So what do you think? am I wrong with my old-school theories that use to work? Or am I all wet from Brake Fluid. Just looking now for theories.
Thanks Tom n Carol, SI,NY
I think we're both right, it just depends which decades we're talking about! It looks like the pre 60's cars were really simple like on that '55 cap. I don't think there was a diaphragm under that and the vent hole could get plugged pretty easily.
Then they started with those big accordian diaphragms and I don't believe they were vented since they could displace a lot of air or fluid if the level dropped, especially with disc brakes when the pads wore.
Now I think the technology is using these smaller caps with the slits. They actually operate like little two way valves which are normally closed. But if there's a vacuum or pressure in the system due to expansion or contraction from temperature change for instance. That diaphragm will get sucked down or pushed up deforming it and opening the slit just enough to keep pressures equalized and letting in as little air and moisture as possible. I hope that makes sense.
Oh and I think those V shaped slits on the Spyder are a bit overkill too. They don't need to be that big.
This has been discussed in previous threads. The conclusions are always the same. The slit is suppose to be there. Most modern vehicles have a slit in the diaphragm and older vehicles did not.
One thing that has not been mentioned yet is. If the caps are put on backwards (vent to the front) they will leak. If the caps are put on correctly vent to the rear less likely to leak.
This has been discussed in previous threads. The conclusions are always the same. The slit is suppose to be there. Most modern vehicles have a slit in the diaphragm and older vehicles did not.
One thing that has not been mentioned yet is. If the caps are put on backwards (vent to the front) they will leak. If the caps are put on correctly vent to the rear less likely to leak.
I wanted to give this a check...the caps have a paint dot and I need to see if it aligns with something.
Caps go on this way with the ribs facing to the rear:
Agree and no problem...as I mentioned, the caps on our machine also have painted dots. I need to see if those are visual alignment marks. I don't see them on yours.
As time permits I will check...the caps are properly installed on our machine.
If put a straw in water (or brake fluid) and then place your thumb over the straw it is possible to lift a straw full of fluid.
The fluid can be held there for an indefinite length of time provided the straw remains unvented.
Without a vent how does the brake fluid travel from the reservoir to the slave cylinder as the brake pad wears and more fluid is required to compensate for pad wear?
I believe the reasoning for the vent hole only in the cap and not in the rubber diaphragm is for two reasons
1 - To let the rubber diaphragm expand into the cap when atmospheric pressure changes, which I believe is the same as gravity.
2 - suction/vaccum When you depress/engage/push/step on your brake pedal, brake fluid is pushed (pressurized) thru the brakes lines, and forces the pistons inside the caliper to push the brake pads against the rotor - VIOLA - STOP
When this # 2 action occurs, a vaccum pulls the brake fluid out of the brake reservoir and into the brake master cyclinder and into the brakes lines.
When you release the brake pedal, that brake fluid under pressure flows back into the brake fluid reservoir because the vaccum/suction has ceased and atmospheric pressure/gravity takes over.
If you have this slit/vent hole in your diaphragm, the vaccum action will pull outside air (which contains mositure) into the brake system, when brakes are applied
I say NO SLIT - NO AIR
Was at a large, large Motorcycle dealer yesterday and I looked at BMW, DUCATI, TRIUMP, SUZUKI, POLARIS, VICTORY, HARLEY DAVIDSON, dirt bikes, ATVs, them 4-wheel large 2-4 people things , in the woods/rough terrain vehicles, and none, to the best of my memory (phone takes lousy pics) had vents in the brake reservoir caps.
This is why when you remove the old style automobile single/double covers, the rubber diaphragm is collapsed.
I believe the reasoning for the vent hole only in the cap and not in the rubber diaphragm is for two reasons
1 - To let the rubber diaphragm expand into the cap when atmospheric pressure changes, which I believe is the same as gravity.
2 - suction/vaccum When you depress/engage/push/step on your brake pedal, brake fluid is pushed (pressurized) thru the brakes lines, and forces the pistons inside the caliper to push the brake pads against the rotor - VIOLA - STOP
When this # 2 action occurs, a vaccum pulls the brake fluid out of the brake reservoir and into the brake master cyclinder and into the brakes lines.
When you release the brake pedal, that brake fluid under pressure flows back into the brake fluid reservoir because the vaccum/suction has ceased and atmospheric pressure/gravity takes over.
If you have this slit/vent hole in your diaphragm, the vaccum action will pull outside air (which contains mositure) into the brake system, when brakes are applied
I say NO SLIT - NO AIR
Was at a large, large Motorcycle dealer yesterday and I looked at BMW, DUCATI, TRIUMP, SUZUKI, POLARIS, VICTORY, HARLEY DAVIDSON, dirt bikes, ATVs, them 4-wheel large 2-4 people things , in the woods/rough terrain vehicles, and none, to the best of my memory (phone takes lousy pics) had vents in the brake reservoir caps.
