This is sort of a retro review. I’ve had this spiffy new Brey-Krause QR and rollbar mount installed in Sharka since December of 2014. It managed to not get blogged about until now for whatever reason.
Er… I know the reason. It rattled and drove me crazy for a few months, but I’ve since fixed that.
Anyways, on with the blog post. Grimlock demands it!
My little girl was getting too big to have the fire bottle attached to the seat. It didn’t really let her hop out of the car seat by herself, and it’s a bummer to have to wait for help when you’re big enough to get out by yourself. I didn’t want her to accidentally set it off while climbing in or anything, so action was called for.
I tried having the fire bottle below my knees on the driver’s side. I didn’t even back out of the garage with it in that configuration. It took way too much room away from the footbox, even just sitting in the seat without trying to drive.
Another solution was required. And I always wanted the BR QR. It’s so chunky and beefy and nice looking. The rollbar mount and QR combo was an easy choice.
The QR slides onto the fire bottle like so. It’s a VERY tight fit. You want that. But… man, it’s not easy to slide on.
The receiving plate grabs on at both sides for a very tight fit. You can’t add even a single piece of tape between the grabber and the receiving plate – the tolerance is too tight. But tight is good. Tight means no rattles.
The rollbar mount is kinda odd. It’s molded in green plastic. It’s a dark green but… GREEN? Super odd. I need to dye mine black or something.
The two parts are made by the same shop, so they’re actually designed to work together. It shows. The holes are all in the right spots and everything bolts up easily. It’s super SUPER awkward getting the rollbar mount bolted to the rollbar, but it’s basically a one time thing. It’s okay if it’s difficult.
It took a while for me to angle and rotate everything to fit nicely. With the bottle rotated like this, there’s enough room to easily release it and no rollbar braces are in the way. Full seat sliding is allowed and it doesn’t look like the bottle will be bothered by harnesses. Everything is juuuust right.
But then I drove around and heard the rattles.
Being mounted to the rollbar like this is basically the same as being bolted straight to the frame. If the car is vibrating, the vibrations get transferred straight to the fire bottle and mount. From 3200 to 3700, there was a nice buzz. I tried adding bits of friction tape here and there, but nothing solved the rattle.
Then I got serious.
Trial and error showed that the rattle was coming from either the bottle or the QR. When I removed it and let it ride in an empty passenger seat, there were not rattles. So I brought the pair inside and hit them with a vibrator.
No, not that kind of vibrator.
I make a lot of molds (window switches, gauge pods, small robots, etc) and have a sort of make-shift vibrating table rig to help remove bubbles from silicone. (I also have a vacuum chamber, but that’s getting off topic.) I grabbed a buzzer and held it to various spots on the fire bottle. I was rewarded with the same pitch of rattle I heard while driving the car.
The thing about rattles – they are usually caused by something that moves easily. And on the BK Quick Release, nothing really moves. Everything is machined to a tight tolerance and everything is bolted down. I scratched my head for quite a while puzzling over what could be rattling until my finger accidentally brushed against the spring.
The spring is… different. Unlike the rest of the unit, it feels pretty low quality. Like a clothes-pin spring. The inner spring diameter is pretty huge and lets it move all around on that perfectly machined metal shaft that holds the two halves of the QR together.
I built up the inside of the spring with a bit of electrical tape and a few plastic zip tie tips. It’s not enough to hinder movement, but it keeps the spring centered on the shaft and stops the insane rattle at 3500.
So, that’s that. My daughter has been very happy with the new extinguisher mount. Every time she climbs in the seat she points at it and says “the red bottle lives back there now!” Sometimes she says it in a happy manner and other times she says it with a bit of force. If that bottle knows what’s good for it, it won’t be moving down under her feet again.
Anything I can do to keep my girl happy with Sharka is worth the effort.