Need help with Brakes,master cylinder

[BIBS]

Hi all...I'm new here...and new to trikes.I built my first trike about 3 months ago and have had very little road time because of various issues...learning and feeling out the "trike" experience.

My latest and worst problems stem from my inability of being able to get a hard pedal on her.
I'm running a 3/4" bore master(wagner lockheed style)off of another bike that had a 4 piston rear caliper on it.
The brakes were outstanding!!
I'm trying to use the same Master on my trike with Twice the brake lines and Two 4 piston calipers(DNA axel,caliper kit)
I believe this is my problem.................................I cant get a hard pedal no matter How I try,I'm using "Speedy bleeders" and a 2lb.residual pressure valve I dont know that anything is wrong with the master....I took it apart,cleaned 'er out put 'er back together as you would for disc brake operation.
The lines are all new....braided steel,clear plastic coat style...all the fittings are Tight and I used thread sealant on all the fittings in the brake system except,of course,the bleeders........................................No matter what combination of tricks I try...I still can-not get a hard pedal!!
I rode the trike this way for 4 weeks,till I got very concerned thinking about "what if".............So I parked 'er in the shop and For the past 10 days I've tried till I'm blue in the face...and walk away frustrated,callin my friends,doin searching on line for similar situations with out any luck

What am I doing wrong???

 

[Doc]

Bibs...Possibly nothing, except not enough! In '00 I picked up an '87 Fiero Coupe (which I eventually turned into a Mini-Monster)...Bleeding the Hydraulic System for the Clutch was always a challange (M/C in the front trunk and Slave in the Rear Engine Area... many feet of lines). The only way to properly to Bleed this Design was to Jack up the Rear of the Vehicle (approx 2 ft off the ground) and after about 8 to 10 bleedings I had Pedal. You may have nothing more than a system that needs to be played with to get all the Air out!

Ed

 

[BIBS]

Doc...she's jacked up off the floor,I've bled the brakes till I'm weary!!
The speedy bleeders simplify the process.....but no hard pedal.
I rode the trike with "some" pedal but lost confidence in 'er.
How many different ways to bleed brakes are there?I've tried back bleeding them with a suction pump also.


Do you think the 3/4" bore wagner is up to the task?

 

[Baz]

Doc...she's jacked up off the floor,I've bled the brakes till I'm weary!!

The speedy bleeders simplify the process.....but no hard pedal.

I rode the trike with "some" pedal but lost confidence in 'er.

How many different ways to bleed brakes are there?I've tried back bleeding them with a suction pump also.

Do you think the 3/4" bore wagner is up to the task?

Are you sure the 3/4 cylinder is specified to to operate your rear brake circuit ?? By this I mean the ratio is probably incorrect meaning the master can't shift enough fluid to do the job ??

 

[BIBS]

No I'm not.This is why I'm asking...or should I redirect the question.............Has anyone used a wagner/lockheed Harley style Master 3/4" bore for a trike with dual 4 piston calipers.

 

[BIBS]

>>>>I just got off the Horn with Christina over at Santiago choppers,they do lots in the way of Trike conversions,She said go with part no# 260-6765 WILWOOD master cylinder from california 7/8" bore.

Anybody hear of one...or them?

 

[1550vt]

If every thing is properly bled (and I think you're sure of that) like mentioned above....the ratio is too great. You have too much volume in the piston area of your calipers or too little volume in your MC. You have made a .750 master cylinder into a .375 by adding the other caliper and doubled your ratio giving you a softer pedal. The 7/8 may be an improvement, but that is only a .875 bore. I think you re going to have to replace your calipers if you wish to stick with this MC. You would likely need a 1-inch MC bore to make this work, which is getting up into automobile type stuff.

I am currently running two 4-piston (opposed) calipers with the stock 5/8 rear MC. My ratio is close to 18....a "little" soft, but she hardens-up real fast and will lock-down the rear end at any speed.

You are going to have to match the volume of the caliper pistons to the volume of the MC in the correct ratio. If you will PM me I will send you some good information on ratio's and help you figure out what you need to do. From what I see so far...the 7/8 is not going to be enough and you need to work on the caliper end.

 

[ultraboy]

Bibs, here's the trick with those calipers on the DNA axels. Remove the calipers (leave the brake lines & banjos connected) get a strip of 1/16" thick steel, and place between the brake pads. Push your brake pedal down a few times, forcing the pistons to come out farther. Let off the pedal, and gently spread the pads just far enough to get the calipers back over the disks, bolt them down, and you should be good to go. The seals in these DNA calipers tend to roll the pistons back when you let off the pedal. Clamping down on a "thin" disk, if you will, will take care of this tendency. Most of the DNA rear ends I have installed also have light springs on the pad pins, which will slightly retract the pads, and make your residual pressure valve unnessary. A 5/8 bore master is really all that is necessary.

UB

 

[BIBS]

Here is what was reccomended By Santiago choppers,the people that sell trike conversion kits>>Wilwood High-Performance Disc Brakes - Master Cylinders Volume Master Cylinder


Scroll down to 7/8" bore master.

 

[ultraboy]

Bibs, just give the above trick a try before you go spending money.

 

[BIBS]

Thanks a gazillion Ultraboy!!!!!...soon as I get my act togetherI'll get out there in the shop and start "operating"!!

