Unbleedable rear brake on 990 (ABS)??

IBJim · 04-24-2010, 07:32 PM

My rear brake on my 07 990 Adventure w/ ABS is driving me (more) crazy and I could use some help! Had next to no rear brake so I tried to bleed--no luck. Rebuilt the rear master cylinder and bled (conventionally)--no luck. Just tried the Mity Vac--no luck. Still have air in the system (continue to produce bubbles when bleeding conventionally).

I think I have an air leak somewhere and I keep pumping air back into the system. If the brake light switch has failed, would this allow air to enter? My brake light isn't working but I'm not sure if this is just due to lack of pressure at the switch. Anything else I should check??

Thanks!!

brents347 · 04-24-2010, 08:58 PM

Your brake light switch is NOT a pressure switch. If the switchisn't working than I would start by assuming that it has failed and is introducing air into the system.

dmckiwi · 04-24-2010, 09:04 PM

I had the same issue with my 950, later found out I had to push the caliper in on the pins to get all the air out, there was a pdf of the service manual showing how to do it, after that it was great and never went away again.

jamesbrown · 04-24-2010, 09:24 PM

You can find the correct bleeding procedure as part of the recall notice for the 950s, here.

brents347: I'm pretty certain that switch is pressure operated (not sure exactly what you mean by "pressure switch" though).

big adv · 04-24-2010, 09:37 PM

You could also try using a large syringe (70-100cc aval at a vet supply store) to back bleed the system from the caliper, fill syringe with fluid, purge air from it and hose, connect to bleed nipple, and push the fluid to the master. On the bikes with ABS, the HCU sits at the highest point in the system, which can make bleeding it difficult. you can also try cracking the line loose (the one to the caliper) at the HCU and bleeding there first. then do the caliper.

Earl

dabracing · 04-25-2010, 01:44 PM

Quote:

Originally Posted by IBJim

My rear brake on my 07 990 Adventure w/ ABS is driving me (more) crazy and I could use some help!

Another reason to hate ABS.

IBJim · 04-26-2010, 02:02 PM

Thanks for the ideas guys. FYI- I LOVE the ABS. It's this bleeding issue (which was also a problem on the non-ABS 950s) that I could do without!

Yascher · 05-18-2012, 01:56 AM

So does anyone have a 100% effective procedure to bleed ABS, or bleeding, riding with ABS in dirt, bleeding again and then rifing with ABS working and so on till you give up or the brakes become responsive?

04-24-2010, 07:32 PM	#1
IBJim ^OP WhoUB? Joined: Mar 2007 Location: NW PA Oddometer: 307	Unbleedable rear brake on 990 (ABS)?? My rear brake on my 07 990 Adventure w/ ABS is driving me (more) crazy and I could use some help! Had next to no rear brake so I tried to bleed--no luck. Rebuilt the rear master cylinder and bled (conventionally)--no luck. Just tried the Mity Vac--no luck. Still have air in the system (continue to produce bubbles when bleeding conventionally). I think I have an air leak somewhere and I keep pumping air back into the system. If the brake light switch has failed, would this allow air to enter? My brake light isn't working but I'm not sure if this is just due to lack of pressure at the switch. Anything else I should check?? Thanks!!

04-24-2010, 08:58 PM	#2
brents347 KOTW 2010 Finisher Joined: Mar 2006 Location: Where the hell is Truckee, CA? Oddometer: 3,038	Your brake light switch is NOT a pressure switch. If the switchisn't working than I would start by assuming that it has failed and is introducing air into the system. __________________ Brents347 Truckee, CA. 07 Yamaha R6 07 KTM 950 Super Enduro 04 KTM 250exc- plated two-stroke

04-24-2010, 09:04 PM	#3
dmckiwi Louder is always better Joined: Apr 2007 Location: Christchurch, NZ Oddometer: 66	I had the same issue with my 950, later found out I had to push the caliper in on the pins to get all the air out, there was a pdf of the service manual showing how to do it, after that it was great and never went away again. __________________ In the words of Juan-Manuel Fangio "Brakes they only slow you down"

04-24-2010, 09:37 PM	#5
big adv I need supervision Joined: May 2007 Location: Kelowna, BC. CND Oddometer: 1,050	You could also try using a large syringe (70-100cc aval at a vet supply store) to back bleed the system from the caliper, fill syringe with fluid, purge air from it and hose, connect to bleed nipple, and push the fluid to the master. On the bikes with ABS, the HCU sits at the highest point in the system, which can make bleeding it difficult. you can also try cracking the line loose (the one to the caliper) at the HCU and bleeding there first. then do the caliper. Earl __________________ BA My dad's a TV repair man, he has an awsome set of tools. We can fix that!

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04-24-2010, 09:24 PM	#4
jamesbrown Lefty tighty. Joined: Nov 2007 Location: Gone Oddometer: 6,413	You can find the correct bleeding procedure as part of the recall notice for the 950s, here. brents347: I'm pretty certain that switch is pressure operated (not sure exactly what you mean by "pressure switch" though).

04-26-2010, 02:02 PM	#7
IBJim ^OP WhoUB? Joined: Mar 2007 Location: NW PA Oddometer: 307	Thanks for the ideas guys. FYI- I LOVE the ABS. It's this bleeding issue (which was also a problem on the non-ABS 950s) that I could do without!

05-18-2012, 01:56 AM	#8
Yascher Gnarly Adventurer Joined: Oct 2009 Location: Moscow, Russia Oddometer: 301	So does anyone have a 100% effective procedure to bleed ABS, or bleeding, riding with ABS in dirt, bleeding again and then rifing with ABS working and so on till you give up or the brakes become responsive?