21 replies to this topic

[nanotech9]

So, I've got this '94 model i'm fixing up and riding a bit... long list so far, but just on the brakes / forks: I've replaced the fork seals and oil, cleaned and buffed the front rotor with 3M scotchbrite pad on an air-tool, replaced the brake pads with pads from the Tryals Shop here in the USA, and replaced all the front brake fluid and vacuum bled the system.

Its much better than it was, but it will barely pull the back tire off the ground even when i bounce the rear end and compress the forks.

I used to ride stoppies on sportbikes and supermoto, and even did a few on my '05 BMW 1200 GS but almost nothing on this aprilia.


Has anyone ever made or mounted a larger rotor and caliper extension kit on one of these bikes? Or maybe replaced the master cylinder with a master that uses a slightly smaller diameter piston? (This should give higher pressures on the slave cylinder making it brake harder).

I mean the stock brakes on my TTR 125 are 5 times better... I can two-finger the lever and raise the rear wheel in the air.

Ideas / Suggestions welcome!

If someone knows of a larger rotor, I have a mill and lathe and can make a bracket to extend the caliper to fit it I think.

[haggi961]

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[haggi961]

What about braided hoses as these did make a diffrence to my car when i changed them. What about a more racing type brake fluid.

[lewisallen]

u said that you buffed up the discs, that will effect the brakes slightly, espically if theres a fine coat of polish left on them. the pads wont be able to grip the disc properly, i tried buffing up my discs on my jump bike and that made the brakes worse, over time they got better but it took a while.

[clay]

Hi bud, not sure if this will help you with your Aprilia, but it worked for me on my monty,
get some real heat in to the front caliper, by rideing around for 3 or 4 mins with the brakes on, then soak the caliper with cold water,
I was a bit worried about warping the disc at first, but id got to the point of madness!!

If you,ve bled it, and its had new pads,
And the seals in calipers, and the m/c are all ok. Then i would give it a go
mine went razor shap after a few quences
(picked this little gem up, of the forum) hope it works for you too bud,,,,

[nanotech9]

Bike has blue steel braided hoses on it. Not sure if they are factory or not. Front and rear are the same as is the sheath for the throttle cable. (all blue matching, not faded at all so maybe fairly new?)

Running MOTUL RBF 600 racing fluid that i use on all my bikes - has the highest temp wet/dry that i've found. Always worked awesome on my ZX10 on track days.

Rode around several miles dragging the front brake just to see if the new pads needed seating... no difference.

When i say scuffed... its the 3M scotch-brite pad... I always use it to "freshen" up the steel clutch plates in other bikes, and scuff up car and truck rotors the same way. It helps seat new pads and takes out some of the high spots or any ridges from the discs. Its a fairly coarse pad, but not as strong as sand-paper.

No leaks from the caliper - I've pumped both pistons out about half way (one on each side) to check them. One side was reluctant to move but once freed up and cleaned they both move equally.

Lots of resistance at the lever - the amount of force i'm putting on the lever would flip even the big 12GS over easily.

The rear brake works VERY well. Haven't touched it - I didn't even change the fluid.



I'll think about the heat-cool method. Very risky on a bike thats hard to find parts for. The idea is to get the rotor very hot then quickly cool it right? Like a heat-treat of sorts?

[lee99780]

Have you tried bleeding it normally aswell as vacuum bleeding?

[lineaway]

Hey the get the brakes hot method is the most effective. Just have a 5 gallon bucket ready of water from your spigot. I know how it sounds, first time I saw it was Tommi Avala with a new bike just out of the crate. If that don`t do it you have another problem. There was nothing wrong with the stock brakes. You haven`t screwed in the adjustor too far have you? Just a thought.
Keep at it, been a lot of work for a borrowed bike!
Bob.

[nanotech9]

I don't mind the work too much... its borrowed but with the option to buy... so potentially i'm doing all this work for my own benefit. I'm really wanting to try a newer lighter bike now though just to see exactly how much better and lighter they really area...



I would feel much better removing the rotor, heating it evenly in a 500deg oven and dousing it in a controlled manner... Any thoughts against that or any reason it would be less effective as opposed to the bucket of water after dragging the brake method?


I will try re-bleeding it once more. I generally finish off a vacuum bleed with a couple of squeezes on the lever with the nipple closed and effectively bleed it the normal way but i don't recall doing that this time. Pretty easy to give it a go.... I'll try it as soon as this rain lets up.

Thanks for all the suggestions so far!

[clay]

Not sure if the heat treatment, is just the disc option?
I was on the understanding that this solution conditoned the caliper aswell,
I wold love to know how this works myself, but it did for me,, good luck bud

[lee99780]

Just be careful not to get it too hot to damage the seals in the caliper, Its unlikely but still possible!

[02-apr]

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[02-apr]

Get the disc hot and spray gently it with water from a hose or watering can. You're not so much treating the metal as removing the fine rubbish from the surface to get full friction. I've never seen a disc damaged this way. More likely to do so by putting in the oven I would have said.

Edited by 2/4, 25 January 2012 - 08:07 AM.

[paul w]

do the ride brake on, hot disc, very hot disc, and water method. if this doesnt work i would suggest your pad material maybe garbage.

[mattylad]

Check that the adjuster screw on the lever is most if not all the way in. This pushes on the master cylinder piston and makes the brakes much more solid as fluid does not seep back into the reservoir, it goes to push out the pads.

Two minutes to do and has worked for me in the past when I have bought bikes.

[grahamjayzee]

mattylad, on 25 January 2012 - 12:08 PM, said:

Check that the adjuster screw on the lever is most if not all the way in. This pushes on the master cylinder piston and makes the brakes much more solid as fluid does not seep back into the reservoir, it goes to push out the pads.

Two minutes to do and has worked for me in the past when I have bought bikes.

Be careful though. If you take out all the slack, the piston cannot return fully and will not refil from the reserviour. Always best to leave a bit of play here.

[geeman]

Hi I have used the method of heating the brake system by riding with the brake on then soaking with clean cool water on my Aprilia some years ago ,and it worked like a charm !!!!!! I think it is just a simple cleaning method , and I never was able to get the disc or pads super hot from riding with the brake on ,but hot enough to clean . Good luck. I think its the 3M scotch-brite pad leaving a residue on the disc and pads ,I stoped using ,when I felt how it affected my brakes . Gbee