Worried now that I unlinked brakes

[Guest Greg W]

So I tried for about 2 weeks to bleed the back and left front brakes of my 85 using mityvac with no luck. I finally just decided to remove the banjo bolt for the front brake from the rear master cylinder, and plug it with another bolt.

Then I just bled the back brake and finally I have working back brakes. So simple.

My only question is now that there is no pressure in the left front caliper line. Will there be a huge dangerous difference in the anti dive system on the right verses the left front fork?

[Flyinfool]

I believe the 85 has the electric anti dive. If it is the electric anti dive there will be no difference. If you have the hydraulic anti dive then you will have 50% less anti dive and there will be an imbalance between left and right.

Since on a 2nd gen having different air pressure in the shocks makes a difference in handling, the difference in anti dive might also make a difference.

 

BUT what you did not ask about is braking power. Most of your braking power is from the front wheel, and you just cut that in half.

 

Skydoc_17 sells a delink kit that will operate both front brakes from the hand brake to get full brake power back.

 

The rear brake has a proportioning valve to meter the difference between front and rear. If you are delinking you also want to remove this valve so it does not reduce pressure to the rear brake as you press harder on the brake peddle.

[Marcarl]

I believe the 85 has the electric anti dive. If it is the electric anti dive there will be no difference. If you have the hydraulic anti dive then you will have 50% less anti dive and there will be an imbalance between left and right.

Since on a 2nd gen having different air pressure in the shocks makes a difference in handling, the difference in anti dive might also make a difference.

 

BUT what you did not ask about is braking power. Most of your braking power is from the front wheel, and you just cut that in half.

 

Skydoc_17 sells a delink kit that will operate both front brakes from the hand brake to get full brake power back.

 

The rear brake has a proportioning valve to meter the difference between front and rear. If you are delinking you also want to remove this valve so it does not reduce pressure to the rear brake as you press harder on the brake peddle.

Amen to that!!!

[GaryZ]

My '85 has the mechanical anti-dive and strange things could happen with only one fork leg getting stiff during a hard stop. My '85 has a splitter from a Ninja and brake lines to both front brakes. The front brake master cylinder works fine. I did increase the "stroke" with the adjuster under the front brake handle. BTW, my '85 has Progressive fork springs and the anti-dives are disconnected.

 

I recommend installing two brake lines from the front master to the two front brakes. I ordered a pair of brake lines from an outfit in Canada for my Ninja and the cost was less than $80. A double banjo bolt at the front master cylinder and the rest is the same as stock. These new brake lines came with single and double banjo bolts with washers.

[Trader]

Boy....sounds like "somebody" sold you a pile of junk!!!

 

I looked up some old threads.....

 

Here is one suggestion I found.

Do the rear brake first, then the front and then bleed the valve that is up by the steering head. It's right in front of the false tank cover, a little to the right side.

 

Because it is a high point, up by the steering head would be a collection point for any air trapped in the lines.

[greg_in_london]

I agree with Flyinfool.

 

You've removed the hose to the front brake, so you don't need the proportioning valve and IMHO you're much better off without it. It was a mechanical widget to supposedly reduce pressure to the back brake when you're slowing down, but it didn't really work.

 

leaving the front left brake caliper discinnected means that you only have two discs working out of three and, even though two working properly is better than three working badly, is hardly an optimal situation. Personally I wouldn't worry about the anti-dive much, but if you connect the left caliper to the front master cylinder you will link up the anti dive again.

 

You will need to upgrade the master cyclinder and use one with a 5/8" - 14mm piston, but other than that it is basically connecting a new brake line.

 

Mind you, if you have the original rubber hoses you really should upgrade to stainless steel brake lines - the originals are 30 years old !

 

Something like this should do for the master cylinder, though you'd need to check that in your market that model had a double disc brake. (Genrally single disc brake master cylinders have 1/2" - 13mm pistons and double disc brake master cylinders 5/8" - 14mm pistons).

http://www.ebay.co.uk/itm/Yamaha-XV750-XV1000-XV1100-Virago-1983-1987-Brake-Master-Cylinder-Lever-Switch-/351120516811?pt=UK_Motorcycle_Parts_13&hash=item51c069e6cb

[jasonm.]

My '85 has the mechanical anti-dive and strange things could happen with only one fork leg getting stiff during a hard stop. My '85 has a splitter from a Ninja and brake lines to both front brakes. The front brake master cylinder works fine. I did increase the "stroke" with the adjuster under the front brake handle. BTW, my '85 has Progressive fork springs and the anti-dives are disconnected.

 

I recommend installing two brake lines from the front master to the two front brakes. I ordered a pair of brake lines from an outfit in Canada for my Ninja and the cost was less than $80. A double banjo bolt at the front master cylinder and the rest is the same as stock. These new brake lines came with single and double banjo bolts with washers.

 

you should not attempt to run 2 calipers off a master cylinder designed to operate only ONE caliper. It's just wrong unless you are using R1 or R6 calipers. Otherwise you need 5/8" = 16mm..master.not 14

[KIC]

You can also try the trick of strapping the lever in a pulled in position and let it sit over night or for a longer time period. It worked on mine as the air bubbles rise to the reservoir

[jasonm.]

You can also try the trick of strapping the lever in a pulled in position and let it sit over night or for a longer time period. It worked on mine as the air bubbles rise to the reservoir

I also have done the trick of strapping the lever. But I can't change the fact pair of OEM calipers need 5/8". Strapping the lever does not allow the air bubbles up. It's actually , you are FORCING the piston seals into place. That air bubble thing was started by people who don't know how brakes work. Think about it...there is pressure in a sealed system..ain't no way it makes it easier for bubbles to come up....cheers

[dingy]

I also have done the trick of strapping the lever. But I can't change the fact pair of OEM calipers need 5/8". Strapping the lever does not allow the air bubbles up. It's actually , you are FORCING the piston seals into place. That air bubble thing was started by people who don't know how brakes work. Think about it...there is pressure in a sealed system..ain't no way it makes it easier for bubbles to come up....cheers

 

If you haven't tried, you are talking out your buttocks.

