Brake lever excessive travel DR650

[andy230]

Hi all,

I recently went to change the pads in the DR’s rubbish sliding caliper front barke.  Ended up (predictably!) having to rebuild the caliper and replace the seals etc.

Got it back on, and bled (i think...!) and took it out for a quick test.  The brake is definately better, but the the lever travel is somewhat excessive.  It doesn’t come right back to the bar, but its not far off...  It feels spongey but firms up with more travel.  Doesn’t firm up when pumped...

Any ideas?  Just keep bleeding it?? 

Cheers

a

[trophydave]

You could try leaving the lever tied back overnight,that usually helps.

[bullet350]

some times its the other end thats the probelm. on older bikes the master cylinder can need rebuilding to get a decent solid feel to the lever. my cbr is just the same.

bullet350

[Steve H]

Have ypu clean the sliders ?, I found the caliper on teh DR750 was corroding round the sliders rubber boot, making the pin sticky.
The DR750 brake used to go off if left!.
Loosen the caliper mounting bolts so they are around 10mm undone. Pump the brake untill it hardens up. Holding the lever in place slowly do the caliper bolts up, this will center the caliper and the sliders properly. Worked for me.

[themoudie]

Aye Andy,

In addition to SteveH' instructions: Take 100ml syringe with clear soft vacuum hose and attach to bleed nipple on caliper. Then you can either suck or 'back bleed' fluid into the caliper rather than tortuous route from the resevoir only. Works well on SRX and Bros.

Regards, Bill.

[andy230]

Hi, thanks guys...

You could try leaving the lever tied back overnight,that usually helps.

Tried that, cheers!

some times its the other end thats the probelm. on older bikes the master cylinder can need rebuilding to get a decent solid feel to the lever. my cbr is just the same.

bullet350

Was rebuilt about 2years ago, so am hoping its not necessary

Have ypu clean the sliders ?, I found the caliper on teh DR750 was corroding round the sliders rubber boot, making the pin sticky.
The DR750 brake used to go off if left!.
Loosen the caliper mounting bolts so they are around 10mm undone. Pump the brake untill it hardens up. Holding the lever in place slowly do the caliper bolts up, this will center the caliper and the sliders properly. Worked for me.

The sliders are ok, checked them out and re-greased

Aye Andy,

In addition to SteveH' instructions: Take 100ml syringe with clear soft vacuum hose and attach to bleed nipple on caliper. Then you can either suck or 'back bleed' fluid into the caliper rather than tortuous route from the resevoir only. Works well on SRX and Bros.

Regards, Bill.

The syringe-thing is always a messy disaster when I try it!! 

Cheers, will try to just re-bleed with a large volume of brake fluid.

Thanks all
a

[pigafetta]

I'm currently having the same problem with my CB900 having just rebuilt my front master cylinder. I think my elderly brake hoses might have something to do with it. I've tried tying the lever back but no joy there. I'll try bleeding them some more and see what happens. I think some nice new braided hoses might be in order.

Dave

[andy230]

I think some nice new braided hoses might be in order.
Dave

Well, I put about 4 resevoir volumes thru it tonight.  better but still duff.  maybe I've just got used to the skorpion's notorious (but I like it...) on-off switch front brake.  Will centre the caliper too...

Already running braided hose dave.

a

[andy230]

Have ypu clean the sliders ?, I found the caliper on teh DR750 was corroding round the sliders rubber boot, making the pin sticky.
The DR750 brake used to go off if left!.
Loosen the caliper mounting bolts so they are around 10mm undone. Pump the brake untill it hardens up. Holding the lever in place slowly do the caliper bolts up, this will center the caliper and the sliders properly. Worked for me.

Steve, I did this to centre the caliper.  No difference.

However, consider the following-

There was already grease on the slider pins.  I put a bit more on for good measure.  I did notice a "sponginess" (ie a tendancy to "return") when I pushed the mounting plate (the bit with the pins on it) in.  However, after a while, and a few pushes, it squelched(air/grease displacing**) and the plate stayed roughly in position.

**I am trying hard not to make the analogy to a particular, amusing, sexual phenomenon......   

However, last night I dismantled it again, wiped the pins and noticed a flat on them.  Presumably to allow air/grease to move about...

If I had over-greased, do you think this could inhibit movement of the caliper on the pins???  Due to a seal being formed between the pin (now becoming like a piston) and the caliper??

Just a thought.  I am nearing the end of my tether.

Next option- back bleed- in my experience just a frustrating and messy way of doing things

And then after that, if it still wont work, rebuild the m/cyl.

And finally (which I quite fancy), I have a few pairs of FZR 400 wheels.  I am going to supermoto the bastard!!  That will make it stop!!!  (but its a hassle with brake caliper brackets, spacer, spindles etc).

Anyone done this??

a

[steveD]

Andy you need to watch that the back brake pad is seating properly. It is not a very good design and can slip off its locating lug which can take an age to resolve! Ask Martin P! You will also note that if the plate is not brand new it will have worn at an angle and will not stay in position as it will have a tendancy to try and get back to its original position. I carefully filed this small lug flat again too its original shape and eventually got the front brake a lot better but then the DR brake is not that good. If I had kept my DR I would have fitted either Super Ten forks or Africa twin which both have twin discs.
Hope this info makes sense but if you look really carefully to see how the caliper works I feel that this will be where the sponginess is coming from. SteveD PS I'll have a beer for you at Dent.

[andy230]

cheers steve, will check this out (after assembly with less grease "packing")

I think I'm going to look at putting FZR400RR wheels on it in the long term.  Not a great look, I know, but I'm not paying 600 quid in rims and brakes!

Agreed, the DR front brake is f'cking pish, to use the vernacular...

cheers for now

a

ps dent is *possibility*... we will see!

[Dave#22]

Hi Andy, I don't know if the hose run is the same as the DR750, but if the hose is higher than the master cylinder air bubbles can collect in the top of the loop, causing spongeyness. I always raise the master cylinder to the highest part of the system before bleeding and it does give a better feel to the lever. Another fault could be the lever fulcrum/ operating heel is worn causing excess travel in the lever before the master cylinder is operated.....if so try a small shim (1mm) on the end of the master cylinder piston shaft.....or a new lever.....or both, like I did.
      Good luck
         Dave