Rear brake puzzle

[Rosie1965]

Replaced my rear pads tonight and noticed somebody has done some modifying. Bike is a 90 MKII. Rear rotor is a vented disc and not offset. Somebody has added spacers to move the caliper closer to the wheel. Has been functional up to this point but I'm concerned about my braking efficiency. The rotor only measures about 304 mm. The rotor isn't large enough to make full contact with the pads, there is 5/16" of the pad not being used. Included are pics of the worn pads, rotor and caliper spacers.

http://i1176.photobucket.com/albums/x337/steve_roseman/Venture/pads.jpg

http://i1176.photobucket.com/albums/x337/steve_roseman/Venture/rotor.jpg

http://i1176.photobucket.com/albums/x337/steve_roseman/Venture/caliper.jpg

[twigg]

Yeah ... It's all wrong

 

I would be looking for the correct rotor, eBay has a few, and new pads. Put it together as suggested by the workshop manual and all should be well.

 

I think the rear rotor should be 320 mm, but don't hold me to that I haven't checked.

 

ps ... I also think that the rear rotor should be the "floating" type ... Mine is on the '86.

 

That one appears to be fixed.

[pmelah]

that does not look good as i would be concerned about breaking too good thing you needed to change the pads to find that problem now is much better than finding it at the scene of an accident

[skydoc_17]

Hey Rosie,

That rear rotor looks to be off of a Virago, it is definatlly NOT off of a MKII VR! You got some shopping to do! How long have you owned this motorcycle? Who did you purchase it from?

I have a MKII VR rear rotor, and EBC HH pads available if this would help. Feel free to PM me.

Or you could try Ebay. Yamaha gets about $350.00 for a new one.

Earl

[Venturous Randy]

Looks like a MKI rotor to me. I wonder if someone swapped out the rear wheel and added spacers.

RandyA

Edited October 1, 2012 by Venturous Randy

[Rosie1965]

Skydoc, I've owned the bike since March. Bought it in Lincoln, NE. Would have to look at the registration to remember the guy's name. Just put new EBC HH pads on it as we are heading to the Ozarks Tuesday morning.

Venturous, the rear wheel swap crossed my mind too. Will definitely be keeping my eyes open for a MKII rotor.

This is still functional, just not optimum.

[Yamamike]

That's about a 25% reduction in contact area on the pads dude. IMHO, that's way less than optimum...bordering on dangerous.:backinmyday:

 

PS; Keep in mind...with that kind of brake efficiency loss on the rear brake...you run a much greater risk of locking up the front.

[twigg]

That's about a 25% reduction in contact area on the pads dude. IMHO, that's way less than optimum...bordering on dangerous.:backinmyday:

 

PS; Keep in mind...with that kind of brake efficiency loss on the rear brake...you run a much greater risk of locking up the front.

 

I think she is right.

 

It's not ideal, but neither is it dangerous. The maximum rear braking force is compromised. In 35 years riding I can't remember the last time I used "maximum rear braking force".

 

I imagine that there is quite enough there to lock up the rear wheel in the dry, so there would be more than enough.

 

It needs fixing, but it is probably rideable.

 

You don't stand a better chance of locking up the front if you use your brakes correctly.

 

I might not be saying the same thing if it were the front brake

[dingy]

Another issue that exists with the pads not fully contacting the rotor is the will touch each other at some point.

 

As the pad wears away about a 1/4 of the way down, the unworn part on each side is now progressing towards the other pad, which is also not wearing down at the top.

 

When they touch above the mid-line of the rotor they will very rapidly decrease in effectiveness.

 

Gary

[Marcarl]

What I see happening here is that the outer edge of the rotor wears into the pad. Now for some reason unknown as yet, the rotor could catch the pad and then jam up, causing the back wheel to cease it's turning, and you might know what that would do. Not a real big issue maybe, well, at least not until it happens, and then it's a way too late to do something about it, it'll be locked and sliding.

[Yamamike]

I think she is right.