 

It works.

 

Gary

[Flyinfool]

Actually it does make it easier for the air bubble to move, and gravity says the bubble will move up.

When you put pressure on the system that has a bubble, the bubble will get smaller because air is compressible. The smaller bubble will fit thru the lines better to be able to float to the top. With the master being the high point in the system that is where the air bubble will end up. The next day when you release the pressure, the air bubble will be at the top right next to the now open ports where gravity will again make it move up and out of the system. Then on the next stroke of the piston the bubble will be gone.

 

This same trick will not work on the rear because the master is not the high point. It also will not work on most cars because the system is not vertical. The front brake of a bike might just be the only place that the geometry is right for this to work.

 

That air bubble thing was started by people that really do understand how the brake system works along with some of the physics involved. That and it sure seems to work for a lot of people.

[jasonm.]

i apologize...it can't hurt. and may help...those who standard bleeding does not get all the air out. I have done it. .... it helped slightly.. meaning i already had the bubbles out. It's not likely to help much because the brakes hoses connect in the middle of the caliper on my 1st gen.. the majority bubbles likely go to the bleeder at 12 o'clock not up the hose. Then bleeding the next day after doing this can help. That's why I say it does not help much with 1300 1st gen. BUT R1 and R6 calipers the hose connects near the bleeder...different..yes

Edited July 24, 2014 by jasonm.

[Trader]

Sorry guys...but you are both wrong.

 

It is the FRONT brake in the LINKED rear brake that's giving Greg problems.

 

The reservoir for the linked brake is NOT the high point so you BOTH are talking out your buttocks! LOL

Edited July 24, 2014 by Trader
typo

[jasonm.]

i don't have linked brakes...as most bikes don't. + Ventures like mine.. I thought he said he removed the linked parts. if the brakes are still linked on his 85. throw the anti dive hose away..if you have progressive front springs

[Flyinfool]

Sorry guys...but you are both wrong.

 

It is the FRONT brake in the LINKED rear brake that's giving Greg problems.

 

The reservoir for the linked brake is NOT the high point so you BOTH are talking out your buttocks! LOL

 

Did you see the title of this thread and read the original post from Greg?

 

Title - Worried now that I unlinked brakes

 

So I tried for about 2 weeks to bleed the back and left front brakes of my 85 using mityvac with no luck. I finally just decided to remove the banjo bolt for the front brake from the rear master cylinder, and plug it with another bolt.

Then I just bled the back brake and finally I have working back brakes. So simple.

My only question is now that there is no pressure in the left front caliper line. Will there be a huge dangerous difference in the anti dive system on the right verses the left front fork?

 

This sure sounds like delinked brakes to me......

 

So now whose buttocks speaks??.....

[KIC]

I bled my front brakes. Then I tried the strap the lever in using a velcro strip. The next day I carefully released the lever while looking into the reservoir and with some very mild pumping I saw air bubbles come up. I am not a master in physics or brake design. I do still have some eyesight left that saw some air bubbles so in my opinion it worked.

[Condor]

:icon_lurker:

[Flyinfool]

You got enough popcorn for everyone??

[jasonm.]

yes...that's what I was going by....delinked

[Huggy]

You got enough popcorn for everyone??

 

I'll make some more if you like!! :icon_lurker::icon_lurker::icon_lurker::icon_lurker:

Now for my two cents:

 

I just did my DELINKED brakes and I did a lot of bleeding!!! Then Tied the brake leaver down!! Both of which resulted in getting rid of the air. I also turned in the screw on the leaver which gave the plunger in the master cylinder more travel. After I did all of this my front and rear brakes now work perfect. It took TWO days of patient work but that's the way it is when you have two brakes to do on the front.

[jasonm.]

with original calipers...you must use 5/8 bore. Took me only 5 hours with new SS brake lines and all... to do the whole job and bleed it down with 5/8 bore. FYI the 86-93 calpiers have the largest bore ever from yamaha..require 5/8 to run 2. A 14 just won't cut it in an emergency. Ask yourself how close the grip can you get the lever to come ? can yu make it touch the grip ever? if yes...

[rbig1]

well I have a question. if you hook both front calipers to one lever the hoses must be the same length or the fluid will take the path of least resistance. ie one will take the fluid first. example if you hook two hyd cylinders to one valve together the ram closest to the valve will move first. is that kit out there making all hoses equal in length

[Prairiehammer]

well I have a question. if you hook both front calipers to one lever the hoses must be the same length or the fluid will take the path of least resistance. ie one will take the fluid first. example if you hook two hyd cylinders to one valve together the ram closest to the valve will move first. is that kit out there making all hoses equal in length

 

While hose length is important in a hydraulic ram system, where copious amounts of liquid are being pumped to and fro; on a hydraulic brake system, there is virtually no volumetric transfer. One is simply applying pressure to the incompressible liquid filling the hoses and calipers. The actual movement of liquid through the system is inconsequential. So, no, the unequal hose lengths are not very important. Consider the fact that brake lines on an automobile are not of equal length.

[rbig1]

so the calipers don't move away from the disc enough to make a difference to the fluid displacement. so there is a very small movement of fluid. so no difference to strokes.

[jasonm.]

look at modern sports bikes ..one hose to right caliper and a short jumper to the left. Thus the right has a double banjo bolt. Note: the modern design is a pain to bleed.