Introducing the Stig Special

[Stigian 1,234]

It is I who is honored Massey to be able to borrow an idea from your fine machine.

Today has mostly been about calipers..

Two of these are good the other two both have broken off bleed nipples so they are only good for spares.

yes, I did try getting the nipples out but that only resulted in a broken bleed nipple with a broken "easy-out" stuck in it!!

This is one of the good ones, I popped the piston out to take out the broken oil seal. It just needs a good clean.

While this was going on the postman appeared with one of my new bigger master cylinders

Back to the calipers and we have two er different looking pistons!!

The one on the left had lost a lot of the "friction material" type stuff! This was quite confusing for a while as is looks just like it could of been a brake pad for a different model bike stuck on the piston. The only other bike that uses the same calipers is a Qwackasaki Z250 Scorpion, a quick look on Fleabay showed they use the same brake pads as the Gpz305 pads, so the bits stuck on the end of the pistons are not in fact brake pads!.. Hope you all followed that, I'm struggling

Spot the height difference..

Although one of my spare caliper pistons does have a good "top" on it, it does however have a small patch of deep rust pits on the side which would soon shred up the rubber seal.

Plan B it is then, repair the broken topped piston. Lot's of filing later it now has a flat top

To build the piston height back up I cut a small circle of ally and stuck it on with chemical metal.

Seen here awaiting to be stuck on, black side down.

Somehow the piston top decided to stay stuck on as two calipers were reassembled, plumbed in to the bigger master cylinder and bleed on the bench.. Feeling good

The new improved test braking system installed on the 'orse, the steering brakes have never felt so good or firm

If the rain stays away and the other master cylinder turns up in the morning, I feel another test drive coming up tomorrow afternoon :)

[Stigian 1,234]

Sorry Guys, the second master cylinder didn't turn up today, so no test drive

Instead after yesterdays brake caliper findings I thought I should take a look at the brakes on the other side..

Yuk!! One of the calipers had a really rotten er.. "non brake pad" pad type thing.. Anyone know what these things stuck on the piston are for?

This piston got the "file the remains off, then stick a bit of ally on treatment.

When I popped the next piston out the last caliper I noticed it was different to all the others! Not only was it in good condition (makes a change) but the pad bit is smaller!

It's the one on the left.

The rubber seal was different as well.. Quite a large difference!! This time it's the one on the right

I guess someone had been in the caliper before. The seal was replaced with the right size one.

I've been lucky with the seals, bar one they have all been good enough to reuse.

All done and waiting to be bolted back on the 6X6.

Phew... Thank you "auto save" for remembering all I have triped so far when Firefox crashes.. A good system

Where was I??

Oh yes, that's it..

While having fun with the calipers I kept thinking about the steering levers, and how it would be quite nice if I could still use the sliding ones..

Just to the left of the spanner is a cylinder, the ruler/mower handle with masking tape bit is a mock-up of a big lever going up to the back of one of the sliders.

Another one.

I measured the lever travel on yesterdays new master cylinder cobble-up.

And found it was a couple of inches longer than the travel on the sliders!!

Then I thought that maybe with an extra lever and connecting rod I could maybe get the force I need with less lever travel..

Here's something I quickly knocked up on the pc, have a look and tell me if I'm thinking along the right lines..

Oh... It's not to scale

[wheeledhorseman 573]

You don't get ought for nought Ian. As drawn, with the pivot on the little lever where shown, you'll get more movement applied to the piston (reducing as you say the brake handle movement but...... at the expense of some of the force applied to the piston.

Theres no way round that aspect of the lever principle - simply put a small force applied to the long end of a lever moves through a large distance - at the short end of the lever theres much smaller movement but much increased force.

Suggest the suck it and see. It's worth trying and there may still be enough force created to do the job once the calipers are sorted.

The thing between piston and brake pad in an auto / car is an anti-squeel device. Given the rate at which the wheels are going to be turning it can be left out. I'm sure a biker will chip in if it has a different function on a bike.

Andy

[Stigian 1,234]

Thanks Teacher, somehow I thought you'd know

I was while reading your reply that I had (or maybe not) a brain wave.. Could I use pulleys to increase the amount of leverage on the cylinder while decreasing the amount of leverage on the er.. levers..

Some farting about with post-it notes, a tape measure, pencil sharpener, monitor cleaning fluid and a phone charge cable on my desk later.. Hhmm this might work!!

The computerized version.. Am I thinking along the right lines this time?

[wheeledhorseman 573]

Ian, I hate to disappoint but pulleys (strung up correctly) offer the same advantage / disadvantage as levers. The outline principle of both is: effort force applied x distance moved by effort = force applied to load x distance moved by load.

