Help on Brake Bleeding for new calipers
Post Reply    Forum -> General Discussion
Author Message
Enthusiast
Yellow GTS 300 Super, Black GTS 300 Super Sport
Joined: 14 Aug 2020
Posts: 81
Location: London
Mon May 03, 2021 8:30 am quote
Hi all

I have fitted a new rear Frando brake calliper on my project GTS 300 Super sport. I used the existing brake line and simply swapped out the old calliper for the new, torqueing up the mount screws and the brake line nut to the recommended torque settings.

After installing I followed Robot's video to bleed/flush the brake line using a big syringe to vacuum the old fluid through the system. The approach partially worked but seemed to drag a lot of air rather than fluid through when the bleed value was opened. I always made sure the top tank never got too low.

When I closed the bleed valve and screw the cover back on the top tank the brake lever is still very spongy.

I tried another approach where I used the syringe as a bleed reservoir and pumped the brake lever to push the brake fluid through the system. That pushed a lot through to the syringe but didn't fix the spongy feel.

Have I missed something and inadvertently added lots of air top the system?


Paul
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3308
Location: East Anglia, a dryer region of the UK than Israel
Tue May 04, 2021 1:08 am quote
What year is your Vespa? Does it have ABS?

If it has ABS you will need the dealer to fix this for you as it's nearly impossible to get the air out of the ABS pump without a good brake charging machine (a machine that pressurises the ABS system to get the air out). Normal bleeding won't do it. Or you could buy a machine yourself but it's really not worth it. For your dealer it's a simple job.
Hooked
2009 MP3 400, 2004 Honda ST1300
Joined: 11 Jun 2007
Posts: 330
Location: Sayre, PA
Tue May 04, 2021 1:41 am quote
Try pushing instead of pulling.

You want to use the syringe to push fluid from the caliper to the handlebars. Positive pressure will avoid sucking in air at the bleeder.
Enthusiast
Yellow GTS 300 Super, Black GTS 300 Super Sport
Joined: 14 Aug 2020
Posts: 81
Location: London
Tue May 04, 2021 2:13 am quote
Itís a non abs bike so I donít have the ABS pump issue. I will try the push rather than pull method and see how I get on.
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3308
Location: East Anglia, a dryer region of the UK than Israel
Thu May 06, 2021 6:53 am quote
Re: Help on Brake Bleeding for new calipers
Rallygeek wrote:
Hi all

I have fitted a new rear Frando brake calliper on my project GTS 300 Super sport. I used the existing brake line and simply swapped out the old calliper for the new, torqueing up the mount screws and the brake line nut to the recommended torque settings.

After installing I followed Robot's video to bleed/flush the brake line using a big syringe to vacuum the old fluid through the system. The approach partially worked but seemed to drag a lot of air rather than fluid through when the bleed value was opened. I always made sure the top tank never got too low.

When I closed the bleed valve and screw the cover back on the top tank the brake lever is still very spongy.

I tried another approach where I used the syringe as a bleed reservoir and pumped the brake lever to push the brake fluid through the system. That pushed a lot through to the syringe but didn't fix the spongy feel.

Have I missed something and inadvertently added lots of air top the system?


Paul
Ok so I note that your bike is a pre-ABS/ASR model.

It should be really easy to bleed your brakes if there is no ABS pump involved. I can only think it's your technique that isn't quite right.

I don't quite understand your description of "using the syringe as a reservoir". Are you saying you 'pushed' fluid through the system pumping the brake lever with the syringe attached to the bleed valve on the caliper? If so that won't work and you will let air into the system. You can only connect a syringe to the bleed valve if you use it to 'suck' fluid through.

Maybe you can clarify?

Ultimately, if you keep adding fluid to the reservoir and synchronising your bleeding by applying just a little pressure to the brake lever, then opening the bleed valve a little, then increasing pressure on the lever, pull the lever firmly to the handlebars holding it there until the bleed valve is closed. Then let the brake lever go. Repeat over and over again several times. You can't go wrong. Eventually all the air will come out of the system doing this, and the lever will firm up. It can take a while to do when the system is empty as air can hide and take time to travel to the bleed valve.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 39540
Location: Pleasant Hill, CA
Thu May 06, 2021 7:48 am quote
Re: Help on Brake Bleeding for new calipers
Stromrider wrote:
You can only connect a syringe to the bleed valve if you use it to 'suck' fluid through.

Huh? I found on both my GT200 and my Fuoco that the only way to reliably get all the air out of the rear brake lines was to push fluid back through the system from the bleed nipple to the reservoir - taking care that the reservoir didn't overflow. Especially important on the Fuoco suspension locks.


The 2010 GTSs seem to be easier to manage conventionally, but I still prefer to back-fill the fluid.
Enthusiast
Yellow GTS 300 Super, Black GTS 300 Super Sport
Joined: 14 Aug 2020
Posts: 81
Location: London
Thu May 06, 2021 10:27 am quote
Stromrider wrote:
Ok so I note that your bike is a pre-ABS/ASR model.

