REFLECTOR: Belleville washers / Brake Vibration

jewen at comporium.net jewen at comporium.net
Sat Jun 20 08:37:15 CDT 2009


To add a bit more light on brake vibration, the majority of vibration from brakes comes from an uneven adherent layer forming on the surface of the rotor rather than the conventional thinking of a warped rotor.  See following link for a very good discussion on this effect. 

If the adherent layer on the rotor has become uneven and vibration results, it can be easily remedied without turning the rotors.  Remove the rotor(s) sand the rotor faces using 220 with a sanding block and cutting lubricant like tap magic or WD-40.  This will remove the adherent layer and you are ready to reinstall and go through your breaking procedure again.  

I have tried this on a family members car which I used to have to cut or replace the rotor every 2 to 3 months due to vibration.  Sanded the rotor and vibration went away.  Heavy braking and holding the brake tight at a stop light seemed to be causing the problem.  Much like the Nascar guy who braked heavily going into his pit box and holds the brake while being serviced, then has a vibration in the corners when he goes back onto the track (often though to be a loose lug nut.)  

http://www.stoptech.com/tech_info/wp_bedintheory.shtml

---- Original message ----
>Date: Sat, 20 Jun 2009 08:19:06 -0400
>From: "Chuck Jensen" <cjensen at dts9000.com>  
>Subject: Re: REFLECTOR: Belleville washers  
>To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>
>   Terry,
>    
>   That shimmy you feel during rollout is probably not
>   nose wheel shimmy, unless you've had a secondary
>   observer confirmation and know that to be a fact. 
>   That sounds more like the disk rotor has gotten
>   heat-warped on one, or both brakes.  If the shimmy
>   or 'throbbing' stops when you let off the brakes and
>   starts when you apply them again, then it is
>   definitely your rotor.  A machine shop can true them
>   up.  A car place that does disc brakes won't be a
>   help, because they can't chuck the rotor, so you
>   have to go to a real machine shop. 
>    
>   Depending on the rotor material, they don't machine
>   real smooth, but if they do a touch up surface
>   grinding, they come out good.  By the book, the
>   rotor thickness has to be 0.345 or greater.  Less
>   than that, the caliper pistons may push out beyond
>   the o-ring sealing range.  True up the rotors put a
>   stop to the 'throbbing' during braking.  It's
>   something you might want to check, Terry.
>   Chuck Jensen
>    -----Original Message-----
>   From: reflector-bounces at tvbf.org
>   [mailto:reflector-bounces at tvbf.org]On Behalf Of
>   Terry Miles
>   Sent: Saturday, June 20, 2009 6:51 AM
>   To: 'Velocity Aircraft Owners and Builders list'
>   Subject: Re: REFLECTOR: Belleville washers
>
>     John,
>
>     Thanks so much for volunteering that.  I recall
>     that they went in originally smooth, primed and
>     un-lubed.  The problem I have is adjusting the big
>     nyloc to setting that is neither too loose nor too
>     tight.  A bit of grease seems to increase the
>     torque range tolerance.   The prime coat of paint
>     is long since rubbed off and I thought the rust
>     was part of my culprit. 
>
>      
>
>     If I were to say, it is steering problems I have
>     and not so much shimmy problems.  I have an XLRG. 
>     The only shimmy I see in when on the brakes in the
>     latter half of the roll out, and then only when
>     there is more wgt on the nose wheel from having
>     someone in the right seat.  I am tempted now to
>     take my 1/7/8 (or whatever size it is) end wrench
>     over to the local welding shop and have then make
>     a 1/2 fitting on it to fit my torque wrench.  The
>     fish-scale-as-tq-wrench method is not working for
>     me...and the end of wrench is so fat I can only
