Bleeding front brakes R1100 gs

Peter · Jan 24, 2023

I am putting my 1995 back on the road. I have had to recondition the master cylinder and both front calipers with new seals. The bores of all components are in good condition.
During bleeding there are no air bubbles appearing in the clear bleed tube. However the brake leaver has long travel and is very spongy. Braking is terrible! Years ago I put braided hoses all round and had no problems at all. The brakes feel as though there is air trapped some where. There are no leaks and I have left the lever slightly pressurised using a cable tie. Has anyone and ideas or suggestions?

GORILA · Jan 24, 2023

Use a piece of string etc to tie up the brake lever and leave it overnight. Also turn the handlebars so that the brake master cylinder is at the highest point.
Any air bubbles should work their way up!

Riceburner · Jan 25, 2023

check the discs are still a good width.

snelly · Jan 25, 2023

I'am also having problems bleeding my front brakes((95 GS 1100) both calipers have been rebuilt and new pads fitted but the lever is too spongy; the front brake also drags a little ; i've also tied the lever back over night without much success; the discs are about on the limit but i would'nt have though that would alter the feel at the lever;

Steptoe · Jan 25, 2023

Are the original brake hoses still fitted ?

snelly · Jan 26, 2023

Steptoe said:
Are the original brake hoses still fitted ?

The original hoses are still fitted ; i've checked for bulging all the way through and they are fine; also new fluid all through the system.

Peter · Jan 27, 2023

Bleeding front brakes

In my case I do have braided hoses from Hel. They were fitted years ago, possibly 15 to 18years ago. Do braided hoses soften in time as do original brake hoses?

hops · Jan 28, 2023

snelly said:
The original hoses are still fitted ; i've checked for bulging all the way through and they are fine; also new fluid all through the system.

I reckon some new hoses might be needed but you could also try pressure bleeding them first. At the age the bike is the hoses are likely to be knackered or certainly not as effective as they could be.

K3FatBoy · Jan 28, 2023

Peter said:
In my case I do have braided hoses from Hel. They were fitted years ago, possibly 15 to 18years ago. Do braided hoses soften in time as do original brake hoses?

Not in that time span, no.

I understand that pressurised vacuum bleeders will sort all this, but I haven't got one.

Has to be an air bubble or bubbles 'caught' somewhere that normal bleeding flow won't dislodge. Try bleeding 'backwards' - pressure via syringe and tube at the bleed nipple, or free off the caliper, pump the caliper pistons almost all the way out, then push the pistons back into the bores in the calipers and drive fluid back up to the reservoir. In between, dismount the caliper and twist and turn it (without stressing the line), and gently tap it to 'help' an air bubble stuck on a sharp edge come free.

Working on an old RD400E with hinging calipers years ago, I had to dismount the entire braking system from the bike - master cylinder, line, caliper - and bleed forward and backward with the m/c high, with the caliper high, real faff.

You'll get it in the end - in my experience, just after thoughts of selling the damn thing start to really settle in.

Smug · Jan 28, 2023

Pump the lever vigorously and then with the lever compressed crack the bleed nipple. Keep an eye on the reservoir level. Usually works.

Peter · Jan 29, 2023

Brake bleed

Many thanks to all for your replies. I will persevere and let you know of the outcome.

Littledumptruck · Jan 29, 2023

Any 1100, and 1150s for that matter should have new hoses by now. The youngest 1150 will be nearly 20yrs old afterall. The OE hoses break down from around 12 years onwards. I’d guess anything used as replacement can be considered to be the same. I tried to refresh the fluid on my 1150 when it was about 12-13 yrs old and had this issue. After much trying I eventually burst one spraying fluid up the garage wall. I replaced the hoses there n then and have done my 850 too.

ThreeDawg · Jan 30, 2023

Oof, 20 odd year old rubber hoses? No thanks.

If the brakes won't firm up I put the bike on its side stand and turn the bars to the left so th m/c is in the highest possible position. Tie the lever down and leave for a day, then knock the bars against the lockstops to persuade any lingering air up and out.

If that (and the reverse bleeding mentioned above )fails then try a new piston kit for the M/C.

Ian J Hartley · Jan 30, 2023

Peter said:
I have had to recondition the master cylinder and both front calipers with new seals. The bores of all components are in good condition.

I don’t want to ask the obvious, but might you have installed the seal in the Master cylinder the wrong way round.

:nenau

Old Codger · Jan 30, 2023

Original hoses break down on the insides without showing bulging DAMHIK .

Disaster Area · Feb 1, 2023

I mentioned on another thread that the main dealer around here denied any knowledge of rubber hoses degrading and couldn't find any braided hoses on his system!

Peter · Feb 3, 2023

Brake bleed.

Success! I tried all suggestions except pressure bleed. Brake lever felt much better. Put it in for MOT and the front wheel locked on the rolling road! So many thanks to you all who gave up their time to reply.

Bleeding front brakes R1100 gs

Peter

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GORILA

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Riceburner

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snelly

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Steptoe

What a waste.

snelly

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Peter

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hops

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K3FatBoy

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Smug

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Peter

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Littledumptruck

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ThreeDawg

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Ian J Hartley

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Old Codger

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Disaster Area

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Peter

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