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Abs brake bleeding?


dcan

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Haynes manual states, BMW abs cannot be bled in the conventional way. The procedure must be undertaken by BMW dealer using the BMW diagnostic tester. Is that correct? 08 rt

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Haynes manual states, BMW abs cannot be bled in the conventional way. The procedure must be undertaken by BMW dealer using the BMW diagnostic tester. Is that correct? 08 rt

 

Evening dcan

 

Yes & no, but more no than yes.

 

To do ALL the BMW bleeding tests you either need a GS-911 or dealer computer (if your brakes are working fine now then no need to do any of the advanced testing)

 

 

You don't really need a GS-911 (or dealer computer) to just bleed the brake system--

 

Bleed the front (both calipers) using the front lever as conventional, then bleed the rear using the rear brake pedal as conventional-- THEN, turn the key on (do not start engine) & spin the rear wheel with your foot (or have someone else do it) then pull on the front brake lever with the rear wheel spinning (you should feel the rear brake lock up)--

 

After the rear wheel locks up a couple of times then turn key off & do a quick re-bleed of the rear using the rear brake pedal (Using the front lever with rear wheel spinning & key-on runs the rear ABS pump & cycles new fluid through the pump)

 

 

 

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I think the Haynes statement was a carry over from the iABS servo system used on 2006 and earlier RTs. An owner can bleed those brakes properly, but the procedure is rather complicated, requiring a special funnel, removal of body work and the fuel tank, and bleeding four brake circuits instead of two. The bleeding procedure is much more conventional with iABSII, used on the 2007 and later models.

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Haynes manual states, BMW abs cannot be bled in the conventional way. The procedure must be undertaken by BMW dealer using the BMW diagnostic tester. Is that correct? 08 rt

 

Evening dcan

 

Yes & no, but more no than yes.

 

To do ALL the BMW bleeding tests you either need a GS-911 or dealer computer (if your brakes are working fine now then no need to do any of the advanced testing)

 

 

You don't really need a GS-911 (or dealer computer) to just bleed the brake system--

 

Bleed the front (both calipers) using the front lever as conventional, then bleed the rear using the rear brake pedal as conventional-- THEN, turn the key on (do not start engine) & spin the rear wheel with your foot (or have someone else do it) then pull on the front brake lever with the rear wheel spinning (you should feel the rear brake lock up)--

 

After the rear wheel locks up a couple of times then turn key off & do a quick re-bleed of the rear using the rear brake pedal (Using the front lever with rear wheel spinning & key-on runs the rear ABS pump & cycles new fluid through the pump)

 

 

Good morning DR!

 

The last part is very interesting procedure that I have never heard of before, and I had never done that! I also know that you have a wealth of data and knowledge, and so....can you please explain what the spinning and brake locking do in regard to the bleeding? I am really curious!!! :)

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Haynes manual states, BMW abs cannot be bled in the conventional way. The procedure must be undertaken by BMW dealer using the BMW diagnostic tester. Is that correct? 08 rt

 

Evening dcan

 

Yes & no, but more no than yes.

 

To do ALL the BMW bleeding tests you either need a GS-911 or dealer computer (if your brakes are working fine now then no need to do any of the advanced testing)

 

 

You don't really need a GS-911 (or dealer computer) to just bleed the brake system--

 

Bleed the front (both calipers) using the front lever as conventional, then bleed the rear using the rear brake pedal as conventional-- THEN, turn the key on (do not start engine) & spin the rear wheel with your foot (or have someone else do it) then pull on the front brake lever with the rear wheel spinning (you should feel the rear brake lock up)--

 

After the rear wheel locks up a couple of times then turn key off & do a quick re-bleed of the rear using the rear brake pedal (Using the front lever with rear wheel spinning & key-on runs the rear ABS pump & cycles new fluid through the pump)

 

 

Good morning DR!

 

The last part is very interesting procedure that I have never heard of before, and I had never done that! I also know that you have a wealth of data and knowledge, and so....can you please explain what the spinning and brake locking do in regard to the bleeding? I am really curious!!! :)

 

Morning PadG

 

On the 1200RT with I-ABS gen-II brakes the rear brake is both a stand alone rear brake from (only) the rear brake pedal & a linked brake from the front lever using the ABS servo pump to apply the rear brake.

 

When bleeding the rear system using the rear brake pedal that bleeds the stand alone portion of the system but doesn't completely flush the linked pump part.

 

By bleeding/flushing the rear stand alone first that replaces most of the brake fluid in the rear system (except the internals of the pump). By spinning the rear wheel with key-on, then using the front brake lever, that runs the rear pump & pumps the new fluid through the rear pump (basically dislodges the old fluid in the rear servo pump).

 

Then a quick re-bleed of the stand alone rear moves most of that dislodged fluid out the bleeder.

 

It isn't the end of the world if the rear pump isn't run during the bleeding as it doesn't hold much fluid but it is so easy to run the pump that it is good practice to purge the pump of old fluid as long as the bleeder hose is hooked up.

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