>     get a few degrees of bolt rotation at a time
>     before it hit the forks. 
>
>      
>
>     So people know, there are several different nose
>     leg assemblies in the field with differing washer
>     count.  Were I to add a nylon washer and not
>     remove any steel washers, it would have to be in
>     the thinner side.  As it is, I barely have 3
>     threads showing. 
>
>     Terry
>
>      
>
>     From: reflector-bounces at tvbf.org
>     [mailto:reflector-bounces at tvbf.org] On Behalf Of
>     John Youngblood
>     Sent: Friday, June 19, 2009 18:18
>     To: Velocity Aircraft Owners and Builders list
>     Subject: Re: REFLECTOR: Belleville washers
>
>      
>
>     Terry,  The idea of Belleville washers is to
>     develop turning friction to subdue shimmy.  You
>     may want to wipe off the grease in order for the
>     washers to transfer torque.
>
>      
>
>     John
>
>     On Jun 19, 2009, at 2:04 PM, Terry Miles wrote:
>
>      
>
>     Jeff
>
>     Whatever you got.  1/16th or so?  This is out of
>     sequence some, but I have been removing, polishing
>     off corosion, regreasing (just stock marine
>     grease) and adjusting the tq to my bellvues on
>     about a quarterly basis.  If you have a better
>     mousetrap I'd be interested that's all.   
>
>     Terry
>
>      
>
>     From: reflector-bounces at tvbf.org
>     [mailto:reflector-bounces at tvbf.org] On Behalf Of
>     Jeff Howell
>     Sent: Thursday, June 18, 2009 10:24
>     To: reflector at tvbf.org
>     Subject: Re: REFLECTOR: Belleville washers
>
>      
>
>     I may still have a few made I will have to check.
>     I made them in different thicknesses. what
>     thickness are you looking for? Jeff
>      
>
>   ----------------------------------------------------
>
>     From: terrence_miles at hotmail.com
>     To: reflector at tvbf.org
>     Date: Wed, 17 Jun 2009 19:31:12 -0500
>     Subject: Re: REFLECTOR: Belleville washers
>
>     Jeff,
>
>     Could I talk you into making a set for me?  I'd
>     gladly trade for free banjo lessons or $5 or
>     whatever plus shipping.
>
>     Terry Miles
>
>     From: reflector-bounces at tvbf.org
>     [mailto:reflector-bounces at tvbf.org] On Behalf Of
>     Jeff Howell
>     Sent: Wednesday, June 17, 2009 17:29
>     To: reflector at tvbf.org
>     Subject: Re: REFLECTOR: Belleville washers
>
>      
>
>     I ordered some 2 1/2" round stock on line and
>     opened up a hole to the right dia. using a lathe.
>     It works great.
>      
>
>   ----------------------------------------------------
>
>     Date: Tue, 16 Jun 2009 14:19:50 -0700
>     From: ajlz72756 at yahoo.com
>     To: reflector at tvbf.org
>     Subject: Re: REFLECTOR: Belleville washers
>
>     Where did you get the nylon sheet stock that you
>     made the washers from and how many did you use?
>
>      
>
>     Andy Ellzey
>
>      
>
>   ----------------------------------------------------
>
>     From: Jeff Howell <jeffreyhowell at hotmail.com>
>     To: reflector at tvbf.org
>     Sent: Tuesday, June 16, 2009 2:07:49 PM
>     Subject: Re: REFLECTOR: Belleville washers
>     I found that a combo of a home made nylon washer
>     and a nose wheel lock makes a great addation to
>     any velocity. no nose wheel shimmy and
>     awsome steering (taxi) on the ground...Jeff
>      
>
>   ----------------------------------------------------
>
>     From: johnt at comp-sol.com
>     To: reflector at tvbf.org
>     Date: Tue, 16 Jun 2009 12:25:25 -0500
>     Subject: REFLECTOR: Belleville washers
>
>     I have the 'thin' belleville washers (with spacer)
>     - and plan on purchasing a new washer kit from the
>     factory, but I thought someone had successfully
>     been using SS washers - and had suggested McMaster
>     as a source...?
>
>      
>
>     John
>
>      
>
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