Brake Reservoir Firewall Penetration

[Loman]

Apart from the paltry instructions and the poor quality of the reservoir itself, I am not happy with what I take to be the 'standard' method of connecting this thing to the brake feed lines.

It seems (though I can't find where it specifically says) that you are supposed to work out where the outlet bung needs to go through the firewall, drill a hole of some appropriate size and just poke it through. Could this be correct?

It seems in marked contrast to the care taken with other firewall penetrations, where we use expensive shields, eyeballs or specially designed bulkhead fittings, in addition to firewall sealant and lots of doublers.

I imagine the least that would be acceptable is to use firewall sealant around the reservoir outlet at the hole in the firewall. But, if this is acceptable in the vicinity of the 'little bomb' why is it not acceptable for all the other penetrations?

I understand that the mechanical loads are supposed to be taken by the reservoir mounting lugs, which are bolted directly to a strong point, but the strength of the mounting lugs themselves has been found sorely wanting in the past.

I found one builder (Roee Kalinsky take a bow) who felt it was unacceptable. He adapted an ACS reservoir with a proper mounting bracket, a T to split the feed on the engine side and two proper bulkhead fittings doing double duty as fixtures for the mounting bracket and separate fireproof bulkhead penetrations for each brake. That eliminates all of the problems with the reservoir (poor quality mount, interference with forward leaning firewall, poor female pipe threads, amateurish firewall penetration and a leaky nylon T piece. However all of that would take me a week, plus lead time on the parts.

Are there any other approaches that people would recommend or have actually implemented?

[6 Gun]

Over 8K of them flying and have not seen any problems.You could build light weight S.S. cover and incluled a S.S. hose clamp for support.

[Rupester]

... I too thought that was kinduv a "chintzy" arrangement - but I installed it that way and used the firewall sealant approach. it's working fine. hard to argue with the near-8000 of 'em flying.

[roee]

Originally Posted by Loman

...

I found one builder (Roee Kalinsky take a bow) who felt it was unacceptable. He adapted an ACS reservoir with a proper mounting bracket, a T to split the feed on the engine side and two proper bulkhead fittings doing double duty as fixtures for the mounting bracket and separate fireproof bulkhead penetrations for each brake. That eliminates all of the problems with the reservoir (poor quality mount, interference with forward leaning firewall, poor female pipe threads, amateurish firewall penetration and a leaky nylon T piece. However all of that would take me a week, plus lead time on the parts.

...

Loman,

Thanks for the compliment!

Two minor correction to your comments:

1) The reservoir I used was from Grove, not ACS.

2) Just to clarify, the bulkhead fittings aren't the sole fixtures for the mounting bracket. The bracket is also riveted at the top to the firewall through the stiffener angle that runs horizontally across the back of the firewall. So the bracket is mounted to rigid structure, not just held to the thin sheet of the firewall by the bulkhead fittings.

Anyhow, it was all actually very easy to build. The only custom fabrication is the one angle bracket and one piece of tubing. You could easily do it in a couple of hours (lead time on parts aside). The hard part was coming up with the design. If you're happy with it, you're more than welcome to copy it. All the parts are listed at the bottom of the page.

Cheers,

-Roee

Originally Posted by 6 Gun

Over 8K of them flying and have not seen any problems.

On the contrary, I have heard numerous reports of the brackets fracturing over time on Van's stock reservoir. Which should be no surprise if you look at how it's designed.

And as to fire safety, admittedly I haven't heard of any reports where the brake reservoir penetration was specifically implicated in allowing fire and/or smoke to enter the cabin. Though partly I attribute that to the fact that engine fires are, thankfully, very rare. But also to the fact that many of the other firewall penetrations for push-pull cables, electrical wiring, etc., leave much to be desired if Van's standard methods are followed. With all that, the brake reservoir might not be the weakest link in a fire on a stock RV. Now, many of us have invested in better methods for fire-proofing our various firewall penetrations, the brake reservoir being just one of them. Consider that the integrity of the firewall is only as good as its weakest link. And so, if we're serious about the firewall's ability to do it's job as a firewall, then each and every penetration through it needs to be scrutinized.

[DanH]

Can't speak specifics about the -9, but with an -8 it is very easy to relocate the reservoir to the corner of the front baggage compartment....no firewall penetration.

[roee]

Originally Posted by DanH

Can't speak specifics about the -9, but with an -8 it is very easy to relocate the reservoir to the corner of the front baggage compartment....no firewall penetration.

With the -7/9, putting the reservoir on the cabin side of the firewall wouldn't be as practical, though I did consider it. The two main problems I saw with it were that there wouldn't be convenient access for servicing, and that there would be greater chance of brake fluid spillage in the cockpit.

With the -8, with its front baggage compartment, it sounds like a great solution.

The best firewall penetration is no firewall penetration. Can't argue with that!

[WingsOnWheels]

I changed my reservoir out to this version. Not because I had a problem with the Vans model, but I am using DOT4 fluid and this reservoir has a diaphram to prevent moisture getting in the system. Fits great in the stock location with good clearance to the engine mount.

[Loman]

Colin,

That's beautiful! Where did you source it?

[Ironflight]

Originally Posted by roee

The best firewall penetration is no firewall penetration. Can't argue with that!

Agree - All of our RV's have master-cylinder-mounted individual brake reservoirs. This allows half the brake line plumbing, no firewall penetrations, easy bleeding (from the slave cylinders, with pressure), and almost no maintenance. Individual reservoirs have been used for decades on certified airplanes, and they are awfully simple.

[WingsOnWheels]

Originally Posted by Loman

Colin,

That's beautiful! Where did you source it?

Or at least hot-rod quality:

http://www.scottshotrods.com/RemoteReservoir.asp

Machined from a single chunck of aluminum, so no welds to break. Only downside is that the mounting holes are 1/4" coarse thread, It rather they were 3/16.

I removed some material on the back (where you can't see it) to cut the weight a bit. If I had a lathe or end mill I could do quite a bit more.