 

It's not ideal, but neither is it dangerous. The maximum rear braking force is compromised. In 35 years riding I can't remember the last time I used "maximum rear braking force".

 

I imagine that there is quite enough there to lock up the rear wheel in the dry, so there would be more than enough.

 

It needs fixing, but it is probably rideable.

 

You don't stand a better chance of locking up the front if you use your brakes correctly.

 

I might not be saying the same thing if it were the front brake

 

Ummm...scuse me...she? Who is "she"?

 

I think you forget the fact this is a linked system...not a question of using the brakes correctly.

[Rosie1965]

I appreciate all the concerned replies, I will be getting this fixed. I have ridden all summer with it like this and am quite confident I will be ok until I do get it fixed. Only have about one good ride left before putting away for winter. Currently have new pads so the scenario of the pads touching each other won't be happening. 42 years of riding experience should help too.

[twigg]

Ummm...scuse me...she? Who is "she"?

 

I think you forget the fact this is a linked system...not a question of using the brakes correctly.

 

I didn't forget, it won't be a problem. It will brake a little more on the front is all ... not an issue as most folk use the front supplementary anyway. Just use it less.

 

Is "Rosie" a he?

[jimmyenglish]

Trying to find a good used one is almost impossible. Get the EBC MD2049 (rotor) and the EBC HH pads. More braking power than you'll know what to do with. However, be prepared for one hell of a prostate check.

Edited October 2, 2012 by jimmyenglish
syntax errors

[Rosie1965]

 

Is "Rosie" a he?

Yes, nickname from high school with last name of Roseman.

[twigg]

Yes, nickname from high school with last name of Roseman.

 

Hah!

 

My nickname from High School is "Twigg", from my last name "Bracken"

[Prairiehammer]

Hah!

 

My nickname from High School is "Twigg", from my last name "Bracken"

 

Bracken is a fern. Why did your 'mates think twig and fern were appropriate?

[twigg]

Bracken is a fern. Why did your 'mates think twig and fern were appropriate?

 

They didn't ... I did

 

I started a new high school when I was 14. On the first morning the teacher was calling attendance and he asked me for my surname.

 

"Bracken, Sir", said I

 

"How do you spell "Bracken"?" he asked ...

 

"As in "twig", Sir".

 

It made absolutely no sense at all. The entire class fell about laughing and I got a detention for my trouble

[Prairiehammer]

Smart Alec at fourteen...

Not much has changed in the subsequent decades, eh, Steve?

[twigg]

Smart Alec at fourteen...

Not much has changed in the subsequent decades, eh, Steve?

For most of us, I would think

 

I have less hair though

[Rosie1965]

For most of us, I would think

 

I have less hair though

 

That's funny, me too!

[Rosie1965]

I figured I would reopen this thread to pose my new question so I wouldn't have to re-explain my situation.

I got my MKII rotor installed finally (Thanks Earl!) but have a question on caliper bolts. To sum up, my bike had an MKI rotor on the back with spacers installed between caliper arm and caliper to make it "fit". I haven't yet applied any pressure to rear brakes but the caliper is able to wiggle around with the bolts tight. The play is where the bolts go through the arm. I looked on the service manual but couldn't see anything I'm missing. Is the caliper supposed to float and I just need to get the pads to make contact with the rotor or should the caliper be snug with the arm? Any help is appreciated.

[dingy]

If the bolts have 'tightened' and caliper still has movement, possibility is that the un-threaded portion of the caliper bolt is to long. The bolt may be running out of threads and feeling like it is tight.

 

Gary

[Rosie1965]

Dingy, you are correct. I have run out of threads. Could someone tell me the length of the correct bolts? Also, are these supposed to be a shoulder bolt that fits snug in the arm or do they just rely on pulling the caliper tight to the arm?

[skydoc_17]

Hey Rosie,

I have the bolts for that rear caliper. If you will pay for the shipping, I'll get them right out to you.

Earl