front brakes and brake lever locked up on first test ride.

a little history first.
i ride with only use of my right hand.. so i had to get rid of the radial masters because they simply do not fit in the configuration i need. and i use 2 new brembo 15mm goldline brake master cylinders mounted on the right side, and had to make my own brake and clutch hydraulic lines...its what i used on the r1 when i converted it many years ago. weve been working on this V4 for 5 months now. and i finally got to test ride butttttttttt

so as i was riding around the block, the first loop was great half way around the second i noticed the engine started lugging in third, so i went to second, then had to go to first , even applying throttle the front brakes were gradually locking then quickly completely locked, i almost went over the windscreen and i was stuck in the middle of the road then had to drag it to the side of the road. my arm still hurts... thats alot of weight even for my slightly overdeveloped right arm.

as it was cooling down i noticed that we could shove it and the brakes were slowly starting to relax but not enough to ride away, luckily my son was following on his crf450 since i have to do some crazy mods to be able to ride i anticipated problems of some sort. so he went to get some tools, and i loosened the banjo bolt on the abs pump that went to the front master cylinder, the pressure shot out fluid and the brakes and lever loosened and went back to normal.

i bought a 4 line to obd2 converter and used a code reader i had. and got
P0500 Vehicle Speed Sensor A code is set when the PCM or engine control module (ECM) detects incorrect speed readings or no signal at all from the vehicle speed sensor (VSS). Other names for this code include: Vehicle Speed Sensor “A” Range/Performance. Vehicle Speed ....this was caused probly from running the bike one the stands rear wheel spinning and front wheel not.

P0475 Exhaust Pressure Control Valve out of range, i know what caused this..

the only relevant one would be speed sensor A which is the front one... maybe this caused the brakes to pump up but i doubt it because the abs pump would have released once we pulled the battery and fuses on the side of the road. which it did not...
the other thing i noticed was that the fluid reservoir was completely full i could not see the upper line when the brakes were locked. so my theory is that because the abs pump is right next to the front header, the heat gradually building on the abs pump and the brake lines as well caused the fluid to expand and pressurized the system to the point of locking. this would explain the gradual slowing of the bike. and the slight bit of release of the brakes after the bike had cooled while we were trying anything to get them unlocked then resorted to loosening the banjo. i used the front brake very sparingly barely used it at all
the reservoir was filled only to the line and not overfilled in any way..

i have dropped the fluid lever to just above halfway and pulled out the center of the rubber sleeve to avoid sloshing during riding but have gone out to test yet
i think you can all agree that the brakes can never ever do this while riding, if they do in a lean..its game over. front of back although the rear brake was unaffected

so my question is have you guys experienced anything like this. what are your theories.

I went through something similar with the rear brake. Turned out the fren tubo line was too short and started rubbing on the tire heating up the brake fluid. Caused me a headache. Make sure your brake line didn’t rub on anything or next to something directly heating it up. All this assuming you bled the system correctly of course

i thought about that.. the brake line is routed through the same route as the original,, and the line i made is rubber coated stainless wrapped 2mm ptfe,
the original brake was combi braided and stainless hard line.. i theorized the line i made would transfer less heat to the fluid than the oem line..
it does run over the radiator like the original but i tied it into the original bracket that the oem brake line was tied into, so ts not touching. but its possible it came loose...ill check it right now
yes we bled the system..first the master to get the aair out, then the left caliper then the right, then the master again..then the calipers again..
we bled the front brakes when i got it back to the house and absolutely 0 air came out of the bleeders of either the master or the calipers.

i just checked and the line is still in the position i zip tied it in, it definitely did not move.

Very strange. Beside the heat theory, I wonder if the ABS is hooked up or are you running an ABS delete? If so, perhaps the pistons in the calipers are the culprit?

I've been riding many many years and never heard nor seen anything like that before. Quite bizarre and potentially life-threatening!

JHTmcrider said:

Very strange. Beside the heat theory, I wonder if the ABS is hooked up or are you running an ABS delete? If so, perhaps the pistons in the calipers are the culprit?

I've been riding many many years and never heard nor seen anything like that before. Quite bizarre and potentially life-threatening!