This is why when you remove the old style automobile single/double covers, the rubber diaphragm is collapsed.
Vaccum>Gravity>Atmospheric No-Slits
Both my previous R1150RT and K1200RS brake systems were vented. Part of the yearly maintenance on the bikes was to drain, fill and bleed both the clutch and brake/ABS system to due to moisture accumulation in the fluid.
Sorry, but I don't agree.
The fluid that enters the slave cylinder has to be replaced by something in the reservoir, otherwise you wouldn't be able to remove the caps due to the vacuum that would result.
If your theory was correct the brake fluid level would never change due to brake pad wear and that is not the case.
The brake fluid returns when you let off the brakes, because the vaccum has stopped, and yes, the level of brake fluid in the reservoir decreases due to wear in the brake pads, and that is why the brake code comes on your screen, telling you the fluid is at a low level.
The brake fluid returns when you let off the brakes, because the vaccum has stopped, and yes, the level of brake fluid in the reservoir decreases due to wear in the brake pads, and that is why the brake code comes on your screen, telling you the fluid is at a low level.
To remove that orange brake code on your screen, you turn the Spyder ignition switch on, do not start, and then you depress on the brake pedal for (not sure, its in the service manuual) 10-20 seconds, turn ignition off, wait a bit, and that orange brake code should be removed, providing that the brake fluid in the reservoir is at the propre level. And if no dissappear, repeat. In the reservoir is a low brake fluid sensor.
Actually he's right and wrong but what has not been figured into this mess of vents or no vents is the actual fluid itself. I'm pretty sure that the DOT 4 and 5 fluid is moisture resistant and can pull off having the vented cap. The small size of the caps and lack of bellows is why the system needs the vents and by using better fluid they can pull it off. He's right in his thinking but wrong in his application, leave the vented caps on your spyder. I do a lot of boat trailer brakes and those systems are vented to and have really small caps with no bellows. We get longer fluid life with DOT 5 silicone brake fluid.
Sold my 14 RTS went back to 2 wheels.
2014 Kawasaki Vaquero SE
I'm pretty sure that the DOT 4 and 5 fluid is moisture resistant ... We get longer fluid life with DOT 5 silicone brake fluid.
DOT 4 and DOT 5.1 are polyglycol based just like DOT 3 and are hygroscopic (absorbs water). DOT 5 as you mentioned is silicone based so it does not absorb water. Both systems do get water in them from condensation though, in a DOT 4 system it mixes into the brake fluid but with DOT 5 you end up with having pockets of water collecting in the system. Couple the water pockets with longer time between fluid changes and you have a recipe for corrosion. Harley was using DOT 5 for awhile but they have gone back to DOT 4.
Clifford Fargason
2013 Spyder RTL
2007 Royal Star Venture
Okay my final word on this is I really don't care how you modify your brake system and master cylinder.
As long as you aren't anywhere near me on the road.
But your original post indicated that there was something defective about the original system and while you still, apparently, maintain there is, I think that anyone who takes your advice is doing so with enough warning that they should be considered forewarned.
I'll also hang my hat on the capable engineers that designed the system!
I keep hearing gasoline sloshing around in that big cavity under the seat.
I think I'll fill that sucker with cement.
I bet this is a problem for every Spyder out there.
I have been doing alot of research, and I will stand corrected, that brakes systems do need to be vented. I have closed examined the old GM master cylinders from the 1960's and they were vented.
I now understand that a small hole is needed in the diaphragm that is in the caps on the brake reservoir. I, way back in a earlier post, said the Dorman #42081 diapragms had no vent hole in them. WRONG I WAS WRONG, they do have a tiny/tiny hole in them. Also, upon closer inspection, I have observed that the diaphragms that are in my 3-Spyders have a v-shaped slit in them, BUT, there is a tiny hole that has turned into a v-shaped slit. Did BRP put this V-shaped slit in them or has that tiny hole developed into the v-shaped slit? One of my original diaphragms did not have this v-shaped slit, but a pin hole like the new Dorman #42081. With this larger slit, I believe it allows more brake fluid to escape then as originally planned. I have replaced, in my 3 Spyders, the BRP diaphragms with the Dorman #42081 diaphragms that have a tiny/tiny hole that acts as a vent. To me, the Dorman diaphragms fit better than the original BRP diaphragms.
I do not know how the clutch master cylinder is vented, so will someone explain to me how they are vented.
I do not wish to panic fellow Spyder owners, it is my wish for all to be safe. I have a very mechanical mind, and like to know how everything works.
