Motorcycles

 

Tuono Rear Brake Bleeding

 

We are very fortunate to have some very knowledgeable people on the Aprilia Forum.  One of those people, KZMille, posted a very detailed walk-through for bleeding the rear brake. Some unconventional methods were called for due to a recurring loss of brake pressure in many owner's 2nd generation Tuonos.  See this thread at Aprilia Forum for all the details.

 

I was very fortunate to never have this issue with my Tuono, while my friend had the issue and it kept coming back.  I'll not speculate here as to the ultimate cause of the constantly weakening rear brake on many Tuonos.  Instead I just wanted to demonstrate that it is possible to easily remove the rear brake caliper and position it properly for bleeding without removing the exhaust pipe as someo people do.  Here's how:

 

Aprilia Tuono rear brake
These are the tools you'll need: A 10mm wrench, 11mm open-ended wrench, sidecutters, zip ties, allen wrenches, brake fluid, some clear tubing, and something to drain the old brake fluid into.  I recommend making your own Coke can bleeding contraption.


Aprilia Tuono rear brake
Start by carefully cutting off the zip ties holding the rear brake line and speed sensor line together. 


Aprilia Tuono rear brake
You'll need to remove the rear brake line guide underneath the swingarm.  To do that, just remove the three allen-head bolts.


Aprilia Tuono rear brake
The brake line guide.


Aprilia Tuono rear brake
Use the 10mm wrench to remove the two rear caliper bolts.


Aprilia Tuono rear brake
Now that the rear caliper is free, maneuver it towards the righthand foot peg and push it through towards the righthand side of the bike.

Aprilia Tuono rear brake
If you turn the caliper like this it will just barely fit through this opening.


Aprilia Tuono rear brake
From another angle.


Aprilia Tuono rear brake
Now the caliper is in a much better position for proper bleeding.


Aprilia Tuono rear brake
Do not depress the rear brake until you place something solid between the brake pads.  A rat-tailed file is the first thing I found laying around.  Anything solid will work.


Aprilia Tuono rear brake
You'll need access to the rear brake fluid reservoir to monitor its level and to keep it topped up.  To gain access remove the water reservoir cover.  (While you are here, check your coolant line for this problem.)


Aprilia Tuono rear brake
The reservoir.  No, that's not windshield wiper fluid.  That's ATE Superblue.


Aprilia Tuono rear brake
According to KZMille, this would be the first position you want to bleed the caliper in...


Aprilia Tuono rear brake
...followed by more bleeding in this position.  Repeat back and forth until you've got good pressure and no more bubbles are coming out the bleeder nipple.  And of course you'll want to ensure that you never even come close to allowing the reservoir to get empty.  Keep it topped up!

 

When you're happy with the brake system, carefully slide the caliper back in the way it came, reinstall it and torque its two retaining bolts back down to 18Ft-Lbs (25Nm).

 

Thanks to Rick Monet for his assistance in making this guide.

 

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