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> Why doesn't my right ebrake work?, It's the asymmetric cables, dummy.
davesprinkle
post Dec 3 2009, 10:14 AM
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Here's why most modern cars have the ebrake handle in the middle of the car -- it's so the cables running to the wheels have identical length and path. How do I know? Here's the anecdote:
For the last year, I've been struggling with my ebrake system. The right caliper just wouldn't clamp as tightly as the left. I've got rebuilt calipers, new pads, new cables, proper clearance, but no worky.

Finally found out why. It's the internal drag of the actuation cables. The passenger-side cable is substantially longer than the driver side. Also, the right-side cable has 3 right-angle bends vs the left-side cable with none. This results in so much internal friction that the cable just binds solid when it's pulled.

I was able to improve the situation somewhat by lubricating the cable. Still not perfect, but much better.
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PRS914-6
post Dec 3 2009, 10:47 PM
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The length of the cable should not effect it. The cable has a T yoke that will equalize the pull. Of course if you have cables that need lubing they should probably be replaced after 30 years of grit and grime. I have stock cables and handle with 911 rears and they work perfectly (new cables and everything clean)
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davesprinkle
post Dec 3 2009, 11:35 PM
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QUOTE(PRS914-6 @ Dec 3 2009, 08:47 PM) *

The length of the cable should not effect it.

A longer cable will have more of the inner cable in contact with the outer cable, so the length WILL affect the friction.

QUOTE
The cable has a T yoke that will equalize the pull.

Yes, the mechanism has a force balance. But it cannot compensate for friction mismatch.

QUOTE
Of course if you have cables that need lubing they should probably be replaced after 30 years of grit and grime.

As I mentioned, my cables are new.
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PRS914-6
post Dec 3 2009, 11:51 PM
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QUOTE(davesprinkle @ Dec 3 2009, 10:35 PM) *

QUOTE(PRS914-6 @ Dec 3 2009, 08:47 PM) *

The length of the cable should not effect it.

A longer cable will have more of the inner cable in contact with the outer cable, so the length WILL affect the friction.

QUOTE
The cable has a T yoke that will equalize the pull.

Yes, the mechanism has a force balance. But it cannot compensate for friction mismatch.

QUOTE
Of course if you have cables that need lubing they should probably be replaced after 30 years of grit and grime.

As I mentioned, my cables are new.



Sorry, the friction difference between two new cables, installed properly would be very minimal. The problem is elsewhere. While you might feel a slight difference by hand, the amount of leverage applied with the handle is a lot. Crawl underneath a pickup and you will see tons of vehicles with one side WAY longer than the other without issue. Most cables are teflon lined and have minimal friction if routed smoothly. Mine slide easlily with the bends. The problem lies somewhere else.....not cable length

Disconnect them at the caliper and have someone pull the handle. Do the cables come back easily?

Cheap aftermarket cables?
Cables not seated properly on the tube?
Calipers not working properly?
Cables kinked somewhere?
Clamps on the cables too tight?

Keep looking....
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914Mike
post Dec 4 2009, 12:11 AM
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My cars both grab the driver's side rotor first, and let the passenger side slip. I just figure it's designed in difference. That's how I rotate the engine while the car is in the air, just put it in fifth and rotate the passenger side rear wheel, there's even timing marks on the bottom of the flywheel for this.
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davesprinkle
post Dec 4 2009, 09:07 AM
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QUOTE(Mike914 @ Dec 3 2009, 10:11 PM) *

My cars both grab the driver's side rotor first, and let the passenger side slip. I just figure it's designed in difference. That's how I rotate the engine while the car is in the air, just put it in fifth and rotate the passenger side rear wheel, there's even timing marks on the bottom of the flywheel for this.


