Minor warping can be fixed with careful bending.
Title: Re: Buying Used Brake Rotors ?
Post by: Scott_ on December 21, 2015, 06:39:20 PM
I'd say go for it.
I've done both used and new.
I did the used ones 1st, still using the semi-metalic pads...... then once they were below spec I went with new rotors and standard organic pads.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on December 22, 2015, 05:52:21 PM
Thanks, guys.

I've ordered the used ones.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on January 05, 2016, 07:33:40 PM
Received the used rotors. They're as described.  :clap:

Cleaned them up and installed them. Ride soon.
Title: Re: Buying Used Brake Rotors ?
Post by: K1300S on January 05, 2016, 09:26:34 PM
love the workshop Tim!
Title: Re: Buying Used Brake Rotors ?
Post by: Laitch on January 05, 2016, 10:21:16 PM
You never can tell when an avocado will be just the tool you need.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on January 05, 2016, 10:50:42 PM
Too cold to work outside :)
Title: Re: Buying Used Brake Rotors ?
Post by: Scud on January 05, 2016, 11:06:00 PM
Still Life with Y-Spoke Rim
by Tim Tyler

Limited edition Artist's Proofs available.
Title: Re: Buying Used Brake Rotors ?
Post by: Gio on January 06, 2016, 09:05:38 AM
Why so many tangerines though - mildly acidic alloy cleaner perhaps? I like your art Tim - but can we lose the floppy flower please ...
Title: Re: Buying Used Brake Rotors ?
Post by: Martin on January 06, 2016, 01:45:42 PM
Tim after replacing rotors I attach a dial gauge indicator to where the calipers mount, and check for run out. If any run out is detected it can be corrected with a 10" piece of broom handle and a nylon hammer. Hit on the inner portion of the rotor, not the disc to correct any run out. It is also important to use a tension wrench when installing and tension up in increments. I have used new EBC discs that had run out from new. As mentioned previously really give them a good clean.
Regards Martin.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on January 06, 2016, 08:43:54 PM
Thanks, Martin.

I sanded the mounting surfaces on the rotors and wheel very well before attaching them. Used a torque wrench and incrementally tightened the rotors. Took the bike for a cautious 60 miles ride today since it has new rotors, a new swing arm and was recently reassembled from a clutch spline lube. Did not notice any pulsing or braking abnormalities. The roads around here are slick with moss though so I was not too aggressive. Got her up to 85 on the freeway and it felt smooth (and cold).
Title: Re: Buying Used Brake Rotors ?
Post by: The Mighty Gryphon on January 06, 2016, 11:02:30 PM
Regarding the photo.  You're single aren't you? 
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on January 07, 2016, 12:03:34 AM
Nope. Just cleaned up before the little lady got home :)
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 03, 2016, 09:53:26 PM
Since installing these rotors I'm experiencing a throbbing action during front braking. And it's not a "good throbbing action" if you know what I mean.  :nono

I'm probably going to reinstall my old rotors which still have a little life left in them. If the throbbing goes away, new EBC rotors are in my future.

Title: Re: Buying Used Brake Rotors ?
Post by: Martin on May 04, 2016, 03:15:10 AM
Try truing them up with a dial gauge and a piece of broom handle. It is doable but don't go at it too hard, go slowly. It takes a bit of patience the first time but you will soon get the hang of it. Remember only tap on the carrier not the disc.
Regards Martin.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 04, 2016, 11:54:14 AM
Thanks for the suggestion, Martin, but I don't think I want to start hammering or bending the rotors. Don't want to risk weakening them.

I'll inspect closer today and see if it's just one rotor that's causing the brake shuddering. Maybe I can get away with replacing just one.
Title: Re: Buying Used Brake Rotors ?
Post by: Scud on May 04, 2016, 11:59:24 AM
Tim -

I put EBC rotors on mine along with the sintered pads that they recommended. Between that and stainless lines, and rebuilding the calipers, braking is much improved.

I have two spare pair: 1) non-ABS from a 1990 and 2) ABS from a 1992. I can provide measurements and photos if you're interested.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 04, 2016, 03:08:55 PM
Turns out the right rotor was the problem. Also turns out my old rotors were not out of spec by a lot. Not sure why I read that value wrong last winter.

Swapped in one of the old rotors and the problem has been solved.  :riding:
Title: Re: Buying Used Brake Rotors ?
Post by: Martin on May 04, 2016, 03:55:39 PM
Tim you are only adjusting in increments of a thousand of an inch by lightly tapping. No need to belt them with a hammer, I have successfully saved heaps of discs using this method without any damage.
Regards Martin.
Title: Re: Buying Used Brake Rotors ?
Post by: Laitch on May 04, 2016, 05:09:14 PM
. . . I have successfully saved heaps of discs using this method without any damage.
Regards Martin.
You seem overly committed to promoting this method, Martin. Are you concealing ties with a broomstick manufacturing company?
Title: Re: Buying Used Brake Rotors ?
Post by: Martin on May 04, 2016, 05:26:03 PM
Left over offcuts from making facsimile Beemerangs for US tourists made out of wood and sprayed silver. This way it doesn't contravene the US OZ arms agreement.
Regards Martin.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 04, 2016, 05:32:31 PM
I have successfully saved heaps of discs using this method without any damage.

I'll happily give you my soon to be discarded rotor if you want it.
Title: Re: Buying Used Brake Rotors ?
Post by: Martin on May 04, 2016, 05:35:57 PM
Thanks Tim
Title: Re: Buying Used Brake Rotors ?
Post by: Scott_ on May 04, 2016, 11:15:30 PM
Tim, any chance you have a glazing build up that could be causing the pulsing?
I have read of that occurring occasionally, and causing a pulsing feeling.
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 04, 2016, 11:19:35 PM
Could be, Scott. Part of the rotor surface felt raised to the touch, but it's so subtle.
Title: Re: Buying Used Brake Rotors ?
Post by: johnny on May 05, 2016, 04:24:59 AM
greetings...

the underpowered k75 is notorious for glazed rotors... the key is proper maintenance... it is recommend that you ride in a backwards motion give it full brakes while at speed... this maneuver will deglaze the rotors... and also realigns the relationship between the brake pads and the brake calipers...

j o
Title: Re: Buying Used Brake Rotors ?
Post by: TimTyler on May 05, 2016, 10:46:16 AM
...it is recommend that you ride in a backwards motion give it full brakes while at speed......

I find that when I do this I end up back where I started.