RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

Air Leak At the Brake O-ring

Reply
Old 04-25-2016, 10:17 AM
  #1
stuka
Thread Starter
 
Join Date: Jan 2002
Location: Hollywood, FL
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Air Leak At the Brake O-ring

I am working on a Cermark F 16 and have a leak at the oring on the brakes.. When you apply the brake you can hear the air escaping around the oring excessively. What is the fix for this? Do I need to replace the oring? Thanks in advance.
stuka is offline  
Reply With Quote
Old 04-25-2016, 10:34 AM
  #2
joeflyer
 
Join Date: Dec 2001
Location: Plymouth, MI
Posts: 2,656
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Coat the o-ring with silicone grease and reinstall it.
joeflyer is offline  
Reply With Quote
Old 04-25-2016, 04:22 PM
  #3
Len Todd
 
Join Date: Jul 2012
Location: Baldwin, MI
Posts: 984
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Maybe you have a unique design. ??? But, typically, if the brake is leaking air, the O-rings on the brake's pistons need replacing/lube. The band around the axle that rubs on the drum does not hold back the air. It holds back the pistons and when the pistons are pressured out, the band rubs on the drum. Maybe you have something different. ?
Len Todd is offline  
Reply With Quote
Old 12-10-2016, 06:57 AM
  #4
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Same problem on my 2m MB339 brakes, loosing air.

Well greased with silicon grease, quite mobile on their aluminium discs...but when applying air pressure - without wheels - I see the O-ring expanding a little bit but a lot of air pressure escaping from O-ring sides. Installing the wheels, same thing, no braking forse at all, lot of air escaping form O-ring sides...

All new, never used still.

Maybe worth to change the O-Ring ??

Thank you
DenisFerrari is offline  
Reply With Quote
Old 12-10-2016, 07:11 AM
  #5
joeflyer
 
Join Date: Dec 2001
Location: Plymouth, MI
Posts: 2,656
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Remove the o-ring and make sure that the grove is well coated with silicone grease. If that doesn't work then replace the o-rings.
joeflyer is offline  
Reply With Quote
Old 12-10-2016, 07:13 AM
  #6
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Thank you for the suggestion! I'll give it a try.

...Question : best method to remove the rings without risking to dent the aluminium discs o-ring housings ?
DenisFerrari is offline  
Reply With Quote
Old 12-10-2016, 07:47 AM
  #7
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

...removed one O-ring, very dry I think...and it broke in fact...
DenisFerrari is offline  
Reply With Quote
Old 12-10-2016, 08:31 AM
  #8
joeflyer
 
Join Date: Dec 2001
Location: Plymouth, MI
Posts: 2,656
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I use a small wood dowel, not much bigger than a toothpick. Sand one end to look like a flat tip screwdriver. It needs to be a hard wood to be strong enough. If the o-rings are dry and stiff then that's your problem. Replace them.
joeflyer is offline  
Reply With Quote
Old 12-10-2016, 08:41 AM
  #9
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Hi,
I used a wood piece in fact. I think that my problems comes from O-rings too stiff and dry indeed.
They too easily broke while bending or applying some reduced tension in my hands...see below.
I see diameter of 35mm, 5mm thickness...same measure or maybe 1mm wider just to test, in case they exist ?
Attached Thumbnails
Click image for larger version

Name:	O-rings MB339 2x2.jpg
Views:	185
Size:	265.8 KB
ID:	2193042  
DenisFerrari is offline  
Reply With Quote
Old 12-10-2016, 09:02 AM
  #10
Dave Wilshere
 
Join Date: Jun 2002
Location: Watford, UNITED KINGDOM
Posts: 9,735
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Denis

Same size, just new and soft. As said speak to C&C

Dave
Dave Wilshere is offline  
Reply With Quote
Old 01-05-2017, 02:46 AM
  #11
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Hi,
just to let you know that C&C Models was so kind to send me couple of new brakes disks + Orings : perfect now !

I think my problem were mainly due to dry/old Orings + potentially some dents in the brakes aluminium disks maybe helping loosing too much air while on pressure.
DenisFerrari is offline  
Reply With Quote
Old 01-05-2017, 10:01 AM
  #12
CARS II
 
CARS II's Avatar
 
Join Date: Oct 2002
Location: Sacramento CA
Posts: 3,842
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Nice that you got it fix when I first read the thread title, dry O rings was my first thoughts.

The O rings that are used on some of our retracts will get dry in time, used or new without use, as suggested by Joe lubrication is the key to keep them nice and elastic.

When I get a new set of retracts I inject Teflon fluid in them, if you do that the retracts will give you more cycles per air tank, refreshing the O rings on your retracts should be done at least once a season, specially where is colder.

The Teflon fluid that I use is comes from the RC car section of my LHS or you could order on line, get a midium thickness bottle and a plastic syringe to inject it into the struts.

http://www3.towerhobbies.com/cgi-bin...&I=LX3305&P=ML



Attached Thumbnails
Click image for larger version

Name:	ascc8074.jpg
Views:	158
Size:	15.6 KB
ID:	2195595  

Last edited by CARS II; 01-06-2017 at 12:26 PM.
CARS II is online now  
Reply With Quote
Old 01-05-2017, 02:30 PM
  #13
DenisFerrari
 
Join Date: Aug 2008
Location: Bologna, ITALY
Posts: 57
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Excellent, thank you !
DenisFerrari is offline  
Reply With Quote
Old 05-14-2017, 09:16 AM
  #14
clavin
 
Join Date: Apr 2002
Location: West Palm Beach, FL
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Can anyone direct me where to get some o-rings for my FB Velox they are 20mm with a 5mm cross section... Also what durometer do I need .. Is A70 ok?


Thanks
clavin is offline  
Reply With Quote
Old 05-14-2017, 06:56 PM
  #15
fw190pilot
 
Join Date: Jan 2004
Location: Mt. Vernon, IL
Posts: 485
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

McMastercar or your local auto parts store should have something.
fw190pilot is offline  
Reply With Quote
Old 05-15-2017, 08:19 AM
  #16
CRye
 
Join Date: Jun 2004
Location: Bartlett, TN
Posts: 121
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

You can also try " O ring Store " on the internet.
I had good luck ordering from them.
CRye is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 08:11 PM.