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same here brother.. 40 plus years riding many different bikes..i fully agree, i raced CMRA so im no stranger to pushing my limit over and over and over and had my share of get offs..... but this has me scared, riding a bike you dont trust is not a good thing .. if it happens more and i cant get it figured out, i will be completely disabling the abs. i really hate all nanny aids..yes im old and set in my ways, i just feel that if i need nannys to get to a certain level then ts the bike and not me ...therefore its not my skills that got me there, a false sense of security is a bad thing..but thats just IMHO,, to each his own.. i like unpredictability. rawness. hard to control...it makes me better and keeps fighting to be better than i was . like waiting so long on the brakes that im riding the front wheel into a turn and sliding the back tire in.

as far as i can tell everything is still connected to the abs pump.. but i have not ridden it long enough to see if the abs is working. i will test the rear brake next time i test to see if it works properly..

share your theory of how the pistons in the calipers could be the problem im interested.
i just though a warped rotor or both could be the culprit.. but they are straight..as an arrow..usually warped rotors will cause you to lose front brakes when you first apply the lever after moving the bike.,

i also thought the pazzo lever might not be allowing the master piston all the way out (and blocking the return orifice) but i checked it. and it felt ok..
the one thing that caught my attention, when i checked this, i removed the pazzo lever to checked for proper and complete return opening of the piston...
is when it put the little crosspin that goes in the lever then keys onto the master cylinders piston pushrod.... it would not easily slide onto the pushrod and would not fully seat.. i had to put some grease into the hole and work it onto the pushrod fully ,,,and finally i was able to get the crosspin to completely seat on the pushrod...so maybe the first time the crosspin was not fully seated thus not allowing the piston to fully return and blocking off the fluid return orifice, which would cause the rise in pressure in the system from heat expansion and cause the lever to be locked from pressure. this is very plausible.

for my next test ride i will fill the master back to where i had before and see if the crosspin was something i overlooked during assembly, i may have overlooked it because when i assembled the lever and master cylinder there was no fluid in it, it was dry so i would not have felt much tension if the piston was being pushed in too far from the crosspin not fully seating on the pushrod.

Are the calipers aligned with the discs? ie, spinning the front wheel unladen with the caliper mounting bolts backed off, applying and holding the front brake to do the finial torque?

1hander said:

i also thought the pazzo lever might not be allowing the master piston all the way out (and blocking the return orifice) but i checked it. and it felt ok..

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If you look into the open reservoir just as the lever begins to move, if there is enough lever free play you will see slight surface fluid motion from fluid being ejected through the vent port. Lack of free play is a common result of incorrect master cylinder piston rest position adjustments after an aftermarket lever installation. A plugged vent port will similarly result in progressive brake application with no rider input.

thomasmryan said:

Are the calipers aligned with the discs? ie, spinning the front wheel unladen with the caliper mounting bolts backed off, applying and holding the front brake to do the finial torque?

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Shazaam! said:

If you look into the open reservoir just as the lever begins to move, if there is enough lever free play you will see slight surface fluid motion from fluid being ejected through the vent port. Lack of free play is a common result of incorrect master cylinder piston rest position adjustments after an aftermarket lever installation. A plugged vent port will similarly result in progressive brake application with no rider input.
View attachment 43198

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awesome that someone else mentioned torqueing the caliper bolts this way, i do it the same way as you with the aid of a zip tie on the lever to get them straight before i tighten and torque the bolts, so yes the calipers are definitely aligned straight. or as straight as this procedure will allow them to be straightened.

as for the illustration.., the first time i put the pazzo on and bled the brakes i did not pay attention to this, i took it for granted that all was well because everything was new but there could very easily have been a burr or aluminum chip from machining or some irregularity from the plateing process used to protect the brembo parts......but its still my fault 100 percent. i have the last call on whether to ride it or not. and i need to be more vigilant , im older and dont bounce like i used too.

the second time when we got it back to the house, and re bled the brakes i did watch the surface of the oil and noticed the little bit of rippling on the surface as i pumped and released the lever. so its looking like right now the most possible scenario. is that i screwed the pooch by not going slow enough and not paying attention.. especially since i completely changed the original components to something that does not come on the bike..48 damn years old and my 21 year old constantly telling me i need to chill out. LOL

looking like 80 percent right now....that this was the scenario that caused the lockup so far.

