156 replies to this topic

[Mark Onofri]

Jay, that's what Tony P. said and, I posted it (credited to TP) in this thread earlier.
So,if you and Tony P. Both say it's to keep the body from being pushed on the chassis then ,that's what it does.
Who cares about harmonics or vibration ? Unless it's a turntable.

[Phil Smith]

I think my ex wife was covered with anti vibration tape.

[Bill from NH]

Who cares about harmonics or vibration ? Unless it's a turntable.

 

 

Mark, you never played a harmonica?

[Mark Onofri]

Juice Harp with the momas and the papas

[Bill from NH]

I had a friend who in his early years was a hobo traveling the East coast on railroads. He learned to play while on the road & still carried one in his 60s & 70s, He could play well. You might like his recipe for Mulligan stew.

[Mark Onofri]

Mmmmmmm Stew

[Mark Onofri]

I just finished changing a motor in my Mossetti. As always I couldn't find the rubber. But, I did find some Slick 7 tape. I let it run at ~=3vdc on a Corian block . Although the vibration wasn't violent, it was audible. This is where the Slick 7 tape comes in.
I applied it to the centre section first. It seemed to be the origin of the sound. I sensed a audible difference. Next was the pans. Even though it's not as efficient as rubber, it was nominally effective.
By applying pressure to various points it seemed like a majority of the sound was from the motor area. The motor is a CR102 stage 2. with a 15T angled pinion.
Comments?

[swodem]

Nothing can dampen vibration unless it itself moves. Trust me, I know.

Have a look at the anti-vibration devices used on recurve and compound bows. They dampen the vibration by moving themselves.

You cannot apply a thin piece of tape to something and expect it to magically remove vibration.

[Mr. M]

One of the tricks in the '80s was to use electrical tape on the stops for the lifters, plumber, bite bar. It smoothed out the car a lot and it was faster. Is it vibration or changing the resonance a bit?

[John Luongo]

I just finished changing a motor in my Mossetti. As always I couldn't find the rubber. But, I did find some Slick 7 tape. I let it run at ~=3vdc on a Corian block . Although the vibration wasn't violent, it was audible. This is where the Slick 7 tape comes in.
I applied it to the centre section first. It seemed to be the origin of the sound. I sensed a audible difference. Next was the pans. Even though it's not as efficient as rubber, it was nominally effective.
By applying pressure to various points it seemed like a majority of the sound was from the motor area. The motor is a CR102 stage 2. with a 15T angled pinion.
Comments?

 

Harmonics can be hard to track down but it sounds like you've done a good job of it thus far, mark. my only wag would be from the gears. you have a very strong and powerful motor there. mesh, concentricity, or tooth condition could be the source. try a drop of 20-30w oil on the gears and see if it goes away. reg oil may be too light to show a change in pitch. i will occasionally need to use a very small dab of water mix valve grinding compound on the drive side of the gear teeth for a better fit and smooth things out. be sure to keep slight pressure on the drive side while lapping the teeth. when done, its important to remove all traces of lapping compound from your gears. best of luck

[swodem]

One of the tricks in the '80s was to use electrical tape on the stops for the lifters, plumber, bite bar. It smoothed out the car a lot and it was faster. Is it vibration or changing the resonance a bit?

No, that just sounds like tightening up the movement and eliminating rattle.

[Mark Onofri]

Swodem,

I thought we had agreed on harmonics opposed to vibration. It (rubber tape) is obviously doing something? Now to identify and quantify it.

[swodem]

I would be seeking the source of the noise and fixing the problem rather than something to muffle or deaden it

[Mark Onofri]

Maybe we are overlooking the modulus of elasticity of rubber, i.e., movement?

[swodem]

No, movement is what dampens vibration.

Because the vibration makes it move, but out of sync with the harmonic (because it’s a reaction) and they cancel each other out.

[Mr. M]

We change vibrations all the time where I work on test fixtures going through vibration testing by acceleration analysis leading to fixture changes to address resonances in the holding fixture design. There is no anti-motion in opposition applied. All resonance damping where the vibration changes.

[John Luongo]

Great experiences and tech information in these responses. After making the D and E Main, my best experiences come from extensive time corner marshalling. I can say that the fastest cars running by my corner are the absolute quietest. You can barely hear a whisper as they pass.

[Mark Onofri]

I think we're getting somewhere!

[Mark Onofri]

I was going to try silicone instead of rubber tonight but, the weather has created a lot of work for me.

[Bill from NH]

You got that white stuff?

[Pablo]

I would be seeking the source of the noise and fixing the problem rather than something to muffle or deaden it

If you put a $15 disposable sealed race motor in a flexi chassis, hold it in your hands by the center section and feed it about 5 volts, the pans are going to vibrate like Mexican Jumping Beans. No matter how well the gears mesh.

 

I look for where the most movement is occurring (usually the rear of the pans) and that's where I put my orange Bartos Tape.

It's not a motor problem and it's not a gear problem. It's the nature of the beast. That's why we sometimes refer to them as "rattle pans" 

[swodem]

And Pablo once the tapes applied is there a noticeable difference (other than the weight of it subduing the movement)


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[Phil Smith]

But you're not factoring in the aero of the body pushing down on the pans.

 

Didn't Tony P come up with this and didn't he eventually admit that he just used it to keep the body from collapsing between the pin tubes?

[Pablo]

And Pablo once the tapes applied is there a noticeable difference (other than the weight of it subduing the movement)
 

 

If there wasn't an improvement you wouldn't see the top racers using it

[Phil Smith]

How did anyone get a car to work before vibration tape came along?

 

Plus, I think it was one of the top racers that told Tony P's reasons for using it.