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brake return springs

Jake14

Well Known Member
Has anyone added brake return springs to the stock master cylinders of the 14? I've had a dragging brake occasionally and had trouble replacing brake fluid from the calipers up. When I put a bungee cord on the top of the pedals to pull them back, the fluid flowed much better.

This seems to be a fairly standard mod on other RV's. Just wondering which springs and retainers to use...

Also wondering which is the best hi-temp lube to use on the brake pad guides

Thanks for any suggestions
 
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Just beware of shaft wear issues. I started out with additional return springs for many hundreds of hours (or a thousand hrs?). I removed them long ago. I think the best improvement is a single bolt through both sides of the pedal.
 
Just beware of shaft wear issues. I started out with additional return springs for many hundreds of hours (or a thousand hrs?). I removed them long ago. I think the best improvement is a single bolt through both sides of the pedal.

A 1/2" nylon spacer on before the spring will eliminate this issue.
 
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The spring mod works great on the -14.
 

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Brake springs

We’ve been just replacing them with Grove Master cylinders. Cures all the Matco dragging issues
 
If the alignment or shift of the alignment during brake application causes misalignment, the shaft will hang up or wear. If the alignment is proper, springs are not needed.
DAR Gary
 
Matco Cylinder external Brake Springs

I had found in my early flight testing the tendency for the brakes to drag on taxi and rollout. Perhaps me or weak internal springs in the Matco Cylinders , the addition of some external springs (just Hardware store stuff) solved all my issues

Cheers

Peter
Rv 6
 
Springs on Matco

George at Matco says not to do that...the set screw scores the shaft and it wrecks the seal at overhaul. So when you overhaul plan to replace the shaft.
 
George at Matco says not to do that...the set screw scores the shaft and it wrecks the seal at overhaul. So when you overhaul plan to replace the shaft.

This is really not a problem. The set screw is at the end of the shaft. If there is a score on the shaft, it can be removed with a fine file. You can also wrap a piece of scotch tape over that area and the seal will slide right over it after it is filed.

Don't use a metal washer on top of the spring, it will score the shaft.... use nylon bushing with flange. Don't use the set screw. Just add enough washers with the collar to set the tension on the spring.... just enough to keep the shaft extended. The rudder pedal bolt will hold it in place.

Internal springs can be damaged by using the full travel to pump fluid through the system. In normal use, the travel less than 10mm.
 
George at Matco says not to do that...the set screw scores the shaft and it wrecks the seal at overhaul. So when you overhaul plan to replace the shaft.

Methinks that George didn't understand the location of the setscrew in relationship to the shaft, the collar, the springs. There's a pic of the installation in post #5; it won't cause any problems.

FWIW, the dragging *May* be caused by an improperly vented brake fluid reservoir...Pressure of the fluid increases with heat and expands closing the relief check valve in the master cylinder. Good venting of the reservoir solves this problem. See https://static.veracart.com/matco/item_pdfs/3995/document1.pdf

Scott alluded to this also, see attached from the -14 plans. Don't use AN3-6, AN3-7 bolts to connect the brake pedal to the rudder bars -- DO buy an AN3-122 (or 124), or use a piece of all-thread, or piece of 3/16 rod with threads on each end to operate as an axle. This will keep the brake pedal and its connection to the master cylinder parallel and eliminate the odd flexing and binding of the master cylinder and its attachment geometry.
 

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George didn't understand the location of the setscrew in relationship to the shaft

No problem until your plane is a decade or two old and you have to pull it through b/c you want to put new orings on your master cyl. Someone said you could possibly smooth or otherwise protect the new rings from that scar....that may be true
 

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No problem until your plane is a decade or two old and you have to pull it through b/c you want to put new orings on your master cyl. Someone said you could possibly smooth or otherwise protect the new rings from that scar....that may be true

I love pictures.

If there's a burr on the shaft from the collar/set screw, dressing it out with a fine file &/or emery cloth should allow the end-gland to pass over the shaft.
 

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