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Brake Return Spring System McMaster Carr

Tcheairs

Well Known Member
Does anyone know of a part number for a brake pedal return system from any manufacturer for an RV7A. I had heard that someone out there was marketing one. McMaster Carr? Looked through their online catalogue but can't find anything. Also, links to this topic on this forum would be appreciated. did the search but can't find anything. Thanks
 
I copied the below parts from McMaster Carr.
 

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Better Hardware Stores

I went to the local independent hardware store, checked their spring drawers and found a couple that work great on my Matco master cylinders. Ace Hardware has good selection, too. I don’t think the actual spring rate is critical, the spring just needs to provide a little extra push in the return direction.
 
On a 7A I've been helping with, the original builders fully tightened the brake pedal pivot bolts. So of course the brakes didn't want to fully return due to all that friction. Duh! Not saying this is your issue, but it is something I've seen!
 
Stainless rod

On a 7A I've been helping with, the original builders fully tightened the brake pedal pivot bolts. So of course the brakes didn't want to fully return due to all that friction. Duh! Not saying this is your issue, but it is something I've seen!

Some of us have install stainless steel rods as a pivot. I still have 5 airplanes worth of raw material.
 

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Looks nice..i'm not much on drilling small SS rods . Think cad plated bolt and nylon lock nut will do me..Thanks for the idea though
 
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Also, think I will go out and attach one of those short rubber bungee cords to the top of the pedal, slip my toe under it and taxi around and see what happens. That should eliminate/confirm the pedal return question. Maybe I'll just fly around with it like that until I quit..(I'm 77)
 
This is what I got from one the posts few years ago and used on mine. Works great.

—Brake Springs (master cylinder )
McMaster-Carr part numbers below for the brake springs
Spring 9657K435
Lower nylon sleeve bearing: 6294K441
washers (for seating the lower nylon sleeve bearing) 90295A470
Top nylon sleeve bearing: 6389K625
Set screw shaft collar: 9946K13
 
Thanks very much for all the helpful posts..I need to diagnose the issue starting with the pedal return..hopefully that's it..
 
Thanks very much for all the helpful posts..I need to diagnose the issue starting with the pedal return..hopefully that's it..

First thing I would check is the cylinder attachment and make sure the cylinder attach points are aligned (no side load on the cylinder rod) and have some play. I had a hot brake due to brake dragging at petit jean last year and I had recently rebuilt the cylinder due to a leak, when reinstalling I had tightened the retaining bolts too much and the cylinder was not fully extending to release the brake pressure. Walt told me to loosen the bolts and no issues since.
I do plan to put the spring mod on during the next condition inspection.
Figs
 
Thanks Figs...I'm planning to check all of the attachments down there (provided I can get my old carcas upside down in the footwell) and loosen and perhaps improve the pedal pivot with a long bolt.
 
Stronger Spring Brake Master Cylinder Return Attachment

Read somewhere in the forum that some have used a stronger spring for the brake master cylinder spring kit (parts from McMaster Carr). The suggested spring is # 9657K435 with a max return pressure of 30lbs. Can someone lead me to the thread what suggests a stronger spring..Thanks
 
Those are the original parts for this assembly, but I had read somewhere in the forum that some are using a spring with a higher tensile strength than 30# which is the rating of the K435 spring..
 
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