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
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
Neeeet. I like the idea of using a coincidental stud to balance the clutch, too.
I also like the adjustable feet on the unit for roughing-in the level of the device. What do you use for leveling it?
What's up with the spacers on the RX-7 strut in the background of the first pic?
Many moons ago ( like, over 500) I worked in a manufacturing plant that designed and built its own manufacturing equipment. It was a munitions plant, so there were a lot of high speed, rotating drawing and loading machines that had been made in our own machine shop. To balance all the rotating bits they had a balancing shaft that was hollow and perforated. You could put a rotating plate on it and apply air pressure so that is was suspended by a film of air. It was virtually frictionless and the machinist could then decide where to take out weight.
Photos do not work for me and I am interested. Every commercial balance job I have had welded weights on to the clutch cover to balance it. I have seen a few that were 100 grams! Never had one come off at 7500 RPM
TurnerX19 said:
Photos do not work for me and I am interested. Every commercial balance job I have had welded weights on to the clutch cover to balance it. I have seen a few that were 100 grams! Never had one come off at 7500 RPM
Here's the links to the pictures...
Pic 1
Pic 2
Pic 3
Pic 4
Pic 5
Pete. (l33t FS) said:
Neeeet. I like the idea of using a coincidental stud to balance the clutch, too.
I also like the adjustable feet on the unit for roughing-in the level of the device. What do you use for leveling it?
What's up with the spacers on the RX-7 strut in the background of the first pic?
To adjust parallel of the support shafts, i just lay the face of the flywheel on them and check to see if it rocks, then adjust until it doesn't rock. Front to back level I adjust with a digital level, side to side i level by letting the arbor roll on the support shafts until i'm satisfied it has an equal tendency to roll in both directions.
The struts are off my sbc powered FB, it's a street/strip car that needs a little extra travel from the spacers to hook on zero prep surfaces. The stock rebuildable struts have been modified to act much like a 90/10 shock, basically flipped the piston and made the deflective discs act like a check valve with a parallel bleed orifice. I also modified them to accept a 5" adjustable sleeve to use a set of 101lb/in stock FB rear springs on the front. You can't really see the fabricated control arms in the pic, i just pulled the front suspension while the engine is out so I can clean/paint/detail everything before next season. Here's a pic of the control arms before they were installed...
Here's a pic of the strut/spring setup before adding the fab'd control arms...
Here's a pic of the engine, i pulled it to add a bung to the oil pan...
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
