I recently installed a version 1 BVM smoothstop in an airplane. After a few uses, its leaking air even when I am filling air in the tank. What could be happening?

Could the piston be pushing to one side? Is the piston pushed all the way in when the brakes should be off? If its not then it could be the brakes that are leaking. Or try re greasing the piston with that thick parkers O ring grease. If all else fails the tiny O rings will need replacing.

J

Jason,
Doesnt seem like the piston is pushiong to one side. Piston IS INDEED pushed all the way in when brakes are OFF. Brakes are not leaking as they work perfect with another brake valve. I did regrease the o ring with an o ring lube. Im going to order the new smooth stop 2 plunger.

Ragz

You will spend half your life trying everything possible and it will work one moment and then not the next. [>:] Just throw it away and buy a Jetronics valve.

Cheers

Springbok Flyer

...or a Ultra Precision UP6 valve...!
Ciao, Mauri

hmmm interesting point of view.

I concur wholeheartedly with the Jetronics / UP6 suggestion.

I used to have a bunch of Smoothstops, just because that's what came with BVM kits. I got fed up with the fact that they would work fine for a while and then suddenly leak like crazy, requiring hours of fiddling and going back & forth thru the instructions to no avail. To me, the Smoothstop is kinda the RAM 500 of brake valves - works sometimes, not others, and figuring out why it suddenly became unhappy involves hours of frustration. Conversely, something like a UP6 is the Jetcat 120 of brake valves ... it just plain works, and works, and works, without constant fiddling.

Gordon

I have to agree with Gordon - I have a bunch of UP-6's and they just keep on working - no problems what so ever...

I will say though that we have a guy in our group that has good luck with the Smooth Stops. He says that as soon as it starts to leak, you just have to replace the O rings. He keeps a bunch on hand and just replaces them when they start to leak and it works for him. Too much fiddling for me though - go with the UP-6...

Bob

Funny!!!! I have a Ram 500 (x model) and smoothstops and they keep on going and going. Did replace the bearings on the Ram once and do lube the smoothstops as preventative maintenence though.

I've been using a mini hobby brake valve for 5 yrs. I haven't touched it since I put it in.

The problem with the Mini-Hobby (and Jetronics) is that they use air at intermediate settings. The Smooth Stop and UP-6 do not - i.e., you can put your brakes in the 1/2 on setting and if you don't have any leaks, they will stay that way forever. Not so with the valves that use "pulsing" like Mini-Hobby...

Bob

I too agree with Gordon. I had three at one time took them all out put them in a bag and gave them to a friend to use at this own risk then replace them with a micro-airvalve, since then I never had an air leak because my brake valve "ever", so simple a servo arm pushing on the buttom to open or close.

Yup- use an on off button valve and lube the wheels to taste. Scott

I've had several smoothstops also. All but one developed leaks, and I only had it for a short time. On the positive though, I was able to get every one I worked on to work just fine. The o-rings do have a finite life. If your valve was not leaking, then starts to leak, pull the cylinder and change the o-rings. Slobbing grease on old o-rings with flat spots does not help. Replace them! (or put them in a bag and send 'em to me!!) ...If you get one that has been sitting around for years, even if its new, chances are the o-rings need replacing. They're not expensive, and it takes all of 5 minutes to change them, NoBigDeal!

Other than o-rings, I had one where the spring in the valve became so compressed, the valve would not work. I'm pretty sure I caused this by storing my plane with the brakes set for a long time with air pressure on. I removed the roll pins to get to the spring, pulled on it a bit, replaced it and stopped leaving my brakes set when not needed. It still works fine after a couple years...

I also have 2 UP6's. They are good valves, but you need a pretty strong servo, preferrably metal geared, to work the valve. You also have to be mindful of your setup if you want to be able to have parking brakes. Initially, I had a more difficult time getting proportional brake action from it than the smoothstop (had to setup some servo slow), but neither stands out as better than the other to me. I think the amount of air pressure used is more critical to get really smooth stopping action than the brand of valve you use, once they're setup correctly. I've also noticed that different planes have different behaviors during braking, and each one needs tweaked a little differently.

I just bought a Jettronics, and I'm looking forward to trying it out. I've read about using a restrictor to keep the air from "dumping" during braking - anyone else have any other Jettronics setup tips? What size restrictors are you using?

