I rember a post a while back about vibration dampers from Fischer Eng. I was hoping some people have tried one so that I might hear the results of putting one of those on as I'm currently debating purchasing one. I'm also wondering if these are for any engine size.
I called the Fischer on Sun ./ to do a little research but I couldn't seem to get hold of Tim, the person that knows most about the products. I'm on the fence for getting one of these as I've heard so many good things about a harmonic balancers on engines one of them is that they help the flywheel hold on and harmonic balancers quite the engine down.
Any thoughts? Anybody have first hand experiance with one?
Years ago when I worked at a VW shop, some guy used to come in and tell everyone that the Fischer vibration damper was the greatest thing ever. He had one on his 1776cc engine and he said it ran much smoother.
I think he may have been trying to sell them for Fischer, though.
That's quit a statment Jim. I'll go over there on Tues. to go talk to Tim and perhaps purchase one of those. I'm just wondering if these dampers are one size fit's all in terms of engine size. My instincts say that it if the length of the crankshaft always stays the same it may not matter how much displacement the crank it pushing. Maybe it's like a guitar string in that it's the legnth of the string that determines the note not how hard you pluck the string.
j-p wrote:That's quit a statment Jim. I'll go over there on Tues. to go talk to Tim and perhaps purchase one of those. I'm just wondering if these dampers are one size fit's all in terms of engine size. My instincts say that it if the length of the crankshaft always stays the same it may not matter how much displacement the crank it pushing. Maybe it's like a guitar string in that it's the legnth of the string that determines the note not how hard you pluck the string.
J-P
Your right about a vibrating guitar string, but when you put your finger on that string it stops vibrating. Thats what a damper does, stop the vibrating.
I don't believe the Berg unit is a damper of any sort, just a heavy pulley that reduces crank flex and adds more inerta weight to the motor.
When you installed the Fischer damper did your car run any smoother? Did the engine seem to mellow out on the vibrations? Are there any immediate noticable differances when running a damper vs not?
j-p wrote:I don't believe the Berg unit is a damper of any sort, just a heavy pulley that reduces crank flex and adds more inerta weight to the motor.
When you installed the Fischer damper did your car run any smoother? Did the engine seem to mellow out on the vibrations? Are there any immediate noticable differances when running a damper vs not?
J-P
You're correct about the Berg pulley, it's just a pulley. Opposed engines have natural harmonic balance so they run real smooth already. However, every time that crank fires there is one giant vibration put into it. Also there is twisting and bending happening. With the damper absorbing some of this action you can imagine the benefits of it. I've had engines with thousands of passes on them down the ole 1/4 mile and the bearings were perfect when I torn down the engine. Also by eliminating vibration it helps the valve train from getting foreign vibs and makes it better for them.
Yup, this damper thing is starting to make sense to me. I've got one last question that might be a little difficult to answer. In many descriptions of dampers out there on the internet many of them talk about the natural frequency of the cranshaft. I'm guessing that the crank has a real bad vibration to it when it's run at a certain rpm kinda like a wheel out of balance. I'm wondering what this rpm is, at what moment does the crank align all the vibrations togather and harmonize them?
I've also read that fluid dampers work throughout the rpm range not like the elastomer type thus making this point of "harmonic vibration" less of an issue when using the fluid type.
j-p wrote:Yup, this damper thing is starting to make sense to me. I've got one last question that might be a little difficult to answer. In many descriptions of dampers out there on the internet many of them talk about the natural frequency of the cranshaft. I'm guessing that the crank has a real bad vibration to it when it's run at a certain rpm kinda like a wheel out of balance. I'm wondering what this rpm is, at what moment does the crank align all the vibrations togather and harmonize them?
I've also read that fluid dampers work throughout the rpm range not like the elastomer type thus making this point of "harmonic vibration" less of an issue when using the fluid type.
J-P
All kinds of situations enter when a harmonic vib will happen in a engine. Bob weight, when torque is at max, etc. So you can see that different engines will have different rpm ranges of harmonic vibs. The Fisher design damper is a "dry friction" damper and has a wide rpm range of dampening like the fluid ones.
For us non-quarter mile-ers, does this damper actually smooth the engine out at highway speeds or how about for normal driving? I guess this is what I'm really interested in along with the long bearing life. I know for me that ther'es a nice sweet spot in the rpm range that everything works well togather along with little vibrations.
As for those Berg pulleys, I really don't understand why people use those things. Seems like alot of weight put on a spot where it wasn't designed for it.
