I'm on a quest this summer to make my car as vibration free as practically possible. What i would like would be some sort of device that i could use to quantify a vibration so that i could tell if my trial and error methods are making things better or worse. I'm thinking some sort of an accelorometer interfaced with a voltmeter might work. I plan to use a hoseclamp to attach the accelorometer to things like lower control arms, axle tubes, transmission tailhousings, etc, and just keep working my way around until i'm satisfied. Does this sound like something that i can put together with $25 bucks worth of stuff from RadioShack?
http://www.pcb.com/Linked_Documents/AutomotiveSensors/AUTO_NVH_Lowres.pdf Has the sensors, not sure what radio shack has. Also Ipod/Iphone http://rikravado.hubpages.com/hub/10-Best-Accelerometer-Apps#slide3538669 But first read this: http://www.fordtechservice.dealerconnection.com/vdirs/training/cdatabase/files/30S03T0.pdf You can find sirometers or small engine tachs on auction sites for 10-30 bucks.
Might look into a Sirometer(sp?),a very simple mechanical tool for measuring frequency that can be bought at lawnmower shops cheap. When I started with Ford I had to take a few classes in NVH (noise, vibration, harshness).. We were taught to use these to find the frequency, and then use simple math to find the faulty part. Had to learn this well before they taught us how to use the electric sensors, but its been many years since I've used one I might be a little fuzzy on the details...
Sirometer Source: http://www.repairclinic.com/buy/1/3...ometer-briggs-stratton-genuine-oem-19200.html
Damn, thats it! Guess I should have read hoop's post a little better, didn't see he already mentioned that, my bad...
I'm looking more at quantifying the amplitude of a vibration in specific areas. For instance, if i mount a sensor to a lower control arm, I'm thinking it will help me use trial and error to balance an entire tire/wheel/rotor as an assembly. I could quantify the vibration at a certain speeds on a designated section of hiway so that i could tell if small adjustments of weight placement/mass are making things better or worse. I'm thinking i would also be able to fine tune driveshaft balance as installed with yokes/flanges/etc in place under real world conditions, which might result in a better overall balance job vs a typical balance job done only to the driveshaft.
This should be a really good thread !!! I dig this kind of stuff. Some wise ass better not ask what this has to do with traditional hotrods
X2 on the sirometer. Btw most first order tire vibrations(one per revolution) are usually around 12 or 13 HZ. Than multiply that by the gear ratio for a driveshaft vibration.
To attach the accels you might want to use inelastic cyanoacrylate-based adhesives, like crazy glue with some accelerant. That's what we use in Aerospace to attach accels to parts undergoing vibe testing. This method avoids any dampening of the vibration that you're trying to measure.
The Ford material gives you some good ides on strategy, calculating frequencies etc... Here is a 85 dollar homebuilt meter, reals ones cost a 1000. http://www.dimensionengineering.com/appnotes/vibration_meter/ See the add notes for making the remote sensor. Hoop
One thing about diagnosing a vibration is it can travel thru the vehicle. One good thing about something like the sirometer, it will pick up the frequency if it against a solid part of the vehicle like a seat frame or something. Iceberg460, same way I learned. Nvh classes thru Ford. I do alot of vibration and driveline work at the dealership.
I was really hoping this thread was going to tell me how to build a shaker of some sorts. Ive always wanted a way to vibrate my vehicles (car or bikes ) so that I could walk around them and try to find squeeks and rattles. Being a machinist for a while means my hearing isnt the best and I have a hard time pin pointing a noise, now add in the engine noise and bouncing down the road , forget it jeff
One way to look at vibration diag is take a look at an electric motor tag. For instance 3600 rpm and the tag will also say 60 HZ. 60 x 60 =3600. The sirometer or whatever vibration analyzer is used and takes the rpm of the vibration and divide by 60.
I just paid $36.25 shipped for the accelerometer in the pic. I'm going to mount it in a separate hard box with a long lead so i can move the sensor around. I'll let you know how it turns out
Please do, one thing I thought of is you measure the magnitude on the mV scale, and then the frequency on the Freq if it is discrete enuf to pick out.
i can't help with the instruments because i don't know jack about that. However, the subject of vibration minimization/elimination is of great interest to me; i might have OCD, but i hope not. i'm much more compulsive than the average person, and even the average car person in the quest to eliminate vibration. But i'd like to offer these suggestions when you get down to eliminating (or even before you start) the vibrations: 1) Hunter Road force balancing: http://www.gsp9700.com/ REALLY good, i highly recommend. 2) Actual rings you can put around the driveshaft (i don't advocate using ONLY these in lieu of actual driveshaft balancing, rather to investigate all possibilities): http://www.balancemasters.com/driveshafts/index.html 3) Investigate what mercedes, BMW do to get such a seemingly smooth ride: i've noticed that Mercedes and BMW seem to have a smoother ride than domestics. Do they balance their rotors (or drums)?
Heck Buick drivers in the 60s were demanding as heck. We used the Hunter strobe balancer to do driveshaft balance, got a form of Force matching with a tire grinder, and weights on the flexplate, and in the balancer holes. Of course we would loan them an OddFire skylark, so when they got back in their 225 it was bound to please. When they took all the weight off the LeSabre V6 for economy it vibrated from one end to the other. The pinion angle on the 64s and 65s would drive you crazy shimming the trans mount. Hoop
They are factory balanced at Manufacture; http://www.youtube.com/watch?v=vIJf29CFnbo http://www.youtube.com/watch?v=uBXS5QhHDHc There are specialty shops like Hendrix Wire Wheel in NC and I am sure elsewhere as well as racing wheel service centers that could perform this service. The closeness to the center of rotation reduces any imbalance effects. Hoop