TeamSwift

Here is a simple 'poor man's' way to statically balance your rotating assemblies.

First, you clean your old pistons and rods. Then you put the new rings, bearings, caps, nuts and bolts on finger tight. Oh, how did I clean those pistons? Warm 'Simple Green', a toothbrush...and a few hours.

I used a triple beam balance similar to those found in science classes:



These can be found from various sources. I got mine from here:



but you can get yours anywhere you like. I got mine from those people because of their positive feedback online regarding the styrofoam packaging/storage box; it's a sensitive balance, and packaging is important for safe shipping, plus she stores handily and safely between engine rebuilds.

Originally, to see if it would work, I 'borrowed' one from the science lab ssssssssssssshhhhhhhhhhhhhhhhhh!!! but returned it. That was many years ago.

Next, you find a clean work place and put the assemblies and the balance in one place. Remember, this balance can be thrown off by a drop of oil, so you have to have clean hands, blah blah blah....

Here we are balancing a three cylinder:

The picture above was taken before the rings were installed. Sorry! You put the rings on too!!!
With everything ready to go, you do the hard part: getting the rod to stand up on it's own. Trust me, it takes practice.


There is a 500 gram counterweight on the right side of the balance, so you will add that amount to your readings...
Above, you can see that the rod is standing tall. Any wind will mess up your readings. Measure all three assemblies individually, and write down the readings.
I'm thinking the one above is around 710.09 g.
Here's a quick review:

There's a total of 711.24 g (roughly) involved. 500 of the 711.24 can be accounted for by the hanging weight. If you have problems here, consult your neighbor, or a science teacher.

Now we get to the fun part. You've weighed the heaviest and lightest and you subtract to see how much you have to take off the heaviest. In my case, the heaviest weighed about 2.3 grams more than the lightest.
I wondered how much metal I would have to remove, and a small coin (here...a U.S. dime) weighing that amount shows how much I ground off the cap...evenly. Here it is:


The last step involves taking the heavier 'assemblies' and matching them to the lighter ones.
Just so you can see what was removed, I put a little picture of what I did:

For fun, I got it close to the correct weight using the sides, and just ground out the letters at the end for fine tuning.

This static balance is very easy to do, requires a lot less money than a professional job, and produces very satisfactory results, judging from the Teamswift member's reaction who helped me with this particular engine. Further, he felt quite able to balance his next engine using the above technique. It is not as good as an expensive professional dynamic balancing job, but is quite respectable and 'price-wise' is within reach of most guys who can afford a good torque or impact wrench. All my engines get this additional treatment, and I've had no problems because of it. It's more preparation than actual grinding.

The first engine that I used this technique (A 1951 Chevrolet 235 6 cylinder) idled so smoothly that I won several bets regarding it's ability to allow a coin(nickel) to stand on edge. (Great way to win free beer ) It is still running. So now you know my 'secret'.

Finally, I've edited this post to reduce the size of the pictures. The large pictures are in my gallery with additional comments.

Happy balancing

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!

Sience class..??? or meth lab
nice right up
a few questions ..
What is up with the size of the pictures you posted there huge..??
and I would thing you would want to brake them down you know balance the pistons then the rods then the complete assembly..??
are those piston from a MK1 turbo motor..??
they look like it

_________________
.

Yeah, the local authorities will wonder what's up when you order a balance like that.
Oh well, nothing illegal about buying one....yet.

Again, sorry about the size of the pictures. I tried to resize them, but it didn't work out the way I wanted. Rather than link to a Photobucket account, I put the photos in my gallery. Anyways, take a close look at the grind. Some guys were worried that the strength of the rod would be compromised, but very little metal is removed.

You can break them down and measure their individual weights. Then assemble the parts so that the assemblies are almost the same weight. Eventually, you will have to weigh the fully assembled parts, so grinding before the final assembly would be wasted effort. The actual time grinding is only about 1 to 2 minutes on a grinding wheel, so take it easy.

Those pistons are out of a 93 Geo Metro. I was going to do the write up using MK1 NA pistons, but this engine got bumped to the front of the line. I can add the MK1's later so you can see the difference: they just have the one boss in the center to grind.

Even the engine rebuilders in L.A. were skeptical of my method; they always send their stuff out for balancing (expensive). All the effort you spend pulling engines apart, and putting them back together, detailing different bolts and nuts...here's another little 'tweak' you can try.

