Suzuki-Lehman Brake Bleeding ?

[Sinical]

Have gone thru this brake job as thoroughly as I can (or as much as my patience will allow anymore, LOL!)

Rebuilt brake master cylinder (from a Suzuki VS1400), flushed all brake lines, replaced hose and hose clamps from reservoir to brake master cylinder, replaced banjo fitting crush washers, replaced all brake shoes and hardware, plus new wheel cylinders. Even lost the original 245 tires and installed 215's, which go on and come off MUCH easier. Put everything together and adjusted the Lehman actuating arm for the brake master cylinder for a clearance between actuating arm and master cylinder piston set at a gap of .035 (approx. 1mm)

Bleeding consisted of a combo of gravity bleed and traditional bleed and it's just not happening. Have a very low and spongy pedal, which tells me that there's a lot of air still in the system. After researching it, my understanding is that the brake master cylinder should be situated above the height of the wheel cylinders. Measured everything today....

Reservoir sits at 16 1/2 inches at the bottom, 18 inches at the top.
Master cylinder sits at 10 1/2 inches
Flexible hose that routes from master cylinder banjo bolt fitting to under the axle tube is 9 1/2 inches, then it routes over the top of the axle tube and threads into the T-fitting for the lines going to the wheel cylinders.
Bleeder valves on the wheel cylinders are at 15 inches, definitely HIGHER than the brake master cylinder.

After fighting with this job for going on 3 months now (working on it as time allows) decided to buy a MityVac brake bleeder and will be giving that a shot. Also strongly considering unbolting the brake master cylinder and propping it up so's it's above the height of the wheel cylinder bleeder valves while trying to bleed this thing.

Does this approach sound hopeful ?



Thanx in advance ThumbUp

 

[Darth]

I just recently did a trike conversion on a HD Sportster with a Champion kit, and encountered issues similar to yours when bleeding the brakes. I could get enough brake pressure to stop the bike, but it was spongy and used full travel. I finally ended up borrowing my neighbors MityVac along with my own so that I had two. I hooked one up to each caliper and was finally able to get a better brake feel. Also, riding it around helped move the air through the system such that it was easier to bleed again, but not recommended if you do not have enough brake pressure to get you stopped in an emergency. When you use the MityVac, make sure you always keep the master cylinder topped off with fluid so you don't pull air into the system via the reservoir.

Good Luck!

 

[Sinical]

Thanx very much, Darth, this is encouraging and am looking forward to getting back in the shop as soon as time allows.

Also checked out your build thread on your OL's 1200 Sporty w/Champion Trike kit and ya done GOOD! Looks GREAT! ThumbUp Plus, with the 1200, there's no doubt that there's plenty of torque to keep rollin' strong and effortlessly. Very right on!

Your description of the low/spongy pedal sure sounds familiar here, LOL! Feeling confident that the MityVac will do the trick and your confirmation and advice have helped greatly. This metric brake master cylinder has a separate brake fluid reservoir (very small one, also from a VS1400) and it connects via a foot long hose between reservoir and m/c. Initially, I had raised the reservoir as high as I could and there were some air bubbles coming up when initially feeding the brake fluid into the system. Will raise the reservoir again as well as unbolt the m/c and prop that up during the MityVac bleeding process.

Once adequate brake pressure is achieved, in full agreement with you about taking it safely out for some rides and then bleeding again as needed after the rides help free up any stuck air bubbles in order to get 'em bled.

Once again, very much appreciated, Brother, and please Ride Safe ThumbUp

 

[Sinical]

An up-date and a question......

Finally got time to try the MityVac recently and it didn't seem to change things much. There were tons of micro-bubbles coming thru the fitting which the MityVac instructions say are normal as the micro-bubbles wouldn't go into the brake line system. End result after bleeding was hardly noticeable.

Admittedly, I hadn't set the initial brake shoe adjustments very aggressively due to a binding wheel on the right hand side (mentioned in another thread) and wanted to start on the low side of adjustment. Got back after it again yesterday, tightening up the star adjusters 3 clicks at a time per side and actually got some better brake pedal action.

