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Discussion in 'Airheads' started by Sabre170, Feb 18, 2013.
What alloy are the aluminum pushrods Dirk?
The pushrods are in the shop now.
395 Euros a set.
I'll have to save up for them
395 euros! I just looked and didn't see any pictures or info?
I am going to call up my supplier of 4130 rods and see if I can get them just a bit thinner walled. If you or anyone else is interested, the cost is way, way less than 395 Euros. I am going to be ordering some soon.
They are in the shop, not on the site itself. You have to go to the webshop
Thanks pj. My German is pretty rough but I didn't see any alloy numbers. I need to know what specific alloy they are made out of before I would buy any but they are too rich for my blood anyway. For that kind of money I would rather fry bigger fish.
you could have a machinist make a one off set for 400 euros. That's about $520. Start looking up tapered aluminum tube. He did say they were tubular right? Or just get a thick walled tube and taper down the OD toward the ends. I'd look at something like 7075-T6. I'd go as wide of an OD as absolutely possible in the center of the rod and taper down at the ends. That's how to make it as stiff as possible. You could pull the ends out of existing pushrods for the sake of simplicity or go to the trouble of making your own shorter tips if you're bent on minimizing weight.
My guy makes tapered rods for WAY less than that. I think about $35 US each. I would think aluminum rods would have to be solid to be rigid enough? My guy will not make them out of aluminum for anybody period. He says they can't be made to not flex but, like I said, I think he is talking about way more spring pressure than I run. I run stock springs. Another thing I like about 336's! Dirk said up above that the stock tips break with more rigid rods. That does not surprise me since I would suspect so. Stock tips are out. Warning: Lots of places over here do not have the proper metric tip and fudge on a real close American sized tip including a US Pushrod manufacturer with a lot of airhead history. That might be PART of the story of why I have seen those particular pushrods bore through the top of a lifter within a 100 miles.
So, I wanted to follow up with what I ended up doing. After all of your suggestions, which I greatly appreciate, I did like the looks of the EMGO shorty's, and to top it all off, they are dirt cheap. I got them off Dennis Kirk for under $30 each. For that price, I took the gamble. I figured that worse case, I'd be out $60.
I wasn't disappointed. Obviously, being a slip on, super easy to install. The hardest part was removing the old pipes. The short low profile gave it the clean look I wanted, and the sound was great. It has a much more "throaty" sound to it. It sounds fantastic.
These mufflers come with baffles that can be removed by taking out one bolt. As of now, I still have the baffles left in. I may take them out someday just to see how it sounds, however, even with them in, the bike is pretty damn loud.....I think I may be pissing some neighbors off
Anyways, I took before and after videos and posted on YouTube. So many people post after videos of their exhaust, but no before videos. This never let's viewers see/hear the difference. I shot both of these videos with the same camera (iPhone 4S), in the same location and only a few minutes apart.
What is this, a comment related to the original post? Oh well, since it is your thread do with it what you will.
On a side note those shorties sound great!
Yeah, it was a reply to my first posted question. I figured I'd post that so that if there was anyone in a similar boat as I, my "solution" could be viewed.
I'm gonna openly presume that a lot of work went into those pushrods. I would not expect Dirk to give anyone the info for their guy down the road to make some up.
Then again, Dirk's generous nature so far might prove that he'll share. But I'd trust a 395 euro investment at 10,000 rpm over some guy's best guess.
I recently shopped all over for pushrods. Here in America at least, all the manufacturers tell you what specific alloy they are made out of. Reminds me of American cam manufacturers giving specs with a lift check point. Anyway, my "some guy" is a major performance pushrod manufacturer. That company and another American company have recently 'reinvented' the pushrod all for one of them coming up with a way to film them in action. Much to everyone's surprise, they were flexing like a mofo. Since that discovery not that long ago, the big money pushrod tuners (NASCAR and NHRA) have doubled and tripled pushrod mass for rigidity and more power.
The way I see it, the notion of a "ROD" is barking up the wrong tree. A tube of wider diameter is a better use of the same amount of material and would create much stiffer push rod that would flex less. A solid rod in compression is just an inefficient use of material. If reducing flex and minimizing weight are two important goals, then a wider OD tube seems like an obvious choice to me. It may be necessary to make wider pushrod tubes to meet this objective, but that wouldn't be too tough.
I don't know about aluminum rods but every steel rod that I have ever seen is a tube. They still call them pushrods instead of pushtubes.
I have run these chromeoly pushrods before. They are under $100 for 2 bikes worth https://www.wolfgangint.com/store/product/3-8-chromoly-push-rods-uncut-1109302/
but at the end of the day unless your turning 7500 plus RPM's stock works fine.
They work just fine at rpm's higher than that in my experience but they flex a lot even at low rpm's as evidenced by the scrap marks they almost always have from getting into the pushrod tubes. If you want rods that don't flex for more power, steel alone isn't the ticket. Steel pushrods of just a few years back turned out to flex a lot. Nowadays the big money pushrod boys are running MUCH heavier steel rods for more rigidity and power. Two to three times heavier than steel rods of just a few years back.
Back in the 90's when I was building campaigning three R75/5's the biggest problem was breaking rockers and rarely a push rod problem.
I have taken aluminum pushrods out of a lot of airheads. Almost every one of them had rub marks where they flex and get into the ends of the pushrod tubes at the top of the cylinders and the bottom of the heads. IF you are looking for all the power you can get out of your setup, that much pushrod flex is a problem since it slows the valve opening and perhaps even reduces valve lift. Just about any pushrod flex is a problem as far as peak performance is concerned and even if pushrods are not flexing enough to get into the tubes that doesn't mean they aren't flexing. At least that is a lot of the buzz lately in performance pushrod engines.
f you are talking about a worn shinny ring around the push rod right about where the edge of the oil return tube is pressed into the cylinder? I think it is created by poor rocker arm alignment. How would you have a prefect ring if it was flexing?
I have seen the same polished rings around the pushrods. I've taken the rocker covers off and turned the engine by hand and the push rods have plenty of clearance to the tubes, but after they've been run, there are polished marks round them. From this I deduce that the pushrods are flexing and touching the sides of their tubes. I don't see how they can get polished like that without flexing.