Dual Brake Rotor Question

[luckyd20]

I'm converting my R65 to dual disc. Do I have to worry about the rotors matching thickness? I haven't actually measured each to see if there was a difference would it affect braking?

[Barry]

If both rotors are within spec I wouldn't worry.

If you think about it logically, a single disc bike works fine when it's putting all of the braking forces through one fork leg. So compared to that any minor imbalance between the brakes on a dual disc set up is not going to be an issue.

[tvrla]

I've even had mis-matched pads side to side. Worked fine! And the discs can wear much thinner than spec and still be perfectly safe.

[Bob_Roller]

If the rotors are close to the minimum thickness, my concern would be with cracks, if there are deep grooves in the rotor face, which the OEM rotors seem to develop .

My '84 LS had rotors that were worn to 3.5 mm thickness, the deep grooves on both sides of the rotor put the thickness in that area, at less than 1 mm .

I also had 17 cracks between both rotors, between the holes in the rotor face .

[mfrias2nd]

Good question thinking of doing the same.

[luckyd20]

thanks guys! I didn't want to spend money that I didn't need to! No cracks on either rotors!

[fbenach]

By the way, how come rotors are so expensive?
I understand is a delicate piece of the equipment, but, compared to other rotors on similar size bikes, I kinda feel is overprized...

[Barry]

By the way, how come rotors are so expensive?

Beats me. On new bikes at least rotors have become a fashion item and that's always the kiss of death for good value. Doesn't explain the cost of ours though. I could replace all 4 rotors on the car for half the cost of 1 on the bike.

I have an original BMW rotor with only 15,000 miles that looks to have a lot of life in it yet so I'm going to look after it. I think it should be good for 50,000.

[mrbindc]

IMHO, the dual R65 brakes aren't worth the money, they are far too weak.  I spent about the same as it would cost to convert to dual R65 brakes and just swapped out the entire front end with a K75.  Bigger forks (41mm) and larger rotors.  Braking has increased by 1000%, I could probably manage a stoppie now if I had a death wish..  

Just my two cents.

 

The K75 fender paint even matched my tank..

[fbenach]

Interesting... did you have to change the whole system? (calipers, pads, wires) in order to fit those?

[steven m]

I wonder why the K75 front end would offer such a phenomenal improvement in braking since they use the same calipers as the R65?  

Pretty neat conversion.  Are the forks the same length?  Assume you are using the K75 triple clamps?  How did you mount the headlight/instrument carrier bracket?  Does it just bolt on?

Steve

[bruce_launceston]

Sounds like the original setup was working at less than optimum. I can stand my LS with it's standard dual brembos on its nose without much trouble at all.

[mrbindc]

I had a host of issues to deal with when the bike arrived.  

It had a single disc brake that was very weak and the forks were locking up.  It was scary to ride in DC traffic.  

After pricing it all out, it was cheaper to swap in the K75 front end (and easier to find) than adding R65 dual brakes and rebuilding/replacing the OEM forks.

I used the K75 forks, brakes, triple tree and wheel.  Total cost was about $300.

The forks are longer, I have them up about an inch in the triple tree and used bar-backs to clear the bars.  The headlight bracket does not match up at all so I made an adapter this weekend with some alloy stock and used rubber spacers to get it mounted.  The picture above just shows the bracket zipped tied in place for the test rides.

Still waiting on the rear section of the front fender to come in from a fleabay seller but I'm pretty happy with the swap.  With the heavier front end, it is a lot less twitchy at high speed and the brakes are great.

I can add more pictures if you guys want to see the finished product.

Bruce, I can't wait to see the video of you doing a stoppie on your LS mate!  

[tvrla]

I agree with Bruce, the dual disc system  works very well. mrbindc
probably shouldn't have said what he did about the duals since his single disc system wasn't working properly. It's difficult assessing the effecacy of a higher powered system from a poorly working one, and I can see how he'd assume the dual wouldn't be much better with twice the anemic power of his poorly working single disc.

The K75 front end conversion does look interesting though.

[mrbindc]

I've ridden R65s with dual brakes, better than the single but I was not impressed.  I did the best option for myself, to each their own I say.

 8-)