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new Ultegra compatibility question

by SteeveB
Wed, Aug 23, 2017 13:40
8

Anyone know if i can replace a BR-RS805 rear disc brake calliper with the new BR-R8070 one?  Seems to be hard to find the RS805 ones anywhere online now. 

SAB

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8 comments

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john latimer | 7 years ago
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It will work I replaced mine with dura ace just case of bleeding up levers on other hand are different m7 thread as opposed to m6 on calipers and old levers

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SteeveB replied to john latimer | 7 years ago
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john latimer wrote:

It will work I replaced mine with dura ace just case of bleeding up levers on other hand are different m7 thread as opposed to m6 on calipers and old levers

 

john, to be clear, you fitted dura ace callipers to replace some RS805s? Did the hose fit the calliper? It seems to be a different diameter.

 

SAB

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part_robot | 7 years ago
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The hose answers are correct ^ (Have looked into this in depth with a Shimano expert and Dura Ace hydro which is basically the same situation). Using the wrong hoses may make your brakes either super rigid feeling or super spongy depending on which way you get it wrong.

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StraelGuy | 7 years ago
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I went through this recently fitting 685/805 hydraulic brakes. Those two hoses are slightly different diameters. The BH59 is the older, slightly wider bore and  uses the olive and brass end fitting kit whereas the BH90 is the newer, narrower standard and uses the olive and silver end fitting kit.

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SteeveB replied to StraelGuy | 7 years ago
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StraelGuy wrote:

I went through this recently fitting 685/805 hydraulic brakes. Those two hoses are slightly different diameters. The BH59 is the older, slightly wider bore and  uses the olive and brass end fitting kit whereas the BH90 is the newer, narrower standard and uses the olive and silver end fitting kit.

 

So, i would need to put in new brake hoses. That probably means the levers will need the BH90  hoses, so i would have to change them too.  So then the Ultegra disc brake callipers arent a replacement for the 805s. 

I wonder if you can make the BH59 hose fit. More digging!

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VeloUSA | 7 years ago
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According to this Shimano compatibility chart it appears you can. Click on caliper model to compare specs.  http://productinfo.shimano.com/#/com/2.7?cid=C-460&acid=C-461

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SteeveB replied to VeloUSA | 7 years ago
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VeloUSA wrote:

According to this Shimano compatibility chart it appears you can. Click on caliper model to compare specs.  http://productinfo.shimano.com/#/com/2.7?cid=C-460&acid=C-461

 

that is a good chart. There is lots of info in there. Good find!

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SteeveB replied to VeloUSA | 7 years ago
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VeloUSA wrote:

According to this Shimano compatibility chart it appears you can. Click on caliper model to compare specs.  http://productinfo.shimano.com/#/com/2.7?cid=C-460&acid=C-461

 

Hmm, when i look at the chart everything seems to be the same except for the hose. My RS805 uses an SM-BH59 hose, but the new ultegra R8070 uses SM-BH90. Not sure what the difference is. Need to do more digging.

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