Author Topic: Bleeding Front Brake (Read 2580 times)

Angus · « **on:** January 18, 2021, 13:41:03 »

Front brake recently has been a bit spongy. Haven't used bike for 2 weeks and now notice that the front brake reservoir is empty. I took off the cover and I'm about to bleed the brakes adding brake fluid as I go. Does the brake fluid go inside(outside) that black rubber membrane ?As when I take the lid off the membrane comes with it? Or should I remove the membrane which is stuck to the lid and filter the brake fluid through that? Where does the fluid go?
Also is it absolutely necessary to use brand new fluid or can I use some fluid that has been sealed and stored for a few months ?

Froglodyte · « **Reply #1 on:** January 18, 2021, 14:07:44 »

I think you need to do some serious research before you start. Plenty of videos on YouTube.

Fat Rat · « **Reply #2 on:** January 18, 2021, 14:14:42 »

Angus,

Take the membrane out. Only use new/unopened fluid.

Please do some research, brakes are important

Froglodyte · « **Reply #3 on:** January 18, 2021, 14:27:21 »

A good place to start

Fat Rat · « **Reply #4 on:** January 18, 2021, 14:30:59 »

The fact that your Master Cylinder is empty may well mean you have a leak.

Rookie · « **Reply #5 on:** January 18, 2021, 14:34:56 »

High Angus, I guess the first thing you need to do, Is find out where the old fluid went. As it just doesn't disappear. The black boot in your picture comes of that plastic plate, and needs a good clean and compressing back together.Do not let any dirt into the reservoir. Fresh fluid is best as over time brake fluid absorbs water and becomes contaminated. You can pour it straight into the reservoir, but do not overfill and be very careful of splashes. It will ruin your paintwork. Make sure you are confident of how to bleed brakes before you start , otherwise it is a reasonably easy task with non abs brakes. I'm sure some of the better versed members will be along soon to offer there help

Good luck buddy

Rixington43 · « **Reply #6 on:** January 18, 2021, 14:45:54 »

Good idea to check pad wear as well. The oil obviously goes down as the pads wear.
My understanding (someone correct me if I'm wrong) is that doing a full bleed and topping up the reservoir with heavily worn pads might lead to overfilling the system and then the slave cylinders won't go back far enough if you then come to fit new pads.

Mr Nick · « **Reply #7 on:** January 18, 2021, 16:51:37 »

Nearly there: filling fluid to the max and then changing pads will result in excess in the reservoir as it will just push back up the system. It doesn't stop the pistons from retracting. If the fluid is at the max mark when you go to change pads, you can either draw some out of the reservoir first, or just crack open the bleed screws & let it out as you push the pistons back: just be sure there's no air let in. Unless you replaced the fluid recently, a pad change is an opportunity to change it anyway.

Rixington43 · « **Reply #8 on:** January 18, 2021, 17:09:49 »

Good to know there's a little leeway in motorbike systems, I've always retracted the pistons fully before a bleed since you have to on push bikes so maybe I can skip that step in future.

Brockett · « **Reply #9 on:** January 18, 2021, 17:43:48 »

I would like to think that, as I have done with all my older bikes, anytime I change the pads I would drain, refill and bleed the system. However I am not all sure this is something I can easily do on an ABS motorcycle.

Mr Nick · « **Reply #10 on:** January 18, 2021, 18:20:30 »

I've flushed ABS equipped bakes and cars many times and the biggest difference, especially noticeable on bikes, is that there's more fluid in the longer pipework to & from the ABS unit to get through. Same principles still apply. Yes, there's been talk on here about getting that last little bit that might remain untouched in the ABS pump, but I'd rather change the 99% of the fluid in the reservoirs, master cylinders, pipes, hoses and calipers myself than worry about the 1% in the hope that a dealer does anything more than I would have.

tallpaul · « **Reply #11 on:** January 18, 2021, 20:46:02 »

Can you cycle the ABS pump on a strom? With my Yamaha you can force the pump to activate which is great for flushing the pump. I wonder if such a feature is built into the vstrom?