So using a block and tackle pulley system to raise an engine a small force will lift the engine but you have to pull lots of rope through for the amount that the engine moves. In essence, pullies and levers do the same job in a different way - what you can achieve with pullies you can equally achieve with levers.

Getting back to the prob in hand I'm still puzzled by the behaviour of the hydraulic system i.e it shouldn't be 'bottoming out'.

A small amount of movement in the master cylinder piston before the brakes take up is inevitable.

Basically, the piston moves forward and the rubber seal on it closes off a pin hole sized port leading to the reservoir.

At this point fluid in the pipes is trapped between the master cylinder piston and the caliper pistons.

You can't compress a fluid (unless it has air trapped with it) so...

Given that the brake pads are already in contact with the disk by design, the lever / pedal should go 'hard' almost immediately and there should be no further movement.

The harder you apply force to the brakes at the master cylinder end, the harder the pads are held against the disc (but without further movement).

Have the master cylinders been overhauled (i.e. new seals fitted) before use?

There's usually at least two rubber seals on each piston, the other one acts as a valve on a second pinhole sized 'by-pass' port to the reservoir.

Just a thought

Andy

[Stigian 1,234]

Hey Andy, yeah I knew my pulley idea was a bit of a long shot.. Good job I quite like playing with vector graphics

Ah yes, the dreaded master cylinders!!

I get what your saying about they shouldn't bottom out if they are working properly and all the air is out the system. It is strange indeed!!

Nope the master cylinders have not been overhauled, well not by me.. I couldn't tell you what bikes they came from, one was from a Yamaha of some sort I think.

The problem got me a bit curious today.. After feeling quite good about caliper work I decided to crack open the cylinders... Almost!!

This one refused to come apart in any way, shape or form... It does look a bit rusty, with a split dust seal. I wonder what the insides look like Saying that, it didn't show any signs of leaking anywhere!

The other one came apart easily, bar a being a bit dirty on the outside all looked well. The rubber seals inside were good as was the dust seal, wonder if it had had a rebuild shortly before I bought it

So I threw it (carefully) back together, bolted it on my test bracket thingy and suddenly noticed the problem!!!

What I noticed was due to the angle of the plunger thingy, it was bottoming out on the side of the cylinder before it got a chance to bottom out the normal way!

A quick move of the pin later and the plunger could be pushed all the way in!

Best test it then... Ah... with two calipers plumbed in I can still get the cylinder to bottom out!!

But if I clamp off the pipe to one of the calipers so only one is working I can't get it to bottom out!!!!

I have no idea what's going on with the blasted master cylinders, they are starting to drive me a tad mad now!!

You can see more about it on the latest video which I'm about to get uploading.

Andy.. There's a bit for you at the end.

[roscoemi 245]

Hi Ian, I can't tell you how many hours I have spent getting up to speed on your project. Good pics and interesting ramblings, although I can't understand the garlic beer thingy (yuck)! I was thinking about your brake issue and went out to my pickup for a look see. The master cylinder feeding the brakes is split into two compartments. The rear drum brakes have a small reservoir and a 1/4" feed line, and the front discs have 3 times the reservoir but about half the line size. The rears are about 12 feet away while the fronts are six feet max away. I believe drum brakes are high pressure and low volume, while discs are high volume and low pressure. You are using disc brakes but I can't remember what master cylinders you are using. What size are the lines feeding the calipers? Are they hard lines or rubber? You can make one at a time work but not two, therfore you do not have enough volume out of the master to do the job, the lines are too big or distort too much under pressure ( rubber lines not tied down well). Does this make sense? Do you have enough room to use an auto master cylinder to do the job? If you used one off a car that has front and rear discs then you could power two bike calipers each with no sweat and most are pretty small.

Keep up the inovative work, you are a inspiration. Russ

[meadowfield 2,545]

Ian,

it's back to where we said, to move that much oil it needs a big master cylinder and big lever. The length of pipe is irrelevant to the hydraulic function - unless the pipework expands by 50% under pressure ! Once it has oil in it doesn't matter....

Heres my simplistic maths

At a guess each cylinder on the caliper is 40mm, and I reckon with disc wobble/distortion the piston will have to move approx 6mm to clamp.

Thats a volume of around 8ml per pot and you have 4 pots per side - so 32ml of fluid is needed to compress the pads.

Looking at your master cylinder I'd say it has a piston diameter of around 20mm and a stroke of around 50mm. Thats a displacement of 15ml - so only a half of what is required...

