Dual rotors for '76

[srastoder]

Hey guys,
I was reading around and found several treads that talk about conversion to dual rotors. I could not find one that talks about a '76, spoke wheel. Is there a bolt on rotor that I can use to add on left side, or what calipers and rotors will bolt on the 34mm forks and spoke wheel? Thank you for your suggestions.

 

[5twins]

You just add a second disc just like your current one, they bolt on either side. I'm pretty sure it's the same for the caliper. The old style like yours I don't think came in left- and right-handed versions. You just switch the mounting bolt and mounting stud to make them go on the right or left. MC may be a different story. You may have to change to one with a different bore size to get the most out of the 2 disc set-up. But, I would try the one you have first, it might work fine with 2 discs.

 

[oldbiker]

hi my 1976 xs650 has 34mm tubes,,,and dual discs,,, with the early calipers that have the round pad with a small T on the end so that the pad locates OK,, regards oldbiker

 

[srastoder]

I could find another rotor, but I don't think the right side caliper will work on the left side even if I flip the bolts unless I flip it upside down and that would not work. I think I would need the left oriented caliper, but not sure from what? Or, replace both rotors and calipers as long as they will bolt on Ok

 

[XSLeo]

The caliper will switch from left to right just as 5twins says. The only problem might be the tee part of the brake pads. This tee part may not have the clearance by the fork legs, if so just cut the tee part off. Leave the straight part just the tee.
Leo

 

[5twins]

Just switch the positions of stud #39 and bolt #38 .....

 

[srastoder]

Great. I will try that. Now I just need to find a caliper, rotor and the line. I will post up wanted tread in classifieds, but I any of you have the parts just let me know. Does another year have the same caliper and rotor? Thanks for all your help

 

[XSLeo]

I think the first year of the disc brake used a rotor that wasn't bolted to the hub, maybe the first two years. I think all the yamaha that used a front disc brake from that same time frame used the same calipers and rotors. 73 to 76. Search Ebay for Yamaha front brake calipers, put in the years to reduce the parts and look through to see ones like yours. Same on the brake rotors. The rotors need to be the two piece ones, different offset on the later one piece rotos.
Mike's has new ones listed now.
Leo

 

[5twins]

I think you can use calipers from '72 to '76 and probably ones from other models like the RD350. Discs would need to be '74-'76. '72-'73 discs mount differently. Look through the parts diagrams for various models here and you'll probably find more to choose from .....

http://www.yamaha-motor.com/sport/parts/home.aspx

 

[XSLeo]

I found 1 on Ebay, the guy is nuts. Mike's wants $66 for his new one. This guy has a 77 RD400 caliper for $124.95 with $12.95 s/h.Get the new on from Mike's. Even with the $8 or whatever for shipping on the less than $150 order is worth it.

 

[XSLeo]

I was in contact with the seller He said "thats a repro not original" He sold the rear one for the same price, so maybe he's not nuts, it's the buyers.
Leo

 

[XSLeo]

While browsing for rotors I fond a 73 rotor. The seller took the two halves apart and i selling each half for $90. Thats $180.
Another guy has the three lockplates for the bolts, $24.
Right next to a later rotor for $18.
Nut's, people are just nut's.
Leo

 

[sreimer]

I run a stainless line with master caliber and single disc all are stock and have no problem with stopping power and even skidding the front tire at any speed. Just gotta ask, why would you add all that extra unsprung weight if you didn't have to? Not to mention the waste of $

 

[retiredgentleman]

I agree with sreimer. The stock front disk brake (and the rear also) works really well.................I can't see the need to add extra unsprung weight and spend dollars to do it. Perhaps its just an appearance thing

 

[irristeve]

you say a 76 presume its a C.on the C the caliper moved from the the front of the fork to the rear of the fork In Aus & NZ they all had twin disc as std.the left & right are differnt mainly in bleed nipple & brake line location you will diffantly need a bigger M C,the twin set up is heaps better,try looking in Aus NZ

 

[XSLeo]

I think if I were to add the second rotor and caliper I would try it with the Master cylinder you have. On the later one piston calipers doing the dual with the stock single M/C works very well.
Ony 75 I put a 79 fork on to use the dual disc set up with the later calipers because the later are were easier to find. I tried it with the stock M/C of the 75, a 16mm. It worked well with strong brakes but the feel was a bit wooden, Hard to tell when the wheel started to lock.
With a later model 14 mm M/C the brakes were stronger and the feel was much better.
I now have a 12.7 on right now, A generic replacement for an older Honda Rebel. This brake is very strong, could do stoppies if I was that brave. A light one or two fingers on the lever gives me the braking action of what the stock 75 two piston brake had with a 4 finger death grip on the lever.
In most riding having the less unsprung weight you might notice an improvement in handling, using a well set up dual disc you will definitly notice the improvement in braking.
If you do much highway travle with a fully loaded bike, two up then the dual brake will be that much better.
On a lighter more performance oriented build were you spend more time one up no load playing in the twisties, a well set up single might be the better brake.
Leo

 

[retiredgentleman]

Some good points there Leo. Yes, I can see if riding much with 2 people on board and especially with extra luggage, the dual set-up could be the way to go. If you mostly just ride single, then stay with the single rotor.

I'd also be cautious of the front brake being too powerful. I recall one time in my youth with little biking experience. I was riding my XS500C and it started to rain. I decided to pull of the road and take shelter until it passed. When I applied the front brake, the rear end of the bike came around, and I found myself going sideways down the road.
I was able to recover OK.

A combination of a slippery road (first part of rain mixed with oil on road) and my overly strong pull on the front lever, almost got me into trouble. I learned that's its better to use the rear brake only when it first starts to rain, and be gentle on the front brake if it is used.

 

[5twins]

I love my single disc set-up. Only changes from stock are the single stainless line and drilled disc. I just bought new Ferodo pads but honestly, the stock ones seem to work fine. It will be interesting to see if the new aftermarket pads make much of a difference.

 

[XSLeo]

With the front brake the way it is, is a bit much. It has taken a few miles to get a good feel for it.
I would use the 14 mm M/C I have, but it leaks, it's also from a Special so it has the angled reservoir and looks bad on my lower flatter bars.
I have thought about using this 12.7 mm M/C and just a single disc to see how well it works.
I think most people will like the stock set up with it properly cleaned up and the braide steel lines. Going one step smaller on the M/C will be an easy upgrade and only put the bike out of commission for the time it takes to replace the M/C and bleed the brakes.
www.vintagebrake.com has a chart that tells the M/C bore size to run with the caliper or calipers you use.
Leo

 

[XSLeo]

Well, I went out and played with the brakes. I removed the caliper on the left side. Rearranged the lines so I have all braided stainless. With the 12.7 mm M/C the brakes are slightly better than the stock brake on the 81. Ride one, ride the other and you can feel a difference. Ride one then wait a few days then I might not feel the difference. I think the MMM reccomended 11 mm M/C would be better.
An improvement, but a small one.
I think I'll pull the wheel and remove the extra rotor. See If I notice any change in the ride or handling.
Leo