Also bled the brakes the traditional way by pumping the pedal, holding, cracking bleeder valves, closing bleeder valves. Did this 9 times per side between short test runs. On the left side, out of 9 bleeds, got 0 bubbles and good brake fluid flow. On the right side, out of 9 bleeds, only got 2 real bubbles, no micro-bubbles and essentially good brake fluid flow.

Now, sometime previous to this wrenching session, once it was established that there's no Residual Pressure Valve on this trike (also in another thread)......did a reverse bleed, pushing brake fluid from the bleeder valves to the reservoir and it worked fine with absolutely no bubbles appearing in the reservoir, so with that in mind plus yesterday's absence of any major air coming out while doing the traditional bleeds, am thinking that there's very little air in the brake line system.



Discovered a new problem and wanted to bounce this off of the experts here. After each brief test run, when feeling the drums, the left side was cool to the touch, but the right side (binding) drum was downright HOT. Quick research indicates possible causes could be:

1) bad wheel/axle bearing (not convinced that's the case)
2) brake shoes adjusted too tightly (that shouldn't be the case)
3) emergency brake cable improperly adjusted

Could it be that the emergency brake cable on the right hand side is causing both the HOT drum as well as the binding wheel on that side ? If so, would someone please offer the needed info for me to sort this out ?

I've lost count of the number of times this trike has been jacked up and the wheels and drums removed to check things out, LOL! Not looking for any free rides here, have been researching the snot out of this job and paying more than my fair share of dues and will continue doing so as I'm not ready to admit defeat yet. orag:

Thanx in advance ThumbUp

 

[cscsonny]

I believe the pulling axle side will run a little warmer because of torque on that side.
Two possible suggestions for soft breakes.If you haven't done so yet.
One,have you pumped and bled at the banjo bolt on master cylinder.Cover any painted area around it before bleeding.
If you have disc brakes on front,sometimes you have to remove bolts that hold calipers,leaving on the rotors,and turn up to 12 o'clock position or straight up and then bleed.Early Goldwings had to be bled this way due to position (about 2 o'clock) of the front calipers.You would be surprised at how much air got trapped there.
Hope this helps,good luck.

 

[Sinical]

I believe the pulling axle side will run a little warmer because of torque on that side.
Two possible suggestions for soft breakes.If you haven't done so yet.
One,have you pumped and bled at the banjo bolt on master cylinder.Cover any painted area around it before bleeding.
If you have disc brakes on front,sometimes you have to remove bolts that hold calipers,leaving on the rotors,and turn up to 12 o'clock position or straight up and then bleed.Early Goldwings had to be bled this way due to position (about 2 o'clock) of the front calipers.You would be surprised at how much air got trapped there.
Hope this helps,good luck.

Thanx for the response, "cscsonny" ThumbUp.......The front brake on this Suzuki is separate from the rear brakes, but am pretty sure that I've got the bleeding process covered O.K. Last 9 bleeds showed healthy amounts of brake fluid and only 2 air bubbles. BTW, a reverse bleeding tool might be very effective for bleeding front hydraulic brakes as well as hydraulic clutches. Principle is that by bleeding in reverse.....pushing fluid thru bleeder valves and up into the reservoir......it pushes the air "upwards" the way that air would naturally prefer to go. There's several varieties of reverse bleeders ranging in price from about $20 all the way up to several hundred for the pro-type kit, but in all reality a cheapo $20 reverse bleeding pump should be more than adequate. You could do a search on eBay for "reverse brake bleeder tool" to see more info.

Am more concerned with the right drum getting hot and the right wheel binding as in this thread:

http://www.triketalk.com/forum/threads/21619-Suzuki-Lehman-Brake-Backing-Plate-Or

If the right side drum only got a little warmer, I could live with that, but I'm talking frying pan HOT:AGGHH:

Going to add a post to the linked thread after this, as I'm running out of ideas with how to fix this thing, LOL!

Thanx again and Ride Safe ThumbUp