UK_Vstrom650 · « **Reply #12 on:** January 18, 2021, 21:06:50 »

I didn't think you could (at least on the Glee and haven't seen it mentioned in the service manual) but someone on here said their dealer eventually said they could using their SDS tool and I think it was c. £50 for a fluid change with their ABS system being flushed.

STORMY · « **Reply #13 on:** January 19, 2021, 02:11:47 »

Quote from: tallpaul on January 18, 2021, 20:46:02

Can you cycle the ABS pump on a strom? With my Yamaha you can force the pump to activate which is great for flushing the pump. I wonder if such a feature is built into the vstrom?

Sadly not, but the dealer can using some nifty software to cycle the pump and purge the old stuff out of the ABS unit. I paid through the nose last year to have this procedure done and to be honest I only have their word this even took place (I’m cyclical). Maybe it’s something you do once in a while, or maybe not, I’m not sure I’d bother in the future because the chances are I’ll have moved the bike on by the time this becomes critical.

Gert · « **Reply #14 on:** January 19, 2021, 06:11:12 »

I recall reading on one of the V-Strom sites, of a member who wired in a switch to activate the ABS pump. Maybe do a search on google for more info on this or have a look at the wiring diagram to locate the ABS trigger circuit.
An easier method to activate the ABS pump would be done manually, if you find a bit of dirt or gravel, it will be easy to activate the abs at very low, safe speed.
Another suggestion to activate the ABS that I recall reading, was if you put the suspension settings on to their hardest settings and it'll trigger the front ABS when braking normally on bumpy roads. Deliberate rear ABS activation is relatively easy to do under normal braking if you press hard/stamp on the pedal.
Have a look at the advice in https://www.v-strom.co.uk/smf/index.php?topic=36199.0 and https://www.stromtrooper.com/threads/I-made-an-abs-triggering-flushing-device.427711/

Angus · « **Reply #15 on:** January 22, 2021, 15:05:26 »

There are no obvious holes in any of the cables and it the fluid seems to be present on most of the master cylinder although I cannot pinpoint any obvious leaking point Any pointers on how best to find a leak or is it the kind of job I need to take to the repair shop- as I am an amateur? And is it an expensive job usually?

Angus · « **Reply #16 on:** January 22, 2021, 15:06:25 »

Some of the fluid seems to have got onto the tyre. I have cleaned it off with water do I need to have any further concerns about this?

Mr Nick · « **Reply #17 on:** January 22, 2021, 16:40:47 »

Water by itself isn't going to shift the brake fluid completely: at least put some detergent in it.

As for leaks, pulling the lever hard will soon identify any as the fluid will make for any exit it can under that pressure.

Going by what you're saying, little things like thinking they're cables instead of pipes & hoses and that the rubber membrane in the reservoir was a filter, you really need to get someone who knows even basic bike mechanics to take a look. Getting in about your brakes with that degree of knowledge is asking for trouble.

Ianmc · « **Reply #18 on:** January 22, 2021, 17:17:45 »

When I first read this topic,I was immediately struck by the lack of knowledge of the original poster.As someone who has worked on vehicle braking systems all my working life,I feel very uneasy that someone who has virtually no skills is working on an essential safety item.
Angus, don’t take this the wrong way but please get someone who knows what they are doing to diagnose the problem and repair your bikes brakes.

UK_Vstrom650 · « **Reply #19 on:** January 22, 2021, 22:28:53 »

I agree braking is one of the most, if not the most important part of the bike and if you're the kind of person who thinks bike maintenance involves an MOT once a year then you ought to take it to a mechanic. That said, the only way you ever learn is by doing it yourself (I'd normally say get a mate over to show you if possible but sadly we can't at the moment).
There are some basic checks you can do yourself (squeeze the brakes & look for leaks) and there are plenty of YouTube videos that will explain how the braking system works and basic maintenance which can assist you to learn these things.