All:

I've got this machine in the shop with a complaint of brake pedal to the floor. Customer tried to fix on own but with no success. He placed a new master cyl and reservoir on it and tried to bleed with no luck.

He brought it to me and I have cleaned out all the lines. what I was able to fine was that the lines from the reservoir were incorrectly connected, so I fixed that and am able to get fluid through the bleeders, but the pedal will not tighten up.

Using a MityVac hand bleeder as I'm a one-person operation.

Suggestions most welcome!!!

Tom

 

i've always bled them short side first like a vehicle. i've had good luck with that technique. although difficult by yourself. you're using DOT 4, correct?

 

Jaster 94:

This thing has got two mechanics with over 40 years experience each STUMPED!! I disconnected each line, made sure it was unblocked, reconnected everything ensuring all areas were clean. Reassembled with new master cylinder and reservoir, added the correct fluid and attempted to bleed the wheel cylinders like I've done on cars, trucks, and heavy equipment. No luck!! We tried the vacuum equipment in addition to the good ol' manual pumping of the pedal. Even tried preloading the master cylinder and ensuring that it had no air locks. For the life of me, I've never had anything do what this thing is doing. Pedal will not build up pressure, and after switching back to the other master cylinder and reservoir (all supplied by the customer as he tried to fix this himself first) still nothing!!! We've got about five hours in the thing and I'm sitting here scratching my head.

Is there something to these Chinese knock-offs that I'm missing? There are no air/fluid leaks that can be found. The next thing I'm thinking about is to replace all the lines, T-blocks, and another master cylinder.

Any suggestions, anyone???

Thanks in advance...

Tom

 

wow, you stumped me! sonofagun........unbelievable that it ain't gonna bleed down.

 

Is the master cyl returning all the way so as to close as well as open the ports in the MC, I am guessing disc. If you old fashion bleed will it squirt from the bleeder? I have had a bad brake line and the fluid would flow between the tube and the casing I only figured it out by accident when I noticed a little bubble grow on the hose when I depressed the master cyl. Other than that I got nothing sorry.
Dave

 

All:

Update on this nightmare: FINALLY got the lines to move fluid. Brake pedal tightens up. Problem now is that the calipers are locking down on the rotors once you drive it for a while. I'm thinking that there's something preventing the return of fluid to the master cylinder. This is a new master cylinder and I know that nothing rules out the possibility that it is also bad. This should be simple system where a finite volume of fluid is pushed by the MC piston to all four calipers to activate the brakes, then return the fluid to the reservoir when the pedal is released. If it was one caliper then I'd suspect a problem there. If you crack the front or rear lines there it connects to the MC, then you get a burst of fluid without air and the calipers release. It's like a check valve is holding the fluid in the pressure position. Worst part is a reverse engineered product like this is almost impossible to get a service manual for that's comprehensive and parts are even more difficult. I don't like to throw parts at things in the hope that something strike gold and fixes it. I've always been a diagnostic mechanic. Seen too much of the former from some others...

Thoughts?

Thanks!

Tom

 

Well I hear ya on throwing parts but sometimes ... ya know however, if ya have any other MC in the shop you can switch it over and quickly check it. I also had a brake line on my 86 trans/am go bad in much the same way I described in my last post and it would not let the right front caliper return drove me batty.

 

What about a brake block "t" where the line from the master cylinder ties into with other brake lines to distribute fluid to each caliper? I guess it would have something of this nature as most machines have.May even have a pressure switch attached that activate the lights that might be faulty or problem in the block itself? Just guessing on this as this is what Polaris has and if you've eliminated any caliper problem.

 

Sounds like the original problem may have been moisture in the system and possibly corroded the t block? Have you tried cracking the line from the master to the block to see if its on the other side of the block when the brakes lock? You have probably already run lots of fluid through the system. When i got my machine it took me a full bottle of brake fluid just to get clear new fluid just to the front brakes. Every time i got it flowing clear i would go out and ride and then come and check and it was dirty again. took me a few runs to get all cleared out

 

Afternoon Update...

I found out in further discussion with the owner that he had "adjusted" the rod connecting the brake pedal to the master cylinder. Well, that explained the locking of the calipers--I'm pretty sure that the MC piston could not travel far enough to full return position and in theory was locking fluid to the calipers once pressure was applied. Seems to be validated in that I backed off the rod adjustment and PRESTO-the rear wheels freed up once the rod was further back in it's travel.
Problem now is that I don't have a solid pedal unless I pump it several times. I get no air from the bleeders; just a flow of clear brake fluid.

This Chinese stuff really has me frustrated. I'm no quitter, but I'm at the point where I tell the owner there's nothing more I can do.

Short of replacing all lines and tee blocks I feel I'm out of options, unless others out there can think of something. It's only got about 300 miles on it. Guess you get what you pay for....