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No back Break Pressure

2932 Views 12 Replies 6 Participants Last post by  J-Pip
Well I picked up a 1999 Speed Triple this weekend and the rear brake has no break pressure. The previous owner told me that he changed the brake pads and got all the air out of the brake lines and it still does not have rear brakes. Is this just a Master Cylinder rebuild issue? Or something else. Our Triumph dealer currently does not have a Triumph Mechanic so I will need to do the work myself. It feels like it is not making pressure, The lever moves freely, but does not work the brake light.

Any Help welcomed.

I do have the service manual, but it does not have the interior of the master cylinder.

Thanks Spanky
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Are you sure there is no pressure or is it just poor performance?

Pull the rear brake pads and give them a light sand with some sandpaper.
This should clean the pads and remove any glazing.

While they are out, push on your brake pedal lightly and see if the pistons move in the caliper.
If they move then the brakes should work.
You will have to push the pistons back in to refit the pads.

I have cleaned brake pads and discs with prepsol but I don't know how safe this is.

Mine had the same thing before i bought it from the dealer. They just bled the brakes, seemed to cure it. Have done over 1000 mils no probs!
I would tend to agree: Sounds like air in the system.
definitely air in system no matter what that dude said. he didn't get all the air out.
Also - the brake light not working is not at all related to the rear brakes working.
the light has nothing to do with the brake performance. it can be a BITCH to bleed the rear brake. There can be a bubble than is impossible to get rid of.

go to any autoparts store, or bike parts store, and by a "Mighty Vac." They are like $30 and make bleeding brakes a SNAP! very very easy to use.
The Vac is good, just don't go to a motorcycle shop and pay $75 for it. Go to Autozone.

Some air in the system will not cause break failure like you describe. You can still have a good amount of air in the system and still get enough preassure to engage the break.

I have a changed a crap load of brakes in cars and on my bikes many times. Many things could be the problem, MC, calipers, discs, breaks, pistons, etc. You are just going to have bleed the system entirely and troubleshoot.

First, Do everything AA told you.

Then, check for leaks around the system, at the MC, calipers, hoses.

If you don't see any visible issues with your system then proceed to bleed.

Bleed the system with a vac or you can just use a hose. You can buy them at autozone. I actually like using syringes for my brake work. I will explain later.

Before you bleed secure the resovior, remove the cap, fit your hoses, lossen the bleed nut, and slowly bleed the system while making sure you add break fluid to the res. Depending on your system you may have more than one bleed nut. Do this on all bleed nuts even if you want a total bleed, it helps purge the system of moisture. Keep bleeding the system until most of the bubbles in the hose are gone.

Note: this can take a while, so have enough fluid handy. YOU WILL NOT BE ABLE TO REMOVE ALL THE BUBBLES, only time will help. remember bubbles will eventually float up to the resovior if we do it right.
Tighten the bleed nut when you are finished. Test your brakes, look at the calipers and make sure that there is movement. If you have a stand put the bike in neutral, spin the wheel, and make sure your brakes bite.

Now, an alternate method which I use is to completely bleed the system dry and then add fluid through the bleed nut with a large syringe. This method usually saves me about 45 minutes. Most of the bubbles are pushed up with the force of the brake fluid.

If you are getting bite, enough to stop the wheel, then use a tie wrap to engage the pedal overnight whle keeping you bike on the stand. This will help float more bubbles towards the res.

If you are still not getting the wheel to stop then you have some other problems which you could look at yourself or take to mechanic. Most motorcycle repair shops can perform brake work on your bike. They have the time and tools to troubleshoot the problem. You can always purchase the parts from your local triumph shop and have another shop perform the labor.
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BTW pump the brake to initiate the bleeding... :blah:
He's high, been smoking too much of his evidence, I rode it and locked the rear up just fine. :slap:
Keep in mind Randy, you're last bike was a Harley with a rear brake that was too strong, this one's just right.
J-Pip said:
Keep in mind Randy, you're last bike was a Harley with a rear brake that was too strong, this one's just right.

Had a harley rider at the track a while back looking at my front brakes. "Why does that thing have those huge front brakes?" he asked. "You know your just going to flip it if you use them."

Had to chuckle at that. Note I didn't bother to argue with him. The therapy is working.
crashmasterd said:
The therapy is working.
That's good to hear.
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