I had mine replaced due to te fact they were leaking and questioned the slits in the diaphragms
the purpose of splits are for the ABS brakes and need to be there, the older cars didn't have them from what I've read that is a requirements for ABS brakes
Bill 2013 RSS Neutron Green
BRP HID's and Fogs
Custom Belt Tension
2014 side panels
HMF Exhaust
K&N air filter
Bajaron sway bar and links
I have been doing alot of research, and I will stand corrected, that brakes systems do need to be vented. I have closed examined the old GM master cylinders from the 1960's and they were vented.
I now understand that a small hole is needed in the diaphragm that is in the caps on the brake reservoir. I, way back in a earlier post, said the Dorman #42081 diapragms had no vent hole in them. WRONG I WAS WRONG, they do have a tiny/tiny hole in them. Also, upon closer inspection, I have observed that the diaphragms that are in my 3-Spyders have a v-shaped slit in them, BUT, there is a tiny hole that has turned into a v-shaped slit. Did BRP put this V-shaped slit in them or has that tiny hole developed into the v-shaped slit? One of my original diaphragms did not have this v-shaped slit, but a pin hole like the new Dorman #42081. With this larger slit, I believe it allows more brake fluid to escape then as originally planned. I have replaced, in my 3 Spyders, the BRP diaphragms with the Dorman #42081 diaphragms that have a tiny/tiny hole that acts as a vent. To me, the Dorman diaphragms fit better than the original BRP diaphragms.
I do not know how the clutch master cylinder is vented, so will someone explain to me how they are vented.
I do not wish to panic fellow Spyder owners, it is my wish for all to be safe. I have a very mechanical mind, and like to know how everything works.
Tom n Carol, SI,NY
Hey stuff happens. I was wrong once, well maybe more than once. I think some were a little hard on you because we have been down this road before on exactly the same topic, with same opinions on both sides, with the same results. On the good side this may have been educational to the newer spyderlovers that were not around when this was battled out before.
limp home message/ brake failure/ brake light dont know what to do please help
Originally Posted by MISTERZ06
This concerns all models of Can-Am Spyders: 2008-2014 GS/RS/ST/STS/RT/RSS/RTS AND WITH ANY TRANSMISSION: SM5/SE5/SM6/SE6
All these models have the same Caps and Diaphragms (BRP Part#219800058) that fit on the Brake Fluid Reservoirs. All Spyders and Models 2008-2012 had the Brake Fluid Reservoir BRP Part#705600735 or 705600549, and all Models 2013-2014 had Brake Reservoir BRP Part#705601072. Even though there was a change in 2013 of the Brake Reservoir, all the Caps and Diaphragms are the same BRP PART#219800058. I have three (3) Spyders. Two (2) are 2009 RS SM5's and one is a 2011 RT SM5. I have discovered that on my 2-RS's, that all four (4) Diaphragms in the Brake Reservoir Caps, had identical tears in them, v shaped. On the 2011 RT, only one of the Diaphragms had that v shaped tear in it, and the other had no tear in it. On one of the Rs's and the RT, brake pad replacements were done, and the Caps were removed while compressing the calipher pistons. The reasoning as to why you remove the Brake Reservoir Caps is that when you are collapsing the pistons, the brake fluid is filling up the reservoir and can cause pressure against the Diaphragm, with no place to go. This could cause a tear, BUT, on my other RS, which has never had a brake replacement done, there are that v shaped tear in both Diaphragms.
That tear in the diaphragm could cause brake fluid leaking down the top of the reservoir and down the inside of the Spyder and landing on the top of the rear Shock mount. In the past I have noticed brake fluid seepage causing paint to peel, BUT, to this time, I could not find the cause. WELL NOW I HAVE! IT IS TEARS IN THE DIAPHRAGMS
This is caused by what? Inferior manufacturing, Bad Rubber, ? Maybe the brake fluid runs so fast back into the Reservoir when you release the brake pedal, that the diaphragm can not hold the pressure? BRP needs to slow down the speed of brake fluid returning to the reservoir with a residual valve? VIOLA A TEAR
I HAVE FOUND, I HOPE, A BETTER REPLACEMENT OF THE DIAPHRAGM
DORMAN HELP! PART# 42081 Master cylinder gaskets These should be availabe at a good auto parts store. These dorman diaphragms look/feel alittle heavier/stronger. When I installed them, I can feel that are making a better seal , I had a harder resistance when tightening the caps.
PHOTOS TO FOLLOW: BRP-WITH V-SHAPED TEARS N New DORMAN diaphragms
Tom n Carol, SI,NY
Dear Tom my bike is giving me the fits i get a brake failure light, then limp home message then it dies and i dot know what to do do u have any ideas
Originally Posted by MISTERZ06
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Are we ready for the "Group Hug" yet? 
I'll also hang my hat on the capable engineers that designed the system! 
