Grooved rear brake rotor- replace, resurface, or ignore?

[myturn47]

I am in the process of upgrading my all of my brake pads to EBC HH on my 2014 TriGlide. As I was checking the rotors I noticed that the left rear rotor has some small grooves in it on the inside surface. The trike only has about 8K on it so I was surprised to see this. The cause is unknown at this point, but I will be giving the e-brake a close look and readjustment as part of the upgrade process. I bought the trike used so who knows what happened in its previous life.

Here's my question - should I replace the rotor, have it resurfaced, or just let it pass? The six or seven grooves are very narrow (about a finger nail's thickness) and shallow (deepest is about .004") and are only in the middle of the surface, but noticeable to the touch. A new rotor (p/n 41500031) is about $150 from Surdyke. I am tempted to just leave them be, but I don't want to be penny wise and pound foolish.

(And, for those of you curious as to why I would be upgrading from stock, I pull a Lee-sure Lite on long trips and want the added stopping power with no fade. In the past I upgraded to EBC sintered pads on my '07 Ultra and EBC red stuff pads on my 2012 Corvette with markedly improved braking performance on both.)

Thanks,

Gary

 

[Jack Klarich]

I will say this from years of brake work

Solid rotors are not worth the aggravation to have machined

1 reason is, it is hard to duplicate the run out on a brake lathe

The run out on your trike to the brake lathe MUST match with in .0003, if not you may compound your total run out and cause a pulsation

IMO, not worth it + hard to find someone willing to take the chance of machining the rotor

IMO, I would replace it and call it a day

 

[myturn47]

Jack, thanks for the excellent reply. I really appreciate your experience and opinion.

Before I spend more money can you confirm the assumption that I am making from your reply which is that the rotor should be replaced and not used as is?

Thanks,

Gary

 

[DK Custom Products]

I do not have the experience Jack has in brakes, the following is what I've observed....

It is rare to see a Tri-Glide or Freewheeler without the scarring on the rotors like you describe. As long as they are function fine AND not squealing, I would leave them be....chances are good if you resurfaced them or got new ones, they would be right back to how they are before long.

Kevin

 

[Jack Klarich]

With sintered metal brake pads one can expect a bit of scoring the rotors ( and some level of noise)

This is MORE pronounced with solid ( non vented or cross drilled ) rotors

These rotors cannot dissipate the heat like the front rotors can

Heat is always generated when braking, this is how the energy is transformed to stop

That said, if you can live with the scoring, I would just replace the pads

 

[Jack Klarich]

Jack, thanks for the excellent reply. I really appreciate your experience and opinion.

Before I spend more money can you confirm the assumption that I am making from your reply which is that the rotor should be replaced and not used as is?

Thanks,

Gary

Gary, I would NOT have a problem using that rotor for at least the next brake job

What I would do, when you put in the NEW pads, match mark the rotor on the Trike( I use nail polish on 1 wheel stud and a corresponding spot on the rotor)

Remove the rotor, sand the rotor faces in a cross hatch pattern

When done rinse off with soapy water( I use dawn dish soap and lots of clean water for rinse) you dont want any residue or oil from your fingers on the rotor or pads

Now since the rotors are match marked put them back on the trike, use some washers for spacers and install 1 lug nut hand tight

Lastly, you can finish up your pad install, remember to clean all mating surfaces and lube ALL sliding pins

I use some

on the back of the pads to keep the squeaking down You can use this on the slider pins also

 

[Firewrench22]

I turned my rear rotors a couple years ago when I put new Lyndall pads on, they had that same grooved look. I only did it because I had access to a brake lathe and I wanted a new surface for the new pads. They worked OK before, they worked good after with the new pads. But when the rotors are thinner, they warp easier. So far so good.

Now that you can buy the rotors from Drag Specialties and they don't cost a fortune, I'll just get new ones when it's time for new pads again.

 

[MDO]

Just a reminder, flush that brake fluid also.

 

[myturn47]

Thanks for all the replies. What a great community!

I decided to not replace the rotor since the scoring was only on one side and was really pretty minor. After removing the old pad I took a long, hard look at it since I would like to make sure I address the root cause if I can. I am wondering if the center part of the pad material actually failed and that is what caused the scoring on the rotor. Everything else with the seems to be okay. Doesn't change my decision, it's just interesting.

 

[rhino 2]

Thanks for all the replies. What a great community!

I decided to not replace the rotor since the scoring was only on one side and was really pretty minor. After removing the old pad I took a long, hard look at it since I would like to make sure I address the root cause if I can. I am wondering if the center part of the pad material actually failed and that is what caused the scoring on the rotor. Everything else with the seems to be okay. Doesn't change my decision, it's just interesting.

/QUOTE]

I would say so.........That gos under the category of , Stuff Happens...:Shrug:

 

[Jack Klarich]

It is possible

OR you may have picked up a rock or sand between the pad and rotor

There is NO running clearance between the pads and rotors

Anything that gets thrown up on the rotor could get swept in between. It usually is followed by scraping noises

I am guessing you checked the pads with a magnet

I hate semi metallic pads they are pretty hard on rotors tho they do stop good

 

[Mykneesbehurtin]

Jack you mentioned heat dissapation ,Years ago i would cross drill the front rotors on the old 900 kaws,since i have a mill and a turn table in your opinion if replacing the rotors would it be worthwhile to cross drill the rear rotors.And i think the ones from Drag are cast iron the strength should not be affected.

 

[Jack Klarich]

Jack you mentioned heat dissapation ,Years ago i would cross drill the front rotors on the old 900 kaws,since i have a mill and a turn table in your opinion if replacing the rotors would it be worthwhile to cross drill the rear rotors.And i think the ones from Drag are cast iron the strength should not be affected.

It sure would not hurt

As long as the swept area of braking is not compromised I would surely do it

I dunno why the MOCO did not shop this out to PM or someone else

Guess they wanted more profit