Experience bleeding left hand rear brake?

roostafish

roostafish

Gold Level Site Supporter
Has anybody done this? It is so far very difficult to get the air bubble out of the foot master cylinder. This is the dual actuated system, so I am adding the LHRB to the foot brake. This is the Rekluse kit, the instructions are easy, but in practice, it's not happening.
 
I have the dual brakes also. The Rekluse kit hose is a little too long and fitting that connects to the foot brake is at such and angle it want to make a hump in the hose to catch air.

Did you put the o-ring in the sleeve that go's into the foot cylinder? The one Rekluse set me was too large and would end up cutting it trying to install the sleeve into the cylinder.

For bleeding I ended up removing the hand brake from the bar but leave the hose connected.

Suspend the hand brake up in the air so the hose is close to vertical.

Pump in the brake fluid from the rear caliper bleeder screw until the air is purged.

Lower the hand brake horizontal enough to fill with fluid and install cap.
Remount hand brake to the bar.
 
Thanks for the tips. All the air appears to be out of the system. I have pushed about a full bottle of DOT 4 through the system. There's no air bubble in the sight glass anymore, and I've bled every junction, including the brake light switch.
The hand brake takes a pull all the way to the bar to lock the wheel, and the plunger is slow to return. This is the mineral oil stock clutch MC, and I'm thinking it's a no no to use it with DOT 4, and hoping it's my problem. I'm getting pretty frustrated.
 
I does not matter on the Foot MC if there is an air bubble in there of not. The sleeve that go's inside with the oring at the bottom should be sealing the pressure out of the MC reservoir other wise when you pulled the hand brake the sight glass could pop out.
Can you feel the sight glass flexing if you pull the hand brake?
Does the rear brake pedal have the return spring hooked up? The rear MC can not be compressed at all other wise when you pull the hand brake the rear MC will have to extend out before pressure is applied to the caliper.

The AJP MC that I got from Rekluse looked just like the stock clutch MC. I believe the only reason they put Minerial Oil Only on the cover is so if you and a clutch slave cylinder leak you would not put brake fluid into the trans. I have been running the Bel Ray Dot 5 for years and have had no problems.

You might try now to bleed the conventional way just to double check for no air. And when you do make sure you push the hand brake lever all the out away from the bar. Every once and awhile you can get a small bubble there also.
 
If your MC is the mineral oil unit, then I'm sure I"m still dealing with air in the system. It's in the upper end though, because the foot portion feels fantastic. It is returned all the way, so I don't think we're dealing with that. It looks as though there's just not much pressure in the upper system because the piston in the master cylinder doesn't return all the way, and I have to pull it out with needle nosed pliers. If I could get a good seal on the caliper, I'd back bleed it, but every time I introduce air. So, it looks like I'll take your advice and bleed it normally, and use my 10' clear hose to pump it back in. I'll post back my results. I've already spent over 12 hours on it, so I'm commited to the stupid thing. Maybe I should be committed to the funny farm.
 
roost,

I suspect most of your problem may be with the rear OEM foot master cyl as far as bleeding goes. Its almost impossible to back bleed. Remove the nipple and use teflon tape on the threads, to seal air leaks. Use a syringe with a plastic tube, and with a hard pull on it crack the fitting. Repeat until no air in tube.

The AJC masters appear the same but must have different seal rubber compounds for DOT3/4 vs mineral oil. Has anyone checked part #s on this? I would think installing the rubber components from an older master would solve this. I know using oil in the older DOT 3/4 systems makes quick work of the seals and resevoir cap bladder (swells bad), as my nephew has done it.
 
Apparrently it's okay to put DOT 4 into a cyl with mineral oil seals, but not the other way around. Still, I'm going to be searching for a seal kit. I found it at AJP America, but no price. At least it's available.

Today I was able to make the thing usable, I'm going to be back bleeding it several times over the next few days, because it has produced several more tiny little air bubbles at the top MC. Just pushing on the caliper and bottoming it out, then slowly, ever so slowly pumping it back up with the hand has produced the results I've hoped for. I still wish it would lock the brake a little further from the bar, but it's definitely usable. Perhaps riding it and bouncing around with break some more bubbles loose too.
 
