Neverending bleeding of brakes

[Hutchison]

I was wondering today what I'd do if I suddenly had all the hours back that I've spent battling the initial bleeding of vw trike brakes. Pretty sure I'd be young again, so....
So I spent another frustrating day farting around trying to do what should be the simplest of jobs, bleeding brakes. I have a new 5/8 cnc mc and a vw type 3 rear end. The mc is lower than the wheel cylinders, so I have a residual valve also. I also lifted the front of the trike til the mc was higher than the brakes. I'm getting full travel of the plunger, full in to full out. I have run an ocean of clear brake fluid through the thing without a bubble, and still scratching my head. I've been through the process on a dozen trike builds, and still don't know how to do this job correctly? This is the sort of thing you don't even want to admit in public.

 

[Sidecarbill]

And u have no pedal,petal is soft,petal travels to far but feels good? Air bleed hole in masters not blocked? I've had good luck with a new clean pump oil can. Just put a hose on it,put it on the bleeder and pump the fluid back 2 the master. Make sure the reservoir has room 4 it.

 

[Hutchison]

And u have no pedal,petal is soft,petal travels to far but feels good? Air bleed hole in masters not blocked? I've had good luck with a new clean pump oil can. Just put a hose on it,put it on the bleeder and pump the fluid back 2 the master. Make sure the reservoir has room 4 it.

Pedal almost bottoms out.
Yeah, that's what I'm doing, just routing the fluid back to the master. Gonna work on it some more today, see how it goes!
Thanks!

 

[Sidecarbill]

I don't know what brakes u have but if they're drums you may not b moving enough fluid. 5/8 bore is considerably smaller 19mm. I have 19mm bore and I can locck the brakes almost 2 easily.

 

[Hutchison]

I don't know what brakes u have but if they're drums you may not b moving enough fluid. 5/8 bore is considerably smaller 19mm. I have 19mm bore and I can locck the brakes almost 2 easily.

I've run the same combination before and it worked fine. I'm gonna remove mc and do bench bleed to be sure.

- - - Updated - - -

I've run the same combination before and it worked fine. I'm gonna remove mc and do bench bleed to be sure.

And if that doesn't work, I think I have a 3/4 mc laying around. I may try that because of your comment.
Thanks!

 

[peteg59]

Drum vs disc. There are 2 different residual pressure valves depending on the type...

 

[DeathBySnuSnu]

Also a few different possibilities on wheel cylinder bore size also.
Assuming drum brakes.
Gonna hafta keep them adjusted close with a 5/8" master.

 

[stinger608]

I've run the same combination before and it worked fine. I'm gonna remove mc and do bench bleed to be sure.

- - - Updated - - -

I was going to ask if you had bench bleed the master cylinder before installing.

Also a few different possibilities on wheel cylinder bore size also.
Assuming drum brakes.
Gonna hafta keep them adjusted close with a 5/8" master.

Was going to suggest that you have to adjust them dang close to get decent braking. I ended up converting to disk and running a residual valve due to my calipers being higher than the master.

If your wheel cylinders are higher than your master cylinder then the fluid will flow back toward the master causing no brakes. I never could get them to work until installing a residual valve.

 

[vwtriker1948]

bleeding brakes

Yep been there done that on my VW Trike.

1/ I tried the normal way filling the reservoir up and pumping the fluid through,messy and frustrating and hard to do.

2/ Used a vacuum pump, the idea is good but air gets sucked in through the threads on the bleed nipples.
Perfect every time