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Erratic ft. stopping power

Old 07-13-2007, 04:20 PM
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Erratic ft. stopping power

This is similar to the other post, but this isn't a lever problem, it's a brake issue. I've already bled the brakes and cleaned everything up, but my front brakes are getting progressively more erratic, almost like there's air in the system. Keep bleeding them and it helps, but it seems to come back within a thousand miles or so. All the bleeders are tight, and the banjos are tight. OE master and calipers, HH pads, braided lines.

When I haven't given the lever any squeeze, it sinks a bit, then gets abruptly hard...bike refuses to stop, then all at once bites in and hauls down. Every pull is either hard or soft, completely inconsistent...and brakes grab at different points in the lever travel. But I do get a better stop by pumping the lever once or twice, like how you do in a car when the master starts bypassing. Think a caliper is hanging, or the master is going?

The bike has never stopped very well, and the previous owner left brake fluid in the thing for almost a decade, and housed it outside...so all the reservoirs were loaded with sludge...cleaned and bled out best I could but it's still backflushing into the reservoir.
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Old 07-13-2007, 04:38 PM
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My old VF1000r used to do this , After all the obvious stuff bleeding, new pads and so on .. I ended up changing the rotors ( oem new old stock ) problem solved . The original ones were warped ! (Its a real heavy bike that was ridden pretty hard so it kinda made sense) I cant say for sure this is whats up with yours. But It sure sounds exactly like what mine was doing .
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Old 07-13-2007, 04:40 PM
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On my old bike I had a similar problem that was caused by a warper rotor. It put inconsistent pressure on the caliper causing it to vary pressure backwards in the system and ultimately making it lose pressure. I replaced the lever, reservoir, lines, and caliper, before coming to that conclusion.

Good luck, I hate brake issues.
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Old 07-13-2007, 04:58 PM
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Sounds to me that it very well could be a hanging caliper or master cyl. as you suggest. Check the caliper slides and pistons for free movement. If that all looks good, maybe it's time for a 954 m/c upgrade? Better safe than sorry.
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Old 07-13-2007, 07:40 PM
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Make sure you have crush washers on all sides of all connections. In a pinch you can use the ones from the local auto parts stores if you are missing some. This is critical as these tiny imperfections in the system can leak air in and make a total mess of things.
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Old 07-26-2007, 06:55 PM
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So I bled the hell out of the front brakes....got an immediate, marked improvement in lever feel and stopping power. Now, just 100 miles later, the lever is still firm, but is getting erratic again, albeit much harder...and the bike isn't stopping without heavy lever input. It's got to be getting air into the system I would imagine...but I can't find where from! Any tips from the guru's? Its getting incredibly irritating
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Old 07-26-2007, 07:15 PM
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Somebody had something like this in the past where a PO used DOT 5 and the seals swelled. Could this be a possibility?

Also, ensure the lever bushing and all contact points between the lever and the piston are lubricated with a light coat of white lithium. Check the rubber boot around the piston. Carefully pull it out without ripping it. I may already be deteriorated. They do that and it's normal. Clean it out with carb/brake cleaner then use some silicone spray in the hole where the piston is.

If this doesn't solve the problem then move toward cleaning the calipers and their associated pistons.
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Old 07-26-2007, 07:26 PM
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I'll do that this weekend.... Thanks Greg.

I have a strong feeling DOT-3 was used if anything...the bike was poorly maintained and when I got it and changed the fluids, I found a SIGNIFICANT amount of sludge in every hydro. reservoir... Scraped it all out and cleaned the reservoirs, and bled the bejesus out of them all with Valvoline synthetic DOT-4 fluid...but nothing seems to work properly. Clutch is bitey....front brake is erratic....rear brake is mushy.
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Old 07-26-2007, 07:29 PM
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Snag a set of RC51/954/929 calipers and MC. Definitely the best upgrade I've done so far. Well worth the hour spent with a Dremmel.

If you think the lines are gummed up too, and you've got some cash, a set of SS lines would be a nice gift for the ole' girl.
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Old 07-26-2007, 07:40 PM
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Originally Posted by NovaWildcat08 View Post
Snag a set of RC51/954/929 calipers and MC. Definitely the best upgrade I've done so far. Well worth the hour spent with a Dremmel.

If you think the lines are gummed up too, and you've got some cash, a set of SS lines would be a nice gift for the ole' girl.
Scored SS lines for free off a buddy a while back....got sent two pairs for his Honda 919 by mistake from ebay...theyre too long so I had to route them creatively but they get the job done Im just worried about the master and calipers...with all the sludge and the fact that this bike was kept outdoors and things have started to rust.... Makes me wonder.
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Old 07-27-2007, 02:14 AM
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It does sound like warped rotors, but also it could be master cylinder.
There is a sets to rebuild pump - seals etc.
I'd do some diagnostic first.
IMHO
1. Warped rotors - get front wheel suspended, unbolt calipers, make smal L-bent strip of tin in a way, that you can bolt it to caliper mounting lug that it will almost touch rotor in a middle of working surface. Get this tin to almost touch rotor, then rotate wheel and you will see when it touches rotor if it warped.
2. If rotors are OK get repair kit (it costs peanuts, something like 20-30 bucks) disassemble master cylinder (pump) and replace all those seals etc.

If all that will not help it could be seizing pistons in calipers. To check that you will have to get pistons fully out and inspect them.

I never ever experienced such issues on my Storm, but did have them on my Suzuki DR800 dual-purpose....ended up repairing brake pump and dumping original caliper for one from Gilera Nordwest.

To be honest I found brakes like ones from SP to be a bit too much for my liking - I prefer progressive feel and hard squeeze of lever if I need to stop fast.
Unfortunately even that progressivness of brakes did not save me from blocking front wheel with one finger braking (4 weeks ago) and crashing in 1500 km from home on my 4000 km rideout in France... thou with aid of epoxy, bits of metal and 3 meters of wire we managed to plug cracked engine cover, reattach footpeg and ride for another 1500 km
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