• Reminder: Seemingly bad GY6 brake components are (almost) never the problem

  • If you've got some feedback for me but aren't ready to write a review, here's the place to voice your concern or comments. I'll also post explanations of the policies that help our programs function. -T@BD
If you've got some feedback for me but aren't ready to write a review, here's the place to voice your concern or comments. I'll also post explanations of the policies that help our programs function. -T@BD
 #11428  by Travis @ Buggy Depot
 Tue Feb 27, 2018 10:19 pm
I tend to see brake parts being returned more often than other types of parts. I received this message today and I wanted to share my response here to raise a bit of awareness to this common GY6 maintenance pitfall. If you're working on your brakes, this might help save both you and I some hassle and extra expense:
Hi, This is J********. I am responding to the last email. I received the master cylinder that you sent a couple of months ago that yall sent and it was bad. There was not enough efficient pressure to get the air out of the system. I tried every method there is and none worked. Please stand behind your faulty parts and send me a good, strong, working master cylinder that I can use...

"Hi ******** ,
To follow up, just want to say that we don't have a problem sending out a new master cylinder. Your new MC is on the way, tracking number is: 9405********************. However, true master cylinder defects are very rare. The most difficult thing to work on with these 150's is bleeding the brakes. We often get warranty request on brake items, only to find that they are perfectly good upon being returned.

The reason this happens is not about pressure, it's about volume. The small piston diameter and very short travel means that very little volume is pushed in the system. Unlike a larger master cylinder in a car or truck, the volume of one stroke of the cylinder isn't enough to get much of anything moving. The fluid moves slowly, and air returns to any high points in the system quickly. Without working out the right bleeding arrangement, you'll be pumping and vacuuming for hours with no progress. You'll need to position all of the lines and the MC/caliper to prevent air traps from forming. I've always had the best results bleeding off of the machine.

Just wanted to add a technical perspective. I've dealt with this too many times personally. Though I won't try to rule out the possibility of a defect, returned brake parts are almost always good and not faulty. These hassles are caused by the design and size of the system itself."

I cover the issue a bit more in depth in this article:

How to bleed your brakes, without wasting hours of time
https://www.buggydepot.com/tech-center/ ... ur-brakes/

 #11489  by myvt365
 Mon Mar 12, 2018 10:15 am
I can vouch on this behalf I was a bit skeptical on bleeding this unit right out the box but I did go ahead with the bench bleed idea. First off as Travis stated you need to take them time and you will need 4 hands lol. First the reservoir has to be tied up quite high as to gravity bleed the unit I zipped tied mine to the back rack. next you need to invert the MC and unscrew the clevis and removed the boot. What I did was tie the master cylinder a couple inches lower then the reservoir. Next you will see a snap ring that is quite a pia granted I have a nice pair of snap ring pliers . Take the snap ring out and the bolt washer and snap ring come out set it to the side. After then you will see the piston I took needle nose and lifted the piston and ring assembly out at this point it was completely open. open the bleeder and keep filling the tank with brake fluid its not a very fast process but once the bleeder was open fluid began run out and I let that go until no bubbles where there just fluid. did the same thing on the other side. I jacked the unit up and tested the brakes worked first time no issues. Now when you close this the MC is going to be filled to the top when you go to add the piston and spring assembly back into the MC fluid is going the spill out which is good there is no air. When you go to add the snap ring back in place your going to need 4 hands to help seat the snap ring. there is going to be some fluid on the outside of the ring is just left over from putting it back together. Flip MC back over and double check its not leaking. when you do this your fluid level is going to raise in the reservoir. I can attest that normal brake bleeding isn't going to work there is very minimal travel in this system maybe a 1/4 of an inch at most. All in all as stated the system is very basic and bleeding this way works it just takes the time to do it and it worked great on my front brake kit!!!
 #11546  by Travis @ Buggy Depot
 Wed Mar 14, 2018 6:13 am