It should be really easy to bleed your brakes if there is no ABS pump involved. I can only think it's your technique that isn't quite right.

I don't quite understand your description of "using the syringe as a reservoir". Are you saying you 'pushed' fluid through the system pumping the brake lever with the syringe attached to the bleed valve on the caliper? If so that won't work and you will let air into the system. You can only connect a syringe to the bleed valve if you use it to 'suck' fluid through.

Maybe you can clarify?

Ultimately, if you keep adding fluid to the reservoir and synchronising your bleeding by applying just a little pressure to the brake lever, then opening the bleed valve a little, then increasing pressure on the lever, pull the lever firmly to the handlebars holding it there until the bleed valve is closed. Then let the brake lever go. Repeat over and over again several times. You can't go wrong. Eventually all the air will come out of the system doing this, and the lever will firm up. It can take a while to do when the system is empty as air can hide and take time to travel to the bleed valve.
I tried the suck method with the syringe originally but it didnít seem to have a good seal so you are right there is still air in the system.

In the later method where I pumped I donít do a good enough job of the pump with bleed open, close bleed and release lever , open bleed pump brake scenario.

I am going to give it another go with a helper using the pump approach.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 39540
Location: Pleasant Hill, CA
Thu May 06, 2021 10:50 am quote
Ensure you have grease or Teflon tape around the nipple threads - that's the main reason air can get in the system, or appear in the output tube when bleeding.
Addicted
BV 350
Joined: 22 Nov 2016
Posts: 892
Location: Nebraska
Fri May 07, 2021 1:05 am quote
Dunno
Dunno about the GTS, but on the BV the bleeder screws are not at the high point of the caliper when they are installed. I ended up making disk-thickness wood spacers, removed the calipers, inserted the spacers, held the calipers so the bleeder screws were at the high point, and bled them in that position so the air rose to the bleeder screw.
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3308
Location: East Anglia, a dryer region of the UK than Israel
Fri May 07, 2021 6:09 am quote
Re: Help on Brake Bleeding for new calipers
jimc wrote:
Huh? I found on both my GT200 and my Fuoco that the only way to reliably get all the air out of the rear brake lines was to push fluid back through the system from the bleed nipple to the reservoir - taking care that the reservoir didn't overflow. Especially important on the Fuoco suspension locks.


The 2010 GTSs seem to be easier to manage conventionally, but I still prefer to back-fill the fluid.
Oh yes jim, you can attach a syringe and back fill ok. But the OP was I believe saying something different. Or did I misunderstand what he had been doing?

Edit: just re-read the op's original post. Indeed I misunderstood what he was doing regarding using the syringe as a reservoir. He was indeed trying to back fill.

Last edited by Stromrider on Fri May 07, 2021 6:15 am; edited 1 time in total
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3308
Location: East Anglia, a dryer region of the UK than Israel
Fri May 07, 2021 6:11 am quote
Re: Dunno
Jimding wrote:
Dunno about the GTS, but on the BV the bleeder screws are not at the high point of the caliper when they are installed. I ended up making disk-thickness wood spacers, removed the calipers, inserted the spacers, held the calipers so the bleeder screws were at the high point, and bled them in that position so the air rose to the bleeder screw.
Yes, the GTS is a doddle to do. The bleed nipple on the rear is at quite a high point where all the air will come out. It just takes a while. In the workshop of course we used a pressure bleeder on just about everything. Takes just half a minute each wheel.
Hooked
2012 LX150ie
Joined: 28 Jul 2018
Posts: 138
Location: Austin Texas USA
Fri May 07, 2021 7:38 am quote
"A Doddle" !!

I love to learn more UK slang. I am absolutely Chuffed about this!
Enthusiast
Yellow GTS 300 Super, Black GTS 300 Super Sport
Joined: 14 Aug 2020
Posts: 81
Location: London
Fri May 07, 2021 9:00 am quote
Re: Dunno
Stromrider wrote:
Yes, the GTS is a doddle to do. The bleed nipple on the rear is at quite a high point where all the air will come out. It just takes a while. In the workshop of course we used a pressure bleeder on just about everything. Takes just half a minute each wheel.
These are Frando callipers so have the bleed nipple on the wheel side on the rear but still reasonably high. I managed to get a reasonably firm feel on the rear by the 2 person method.

The bike is starting to come together now..



Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 3308
Location: East Anglia, a dryer region of the UK than Israel
Sat May 08, 2021 1:20 am quote
Oh yes, that's looking good. Sorry I forgot you are not using a standard caliper. That one looks great! Two people makes a big difference if you have to reach out a bit to get to the nipple. Well done!
  DoubleGood Vespa T-Shirts  
Post Reply    Forum -> General Discussion
[ Time: 0.0542s ][ Queries: 27 (0.0358s) ][ Debug on ][ Thing Two ]