 

[1550vt]

Give what Dave said a try. I think I understand that he is saying the pistons are not being forced out against the rotors for you to get a good bleed on your system, because the caliper pistons are simply forcing the fluid back into the system between pedal strokes. This will "reset" the pistons so they can be forced against the rotor allowing you to build the pressure and bleed them. He wants you to "make" those pistons clamp-down on something smaller than the normal .250-or-so rotor.

I don't know beans about those calipers and apparently Dave does. My approach was to have you give me the caliper piston diameter so I could figure the ratio you would have with the .75 MC you said you have on there now and then go from there. I do agree that a larger MC was not needed....unless I had discovered the caliper bores were too large. I do submit that you will have more travel in the brake pedal as you did with this set-up on the 2-wheeler, simply because you are adding 100% more volume for the MC to move. It will work. I have a the stock Harley 5/8 on mine and I do not run a residual valve. Mine has a little more brake pedal travel, but they harden-up well before they bottom-out.

Let us know if this overcomes the problem and if it doesn't....lets talk again.

 

[BIBS]

DAMN...you guys certainly have been Helpful!!!!...Now all I have to do is get my dead ass in gear long enuff to do as suggested!!
I'm hopeful that tonight will afford me the time to light in one spot long enuff to git'er done.
I WILL offer up a full report and let yall know!!!...Thanks Guys!

 

[BIBS]

Well I tried it...no worky.
I've never seen anything so simple be so friggin difficult in all the years I've wrenched on bikes,etc.
Ultra....the Master is so friggin Lame that it wont push the pads out with any clamping pressure on the 1/16" sections of Flat....I tried 1/8" as well...Same ****.

Are there any other calipers out there with the same bolt pattern?

I'm willing to try anything at this point...........................everyday that goes by is one less day of riding.

 

[1550vt]

BIBS....just do what we talked about last night and what I have in those messages I sent. No reason at all why the 3/4 MC will not work with those 32mm 4-piston opposed calipers. Do what we talked about and then you can report your success....I am sure of it, unless the caliper bores have been damaged. Do it....and we'll see if anything needs replacing if it doesn't work.

 

[ultraboy]

Bibs, all else being done correctly, what I told you does work. You obviously have other problems if the pads won't even clamp down on the 'thin' disk. Normally, when this situation occurs, you do get decent pedal after correctly bleeding the system, however after letting the system sit for a couple minutes, and the pedal going all the way down on the first stroke, but able to pump up in a couple strokes, is when re-setting the travel will work. If you have thrown other things in the works like a bad master, or wrong fluid, then all bets are off.

 

[BIBS]

Bibs, all else being done correctly, what I told you does work. You obviously have other problems if the pads won't even clamp down on the 'thin' disk. Normally, when this situation occurs, you do get decent pedal after correctly bleeding the system, however after letting the system sit for a couple minutes, and the pedal going all the way down on the first stroke, but able to pump up in a couple strokes, is when re-setting the travel will work. If you have thrown other things in the works like a bad master, or wrong fluid, then all bets are off.

I'm now in the process of flushing out the system(yes,I tried 2 different types of fluid...5.1 and 5).....I even bought a new wagner 3/4" bore master just to be on the safe side.
I'm also going to flush out the calipers....I'll keep ya posted.

 

[1550vt]

Good deal....just remember....do not ever mix DOT 5 with anything but DOT 5. DOT 5.1 is just a better grade (higher boiling point) of glycol based fluids like the 2, 3 and 4. Only our government could hang a number like 5.1 on it...go figure! No wonder it's easy to get confused.

The only advantage one will ever realize from the use of DOT 5 is that it is paint-friendly.

Like I had told you in some messages...even if the cover says DOT 5 only....forget it and use DOT 4. Most of us do not approach the bike and start pouring brake fluid all over the fenders and gas tank. Just simply clean-off any spilled DOT 4 from the paint and rock-on.

Those that feel the need to argue the merits of DOT 5....go do the research and you will discover it's not that great and offers more risk than benefits for the average HD rider. I think the MOCO specifies it for paint protection.

 

[ultraboy]

Mixologist huh? OK Bibs, you know what ya gotta do. Good luck.

 

[BIBS]

Good deal....just remember....do not ever mix DOT 5 with anything but DOT 5. DOT 5.1 is just a better grade (higher boiling point) of glycol based fluids like the 2, 3 and 4. Only our government could hang a number like 5.1 on it...go figure! No wonder it's easy to get confused.

The only advantage one will ever realize from the use of DOT 5 is that it is paint-friendly.

Like I had told you in some messages...even if the cover says DOT 5 only....forget it and use DOT 4. Most of us do not approach the bike and start pouring brake fluid all over the fenders and gas tank. Just simply clean-off any spilled DOT 4 from the paint and rock-on.

Those that feel the need to argue the merits of DOT 5....go do the research and you will discover it's not that great and offers more risk than benefits for the average HD rider. I think the MOCO specifies it for paint protection.

Sounds great!!,Just one more question before I start boltin stuff back up.....is the DOT 4# going to do anything weird to the seals in the calipers or the master?
(psssst...anybody wanna buy 3 cans of DOT 5#?)