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> Rear venting clearance
Setting Venting Clearance
After installing a rebuilt/new rear caliper, I set venting clearance:
Before adding fluid [ 9 ] ** [16.98%]
After adding fluid/bleeding [ 31 ] ** [58.49%]
Both before and after [ 6 ] ** [11.32%]
What's venting clearance? [ 4 ] ** [7.55%]
I'm Eric Shea and set venting clearance with my godlike ESP powers over brake systems. :) [ 3 ] ** [5.66%]
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Rusty
post May 25 2009, 09:25 PM
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We had a discussion about this today... didn't really come to any agreement.

Thoughts?
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davep
post May 25 2009, 09:28 PM
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No point to setting venting clearance (0.004") until everything else is completed.
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r_towle
post May 25 2009, 09:55 PM
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It should not matter.
The piston is physically held there by the adjustment.
Fluid or not, it will still sit in the same place based upon the screw.

Rich
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john rogers
post May 25 2009, 09:56 PM
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Rule of thumb is to set the clearance after you do the bleeding and then set it to 1/2 of the factory spec or your pedal will have a bit long travel.
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SGB
post May 25 2009, 10:01 PM
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but you will have increased sensitivity to rotor warping- which
i think will always happen eventually.

Edit- of course, I do...
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drive-ability
post May 25 2009, 10:27 PM
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Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)
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SLITS
post May 26 2009, 07:47 AM
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QUOTE(drive-ability @ May 25 2009, 09:27 PM) *

Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)


How close your a$$ is to the seat when you roll a cheek to phart!
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914Sixer
post May 26 2009, 07:55 AM
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Please disconnect the handbrake cables when adjusting the rear calipers. Added tension from these can sometimes mess things up.
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SGB
post May 26 2009, 08:40 AM
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QUOTE(drive-ability @ May 25 2009, 11:27 PM) *

Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)


There is an adjuster on the rear brake calipers to set the gap between the pad and the rotor...
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drive-ability
post May 26 2009, 09:06 AM
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QUOTE(SGB @ May 26 2009, 07:40 AM) *

QUOTE(drive-ability @ May 25 2009, 11:27 PM) *

Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)


There is an adjuster on the rear brake calipers to set the gap between the pad and the rotor...


That must be an aspect of the 914 factory brakes. My Carrera brakes aren't equipped with an adjustment . The (IMG:style_emoticons/default/confused24.gif) was in the word venting.

I did some reading on the subject and I'm glad I did, it seems my rear calipers are installed (by Me) incorrectly on two points. I didn't shim them and they are upside down. (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/smash.gif)
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Rusty
post May 26 2009, 09:14 AM
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QUOTE(SLITS @ May 26 2009, 07:47 AM) *

QUOTE(drive-ability @ May 25 2009, 09:27 PM) *

Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)


How close your a$$ is to the seat when you roll a cheek to phart!


What spec do you use for that, Slits? (IMG:style_emoticons/default/w00t.gif)
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Cap'n Krusty
post May 26 2009, 11:03 AM
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It doesn't matter when you adjust them. What counts is the rotor is held flat against the hub and that the adjustment is made to .004". I do the outer, then the inner, then I recheck them both. The E-brake cables should be exerting NO force on the lever, other than taking up the slack in the lever itself. I've yet to see significant warpage in a rear rotor, but there's always a little runout. That's why you turn the rotor at least 360 degrees while checking the gap. It's marginally easier to bleed the brakes after the venting clearance has been set.

The Cap'n
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SLITS
post May 26 2009, 01:45 PM
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QUOTE(Rusty @ May 26 2009, 08:14 AM) *

QUOTE(SLITS @ May 26 2009, 07:47 AM) *

QUOTE(drive-ability @ May 25 2009, 09:27 PM) *

Gentlemen ,

What are you talking about ? Rear venting ? (IMG:style_emoticons/default/confused24.gif)


How close your a$$ is to the seat when you roll a cheek to phart!


What spec do you use for that, Slits? (IMG:style_emoticons/default/w00t.gif)


My exact measurement is 0.125" ..... relieves the pressure on the cushion (IMG:style_emoticons/default/help.gif)

I realize you may consider this setting loose, but it is absolutely necessary to get the appropriate audio from the flapping.
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MDG
post May 26 2009, 03:13 PM
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QUOTE(SLITS @ May 26 2009, 03:45 PM) *

My exact measurement is 0.125" ..... relieves the pressure on the cushion (IMG:style_emoticons/default/help.gif)

I realize you may consider this setting loose, but it is absolutely necessary to get the appropriate audio from the flapping.


I have squareweave in my '76 and basketweave in my '73 - does 0.125" work for both?
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SLITS
post May 26 2009, 03:44 PM
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QUOTE(MDG @ May 26 2009, 02:13 PM) *

QUOTE(SLITS @ May 26 2009, 03:45 PM) *

My exact measurement is 0.125" ..... relieves the pressure on the cushion (IMG:style_emoticons/default/help.gif)

I realize you may consider this setting loose, but it is absolutely necessary to get the appropriate audio from the flapping.


I have squareweave in my '76 and basketweave in my '73 - does 0.125" work for both?


Basketweave diffuses the sound (IMG:style_emoticons/default/lol-2.gif)
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r_towle
post May 26 2009, 04:23 PM
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Actually the basketweave enhances the sound while diffusing the smell.

Rich
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mskala
post May 27 2009, 06:35 AM
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Semi-serious question, I've always figured if I set the clearance too low it will work
itself out, by wearing the pads a little, and if I set it too high, itr will work itself
out as the mechanism adjusts.

So aren't we really setting the clearance only for about the few days/weeks/months
until this happens?
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SGB
post May 27 2009, 07:50 AM
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i don't think so...
I believe the clearance will track with the pad wear.
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VaccaRabite
post May 27 2009, 08:15 AM
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QUOTE(SGB @ May 27 2009, 08:50 AM) *

i don't think so...
I believe the clearance will track with the pad wear.


Nope. At least, that is not my understanding as to how it works.

The 914 rears do not self adjust at all, so you need to re-adjust them every 6 months or at the start of every driving season. As the pads wear, the calipers have to push them farther to get to the rotor, until they just don't work at all.

Zach
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mskala
post May 27 2009, 10:58 AM
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QUOTE(Vacca Rabite @ May 27 2009, 10:15 AM) *



The 914 rears do not self adjust at all, so you need to re-adjust them every 6 months or [...]
Zach


If they are not meant to adjust, please explain the purpose of all the parts
inside other than the screw and locknut and why they are not directly connected
to the piston.
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