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Proportioning valve

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POSHAN AGRAWAL View Drop Down
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    Posted: Jun/29/2019 at 11:21am
We used a tandem master cylinder in our brake assembly. Although we didn't used any proportioning valve still had the problem of front wheel locking before rear. I can assure you that bleeding was perfect. Any explanation why this is happening?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sujandinesh Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2019 at 1:20pm
Well this is not surprising and there can be multiple reasons why this might be happening. 

It depends on your chosen brake components for front and rear, your weight distribution, considered deceleration values, friction coefficients etc. 
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POSHAN AGRAWAL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote POSHAN AGRAWAL Quote  Post ReplyReply Direct Link To This Post Posted: Jun/30/2019 at 2:13am
we have considered the weight distribution to be 60:40 and pad friction 0.45
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dnt Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2019 at 12:31am
This might happen if you have braking in the front when as compared to rear. Please refer the braking chapter in "Tune to Win" by Carroll smith. Many such possibilities are addressed there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote buckinghams_pie Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2019 at 10:02am
What calipers are you using? What layout are you using (3 or 4 calipers)?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sujandinesh Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2019 at 11:47am
Like I mentioned already, there can be multiple reasons why this issue is there and people in this forum will not be able to look at your entire design procedure and pinpoint the issue to you. That would be your job. 

Instead, we can help you streamline this process if you ask the right questions. 
Please understand that if the necessary brake torques (for a chosen deceleration) for front and rear are not met accordingly, there will be a difference in the respective performance. I would suggest you revisit your brake calculations and see the differences in the design for your front and rear braking. 
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POSHAN AGRAWAL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote POSHAN AGRAWAL Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 2:21am
3 callipers
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POSHAN AGRAWAL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote POSHAN AGRAWAL Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 2:23am
IN CALCULATION THE OUTER DISC DIA IS 10 MM FOR FRONT WHILE FOR REAR IT IS 8MM. ISN'T IT TOO SMALL?
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POSHAN AGRAWAL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote POSHAN AGRAWAL Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 2:33am
SORRY FOR MM ITS CM
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sujandinesh Quote  Post ReplyReply Direct Link To This Post Posted: Jul/02/2019 at 10:25am
Originally posted by sujandinesh sujandinesh wrote:

Like I mentioned already, there can be multiple reasons why this issue is there and people in this forum will not be able to look at your entire design procedure and pinpoint the issue to you. That would be your job. 

Instead, we can help you streamline this process if you ask the right questions. 
Please understand that if the necessary brake torques (for a chosen deceleration) for front and rear are not met accordingly, there will be a difference in the respective performance. I would suggest you revisit your brake calculations and see the differences in the design for your front and rear braking. 
i couldn't be more clearer. Do your own research and analysis and ask the right questions. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RLM Quote  Post ReplyReply Direct Link To This Post Posted: Jul/03/2019 at 10:07am
So you assumed a weight distribution of 60:40. is that static or dynamic taking into account weight transfer? did you validate that weight distribution? if so how? if the actual weight distribution is different from your assumed value, do you think that could cause your calculations to be a bit offf, causing more front braking torque than rear which in turn causes the front to lock sooner? 

start asking yourself questions like this and your reason why front is locking first will become clear. as said above, revisit your hydraulic calculations. then redo them with physical data from the car instead of assumptions. doing calcs with hopes and dreams will achieve nothing. 
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POSHAN AGRAWAL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote POSHAN AGRAWAL Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2019 at 1:50am
IF MY CALCULATED VALUE FOR FRONT ROTOR IS 10 CM DIA AND I USED 15CM HOW WOULD IT WILL AFFECT MY BRAKING?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aman2610 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2019 at 11:51am
It's definitely going to affect your braking, as increasing the rotor dia. will also increase the braking torque. And in this case your will lock at a lower pressure which in turn means it will lock early then expected.
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