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Rear Brake Woes


lebby
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Finally have the Gasgas going and its been great apart from a spot of bother from the rear brake. I hear they are a pain for air bubbles.

Anyway, so I started off with no rear brake. I bled the system normally and it made a bit of difference but still no rear brake. I then bought a syringe and back bled it to which I got some brakes but only with the adjuster screwed very far out. The threaded rod for the brake lever must be on its last 3 or 4 threads. I'm starting to think the seals in the master might be gone, because surely with the amount of bleeding i've done (i've gone mad with it) it should have some feel by now. 

Am I being thick? Is there a trick to it? or is it probably the seals? I can't really think of doing anything else beside removing the whole system and checking it all but I'd rather not. I can lock the rear wheel the way it is now, but I subconsciously hate that it isn't right. 

Its a 2004 TXT Pro 250.

26608120438_8489f527b4_c.jpgDSC_2465 by Jack Ledingham, on Flickr

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Perhaps with the adjuster all the way out the piston is not working in the correct range to pick up fluid from the reservoir.  I had this problem on my KTM once.

I would suggest winding the adjuster all the way back in so the piston is able to return much further when you release the pedal and then re bleeding.

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They are a pain to bleed. Took mine to a friends garage who had a kit to suck the fluid through the caliper bleed nipple. I just poured fluid into the master cylinder at the same time and it was perfect in 30 seconds. 

For some reason the syringe method didn't work. 

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3 hours ago, lineaway said:

 Do you have new pads? It usually is just pads as the brakes are not real thick to begin with. I have seen this happen dozens of times.

No I don't. There's maybe 3mm meat on each pad though I haven't had them out for a look. Probably worth a shot! 

3 hours ago, bluey said:

Perhaps with the adjuster all the way out the piston is not working in the correct range to pick up fluid from the reservoir.  I had this problem on my KTM once.

I would suggest winding the adjuster all the way back in so the piston is able to return much further when you release the pedal and then re bleeding.

I have only ever bled them with the adjuster backed off, then readjust it up to where I have brakes. Not fully in however. May try that. 

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19 minutes ago, baldilocks said:

They are a pain to bleed. Took mine to a friends garage who had a kit to suck the fluid through the caliper bleed nipple. I just poured fluid into the master cylinder at the same time and it was perfect in 30 seconds. 

For some reason the syringe method didn't work. 

I wanted to try and get my pressure bleeder on it, but I'll need to find another res cap to make a fitting for the bleeder. Though I have heard of folk doing that! I don't think the suction one is expensive I may buy one anyway. 

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My suggestion:

1, check pads make sure they are good or replace to make sure

2. Make sure the push rod has just a little play before it hits the master cylinder piston.  this allows the piston to fully return in the master cylinder.

3. for some reason air gets trapped at/near the top of the master cylinder and it just does not go anywhere.  The following method works for me to get rid of the air.  Raise the front tire, on a truck tail gate, work bench or whatever.  Using the brake pedal pump up/get pressure on the brake system.  Loosen the banjo bolt for the hose on the master cylinder.  You should hear the air escaping.  The banjo bolt is a little odd to get to and is easiest accessed using an offset box end wrench.  I think it is 14mm but I may be wrong on the size.

 

913700.png

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7 hours ago, zippy said:

My suggestion:

1, check pads make sure they are good or replace to make sure

2. Make sure the push rod has just a little play before it hits the master cylinder piston.  this allows the piston to fully return in the master cylinder.

3. for some reason air gets trapped at/near the top of the master cylinder and it just does not go anywhere.  The following method works for me to get rid of the air.  Raise the front tire, on a truck tail gate, work bench or whatever.  Using the brake pedal pump up/get pressure on the brake system.  Loosen the banjo bolt for the hose on the master cylinder.  You should hear the air escaping.  The banjo bolt is a little odd to get to and is easiest accessed using an offset box end wrench.  I think it is 14mm but I may be wrong on the size.

 

913700.png

I'll give this a go as soon as I have time, thanks. Snowstorm is stopping me doing anything at the mo since my fingers freeze about 3 minutes into working in the garage.

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16 hours ago, lebby said:

I'll give this a go as soon as I have time, thanks. Snowstorm is stopping me doing anything at the mo since my fingers freeze about 3 minutes into working in the garage.

You need to get yourself a "garage cat" that is not allowed in the house.  (I had one for 14yrs)  Use the excuse that you want to keep the rodent population down.  Once you have said cat, then you need to explain to the significant other that it would be inhumane to not have a warm area for the cat during the cold months.  Now you need to install a furnace in the garage, just to keep it at a steady 40 degrees(F) for the cat.  Upside is when you go to the garage you will then be able to kick the heat up to 60F or so to keep you warm while out in the  garage.  (this worked for me :D)

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23 hours ago, oni nou said:

Is this the kind of garage cat you have

 

Not exactly.  HAHAHA

She was an outside cat that lived for 14yrs.  She would look both ways before crossing the street, but sadly the last two years she would not leave the garage in the winter (heated) and stopped moving for cars pulling into the driveway.  She didn't move one day and is no longer with us.

DBv7SNaXYAM7l88.jpg

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