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!

cool, next time im messing with the internals ill be sure to give it a shot.

how about the crank? I recall you saying something about doing a DIY lightening and balance on that (unless you were only referring to this post). that 3cyl crank sure has some weight to it

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

I've been using this method and so do my friends, it's okay for piston /rod assemblies but you need the dynamic balance for parts with rotational forces like the flywheel or the crankshaft, camshafts.
Btw i'm building an mk1 gti engine for hillclimb and yesterday i was ballancing the pistons.I found that the rods and pistons/conrods with the same markings have only 1g difference, so that isn't important. Above 2 g difference it's kinda tricky but if your not doing 6000 rpm frequently that isn't a problem.

A stabile engine @ idle has nothing to do with balancing , but good spark plugs and even compresion on all cilinders is a must.

_________________
G13B 1.3L 16v 115hp

First...thanks for taking the time to take pics and do a write up.

Now, if you were going to bore the cylinders, would you weigh the old set of pistons and rods? Then bring the new set of pistons and rods down to the old weight? Just thinking that the crank would be balanced to a standard set instead of an oversize set.

I used to know this kind of stuff a very long time ago. I already got the scale from reading a post you did about something else. Light bulb went on in my head "Oh Yeah, I forgot about that".

_________________
"You can lead a horse to water, but a pencil must be lead." Stan Laural

91 & 92 1L 5 spd metro

i don't think that the crankshaft has dynamic balance along with the pistons and rods. i don't know how that could be possible???
You just have to have the same weight on all pisons/rods and the crankshaft plus flywheel and pulley dinamically balanced.

_________________
G13B 1.3L 16v 115hp

Interesting write up, Phil. Might try it the next time I'm fixing an engine. Though your point on the popo is right.

_________________
Love the way the West coast feels.

Very nicely done, too bad we don't have those old karma buttons from back in the day anymore

_________________
"We don't make mistakes here, we just have happy accidents... If you want sad things, watch the news. Everything is possible here. This is your little universe."
-Bob

im curious though, if removing material from the crank and doing a self "knife edge" job is okay so long as you mark fairly accurately and take the whole rotating assembly (crank, rods, pistons, rings, pulley, flywheel) and have it dynamically balanced afterwards. I want 7800rpm out of this 3cyl, so thats going to mean going back to t3 rods and better pistons, might as well go 76mm bores then and have it balanced.

Besides the obvious balance downfalls of the 3cyl vs 4cyl what is really holding this motor back on rpms? im scared lol. ive got all the control in the world, but that doesnt mean the rods wont let go at 160. im holding my bottom end at the stock 6500 redline for now. plus its a torque monster compared to the 4cyl I dont need the rpms right now. its getting wintery soon anyways. gonna buy some wiseco 76mm's on my t3 rods and go from there

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

so im gonna find me another g10 bottom end to mess around with. really all I need is a block and a crank, ive got the rest, but whatever. Ive got my old t3 rods that im gonna use on my next build, and some quality 76mm pistons. I will have the block o-ringed for my newly acquired copper head gasket and arp studs and I am going to use this method to balance the reciprocating parts. From my understanding its pretty much pointless to do the pistons and rods seperately as long as that "cylinder" is balanced to the next one.

I would like some comments on the crank cutting thing, the crank is heavy as hell for a small 3cyl motor, and even a 10% reduction would be worth it (since its got aluminum pulley and a lightened flywheel) but like I said, I want lots of rpms next year. and I sure dont want to risk it with n/a rods.

Can I chop up a bunch of material off my crank (which measuring and doing it as well as I can) and have the whole thing balanced? my machine shop said theyd do the whole shebang for 275 bucks.

Now I dont know if this information is out there, but is 8000rpm too much for a 3cyl even if its zero balanced? the t3 rods are the same as the gti rods, and I know those guys are revving them to that and more, but being a 4cyl it has a balance advantage.

philned, any comments?

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

Once again, a longer post than I intended:

Balancing like I've done above is quick and easy. Writing it up, and answering questions takes a LOT more time!

chuck222 mentioned an improvement in this procedure, and it sounds good to me. Just remember the old assembly that you balance (there is both a 'rotating' and a 'reciprocating' component to the assembly- the rotating part is ground to achieve equal weights/masses) is connected, and the rings will have worn. So you will have to add some weight to your old 'assembly' to account for the wear/ loss of metal on the rings and bearings. If someone has that mass/weight, maybe they could post it for future reference.

