Brake problems

[lwinders]

I have been trying to get the brakes on my '83 to the point that I feel safe riding it for quite some time now. I've read many posts about the brakes and understand that the brakes on this model are a know problem. I have not de-linked them yet. last night I decided to just concentrate on the front brake. I bleed it and feel that I have all the air out of the lines. But the brake lever still feels very spongy. I am thinking about disconnecting the anti-dive and see if it makes a difference. What are the pro's and con's to doing this?

[Peder_y2k]

To properly bleed the front brake line on the MK1, one must crack open the fitting at the highest point in the system, and that's the one running from the master cylinder to the metering valve at the frame next to the fork clamps. The MK2 has a bleed valve at this point making it much easier. Use a fitting wrench or you'll damage the fitting. One can reach up along the forks, or down through the fork opening in the fairing to access. Use rags to soak up the brake fluid that comes out, and listen for the sound of squirting as air pushes out. Not easy work, but can be done. Repeat as necessary. YMMV

-Pete, in Tacoma WA USA

'83,88

[bongobobny]

Two words, vacuum pump! Speed bleeders also help. Don't forget one front brake is the front lever, the other one is the rear pedal!

 

Delinking is a debate for sure! Personally I like the linked brakes better for the most part, and delinking won't do as thing for the front lever! Removing the anti dive will give more power to the front brake but then the bike will tend to nose dive when braking. This too is a hot topic and I personally like the anti dives.

 

OK now to the meat and potatoes. If your front lever is spongy, this can be due to two or three things. First, the master cylinder needs rebuilding. Your seals in the master cylinder are most likely experiencing blow by from worn seals, corrosion on the cylinder walls, or both. There are rebuild kits out there that are inexpensive but I also recommend honing the cylinder wall, or replacing the whole master if the walls have major pitting. Secondly, your caliper may have the same issue as the master, same things apply. Now lastly, your rubber lines are 30 years old, most likely!! Replace them before they blow out!! Replace them with stainless steel braided lines. Rubber expands robbing power to the caliper, even when new. The SS braided ones resist this expansion and provide more working power to the front.

 

Other possible causes of spongy lever are somebody loosened a brake line and did not replace the crush washer! Even though there may not be a visible leak you could loose a certain amount of pressure from weeping. Also crush washers can develop corrosion thru the years and loose a small amount of seal. When you replace your brake lines, including the ones to your anti dives, use new crush washers. Speaking of the anti dives, yes I suppose it is possible you have an internal leak in them. Your best bet, find front forks off of a MK2 along with rotors, and put better 4 piston calipers from a Yami R1 or R6 and be prepared for some real stopping power! The electric solenoid anti dives are powered via the brake lights...

[lwinders]

First of all, thank you for your responses. Where can I get the stainless steel braided line with the correct fittings on them. Next, what year did it change from MK1 to MK2?

[Prairiehammer]

First of all, thank you for your responses. Where can I get the stainless steel braided line with the correct fittings on them. Next, what year did it change from MK1 to MK2?

Earl (Skydoc17 on here) can set you up with everything.

MKI= 1983-1985

MKII=1986-1993

[MiCarl]

Once it's all bled, there is one more place to bleed. It tends to trap air at the banjo bolt on the master cylinder.

 

Squeeze the lever, lots of towels or rags around the bolt, crack it open ever so slightly until fluid flows. Tighten bolt before releasing lever. You may have to repeat if you didn't get a good fluid weep the first time.

 

A helper to squeeze the lever makes the job easier.

 

I did a sport bike a few weeks ago where they had the good sense to put a bleed nipple at that spot. Too bad they aren't all that way.......