I made this simple balance checking fixture yesterday, wanted something to quickly verify flywheel and PP balance at home. My first pass at this was just proof of concept using materials I already had on the rack, basically angle iron and some cold rolled shafting. Turned out it works pretty good for what it is, detects an an out of balance 2 grams on a 6" radius. Plan is to use it to verify neutral balance of the flywheel first, then add the pressure plate to further balance the assembly. Here's some pics with an old cast flywheel i had laying around, here you can see some leveling screws installed in the base... Here you can see that one end of the support shafts non-adjustable, just holes for the pins that are threaded into the shafts... Here you see the other end of the support shafts, which go into slotted holes with adjustment screws to allow adjustment for parallel of the support shafts... Here you can see that the old flywheel, supposedly neutral balanced originally, required 43 grams applied to it's rim to achieve neutral balance... To further reduce friction and improve resolution, i'm going to order some chromed hydraulic cylinder shafting. Flywheel is a simple disc with not many choices as to where to put balancing holes, if I can get resolution down to 1 gram @ 6" i'll call it good. I know static balancing isn't as good as what's possible using an actual dynamic balancing machine, but at least I'll know it's close enough for what i'm doing. Think i'll also make some arbors to check my clutch discs and brake rotors too. Grant
Nice work. There a few wheel balancers that work good for same,they use zero clear bearings;2 at each side for shaft to ride in.. Shaft with a number of wheel hubs that fit shaft. So rim n tires can be mounted. The simplest design one is for Bike wheels,the trick is making adaptors for def hub
I think I understand the concept, if you place the flywheel on you fixture and it rolls, that indicates out of balance?
I think with chrome shafting, friction on my version may be less than versions that use 4 bearings. Grant
What your doing will work fine,but can be EZer. Some time the fun factor is best anyway ! DIYS Friction your talking about is not a factor def. on flywheels or hubs*,but yes your right if your dead level both sides and center shaft is dead on 90*/:::the 4 bearings keep that PITA adjustments out of the play. But we did do, some still do balance toy props,slot car motors on two raz/blades. I'm retired,but did SW Engine Balancing for 30 years at my speed shop. SW use 4 bearings also.
A little off topic but i have been balancing mower blades on a nail for 50 years and they ar e just fine
Seems like a nice concept. Have you considered double checking your readings on a real balancer,,,just to verify the findings . 43 grams is a fair amount,,,,not impossible,,,,but I would Feel better with a Verification before I machined anything . Tommy
I wonder if you could make an adapter to mount the flywheel on electric motor (1725 rpm) and spin it just to verify your results. Obviously the motor would have to be attached to something substantial. First put a small container of water on the motor to see if it runs smooth, and maybe adjust it if necessary. Then mount the adapter and check it again. Then mount the flywheel and check it the last time. This way you are using the same flywheel bolts that will hold the flywheel in place. It would require some safety measures to prevent the flywheel from coming off and hurting someone. Even at 1725 a flywheel could do some damage if its not secured well. Might even try a flex plate before a full flywheel. This would just be a proof of concept type thing. Like your idea and your work........
LawnBoy suggested balancing on a saw blade held level in a vise. This works, a straight, sharp, and balanced blade revs higher, with less vibration to fatigue the operator and cuts nice. When I was in the .mil they still tracked & balanced Huey blades with a crayon and a broom stick or somesuch. The BlackHawks had some pretty high speed optic sensors and accelerometers, and would tell you to add 1oz of weight on a rotor hub and raise a PC rod one click. Amazing stuff, whatever gets you there. Any assembly that rotates for a living, minimizing runout and vibration etc, always results in longer life and a smoother ride.