Some of you would like to delve into high performance modifications. High lift on a ground/reground camshaft will certainly cause the engine to 'lope' at idle. The balance mentioned above is a nice starting point, but the entire engine should be balanced professionally for best results.

This is a simple DIY with tools obtainable for less than many nice torque wrenches. I have used it for years, and have had very reliable results.

Teamswift members wishing to know more about the 'theories' involved should read a set of articles written by a German fellow some years ago; it is the most comprehensive article that I have read, and it took me a while to locate it, as my old hard drive crashed, and I didn't want to slave it to find the bookmarks. (Actually, it's my MBR, and if Raygo comes over and fixes it, I'll post his original article here for all to see; it starts with one cylinder engines, and moves up the line, one at a time, to the 12 cylinder engines.)
The crossfire and flatplane crankshafts are covered, as well as the integral balancing shafts.
Now it's been updated, as he's become fairly independent, financially.
He used to sell parts so that we could make our own balancer for our turbochargers.
He started small, balancing turbochargers, and worked his way up the food chain. He's done some turbine engines for the airlines and some wealthy helicopter pilots, last I heard.

I recommend you read: Engine Smoothness
It used to be longer but is now condensed to only 5 pages.
It begins here: http://www.autozine.org/technical_schoo ... mooth1.htm


Inline 3-cylinder engines
As the engine fires once every 240° crankshaft angle (720° / 3 = 240°), the crankshaft design is as shown in the below picture. (Firing order is: 1-3-2)

It seems that no matter how the crankshaft rotate, the combined center of gravity of all 3 pistons and con-rods will remain at the same location, hence no vibration generated. By mathematical analysis, you can also find there is no forces generated in vertical direction as well as transverse direction. (actually, I really performed such calculations) So why did we hear that 3-cylinder engine need balancer shaft ?

In fact, the calculation is wrong because it assumes the engine is one point, thus the forces of all 3 cylinders act on this single point and result in complete cancellation. In reality, the forces act on 3 different locations on the crankshaft, thus instead of canceling one another, they make the crankshaft vibrating end to end.

Don’t understand ? look at the above picture, the side view of the engine. Piston 1 is at the top now and is going downward, thus generates an upward force to the left end of the crankshaft. Piston 2 is also going downward, thus generates an upward force to the middle of the crankshaft. Piston 3 is going upward, thus generate a downward force to the right end of crankshaft. As the engine’s center of gravity locates in cylinder 2, you can see forces from piston 1 push the left end of the engine upward while forces from piston 3 push the right end of the engine downward; After 180° rotation, the situation will be completely reversed - downward force at left and upward force at the right. In other words, this is an end-to-end vibration with respect to the center in cylinder 2.



He has a new section AutoZine Technical School which can answer more of your theoretical questions here:
http://www.autozine.org/technical_schoo ... index.html

For those of you wishing a little Wiki action, here's a link:
http://en.wikipedia.org/wiki/Engine_bal ... _balancing

Knowing that there is a difference between dynamic and static balancing, the technique I've described gives you more 'bang for the buck' than any I've seen described so far. However, if you have some neat ways of balancing an engine (including the crankshaft)-bob weights or no, clue us in. If it's something we can try in our garage...so much the better

Happy Balancing....!

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!

Hmmm... The information he wrote about balancer shafts on the 5 cylinder seemed to be a little more in depth than the section on the 3 cylinder, but he indicated that they function the same. How might one go about incorporating a balancer shaft onto one of our vehicles... it seems that there would be plenty of room in the engine bay to rig one up externally, but would that be a viable option?

_________________
"We don't make mistakes here, we just have happy accidents... If you want sad things, watch the news. Everything is possible here. This is your little universe."
-Bob

thanks for the read phil, suzuki claims these motors are balanced very well from the factory, but that only includes the equipment it left the factory with. with any internal modification (bottom end) a balance should be done. though that should mean the rods themselves should be balanced to each other from the factory and if you change pistons you shouldnt have to worry about it. but there are casting errors present, especially in aftermarket parts. good work phil, you know ill be trying it out!