If we say the pads are pumped up and touching the discs and barely move back and under compression the pistons move 3mm (a half of my guess) then thats 16ml needed and we are still short of reaching that. As we are at the end of the travel of the master cyclinder - but I haven't seen inside the master cylinder... I bet the inlet port is 10mm down the travel, so displacement is probably 20% less.

Do you think I'm on the right lines with the sizing? or way off? Hydraulic principles are easy to work on - just the same as levers and mechanical advantage... Only with volumes and displacement.

mark

[Stigian 1,234]

Hi Russ, maybe it's just as well you didn't count the hours you have spent reading through this thread.. It has got rather long now

Ah yes, the garlic beer... Rob bought it for me while he was on holiday on the Isle of White, where there is a big garlic farm..

I quite like garlic, love it in fact, but garlic and beer don't mix!!! I won't be indulging again in the stuff!!

The look on Pete's face when he tried it is quite funny though

And onto the brakes..

"I can't remember what master cylinders you are using". At the mo using two bike rear master cylinders of 1/2" bore, soon to be replaced by a pair of Honda Fireblade rear cylinders of 5/8" bore.

"What size are the lines feeding the calipers?". No idea of the internal size, but I think they are all Qwackasaki lines.

"Are they hard lines or rubber?". Rubber.

"You can make one at a time work but not two, therefore you do not have enough volume out of the master to do the job". I think the 1/2" cylinders are very close to handling two calipers but not quite. I'm hoping the new 5/8" will sort that problem out.

"The lines are too big or distort too much under pressure ( rubber lines not tied down well). Does this make sense?". Yep it does make sense.

If I can find a way of mounting the cylinders somewhere around the trans area then I can keep the hoses as short as poss, only two small hoses each side.

Yep, the hoses are moving a bit when under pressure, but I've not tied them down yet.. Maybe I should.

I might have room for a couple of auto master cylinders, do any of them come with remote reservoirs? It would help making car cylinders fit.

I keep thinking of something that Scott (Smoreau) mentioned way back on page 20..

"So my thought, or if you could figure out something better, If you could swap out your brake disk with a sprocket and a chain to a smaller sprocket on a jack shaft with your brake disk attached and caliper setup, Your could greatly increase your turning ability with the increased stopping power of reduction. I know that there would be a lot of things to change to do this, but I think it would work."

Maybe I should try something along these lines but swapping the brake discs for Wheel Horse trans brake drums and pads, do away with the whole "hydraulic brake thing" altogether..

Another idea I have been "toying with" is tracks..

After watching how well the tracks slide on Massey's fine machine, it got me wondering if I rubber tracks would help with my turning problem!!

Any thoughts on this guy's???

To finish off here's episode 28 of the build vid.

Enjoy..

[Stigian 1,234]

Morning Mark.. Ouch that's quite a bit of painful (well it is for me this time of the morning) maths to get my head around!

Even though the pipes are "moving a bit" under pressure they are not "ballooning"

No "disc wobble" amazingly enough, and now I've sorted the caliper piston tops the brake pads sit squarely against the discs now!

The current (well one is) master cylinder has a bore of 1/2" or 14mm in the biking world it would seem!!

The new cylinders are 5/8" or 16mm bore with a longer stroke than the smaller cylinder.

I did try and find some monster 3/4" rear bike master cylinders but it would seem only a couple of bikes use them and they are very hard to find second hand. New prices are well out of my reach.

If I get a chance to get out in the Shack today I will have a measure of the caliper pistons.

Er.... struggling a bit with the maths on this (never my strong subject), but what your basically saying is I need bigger master cylinders with bigger levers??

[meadowfield 2,545]

Ian,

when you get chance send the piston sizes and stroke for both master and caliper. Basically you need enough volume of master cylinder to move the four pistons worth of displacement. The pipework is already full of fluid (unless unbled) so does not need any oil.

Ideally you need a small bore master cylinder with 60mm+ of stroke - or a larger diameter one with less

But yes, you can have too much braking power ! big levers are the way to go !

[Stigian 1,234]

Thanks dude for lending your amazing math skills to this conundrum..

A quick bit of Google work found some specs..

The caliper piston diameter is 34mm and the length is 32mm

The second bigger cylinder has just turned up in the post so I thought I'd look up the specs for them.

The bore is 15.80mm and the length is 32mm.. These specs were taken from a rebuild kit on Ebay..

[meadowfield 2,545]

You'll never work that out - poor maths, been up since 3. Factor of error is out by a thousand....

For the new measurements, to move a 34mm piston 2 millimeters it will take 1.8cc of fluid. x4 = 7.2cc.

