[-BB-]

I found these instructions online.....

Is this the process everyone uses? i've heard that you can bleed them top down or bottom up... I've also heard that the step in ITALICS is not really needed.

I'm aiming for the most simple fool-proof process and am willing to use more fluid than I need (ie I am willing to push out all the old fluid and replace with all new) Better that than to get up to Mammoth and have a brake that still pulls into the lever after 1-2 runs.


Instructions found online:
- Marta SL, Marta, and Gustav M – Fix the caliper in a position so that the hose connection to the caliper is at the highest point possible. Hose must be positioned vertically. You may have to loosen or unscrew the caliper fitting bolts that connect the caliper to the frame or fork to get the caliper in this position.

- Remove pads and push the pistons back into their cylinders completely with a plastic tire lever. It is important to remove the pads during a bleed to ensure they are not contaminated.

- Assemble your Magura syringe, tube, and m6 threaded bleed fitting. Fill this completely with Magura Blood only. Make sure your bleeding syringe is totally full and air free. Unscrew the 3 mm or 5 mm bleed plug located on the caliper with a hex wrench and attach your bleeding syringe. Tighten fitting 1/8 turn with an 8 mm open end wrench.

- Loosen the 5 mm clamp bolt and level the master cylinder (lever assembly) so that the reservoir is horizontal and slightly tighten the clamp bolt so that it stays in place.

- Take the reservoir cap off with a T7 torx wrench and remove the rubber membrane.

- Start the bleeding process by pushing the fluid through the system from the bottom up using the bleeding syringe. Use a second syringe to take the excess fluid out of the reservoir before it over flows. Also, it is important to tap the caliper and line while pushing the fluid through with the handle of a screwdriver, etc. Push almost the entire amount of fluid through the system.

- Slowly start cycling the lever blade. This will push the fluid through the system from the top and out the caliper and into the bleed syringe. Keep the reservoir full of Magura Blood with the second syringe so you do not introduce air into the system. Cycle lever 20 times or until air bubbles are no longer coming from caliper. Your system should now be totally air free.

- Make sure the reservoir is completely full and re-install the reservoir membrane and cap with torx screw.

- Important step – Place the pads back in the caliper, but do not secure them. Take the caliper fitting screws completely out of the mounting tabs so the caliper is free. Now re-install the wheel with the rotor. Place the caliper with pads on the rotor without fitting screws. Push fluid into the system with the bleed syringe still attached to the caliper. Stop pushing on syringe when you feel resistance. This will set the pistons/pads on the rotor for the particular pad wear and put the maximum amount of fluid in the system.

- Take the caliper off the rotor and take the pads out of the caliper. Loosen and take the bleed syringe off the caliper. Then re-install the bleed plug and tighten.

You are now ready to re-install your pads and properly set-up your caliper on the rotor.

 

[davec113]

I used to have Gustavs... what I did is push fluid in from the caliper. I got a plastic syringe from the hardware store ($2), this is all you need for equipment. Unscrew the bleed port and take off the res.cap on the lever assy, let the old fluid drain out, then thread the plastic syringe (with fluid in it) into the bleed port. You might need to trim excess material off the end of the syringe depending on what you get. Just screw it into the bleed port using the threads in the bleed port to cut into the syringe and make an airtight seal. I bled successfully with the brake installed on the bike, but if your brake line does a loop or goes down, then back up you might need to remove the brake and hang it vertically (with the lever up top). Then, push fluid from the syringe into the system. You might want to tap on the caliper and line gently to dislodge trapped air bubbles... once the fluid reservoir in the lever is full (lever needs to be kept level), collapse the rubber boot that goes between the res and cap to it's smallest volume, and replace the res. cap. You should push excess fluid out of the res while doing this so keep a towel handy. Then unscrew the syringe and replace the bleed port plug. DONE.

As far as piston position while bleeding, if you set the position using a new set of pads before you bleed you should be fine... if your brakes are working well enough to do so. If not, it only takes a minute to follow the instructions in italics and it makes sure you won't draw air into the system as your pads wear down. If you bleed with the pistons fully retracted you might not have quite enough fluid in the system to account for pad wear. TBH, I haven't tried bleeding with the pistons fully retracted so I'm not sure if it would be an issue or not.

 

[-BB-]

Thanks... I have the Magura Mini-service kit, so I have the needed "tools".

Would there be any benefit to keeping the brakes "full" as you do this and then jsut let all the existing fluid spill out the top of the lever reservoir? That way you have less air in the system to start? It might be messier, but this is mineral oil, not brake fluid. I can just wrap a towel around the top or do this over the grass in my lawn.

 

[DirtMcGirk]

I just did the old fashioned "fill 'em til I like the grab" trick. It worked pretty well.

 

[local717]

Thanks... I have the Magura Mini-service kit, so I have the needed "tools".

Would there be any benefit to keeping the brakes "full" as you do this and then jsut let all the existing fluid spill out the top of the lever reservoir? That way you have less air in the system to start? It might be messier, but this is mineral oil, not brake fluid. I can just wrap a towel around the top or do this over the grass in my lawn.

I have had Gustavs since 05 now, and have only had to bleed them a few times. Just bled them at the start of the season. And I agree with your thougt of leaving the original fluid in and pushing it out from the bottom up using the Magura service kit. That would def help keep any potential air out. And the other thing you can do is hang a soda bottle cut in half from the bottom of the lever. That will catch most of the old fluid getting pushed out.

 

[-BB-]

I did my bleed last night. Another quick question.... if the pads are in too close now can I just loosen the bleed port on the caliper and squeeze out a drops of fluid to open them up a bit more?


When I did the bleed...
The brake was off the bike (in process of building a new frame up) so I clamped the lever to the top of a ladder and put a rag under it. Figured this way the hose would be positioned straight up. Yeah, there was a lot of fluid everywhere but I did it over the grass so not a big deal. I'm sure my ladder could use the oil to keep it from rusting.

 

[local717]

I did my bleed last night. Another quick question.... if the pads are in too close now can I just loosen the bleed port on the caliper and squeeze out a drops of fluid to open them up a bit more?

When I did the bleed...
The brake was off the bike (in process of building a new frame up) so I clamped the lever to the top of a ladder and put a rag under it. Figured this way the hose would be positioned straight up. Yeah, there was a lot of fluid everywhere but I did it over the grass so not a big deal. I'm sure my ladder could use the oil to keep it from rusting.

I would just try pushing the pistons back without the pads first, and see how it feels. Because Maguras are self adjusting. And if thats not the desired feel, then try messing with fluid levels

 

[-BB-]

I would just try pushing the pistons back without the pads first, and see how it feels. Because Maguras are self adjusting. And if thats not the desired feel, then try messing with fluid levels

Thanks, I'll give it a try. Also, I just realized that the rotor I was testing it on is thicker than the one that will go on the bike, so I may not have an issue.

 

[bjorn]

If you take excess fluid out of the system at the lever you don't risk putting air into the caliper. I know that this works for Marta/Julie/Louise but I've never worked with Gustav so they may be different.