Mike, this is exactly the problem that I fixed when I lubricated the cable. Both brakes should grab equally.
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Posts in this topic
davesprinkle   Why doesn't my right ebrake work?   Dec 3 2009, 10:14 AM
jim_hoyland   I have the same issue.....where did you lube the c...   Dec 3 2009, 10:34 AM
davesprinkle   I have the same issue.....where did you lube the ...   Dec 3 2009, 10:46 AM
tat2dphreak   dunno about OR, or CA, but a hydraulic Parking bra...   Dec 3 2009, 12:02 PM
davesprinkle   dunno about OR, or CA, but a hydraulic Parking br...   Dec 3 2009, 12:56 PM
tat2dphreak   new cables should not bind, perhaps it was bent be...   Dec 3 2009, 01:06 PM
davesprinkle   new cables should not bind, perhaps it was bent b...   Dec 3 2009, 01:27 PM
tat2dphreak   new cables should not bind, perhaps it was bent ...   Dec 3 2009, 01:59 PM
Shade Tree   I've been considering just putting a line lock...   Dec 3 2009, 01:18 PM
JJ914GT   That's exactly why my car has the handbrake in...   Dec 3 2009, 01:45 PM
JJ914GT   The PO installed it before I got the car, so didn...   Dec 3 2009, 04:13 PM
McMark   Dave, did you try adjusting the ebrake cables? An...   Dec 3 2009, 10:37 PM
davesprinkle   Dave, did you try adjusting the ebrake cables? A...   Dec 3 2009, 11:37 PM
PRS914-6   The length of the cable should not effect it. The...   Dec 3 2009, 10:47 PM
davesprinkle   The length of the cable should not effect it. ...   Dec 3 2009, 11:35 PM
PRS914-6   [quote name='PRS914-6' post='1246177' date='...   Dec 3 2009, 11:51 PM
Mike914   My cars both grab the driver's side rotor firs...   Dec 4 2009, 12:11 AM
davesprinkle   My cars both grab the driver's side rotor fir...   Dec 4 2009, 09:07 AM
davesprinkle   Sorry, the friction difference between two new ca...   Dec 4 2009, 09:40 AM
PRS914-6   It cracks me up when people get on a forum and ask...   Dec 4 2009, 10:17 AM
davesprinkle   It cracks me up when people get on a forum and as...   Dec 4 2009, 10:44 AM
Solo914   Dave, First off, Thanks, I know if you were able ...   Dec 4 2009, 11:01 AM
davesprinkle   Dave, First off, Thanks, I know if you were able...   Dec 4 2009, 11:22 AM
Chicken   This is not a design flaw/issue it is an expectat...   Dec 4 2009, 11:16 AM
davesprinkle   This is not a design flaw/issue it is an expecta...   Dec 4 2009, 11:40 AM
Cevan   The "E-brake" as you call it is not an ...   Dec 4 2009, 01:00 PM
SirAndy   The "E-brake" as you call it is not an...   Dec 4 2009, 01:11 PM
messix   Dear Dave, I really don't think that you are...   Dec 4 2009, 11:45 AM
davesprinkle   Dear Dave, I really don't think that you ar...   Dec 4 2009, 12:37 PM
messix   Dear Dave, I really don't think that you a...   Dec 4 2009, 02:58 PM
Chicken   quite simply adjust the cables so the RR makes co...   Dec 4 2009, 11:51 AM
davesprinkle   quite simply adjust the cables so the RR makes c...   Dec 4 2009, 12:26 PM
SirAndy   I call the system an "emergency brake...   Dec 4 2009, 12:45 PM
davesprinkle   I call the system an "emergency brake...   Dec 4 2009, 12:56 PM
SirAndy   Its other function is as an EMERGENCY brake. Firs...   Dec 4 2009, 01:18 PM
davesprinkle   I stomp on the brakes, *POP* it said and the peda...   Dec 4 2009, 01:33 PM
SirAndy   [quote name='SirAndy' post='1246418' date='Dec 4 2...   Dec 4 2009, 01:37 PM
davesprinkle   Did you also read my question? I'll ask again...   Dec 4 2009, 03:09 PM
Solo914   [quote name='SirAndy' post='1246428' date='Dec 4 ...   Dec 4 2009, 03:18 PM
SirAndy   From the owners manual:   Dec 4 2009, 12:53 PM
tat2dphreak   that happened to me on an old hunting truck we had...   Dec 4 2009, 01:56 PM
Chicken   guys i am glad we can all give each other a hard t...   Dec 4 2009, 02:50 PM
SirAndy   A+ for your lubrication skills :thumbsup: D- for ...   Dec 4 2009, 03:13 PM
Shade Tree   Don't the brake lines travel through the tunne...   Dec 4 2009, 03:17 PM
messix   Don't the brake lines travel through the tunn...   Dec 4 2009, 03:22 PM
SirAndy   :lol4: http://wtanaka.com/node/7745   Dec 4 2009, 03:38 PM
MDG   :lol4: http://wtanaka.com/node/7745 :rotfl: ...   Dec 4 2009, 08:14 PM


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