how to weaken rear brake?

b/fluid

Correct me if I'm wrong?, but what b/fluid are we suppose to use? It says in the manual dot 3? But the KTM (which has the same brakes) says use "only" dot 5? Silicone? I actually filled mine with dot 5 but after reading the manual I drained it and went to the original and now the front feels spongey?? Will dot 5 damage the seals???

http://www.babcox.com/editorial/bf/bf40142.htm

Good, quick article on brake fluid...

Hi Taffy,
To decrease the rear brakes sensitivity simply reduce the existing pads surface area. (ie mill slots into the friction material).
Hope this helps.
Best Regards,
Dale

Taffy said:

sorry simon but it's a regular trick to this day!

in roadracing they don't want a rear brake, riders used to go to scrutineering with a rear brake, go back to the van and just undo the top banjo bolt and let all the air in ready to race.

i kid you not! ask any old road racer-oh they're all dead due to no...... :twisted:

Taffy

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There's no need to apologise taffy, but unless I'm mistaken, there seems to be a bit of logic, or sense, missing there somewhere :wink: :wink:

If you don't want a rear brake you just don't use it - most [1] racers of the tarmac variety will never use their rear brake because it's useless when you're at max. braking capacity because the rear is nearly in the air anyway. Oh, and they happen to have the balls of their foot on the peg, nowhere near the brake pedal. Why even waste any time getting air into a system you're not going to use, it's beyond my brain capacity anyway :?: :?:

And that trick you'r describing seems to be for a brake system somebody's not going to use. I thought you still wanted to use your brake?

I'll be remaining air free, thank you very much

[1] some do use the rear

Cheers,
Simon "sticking with hydraulics"

Taffy said:

now the reason they do it simon is for this man: the S********R

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We playing blanketty-blank now are we? :wink: :wink:

Of course....oh silly me, I just got it :idea: , it's a wind up innit? Ah, I'll just have to try and be quicker next time

Simon "bit slow me"

LINEAWEAVER said:

Hi Taffy,
To decrease the rear brakes sensitivity simply reduce the existing pads surface area. (ie mill slots into the friction material).
Hope this helps.
Best Regards,
Dale

Click to expand...

Does cutting more holes or slots in the rotor have a similar effect without removing so much brake pad material?

Hi Brad,
Yes, though to a lessor degree.
Dale

Just wanted to add a thought about this topic.

Taffy told me that his cutting works well so you can probably do this in many ways.

Many times theory and practical experiences don't agree. In the ideal world the friction coefficient is independent of pressure and contact area. Off-road, we have dirt on the pads which we normally don’t have on cars. If bikes work different I don’t know but to get less brake moment in cars you need to decrease the efficient radius. If you cut material on the left and the right side you have a similar radius. Decreasing the pad material this way gives less fade resistance. If you instead cut material from the top of the pad and down to the piston you decrease the efficient radius. Shorter radius gives warmer brakes which give an earlier fading but the brake behavior should be more consequent.
How far you can cut I don’t know but it should be possible to cut some mm into the piston area.

mikst said:

we have dirt on the pads which we normally don’t have on cars. If bikes work different I don’t know but to get less brake moment in cars you need to decrease the efficient radius.

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Mikst,

It is the same whether it's a car or off-road bike but the total brake torque is gained through the relationship of several factors - hydraulic pressure, caliper piston area, the effective radius of the disk as you mention, tyre radius and the coefficient of friction between the disk and pads.

Far the simplest solution is to just fit really crappy rear brake disks (e.g much less friction).

Cheers,
Simon

Re: b/fluid

Scully said:

Correct me if I'm wrong?, but what b/fluid are we suppose to use? It says in the manual dot 3? But the KTM (which has the same brakes) says use "only" dot 5? Silicone? I actually filled mine with dot 5 but after reading the manual I drained it and went to the original and now the front feels spongey?? Will dot 5 damage the seals???

Click to expand...

Ktm and Husaberg recommend DOT 5.1, not 5.0

DOT 5 is silicon based.
DOT 5.1 is glycol based. Compatible with DOT 4 and DOT 3.

Your front probably has a little air in it. Try removing the caliper and raising it above the master cylinder and bleeding. It sounds awkward, but it does work and is effective if you have a stubborn air bubble that won't bleed out the regular way.

Good Topic Taffy,

I had asked around for a while about how to lessen the power of my rear brake on my 2001 FE501. A guy at the shop suggested chamferring the leading edge of the brake pads, but, as you may guess, it didn't do too much.

