| Author | Message | ||
     Dsarabia25 |
So just installed a new rear M/C on my 1125r. System is full of fluid. No more bubbles that I can see. Even pushed fluid upwards through bleed nipple to ensure flow. Watched the reservoir fill up then worked the system over again for a good while. No bubbles. Still no stopping pressure... Any ideas on what I may be missing..? | ||
| Terrys1980 |
Is the plunger properly adjusted? | ||
| Dsarabia25 |
Installed as it came from St. Paul Harley D. Was told should be set and ready. Looks about the same as the original I pulled off and I have looked for plunger setting information but have not been able to find anything... | ||
| Terrys1980 |
Did you pull the caliper to see if it is not stuck and the pedal pushed the piston out? | ||
| Dsarabia25 |
Have not but wheel was moving freely when I put her up for the night. Will check that next though. | ||
| Terrys1980 |
If all else fails replace the caliper with a Brembo P32 | ||
| Willmrx |
If you can get your hands on a Mityvac, Try sucking the brake fluid from the caliper fitting, down from the reservoir. You may have air still trapped in the caliber,FWIW. Here is a link to a Mityvac https://www.tooldiscounter.com/ItemDisplay.cfm?loo kup=MITMV8000&source=froogle&kw=MITMV8000&gclid=EA IaIQobChMI0uO6tsCK4gIViNdkCh3G4wAaEAQYASABEgKO1_D_ BwE | ||
| Xbuell12s |
I usually pump the brake 3-4 times then hold, while holding, momentarily open the bleeder. Repeat until firmness comes back to the brake lever/pedal and make sure the reservoir doesn't get too low. | ||
| Fresnobuell |
This. Easy, cheap upgrade to the sucky stock rear brake. Braking power is still weak, but at least it won't drag on the caliper after use. The rear brake is easily one of the worst components on the this Buell model. I used a washer behind each bolt to shim the caliper out just a bit. Other than that, it's a drop in replacement. | ||
| Shoggin |
The only improvement worth a damn on the Buell wooden rear brake is a smaller bore master cylinder.. The P32 works a little better because it has a slightly lsmaller piston but a much better and cheaper improvement can be had by changing the master. | ||
| Stevel |
This thread is an example that happens all the time. First, The rear brake does not work. It is supposed to work. Thousands of these bikes were made that did work as designed. This brake needs a repair, not a redesign.Recommendations to modify are grossly out of order here. I suspect the piston return spring is too weak. This is a common fault. If the spring did not receive a correct heat treat, it will suffer a set reducing its ability to return the piston far enough to pass the fluid inlet port, consequently the master cylinder won't pump. If it doesn't pump, you cannot correctly bleed the system of air. Guess what , no brake. Remove the master cylinder and disassemble. Then stretch the spring and reinstall. Tip, use compressed air to remove the piston. | ||
| Terrys1980 |
I'd rather spend a few extra dollars upgrading than wasting time rebuilding something that will likely cause issues again later. | ||
| Nuts4mc |
like Steve sez...the spring is of poor design choice ( you may be able to source a better one from McMaster-Carr...make sure it's made from Stainless Steel (316 or 302 alloy) brake fluid is Hygroscopic and absorbs water...you don't want that spring to rust and contaminate the brake fluid ...some early Mater Cylinders had a plating problem...(Honda Gold wings also had a similar problem)...the plating would flake off and seize the piston in the bore...not only did you not have a rear brake , but some early owners wound up with a locked up rear wheel...had to open the rear caliper bleeder to get the rear wheel to roll...the supplier for the MC was not a good choice... | ||
| Stimbrell |
OP, why did you replace the rear master cylinder? if the old one stopped working in the same fashion then the fault is likely in the line or caliper, if the old one was working I would return the new master cylinder as faulty. I replaced my caliper with a used Brembo because it was cheaper than buying the brake pads for the oem in the UK. (Message edited by stimbrell on May 08, 2019) | ||
| Fresnobuell |
Mine never locked up, but it would drag. I changed the caliper to Brembo due to the stock caliper being non-serviceable. I thought it was just dirty pistons causing the dragging. As long as the rear brake doesn't drag, I am happy. I use it infrequently. | ||
| Nuts4mc |
stimbrell...like you, I have replaced my rear caliper...what is the P/N or bike model for replacement pads?...need for future reference...Thnx | ||
| Stimbrell |
They are the EBC FA 47 or equivalent. Readily available as they are used on many Ducatis as well as others and are cheap. | ||
| Shoggin |
