Leaking Front Master Cylinder Cover | GTAMotorcycle.com

Leaking Front Master Cylinder Cover

MaksTO

Well-known member
Hey all!

Finally changed my front brake line to stainless on my 2000 KLR. Feels nice to be able to stop!!!

I noticed this issue last year when I topped up my brake fluid, and now it happened again. After riding for a while, I see some fluid leaking up out of the cover at the top. Brake pressure is still fine, but its a little odd and disconcerting... The rubber insert on the lid still seems to be in good shape, and I have the screws as tight as I am comfortable (they are tiny 4mm screws so I hand tight with the short side of an allen key... Otherwise they strip when you try to remove them a year later...). Maybe I overfilled it? But I thought I was pretty careful about it. My window is totally opaque now from age, so I just looked from inside before closing, but it wasn't above the sight glass.

Anyone have any ideas to fix or troubleshoot this? Do I need to change the cover? or the whole master cylinder? Seems OEM ones are super expensive so I'd love aftermarket solutions if they exist and are reputable (not sure about those $25 master cylinders on Ebay...)...

Would appreciate any tips!
 

Mad Mike

Well-known member
There are really 2 options - seal or cover.

If the cover is bent or cracked, it may not seal. Removing the cover, and visually inspect the seal and the cover plate for cracks first. If you don't see any, check the cover for warpage - place on a flat countertop or piece of glass, if you can slip a piece of newsprint under any side or corner, you're warped.

I understand hesitation with Chinese brake parts -- I used one of these on my Suzuki enduro which was about the same size as a KLR -- worked like a charm. They are a universal part, not sure whether you'll find one specifically stating it's for a KLR.

 

MaksTO

Well-known member
There are really 2 options - seal or cover.

If the cover is bent or cracked, it may not seal. Removing the cover, and visually inspect the seal and the cover plate for cracks first. If you don't see any, check the cover for warpage - place on a flat countertop or piece of glass, if you can slip a piece of newsprint under any side or corner, you're warped.

I understand hesitation with Chinese brake parts -- I used one of these on my Suzuki enduro which was about the same size as a KLR -- worked like a charm.

I will try this out tonight or tomorrow, thanks!

Maybe I will give the Chinese Brake Masters a try in that case (if my cover is pooched). Though I think I might have a spare one too - from an even worse off master I pulled off a donor bike - maybe it's flat at least.
 

TwistedKestrel

King of GTAM
Site Supporter
Also, if the top of the seal was wet with brake fluid when it was reinstalled, that might be what is weeping out - the master cylinder cover should be flat as MM said but it is NOT airtight by design, there will be a notch on one side to allow the seal to expand/contract
 

MaksTO

Well-known member
Also, if the top of the seal was wet with brake fluid when it was reinstalled, that might be what is weeping out - the master cylinder cover should be flat as MM said but it is NOT airtight by design, there will be a notch on one side to allow the seal to expand/contract
That's a good point too. It looks like quite a bit of fluid that came out, but that might just be how it appears. Maybe I will pull it off and try to dry it with a paper towel or something and see if that helps the seal as well.
 

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