In years past on drum brakes, I used to cut a longitudal groove, as well as angled cross cuts with a hack saw blade to help remove water. It didn't dawn on me till now that just removing brake pad material would work to reduce brake effectiveness. My rear brake on my 01 usually just locks the rear wheel unless at high speed. So I'll be modifying those brake pads as suggested. The rear brake on my 04 550 seems to work more progressively, but this advice will come in handy if I want to try and improve action. Fading of the rear brake is usually not a problem for me anyway.

I have had some recent experience bleeding my front brakes with an irrigation syringe ( you can buy them at any medical supply store as they don't have the ability to attach a needle to them), and this is what I did to get all the air out ot the system.

First, bleed the system the old fashioned way from the master to the caliper, this will help remove any garbage that might be in the caliper and line, it just seemed to make sense to me as you wouldn't want to push any of this crap into the master cylinder.

Then fill the syringe with brake fluid ( I have been using Castrol brake fluid since my shifter Kart racing days) then attach the syring with a piece of clear line to the brake bleeder with a tie wrap or something like it. Then I tie wrap the syringe to the fork leg. Open the bleed valve on the caliper and push some fluid into the syringe with the master cylinder, this will get the air out of the bleed nipple and the line, simply tap the side of the line and syringe to get all the bubbles up to the top.

Now, close the bleed nipple. Remove the caliper with the pads still installed. Make sure there is enough fluid in the master resevoir, and pump the lever until the pistons and pads bottom out in the caliper. Open the bleed nipple and use a suitable tool to compress the pistons all the way in, if there is any air in the caliper/piston area you will see it in the clear line. I even went so far as to tap on the caliper to loosen any air bubbles while I held the caliper in a position that allow any air bubbles to collect in the bleed nipple area. Tap the line and syringe again to get any air up to the top. Close the bleed nipple. (I was amazed at how much air was in there from the factory)

Re-install the caliper. Using an ear syringe or other suitable tool, remove the majority of the brake fluid from the master resevoir. Open the bleed nipple and depress the syringe pushing the fluid into the caliper and up the brake line. Keep an eye on the master resevoir and evacuate it as neccessary. Again, I was amazed at how much air came out of the line.

When you can no longer see ANY little air bubbles coming up into the master resevoir, close the bleed nipple. Pump the brake lever until the pads contact the rotor. You should notice (if you saw air come out) a huge difference in the feel. I'm a little anal, so I even bled it a few more times after I had got the pads back onto the rotor.

With all this work I ended up having to put slack in the front brake adjuster as the point at which the brakes really started to grab had moved farther out, and the feel was much more positive.

All this work was a bit of a pain, but in the end, (get it?) it was all well worth it.

Don't spose you happen to wear high heels all the time do you Taff :?:
That'd make your feet point down!

This is what I did to take the on/off feel out of my FC470 02. I went at the pads with a cut off wheel. By removing about 50% of the pad material, making sure that the remaining pad material still sweeps over the whole disc area. I have gotten a nice linear feel to the pedal. It locks up when I want it to, not when it wants to. Now I feel I should mention that the DOT5 brake fluid is a silicone based fluid and is the only brake fluid that is comprisable. It also has a tendance to hold small air bubbles when shaken. Harleys are really the only company to use it. It doesn't eat there pretty paint jobs. What is really important with brake fluid is it's wet and dry boiling points.

In one of the Swedish car brands you can use 5.0 or 5.1 both. The seals have no problem with silicon based brake fluid. If KTM and Husaberg use similar seal quality I do not know. What the seals cannot handle is ordinary oil. A small splash of oil and the seals do not have the shape of a functional seal any more. It is probably similar the other way round; brake fluid in the clutch could/will harm the seals.

Silicon based brake fluid can handle higher temperatures but is compressible as written above. Silicon based fluids have problem to absorb water. If a drop of water is in the wrong place it will give some trouble. It could be ice in a narrow pass or boil and raise steam. Hence, you have a soft and nice spring in the system.

Take the pedal spring off. Put a dab of silicone on the end of the shaft where it goes into the master cylinder to hold everything together and stop rattles.
Enjoy much better braking control. The previous owner of my 400 explained the reason why it didn't have one.
Cheers Ice.

Beringer do compensators and distributed in UK by Corsa Italiana in London, ive just got a 650 Berg but also have an ex-Yamaha France YZ 450 Supermoto and ive got the opposite problem on that im desperate for more powerfull brakes, ive got 310mm Beringer with 6 pot on the front and got an oversize front disk on the back and just got a brand new R1 rear caliper to try and clamp it, think i'll then use a bar mounted hydraulic clutch for the rear brake, what do i do then for the cable operated clutch????
Please help