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Discussion Starter · #1 ·
Hey guys, I've had this problem on both the SV and my last bike (Katana) after I switched from OEM to HEL SS lines. With both the front and rear brakes, if I press them too hard when needing to quick stop, I'll lose a lot of brake handle pressure. I quickly found that The rubber cover/gasket thing inside the reservoir gets sucked down (from the reverse pressure of braking) and I have to take off the caps and "reform" the rubber seals back to their natural shape before continuing.

EDIT: Forgot to mention this happens on my Hydro clutch as well, making the effect of the HEL line installation very consistent.

I'm assuming that all of this is due to the higher pressure/less give of the HEL lines because it never happened before to my knowledge. Is this something I can fix by just ordering the new seal/gasket and hoping that they're a little stiffer and that these 7yr old OEM ones have just broken down over time, or do I need to find some aftermarket one somewhere?

Thanks in advance guys!
 

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Discussion Starter · #3 ·
Never heard of that happening before. I dunno. :HMM:


Sounds bizarre to me. :confused:
LOL You think you're confused. Try having to deal with it. It's a PITA, especially when you really do need to brake hard and then you have to deal with it crappy brake feel until you stop next. I'm hoping someone just tells me it's old rubber and to replace the seals, although I haven't looked up the parts cost yet (so maybe not so nice).
 

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A square wheel rollin' !!
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After re-reading your post, the only thing I can come up with is that you either need more fluid in the reservoir, and/or you aren't tightening the lid very much.


I know you have to be careful tightening the lid, they crack easy . . . .



Ah, just realised you have an S , and the reservoirs are different. I dunno, perhaps someone else can chime in soon ?




............................Blake
 

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Discussion Starter · #5 ·
After re-reading your post, the only thing I can come up with is that you either need more fluid in the reservoir, and/or you aren't tightening the lid very much.


I know you have to be careful tightening the lid, they crack easy . . . .



Ah, just realised you have an S , and the reservoirs are different. I dunno, perhaps someone else can chime in soon ?
Yeah I tighten the caps on there pretty tight (any more and I'm afraid I'd crack them). The fluid is always at the max line. Yeah hopefully someone will clue me into what I'm doing wrong soon...
 

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The rubber seal in the reservoir gets 'sucked down' gradually as your brake pads wear and more fluid has to go into the lines to compensate - and that's rather normal.

The only way I could imagine this to happen while braking hard is a (high pressure) leak - so when you brake hard, you actually loose some fluid which will be replaced from the reservoir eventually. But in the meantime the pistons get 'sucked back' into the caliper instead, so your lever travel increases...


D.
 

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KNEE DRAGGER
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This rubber diaphragm is there for several reasons. As Danci states, the rubber piece should slowly move down and fluid levels drop in the reservoir. It acts as a barrier from the outside air, you don't want to expose your fluid to ambient air because is is hygroscopic (absorbs water) and will deteriorate the fluid very fast. As the fluid level drops, you do not want to draw in any more air with moisture in it. It also acts as a seal so it does not leak out of course. It is also critical in a remote reservoir system that the plastic ring goes in on to of the rubber piece. That plastic piece allows air to enter or exit on top of the rubber piece as the fluid level changes. Remember your fluid level can actually go up some too, when the brakes are really hot the fluid will expand and push some back into the reservoir. If this plastic ring get left out or flipped over it can cause a serious problems that can make you crash...
Way over tightening the cap can also in some cases block the path for the air to enter above the rubber piece and again cause huge issues.

Even with non remote masters there are vent channels cut on the bottom side of the caps to allow air in and out. I was trouble shooting brakes on a Hayabusa once that after hard braking the brakes would almost be gone completely. The problem ended up being an eBay brake master cylinder cap that did not have the vent channels milled in. I went back to the OEM unit and all seemed fine.

-MS
 

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Hi my name is D and I have a 2006 Pontiac G6. I had my rear brakes done in February. Almost immediately after the front passenger caliper began to lock up. But I want to change my front brakes got them on went to bleed the brakes learned that there’s been no fluid going to my back brakes since they had changed them. During this time my cab on my reservoir of my brake fluid became torn it had been sucked inward into the reservoir so hard that it ripped.
I replaced the cap. And while trying to bleed my brakes the cab again was sucked into the reservoir. My reservoir fluid was topped completely off and remained that way my fluid never seem to go down. However I could begin to feel my brakes becoming worse and as a result I would check the cab and again it would be sucked into the reservoir. I don’t see any leaks anywhere I’ve obviously got a blockage. I just don’t know where any help?
 

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Disturbed, very...
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Hi my name is D and I have a 2006 Pontiac G6. I had my rear brakes done in February. Almost immediately after the front passenger caliper began to lock up. But I want to change my front brakes got them on went to bleed the brakes learned that there’s been no fluid going to my back brakes since they had changed them. During this time my cab on my reservoir of my brake fluid became torn it had been sucked inward into the reservoir so hard that it ripped.
I replaced the cap. And while trying to bleed my brakes the cab again was sucked into the reservoir. My reservoir fluid was topped completely off and remained that way my fluid never seem to go down. However I could begin to feel my brakes becoming worse and as a result I would check the cab and again it would be sucked into the reservoir. I don’t see any leaks anywhere I’ve obviously got a blockage. I just don’t know where any help?

Hi Dee R...

Just as a quick idea, i wold say that the fuid is not returning form the calipers to the reservoir...... which could be the push rod form the brake pedal to the master cylinder is out of adjustment maybe..
Probably too long. I woudl also guess if thats the case that your brakes, probably the rear ones are getting hotter than they should...... Anyway, even if it isnt the push rod, there is something blocking return......

An, as a seond notation....this is a motorcycle specific forum, especially for Suzuki SV1000 owners, so maybe there is a Pontiac forum where you could maybe get some help ?

Hope all works well....take care
 
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