The master cylinder will push 6.2cc, I'm thinking even if the pads are touching it will take 1mm just to clamp which is 3.6cc and then with flex, expansion and the lever twist, etc you will lose another cc or so. You don't get anything for nothing - as efficient as hydraulics are there is friction and distortion to overcome.

I guess the easy way to prove this is to run with one caliper using a huge lever and prove once and for all it's either not enough oil pushing the pad (you will run out of travel) or to pull so hard that the lever stops halfway (plenty of oil) as you cannot compress the pads anymore. If it still does not steer then you need more brake pad (friction) and we are onto the second caliper...

mark

[Stigian 1,234]

Up since 3!!! Ouch..

As I've got two calipers and the bigger cylinder plumbed in one side I will try them as they are, the other side I will try just one caliper.. We shall see what happens..

Not sure if anything will happen today though, got a hosp appointment this afternoon... and we all know how good hospitals are at running on time! :rolleyes:

[meadowfield 2,545]

Up since 3!!! Ouch..

As I've got two calipers and the bigger cylinder plumbed in one side I will try them as they are, the other side I will try just one caliper.. We shall see what happens..

Not sure if anything will happen today though, got a hosp appointment this afternoon... and we all know how good hospitals are at running on time!

thats before the 250 mile drive

good luck at the hospital (if you need it)

Might be down your way in the coming weeks - best make sure it's all working !!!!! :D

[Stigian 1,234]

The hospital visit is just for a scan... think they are looking for the loose screw

Working on getting it working :)

[meadowfield 2,545]

The hospital visit is just for a scan... think they are looking for the loose screw

Working on getting it working

you had boxes of screws... I've got a 1/4 UNC tap if thats whats needed....

[Stigian 1,234]

The hospital visit is just for a scan... think they are looking for the loose screw

Working on getting it working

you had boxes of screws... I've got a 1/4 UNC tap if thats whats needed....

Think I need a "tap" on the head with a large hammer instead for selling one of my fleet (see classifieds)

Well, they didn't find the loose screw, or anything else that should not of been there which is good news :handgestures-thumbup:

[roscoemi 245]

Hey Ian, I agree with Meadowfield. You need to get enough volume out of the master to do the job. Also a grippy set of pads, and hard lines to the calipers to put the most work to them. There are stainless braided lines for crotch rockets to minimize deflection and increase feel and stopping power that will work if you can't bend your own lines.

[Stigian 1,234]

I also agree with Mark, having trouble finding softer pad though. I guess no one thought a Gpz 305 "sporty" enough to make "other" brake pads for

Hard brake lines are a little out of my price reach at the mo, but some of my spare rubber brake pipes have springs around them which I guess stiffens the pipes a bit.

Maybe I should swap them onto the pipes I am using..

[Stigian 1,234]

Evening all, it's been quite an eventful day in and out of the shack..

The day started wet and windy (the weather not me!), first job of the day was to sort out my Raider 10 for sale. Decided I will sell it with a pair of AG tires on the back.

Next on the list was to plumb the second new brake master cylinder in on the project. Out of interest only one caliper was plumbed in on the right side, just to see how the brakes would perform really..

No photo's of this as you must be sick of seeing bit's of bike brakes by now.. I'm getting that way!

While waiting for the rain to stop, I thought I would see how the engine sounds with the stack exhaust from my 312-8..

Rather good I have to say

As my 312 is going to need a bit of converting (taking bit's off and swapping some bit's) for grass cutting, I decided to reunite it with it's original muffler..

I'm afraid your going to have to wait a little while for me to edit the video footage of today's fun, so to tide you over here's a few photos.

Right turn..

For the first time ever, a left turn

I'm glad the gate was open!!

I didn't get too far as I'm still having problems with a bit of drive belt slippage, but it was nice to of finally driven the beast more than just up and down the garden.

A bit of cramp set in to my hip

Closely followed by the stack falling off!!

I think it may of been a tad hot as it branded the lawn!!

To finish off this update.. Wide tire tracks where these tire tracks have never been before.. I'm sure my lawn was more than happy that I drove the beast somewhere else today

[zieg72 209]

That is great!!! I know how you must feel to know for sure it is gonna work, just need to work out the details...

[meadowfield 2,545]

top stuff.... hurry up with the vid :)

[Bobie01 22]

Whoop Whoop!!!now the vid please :sad-bored:

[COMMANDO6 20]

I think it may of been a tad hot as it branded the lawn!!

Why didn't you reach out and catch it!

Can't wait to see the video of this beast turning to and fro!