Front Brake questions

[HappyHunter]

Howdy All!!
A year and a half ago I picked up a mess of an old 1982 Heritage Special with no PA title. I received my PA title this past Saturday and am anxious to get this on the road.

The front brakes did not work when I rode it home about 40 miles when I bought it. (yes that was probably pretty stupid....) So here's what I found out so far. I had the caliper apart last summer and it seems fine, no rust, piston moves in the cylinder and seems OK. The master cylinder seems OK, builds enough pressure to shoot a good squirt of fluid out the bleeder valve. I bled the brakes and I do get some braking action but not at all satisfying or even comforting deceleration. Seems I have lever pressure but no stopping action.

What to do? I am thinking about replacing the pads, thinking maybe they just don't have enough friction against the rotor? I am also thinking about replacing the hoses, they may be expanding rather than forcing the pressure against the caliper piston. Do these seem like good ideas? What else? Does my evaluation of the master cylinder and caliper seem correct?

What is the proper thickness of the rotor? It's dark outside right now so I can't measure what mine is now. I will check tomorrow.

Thanks,
Steve

 

[bosco659]

Does the caliper slide freely on the guide pin? If not, pads can only push from the piston side and there’s no ‘“clamping” force being applied to the rotor. I trust you’ve thoroughly bled the system?

 

[motormike]

Caliper slide rubber.... brake fluid.. other petroleum based products will cause it and other brake " rubber " to swell.... carefully clamp off the hose just below the master cylinder connection.. is the lever hard.. if so.. M/c should be ok.... if it sinks... replacement .... based on the age of the bike.. I'd replace it as a matter of preventive maintenance. If the the lever is hard... hold it.. and release the clamp.. if lever drops... air in system... on rare occasions... I pressed the lever and cracked the banjo bolt and left brake juice ..air... release.... have a rag wrapped around the bolt...

 

[arcticXS]

I would check what bore size the MC has. Yamaha did use fairly large bore MCs on many bikes. A 12mm, 1/2" or 13 mm MC Will be a good upgrade, especially if combined with a steel braided teflon hose.

 

[gggGary]

Above plus once brake pads have been soaked in fork oil from a leaky fork seal they cannot be brought back to decent working condition, replace them.
E bay vendor Caltric sells a set for about $10.00 shipped.
https://www.ebay.com/itm/Front-Brak...:XS650&hash=item4174642aca:g:6aIAAOSw1Qxfx9Ji
Stainless steel brake lines also a good investment.

 

[jetmechmarty]

As far as brake hoses go, I believe Yamaha said to replace them every four years. I just replaced mine this evening, I’m only 34 years behind schedule! Do as I say and not as I do.

 

[5twins]

With the availability of cheap stainless lines now from China (less than $10), it's a no brainer just to replace them. Before they came along, I would usually try to use the original rubber lines but I did encounter several over the years that were shot. No amount of bleeding would give a nice hard lever feel. Replacing the line fixed the issue.

 

[RustiePyles]

I second replacing the hoses with modern SS braided hoses. The hoses Yamaha used are pretty big and rubbery and are very prone to degradation and expansion soaking up all your braking power. Plus getting rid of the brake hose union block on the bottom yoke cleans up the front end quite a bit.

 

[member28833]

Plus getting rid of the brake hose union block on the bottom yoke cleans up the front end quite a bit

Hey now, I like that union block...
Where do I get both left and right appropriate brake lines now and the one to the master cylinder? Really where?

 

[RustiePyles]

Hey now, I like that union block...
Where do I get both left and right appropriate brake lines now and the one to the master cylinder? Really where?

Dual disk is the exception (in the US) not the rule. If you're running dual disk you're stuck with the union block or something similar to it.

 

[jetmechmarty]

I just installed these Chinese brake lines I bought on eBay. Brake application is much improved. Now, what do you folks do with the clamp on the fender?

 

[5twins]

I just take it off and don't use it anymore. I've never had an issue on either bike.

I do install a guide for the line where the junction block used to be though. I think this helps hold the line in against the fender .....

The above came from this HF assortment .....

https://www.harborfreight.com/hardw...-rubber-insulated-clamp-assortment-67657.html

This is fine on the '83 because it gets hidden behind the "beauty" plate. On my '78, it's exposed so I made up a little nicer clip out of stainless strap .....

 

[jetmechmarty]

I do install a guide for the line where the junction block used to be though. I think this helps hold the line in against the fender .....

Thank you! I left the junction in place with two lines. It made the swap more expedient in this case.