I had same issue with my track bike many years ago, installed aftermarket levers and head out for test ride in neighborhood… needless to say after few applications brakes locked up, beed the brakes to release pressure. Put stock levers on and problem solved. I contacted distributor and explained the issue, they pulled levers from the market. If this turns to be your issue, I suggest you do the same to prevent someone getting hurt!

thanks for that info.. good to know, ill be testing this afternoon to see if the problem was the cross pin on the pazzo lever not fully seating on the piston pushrod. or if the pazzo is pushing the piston in to the point that its causing the problem your describing, ill post back

i went and checked to see the piston on the master had slack in it.. and was not piushed in too far covering the relief port in the master.
as i was pitting the lever back into the master.. and sliding the crosspin onto the pistons pushrod it snagged again and would not slide completely onto the pushrod.
thats the second time thats happened.. if the the brakes do not lock up with the reservoir filled to the full line on this test ride.. i will be convinced that this is what happened the first time the brakes locked up.. which still would make it my fault for not paying better attention. and that will the second thing i screwed up while tearing down and rebuilding this thing ..patience has never been a virtue of mine but im getting older.

just went for a test ride. 4 times around the block about 2 miles.. its a big block ..and no brakes locking up .and the clutch lever feels like it should i think..
i marked the fluid level on the reservoir and it did rise just a bit as it should .. i exercised the front brakes to see if i could get them to start locking up.
but it went perfectly. except for the dreaded stalling coming to a stop when i pulled the damn clutch, next time ill allow more warmup up time. if that doesnt stop the stalling out the evap canister goes.
so im gonna say that im now 99 percent sure that it was the improper seating of the crosspin in the lever that caused the piston to be pushed in too far..so back to modding so i can ride.. ill start another thread for that one.. although i gotta say just the second time on it, i feel much more comfortable on it flicking the bars side to side.. no damper on it yet but i feels like my r1 after all the track mods, its very flickable and want to just fall into the turns.
thank you guys for all of your insight on this matter
im calling this one fixed ..even though it was me that broke it.

1hander said:

just went for a test ride. 4 times around the block about 2 miles.. its a big block ..and no brakes locking up .and the clutch lever feels like it should i think..
i marked the fluid level on the reservoir and it did rise just a bit as it should .. i exercised the front brakes to see if i could get them to start locking up.
but it went perfectly. except for the dreaded stalling coming to a stop when i pulled the damn clutch, next time ill allow more warmup up time. if that doesnt stop the stalling out the evap canister goes.
so im gonna say that im now 99 percent sure that it was the improper seating of the crosspin in the lever that caused the piston to be pushed in too far..so back to modding so i can ride.. ill start another thread for that one.. although i gotta say just the second time on it, i feel much more comfortable on it flicking the bars side to side.. no damper on it yet but i feels like my r1 after all the track mods, its very flickable and want to just fall into the turns.
thank you guys for all of your insight on this matter
im calling this one fixed ..even though it was me that broke it.

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Re the stalling,I guess yours is a 23? I removed the stalling issue completely on my sfv4sp2 by removing the blue and black one way valve on the left side from the tank to the evap. I also at the same time changed out my gas cap for a motocorse one, so not sure if it was one the other or both. The stalling was related to a massive vacuum build up in the tank when riding,open your gas cap after you have done a few miles see if it sucks air. Anyway no more vacuum ,no more stalling.

bp_SFV4 said:

I don't think that's too terribly different from the OEM Panigale V4 front master cylinder and is a big reason why guys switch to the RCS 17. The OEM master certainly has a lot of stopping power. My last track day I managed a stoppie at the end of the straight. I just kept pulling more and more and it gave more and more. I would prefer a more direct lever to braking force feel and have been thinking about upgrading. I'm also wondering if a RCS clutch master would make launching it easier.

Have you considered injecting fluid from the calipers up to the master to remove air?

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akai said:

Re the stalling,I guess yours is a 23? I removed the stalling issue completely on my sfv4sp2 by removing the blue and black one way valve on the left side from the tank to the evap. I also at the same time changed out my gas cap for a motocorse one, so not sure if it was one the other or both. The stalling was related to a massive vacuum build up in the tank when riding,open your gas cap after you have done a few miles see if it sucks air. Anyway no more vacuum ,no more stalling.

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its a 2019 .. and mine was the same issue, the one way valve was the problem.. once i dissected it, the problem seemed to go away..