You mite try holding the lever to the bare with a zipty over night and tapping on the line when you pass by to get your favorite adult beverage :D .This has worked for me in the past.

I do not know if it is the same but when I was over on CRFSonly everyone that put a LHB said they had to really pull the lever to get it to lock the wheel.
 
I've been having a nightmare with this too. I'm pretty sure there's no air in the lines. The foot brake works the same as it ever did but the hand brake comes back to the bar without enough force to lock the wheel when riding. Interestingly if I apply the foot brake everything goes solid and works including the hand brake! Not sure what's going on, it's as if using the hand only causes something in the foot brake to give dissipating the pressure. I have bled it every way possible, as they advise, forward, backwards and with a vacuum. Still doesn't work properly.

I noticed when I had the bike on it's side a bubble shows up in the foot m/c window. In theory this should be outside the circuit but I'm wondering about it. Is it normal that applying the foot brake puts pressure up to the hand brake?
 
The pedal on the foot certainly affects the pull at the bar, I do think that's normal. After pushing the caliper in, bottoming the piston out and pumping it back up about a million times, my hand brake actually has the same travel as the front hand brake. I am anxious to go ride it now and see how it perfoms. It works fine riding around the house, but I need to go ride some trails to sort it. If I can get used to using my hand, I may just have a line made to go from the hand to the caliper and forgoe the foot. I don't have a foot brake on my mountain bike, I don't see why not. Time will tell.

This has been a big headache!
 
roostafish said:
The pedal on the foot certainly affects the pull at the bar, I do think that's normal. After pushing the caliper in, bottoming the piston out and pumping it back up about a million times, my hand brake actually has the same travel as the front hand brake. I am anxious to go ride it now and see how it perfoms. It works fine riding around the house, but I need to go ride some trails to sort it. If I can get used to using my hand, I may just have a line made to go from the hand to the caliper and forgoe the foot. I don't have a foot brake on my mountain bike, I don't see why not. Time will tell.

This has been a big headache!
Click to expand...

I wanted a foot as well as I find in moments of panic like too high corner entry speed I automatically go for the foot. Strange as I also ride mountain bikes but when I have an engine years of using a foot brake have conditioned me. I may give up on it and just go for hand as I can't seem to make both work together satisfactorily. Had a final attempt last night but haven't had time to try it. I don't think it's fixed as not as firm as the front brake.
 
I may eventually give up on it too if it doesn't feel right. I still wonder if there's a difference between the mineral oil mc internals and the DOT 4. There's a guy here locally that has the lhrb that just raves about it, so I'm going to try to get in touch with him to go grab his rear brake lever and see if it sucks as bad as mine.. I'd like to try a different brand mc. Maybe even an actual Nissin front brake. Even if I had to put it on backwards and cob up some sort of thumb actuator. That's getting ahead of myself though. I'd like to see if it works better first.
 
Even mine is not as firm as I would like but works good enough that I would not give it up. It pulls back about 2/3rds of the way to the bar.
I have had thoughts of ditching the rear foot brake but to many times of sitting on a hill with a bottle necks I keep thinking it would suck not being able to take your hand off the bars to readjust goggles and such.
 
HydroDog said:
Even mine is not as firm as I would like but works good enough that I would not give it up. It pulls back about 2/3rds of the way to the bar.
I have had thoughts of ditching the rear foot brake but to many times of sitting on a hill with a bottle necks I keep thinking it would suck not being able to take your hand off the bars to readjust goggles and such.
Click to expand...

Good point and I really would like both working. I might open the foot mc and try filling it with fluid before fitting the insert. I keep wondering if the o-ring is giving a bit and dissipating pressure from the hand lever. As I fitted the insert with the foot mc virtually empty I wonder if the o-ring is not clamped tight enough and expanding under pressure as outside the insert there is air gap.
 
Have you tried clamping the line in diferent places to see where the air is in the system? At least then you would know what to look at.
 
You can, I would'nt keep doing it, but once would be fine. I've done it on braided nylon pipes on bikes and cars, never had and adverse effects.
 
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