Standard Robart airline restrictor - http://www.quicktechhobby.com/Airpla...ies/robart.htm - ROB189

only real problem w/jetronic valves is that they are not really proportional like the bvm valve and even w/ restr they use quite a bit more air -- but they are easy to use and eliminate some servos

I believe Jettronics now has new valves that are better in pulsing air and use MUCh less air. I am waiting for those to arrive at Todd's.

As the inventor of the Smooth Stop I probably have a bit more experience with them than most. If I am at a jet rally and any one on the field is having a problem with one, or is looking for help setting one up they almost always get directed to me.

Over the years I have found two that where defective, one I fixed, the other need to go back to BVM so that they could correct the problem and figure out how it happened. The later case was in the last couple of months and I do not know if it was sent back or not.

I have come across a couple that where plumbed backwards.

Many did not have the linkages installed correctly, and the original version was sensitive to that.

Several needed the “O� rings re-lubed

Several needed new “O� rings.

Several the leak was found down stream of the Smooth Stop.

In the end after the plumbing was corrected, the linkages where done as the instructions call out, or the “O� rings where tended to, all but the one worked correctly and did not leak.

For years BVM had a simple offer on their web site, if you have a problem with a Smooth Stop, no matter how old it is, we well fix it free of charge. A couple years ago Bob told me that not one single person had ever taken them up on that offer. So when you hear some one complaining about a Smooth Stop remember, they had rather complain about it than have it fixed free of charge.

Back in the DF only days I had a some what troublesome BVM 91R, I just could not get the mixture to dial in right. I called Bob and after a few minutes he told me to quit frustrating myself with it and send it to him, which I did. That engine can consistently push my Aggressor III 230mph. BVM wants you to be happy with your models; you just have to be willing to let them make it happen. How many of you ever bought a car that never had to go in for repair?

Nope – it’s that I'd rather use something that just works without:
[ul][*] having it fixed for $X each time (It aint free when we have to pay for shipping it back & forward each time)[*] having to fart around with it each time it chooses not to work.[*] having down-time for the airframe each time it has to go back (or have the cost of having multiple spares to use while the non-working parts go back to BVM)[*] having to deal with BVM folks saying “It works for me when I bench-test it – must be something about your installation� even though the installation has not changed one iota since the last 30 flights in which the valve worked fine.
[/ul]
Why should I choose to put up with all that, when I can have something that just works, plain & simple ?

Gordon

I whole heartedly agree!! I gave up on using SS because of above mentioned problems. I rather concentrate on having fun then constantly having to tinker not to mention haing a spare box of parts just for a brake valve..

Adil

I been using jectronic valve in non proportional mode for the brakes....the trick is to use it putting a Robart restrictor about 6 to 8 inches before reaching each tire.
This produces a smooth stop effect...

The distance to install the restrictor before the tire is critical. The remaining air line between the restrictor and the tire will work as expantion chamber were the air preasure will build up slowlly until activate the brakes O-Rins. By shortening this line...the preasure will build up faster reduding the smooth effect.

Mi 2 centavos....

Adil, did you buy the real smooth stops or the Asian ones I have over a hundred flights on the Bobcat now and its never given me any problems nor have any of my other 5 smooth stops. Maybe Im just lucky but I have nothing but good luck with them. If your not going to be using yours feel free to donate them to me.

Don

Been using the Smooth Stop since its introduction.On the original valves it took setting the servo arm to the plunger exactely per instructions.It gave us true proportional brakes on our jets.Now with the new plunger,you don't have to be as precise on the setup as the original.Also it uses very little air to operate and maintenence is very low on what your getting in return.The only thing that really wears out is the 3 o'rings which I change yearly for maintenence.If something fails in the Electronic valves,it usually means a new valve.

Dude, I don't think you have TOTAL 100 flights on ALL your planes let alone the Bobcat. It may be a good product but requires TOO much maintenance for my liking. Now your situation is a little different - your planes get too much pampering but not enough usage...

Adil

Are you sure you want to do this, You forget all the flights you put on it when your Asian airplanes where broken and you already broke or destroyed any good made in the USA planes you may have owned. I understand your reasoning for flying what you fly, there cheaper by the dozen I need brakes that work on my planes. I understand you could care less about the smooth stop becuase from what I have seen your gear most of the time wont go up and if it does come down it always collapses and your plane is stopped even before you can reach for the brake switch.[X(] And whats with your Bandit , do you want me to give you some tubing so you can hook up that front gear. Im sure the instructions say to use air line and not just gravity to make it come down. And speaking of maintenence maybe if you did some your stuff would work. Thank god you just joined a club with a grass field.