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  #1  
Old 01-11-2012, 07:58 AM
jmitchell jmitchell is offline
 
Join Date: Oct 2006
Location: Phoenix, AZ
Posts: 132
Default Grove Gear lower brake line tip.

If you are installing RV-8 Grove landing gear legs (which have internally drilled brake lines) and are pondering your options for connecting the fitting at the bottom of the leg to the brake caliper you may consider this simple solution:

I was going to bend hard aluminum lines to connect these two points as the plans suggest but decided (as many others have) to use flexible lines instead.

For reference I checked to see how VA-102 (a braided fuel pressure sensing hose included in the firewall forward kit) would work and to my surprise the length was perfect.

So, I decided I’ll go with that instead of having custom lines fabricated or buying the special tools needed to make my own.

I Ordered Van's VA-102 hoses ($15.50) and a 45° AN823-4D fitting at the caliper with a 90° AN822-4D at the bottom of each gear leg to make the hose curve comfortably and applied LocTite 567 to the threads (not the flares).

Hope this may be useful to others.










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Last edited by jmitchell : 01-11-2012 at 08:50 AM.
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  #2  
Old 01-11-2012, 08:05 AM
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islandmonkey islandmonkey is offline
 
Join Date: May 2009
Location: Zurich, Switzerland
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Default

I would take care that the flexible hose has no chance on rubbing on the tyre. (tire for my US cousins).
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Last edited by islandmonkey : 01-11-2012 at 04:54 PM.
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  #3  
Old 01-11-2012, 08:38 AM
jmitchell jmitchell is offline
 
Join Date: Oct 2006
Location: Phoenix, AZ
Posts: 132
Default Agreed.

Good point, I should have included the fact I am planning on securing the hose to the wheel pant bracket with an Adel clamp before final assembly to make sure it can't contact the tire.

Cheers.
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Last edited by jmitchell : 01-11-2012 at 08:51 AM.
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  #4  
Old 01-11-2012, 04:50 PM
larryj larryj is offline
 
Join Date: Dec 2005
Location: Bellevue, WA
Posts: 168
Default aluminum tubing at brake caliper

I am wary of using flex line at the brake caliper. The brakes create heat; and if they generate too much heat it will melt the flex line. Loss of brakes. Best practice I have seen is to maintain soft aluminum tubing at the brake caliper. Some may never see this failure mode; but I have seen it.
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  #5  
Old 01-11-2012, 07:09 PM
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Rick6a Rick6a is offline
 
Join Date: Jan 2005
Location: Lake St. Louis, MO.
Posts: 2,346
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Quote:
Originally Posted by larryj View Post
I am wary of using flex line at the brake caliper....Best practice I have seen is to maintain soft aluminum tubing at the brake caliper....
So you are saying best practice is to use soft aluminum tubing instead of flex line? How does that rationale square with Cessna's decision to use braided flex line on a certified C150 as installed on my 1966 model shown below? With 4700TT, it was years of trouble free service that convinced me flex line was a desired upgrade for my -8. Of course, when I did replace the worn braided brake hoses on my 150 prior to selling it, I was required to use approved materials and that did not include soft aluminum tubing. Unlike certified aircraft, we are free to install what we choose. In my case, I kinda doubt the decision to go with flex line will ever become an issue worth revisiting.

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  #6  
Old 01-11-2012, 08:06 PM
John Ciolino John Ciolino is offline
 
Join Date: Jan 2006
Posts: 54
Default Grove gear lower brake line

I used the same setup you described. I found that when it comes time to change the brake pads, a 45* or straight fitting in the caliper will not allow you to remove the old pads without opening the brake line. The fitting/ hose hits the rear leg of the wheel pants bracket so you cannot remove the plate that the pads mount to.

You need a 90* fitting at that location and a longer hose to slide under the mounting bracket arm. I bought my lines at Bonaco and gave then dimensions and pics. The hose length fits well and does not rub on the pants or tire. (I forget the length, but I'll bet Bonaco can tell you.

John Ciolino
RV-8
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  #7  
Old 01-12-2012, 12:33 PM
larryj larryj is offline
 
Join Date: Dec 2005
Location: Bellevue, WA
Posts: 168
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"So you are saying best practice is to use soft aluminum tubing instead of flex line?"
In a word Rick, Yes. Like I said, you may never see or experience a failure using flex line to a caliper; you and everyone you know may not use the brakes hard enough to cause a failure. And OK, some certified aircraft use it; my Super Decathlon included. But I have seen this failure mode and I have determined that for me the best decision is not to use flex line in this location; especially given no appreciable increase in work or weight or any other factor I can think of. And in this application using gun-drilled gear legs, it seems to me to be a very clean set-up to use soft aluminum tubing. Then, these are experimental and we do get to make our own choices.
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