
Brake Fluid
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Brake Fluid
Changing the fluid in the brake lines at the weekend , sure the last time I used 5.1 synthetic am I right in saying that this grade is more suited to heavy use . 

Hi John1000, I believe there were issues with what was considered a race item Dot 5.1 fluid, some formulas eroded rubber seals. I believe most formulations are now OK but read this http://www.xs11.com/tips/maintenance/maint1.shtml
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There was a big discussion on AF1 on this.
From memory (ie This Needs Checking Before You Act On It) it's OK to use DOT 4 or 5.1 but not DOT 5 as it's quite different. I'm pretty sure they concluded that the DOT 5 was a misprint because it isn't the same as DOT 4.
I'll go and search for this and edit this if I find anything.
EDIT:
Yep read these links to discover more:
http://www.apriliaforum.com/forums/show ... hlight=DOT
http://www.apriliaforum.com/forums/show ... hlight=DOT
I'd read these in conjunction with the link posted by Thumper for the best understanding.
Anyway - the advice is Avoid DOT 5
From memory (ie This Needs Checking Before You Act On It) it's OK to use DOT 4 or 5.1 but not DOT 5 as it's quite different. I'm pretty sure they concluded that the DOT 5 was a misprint because it isn't the same as DOT 4.
I'll go and search for this and edit this if I find anything.
EDIT:
Yep read these links to discover more:
http://www.apriliaforum.com/forums/show ... hlight=DOT
http://www.apriliaforum.com/forums/show ... hlight=DOT
I'd read these in conjunction with the link posted by Thumper for the best understanding.
Anyway - the advice is Avoid DOT 5
Last edited by D-Rider on Thu Mar 01, 2007 12:02 am, edited 1 time in total.
Basically you don't need dot 5, dot 4 is more than adequate for a road bikes so that's what I use.
However fluid speck moves on and more manufactures are producing higher spec fluids now.
Many falco owners were having problems with clutch cylinders leaking in the last few years and I was reading about troublesome brake master cylinders also, these things are usually very reliable.
I suspect the systems were being filled with Dot 5 fluids and it was causing premature failure of seals but It's only a hunch, I have no evidence for that.
However fluid speck moves on and more manufactures are producing higher spec fluids now.
Many falco owners were having problems with clutch cylinders leaking in the last few years and I was reading about troublesome brake master cylinders also, these things are usually very reliable.
I suspect the systems were being filled with Dot 5 fluids and it was causing premature failure of seals but It's only a hunch, I have no evidence for that.

Last edited by Thumper on Thu Mar 01, 2007 11:34 am, edited 1 time in total.
Always expect the unexpected
Just to add some confusion:
http://www.apriliaforum.com/forums/show ... stcount=12
http://www.apriliaforum.com/forums/show ... stcount=12
Just as on our forum, over on AF1 some posts within a thread are more helpful than others.sabestian wrote:Just to add some confusion:
http://www.apriliaforum.com/forums/show ... stcount=12
Read the whole thread, understand what is consistent and check against other authoritative sources -like the link that Thumper posted.

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