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05-28-2017, 03:32 PM
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Join Date: Feb 2005
Location: LSGY
Posts: 3,198
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brakes
Quote:
Originally Posted by High_Flyer
I can't see the brake line while braking... I'd have to check that with someone pressing the brake pedals while I watch.
Why are you asking that??
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If the brake hoses (on the high pressure side) are moving a lot when you press on them, then some of the pressure you want to go to the discs is being "wasted" moving the hose. Based on what I've read here, I doubt that is your problem.
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05-28-2017, 05:27 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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Quote:
Originally Posted by rv8ch
If the brake hoses (on the high pressure side) are moving a lot when you press on them, then some of the pressure you want to go to the discs is being "wasted" moving the hose. Based on what I've read here, I doubt that is your problem.
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The brakes are essentially a hydrostatic system. No pressure is ever wasted. If you have hoses expanding/moving, that can change the volume, which will drop the pressure everywhere - including what you feel with your toes. But if you maintain, say, 20 lbs of force on the pedals, then you have to get the same brake force, regardless of whether or not the lines are solid or can flex. Unless, of course, you actually run out of travel on the master cylinder.
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05-28-2017, 08:41 PM
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Join Date: Mar 2014
Location: Laguna Hills, CA
Posts: 1,805
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Here's my experience after replacing the linings for the first time:
1) Did the break-in procedure...about four hard successive applications, from about 35 mph to 5 mph. Keep it rolling; no stopping in between.
2) Let brakes cool for 30 minutes. Brakes had somewhat more bite at this point.
3) Went for a 20-minute flight and landed. Pedal pressure was a little higher than normal, but I could easily stop in the normal distance.
4) Next landing with two aboard...still needed higher pedal pressure; could smell the brakes while taxiing after landing.
5) Next landing, everything felt normal again.
__________________
Doug
RV-9A "slider"
Flew to Osh in 2017, 2018 & 2019! 
Tail number N427DK
Donation made for 2020
You haven't seen a tree until you've seen its shadow from the sky -- Amelia Earhart
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05-28-2017, 10:28 PM
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Join Date: Sep 2010
Location: Saint-Jorioz, France.
Posts: 199
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Tanks a lot
Thanks a lot for all your replies.
What I can get out of all the replies is that my brakesmost likely need "breaking in". I'll do that as soon as I get back home (I'm away for work for a week) and will report further once it's done.
Alain
__________________
Location: France
RV7 (F-PRVZ), Tip Up, Aerosport IO-375, Dynon Skyview, VP-X, Day VFR.
Flying since June 2017.
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05-28-2017, 10:49 PM
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Join Date: Feb 2007
Location: San Diego, CA
Posts: 1,670
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Be sure to re-read the post about "glazing". If that's the case, the best solution is to replace the linings.
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Pete Hunt, [San Diego] VAF #1069
RV-6, RV-6A, T-6G
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05-28-2017, 11:14 PM
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Join Date: Sep 2010
Location: Saint-Jorioz, France.
Posts: 199
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Quote:
Originally Posted by PCHunt
Be sure to re-read the post about "glazing". If that's the case, the best solution is to replace the linings.
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Thanks, the brakes are new, only used during the two initial taxi tests a few days ago and at speed of around 10Kts, so I'm pretty sure they are not "glazed", my braking attempts didn't generate enough heat for that (the discs were cold enough to keep my fingers on them after shutdown and post taxi checks)
__________________
Location: France
RV7 (F-PRVZ), Tip Up, Aerosport IO-375, Dynon Skyview, VP-X, Day VFR.
Flying since June 2017.
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05-29-2017, 04:01 AM
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Join Date: Jun 2011
Location: Mansfield Australia
Posts: 19
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Brakes Ineffective
It does sound to me that the Parking brake is partly closed.
I found this a bit confusing when I installed mine. It needs checking and if the cause , adjust the position of arm to the brake cable.
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05-29-2017, 04:49 AM
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Join Date: Feb 2005
Posts: 1,082
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Based on what you said I would also doubt the brakes are glazed, that would require a lot of heat. I would also say that the beding proceedure (breaking them in) should be done. There are compounds in brake lining material that require some heat which is why you should bed in new brake linings. Since you have SS lines through your system you may always experience a slightly firmer pedal than if you had the plastic lines. This is because the plastic lines flex more when pressure in applied (steping on the brakes) and give a little through their length. This is one of the reasons why in a race car the rubber brake lines are replaced with braided SS lines. It doesn't sound like you have air in the lines since you have firm pedals. If there was air in them the pedal would feel mushy. Before doing any more taxiing and the bedding proceedure clean the rotors with some mineral spirits, gas, or acetone to remove any oils. There may be a coating on them from the factory to keep them from corroding.
__________________
Mike
JAMES AIRCRAFT.com
Flying - RV8 Hot Rod "Drone Killer"
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Last edited by Capflyer : 05-29-2017 at 04:52 AM.
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05-29-2017, 05:43 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Not "may be". These is a coating. As Alex noted, plenty of folks neglect to remove the protective paint before first use.
Quote:
Originally Posted by AlexPeterson
Are you guys cleaning the silver paint off from the new rotors? A little lacquer thinner takes it right off. Otherwise, it is a gummy goo until it cooks off.
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__________________
Dan Horton
RV-8 SS
Barrett IO-390
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05-29-2017, 09:13 AM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by DanH
Not "may be". These is a coating. As Alex noted, plenty of folks neglect to remove the protective paint before first use.
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Not according to the manufacturer.
http://www.parker.com/static_content...emos/PRM68.pdf
I didn't remove the paint. I followed the bedding instructions from the manufacturer. No "gooey" mess. It burns off quickly.
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Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
Last edited by JonJay : 05-29-2017 at 09:16 AM.
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