I static balanced the steel flywheel i've been using on my 355, forgot to write down exactly how much weight it took before I started drilling. I had taken a little weight out of the backside a year or so ago, i'm guessing it took about 12g to balance it out today. With the flywheel zero'd out, I bolted the Ram pressure plate on to check it's balance. Turns out it needed 22g. I then rotated the PP 180 degrees on the flywheel and checked it again to verify. Took the same 22g on a 5-1/8" radius in the same "6" location. Looks like depending on how the two were bolted up before, balance of this assembly could have been out a minimum of 10g or a maximum of 34g overall... I don't really want to drill the cover and weaken it. Looks like I could install long studs and make a weight to install on that stud, take advantage of the coincidence that it just happened to need weight exactly in-line with that cover bolt. Thought about welding on a weight, but afraid it might distort the cover a little. Looks like this verifies what I suspected, pressure plates may need balancing too. Grant
While I like the idea that you are inquisitive and solution oriented, I think extreme caution is needed in the area you are experimenting in. Welding on either of these components is not a good idea, and drilling should be done selectively. I still think some way to test your results rotationally at lower speeds would be prudent. It might save a lot of work later. You could probably just bolt it in place without the disc on your motor........and start the motor at a slow rpm. Gradually increasing speeds to see if it is in fact balanced properly. There are reasons why tires are spin balanced rather than static balanced, and flywheels are even more important. Remember, there may be occasions when its spinning at 5,000/7,000 rpms and the modifications you make must be correct or they may be deadly. Once you prove that your process works properly, its a little different consideration.......but at least the first try at balancing needs extreme care. One other thing. The nuts with the star washers don't appear to be Grade 8 stuff .
This engine regularly gets spun past 8500, that's why I don't really want to drill or weld on the clutch cover. Probably just install one longer stud for the #6 position and make a suitable weight to fit that stud. If tires/wheels were narrow, there wouldn't be much need to spin balance them. Spin balance is mostly to be able to identify proper placement of the weights inner vs outer. Even then, very few with nice aftermarket wheels ever want weights on the outside where they can be seen. In the end, you get close to the same result with a bubble balancer. Those nuts/star washers on the pressure plate are the ones installed by Ram when they built it, i've never touched them. The flywheel and cover bolts are all ARP, also sfi steel flywheel inside of a steel can with a block plate. Grant
You are talking about extending a bolt to get balance. While that seems simple enough, watch this video and notice how much vibration he gets at very low rotation speeds. At 8,000 rpms its going to be significant. I saw another video where a guy rotated his flywheel and clutch at maybe a couple hundred rpms and put a dial indicator on the shaft to see how much it deflected. Here is the other video. These are just suggestions because I hope you have a good outcome to what you are doing.
Thanks for the concern and suggestions, but i'm one of those guys that likes to learn thru hands-on experience. Extending a bolt actually places the added weight closer to being in alignment with the PP's center of mass, which is dominated by it's nodular iron pressure ring. Should be closer to being in balance than it was before without a static balance. Grant
Never weld on a clutch cover. Never drill on a clutch cover. There are places to drill on some clutch covers but NOT a diaphragm type. On your application the proper place to drill for cover correction would be the flywheel. Chamfer the edge of the holes.. JUST BE SURE THE FLYWHEEL AND CLUTCH COVER ARE INDEX MARKED WITH AN ELECTRIC PENCIL. NO PUNCH OR CHISEL MARKS. Also, it is a good idea to be sure the SHOULDER bolts that hold the cover to the flywheel actually hold the cover so it CAN NOT move. I have had a Stewart Warner balancer with an add on amplifier that is capable of balancing to .0001 inch ounces, since the mid 50's. We have balanced every conceivable rotating part you can think of. I would not even think of turning a cast iron clutch and disc 8500.
Thanks for the input. Ductile iron pressure ring in the diaphragm PP, not regular cast. Flywheel is sfi billet steel. Fasteners are ARP purpose designed as cover bolts with appropriate shoulders. I'm going to replace that cover bolt in the #6 location with a longer double ended stud with a shoulder, and make a weight to fit over the stud. I've got several feet of .75"od x .375"id dom tubing on the rack that's a snug fit over a 3/8" shoulder, perfect material for making the weight. Ram says they balance to .5 ounce inch, that's around 2.5 grams at the radius i'm working with. Don't want to balance the pressure plate by drilling the flywheel, as I need the flywheel neutral to allow different components to be swapped in. The car is a street/strip test mule for my ClutchTamer products. Grant
Found that if I set up the fixture on the concrete floor instead of the bench plate, resolution improved to 1g with the cold rolled shafts. The 65lb bench plate plugs into a single 2" square receiver style socket in the bench, turns out there was a little flex when the parts were rolled from one side to the other... This dual friction disc was only out 1g @ ~ 5". Also need to make a slightly larger dia arbor to check my heavy full face iron discs, their narrow hub id's are slightly larger dia. Grant
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