Doesn't the new rear MC come with the spring?? When you are pumping the rear brake, pull up on the pedal too. That will tell you if the problem is the spring/MC piston not uncovering the hole. You can remove the snap-ring and inlet nipple to see for yourself if theres a MFG defect plugging it. Use a small pin or jewelers drill bit to check both holes. Also, watch the rear caliper very close when pumping, is the piston pushing out then sucking back in? Thats a clue the M/C in not uncovering the hole and re-filling the line. I 2nd getting a vacuum pump, cheap and well worth it! | ||
| Shoggin |
I have had almost every kind of Buell. None of the rear brakes have been satisfactory, honestly dangerous. Just because something is OEM does NOT mean it's perfect. A very inexpensive solution ($30) is a smaller rear M/C bore. You get a longer stroke, more progressive pedal, and the bike stops MUCH better because of the additional pressure to the caliper you get from the ratio change. They aren't called the 'suggestions' of Physics ya'know  | ||
| Fresnobuell |
I seem to remember the Brembo caliper was cheap? Like $40-$50 bucks? Not sure if that is still the case. I believe the banjo bolt connected to the Brembo caliper is a slightly different place than the stock caliper, but it was workable. The M/C replacement might be the best solution to the problem, but he caliper swap is probably the easiest. I have not had a dragging brake issue since I switched over some years back. | ||
| Dsarabia25 |
Gracias Gentlemen for all the input. Will take note and apply and report back after the weekend. Cheers... | ||
| Stimbrell |
I have to admit I am a bit confused, on my 1125 and every other sports bike I have ridden the rear brake is basically a parking brake, on my HD Sportster it is used in conjunction with the front brake all the time, but true sport bikes, park brake only. the front brake can lift the rear tire off the road no problem. | ||
| Fresnobuell |
I tend to agree. I rarely use the rear brake, however when it's dragging it's an issue that needs to be addressed. That being said its nice to have when launching on a steep uphill slope. Also, to have any chance at saving an off road excursion you better use the rear brake as touching the front brake usually means a front tire wash out. I haven't really used this technique, but I understand you can tighten up the U-turn radius by revving the motor for its gyro effect, slipping the clutch and modulating speed using the rear brake (I guess the is a LEO technique?) For actually stopping a motorcycle at speed, the rear brake might be of some use at the beginning but once the weight transfers to the front, it's gonna lock up. A locked up wheel has no gyro effect and is usually a precursor to a crash. I would bet this lock up phenomenon (plus the amount of the rider's "attention pie" modulating the rear brake consumes) more than counteracts the safety benefit of a slightly shorter stopping distance. (Message edited by fresnobuell on May 08, 2019) | ||
| Terrys1980 |
The final letter of the Brembo part number indicates which direction the brake line comes off. The one I put on my 1125 was G and was $40. There is also an F. (Message edited by terrys1980 on May 08, 2019) | ||
| Willmrx |
Shoggin, do you know if there is a direct replacement MC, with a smaller bore? I agree with your Buell, rear brake opinion! | ||
| Dsarabia25 |
Totally agree with which brake has all the stopping power. Known that since I was 11. Do a lot of hill country riding and is nice to have on a hill stop or an intersection while adjusting at night far as traffic behind me. Going to try vacuum pump this weekend. If doesn't work, may go with a Brembo. Seeing them on ebay for around $130. Thoughts on price or recommend another site to purchase.? I'm in Texas btw... Shoggin, curious about your bore fix though. you have a part#..? | ||
| Stimbrell |
Fresnobuell, interesting, will give the u turn technique a go and see. | ||
| Fresnobuell |
Regarding the U turn technique, I will also add you are supposed to put your weight on the outside for counter-balance. I take it to mean when you are making your standard left hand U-turn, toss your right butt cheek towards the outside of the saddle. This is the opposite of what we do the other 99% of the time when cornering a motorcycle. | ||
| Dsarabia25 |
Great News.! Got my original caliper working. Took it off and worked pistons with fluid still in the system then tied it to rear foot peg to see if gravity might help in any way. lol. Then used a vacuum pump. Immediately saw air come out. used pumped a total of three times. After two, no air detected. Mounted brake. Bled twice old-school way. No air and BAM.! Brakes are back. Little over-kill maybe but who gives a crap when the brakes are back... Thanks to all for tips and advice. I'm ordering a Brembo to keep as back up. Cheers!!! |