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

He says all 2 bangers run with the pistons going up and down at the same time/speed.

Guess he must mean 4 strokes, because all my 2 strokes, have the pistons travelling opposite of each other, and they purr like kittens(hearing protection advised once the throttle opens though)

I always wondered why they didn't make I4's into 90 degree engines... so that it's a self balancing assembly. Also overcomes the inherent disadvantage of a 4 stroke, in that every half a a turn of the crank you'd be making power, but I suppose it would have a bit of a shake.

Edit: Hmm... The custom ignition, the custom crank, custom cam, and then the custom MS setup... Would be cool though...

_________________
My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro!

double v-twin ?

_________________
1995 Firefly 1.3 SOHC 8VALVE MANUAL
2000 Firefly 1.3 SOHC 16VALVE AUTO. Goals: full restoration, achieve stock MPG and HP or higher, finished look should be 'stealthy' and unassuming. Engine will need to be rebuilt later on to restore compression levels.

Pretty muchly, with Harley, they have the 2 cylinders fire almost on top of each other, it's what gives them so much torque, and that way they all seem to idle.

What I was suggesting was a setup where the crank gets two power pulses per rotation, instead of one, all the the time. So you'd get alot more power out of the number of rpm.

Of course this is just daydream, so it might be all sorts of wrong, but it seems plausible. Could even build the crank like a 2 strokes. Piece built, solid circle connectors, since you wouldn't need the counter weight to get you over the 270 degrees there isn't any power being made in the standard design, so that could help absorb alot of the extra vibration, hmm... It would be pricey...

_________________
My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro!

That's a worthy picture to keep, I hit triple 7's(What's my prize?) and you hit the number of the beast...

Yep, dreams are only worthwhile if they are attainable but incredibly hard to obtain... Guess I'll go buy my 649 ticket tomorrow...

_________________
My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro!

I found your post very interesting but I wonder if it isn't over simplifying engine balancing a bit. I'm a far cry from an automotive machinist or engineer but everything I've ever heard regarding balancing connecting rods involved a special jig so you can measure each end of the rod individually.. weighing the large ends and then matching all the large end weights to the lightest of the rods. Then repeating the process with the small ends and matching all of those weights to the lightest.
The reason for this being the fact that the small end is a reciprocating weight while the large end is rotating weight.
And, an FYI for other DIY'ers.. making a jig to weigh each end separately isn't as easy as it would appear.. the following is a link to a home made jig.. http://www.angelfire.com/ca4/CorvAIRCRAFT/RodBalance.html the author claims it works great for him.. I replicated a similiar device but haven't been able to get consistent readings with it.
Just my thoughts on the subject.... thnx

Well, my thinking is like this...
-this is not a technique for 'balancing a connecting rod'
-this is an inexpensive technique
-this DIY technique is repeatable within at least a 100th of a gram
-there is no 'jig' to set up
-yes, this is a very simple technique, but 'oversimplification' is a qualitative term. Post a thread which is reasonable, understandable, repaeatable, easy to do, inexpensive, and available to the ordinary garage mechanic (without disassembling the rods, pistons, and rings) and I will use your technique.

Until then, I will add about 15 minutes to my rebuilds using the procedure outlined above.
Several Teamswift members have been in cars with these 'DIY balanced engines', and so far, their comments have been positive. I've logged hundreds of thousands of miles with engines subjected to this simple balance.

Again, this is not a replacement procedure for balancing and blueprinting an engine...it's a DIY technique which shaves about $150 off a professional engine balancing...and you get to keep the scale for the next engine. Try it, you'll like it.

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!

I did this aswell as machine shop balance my crank pulley and flywheel. and have nothing but good things to say about it. I added 2500 to my rev limiter and 15000 later engine is still brand new

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

It will work, kinda, its not accurate, and only for the 3 or 6 cylinder jobs.
Your missing some other weights doing it this way, but who cares if it gets you by.

_________________
I like my Metro's 96 and 2000.
The most trouble free cars on the road.
Chevrolet goofed up the day they stopped selling them.

like what??

_________________
1991 Swift GT Build G10 +25 psi + other goodies
1996 Metro Build QR25de swap, still undecided where to take it
the lolcar family

It's only accurate to the hundredth of a gramme, you're right. Triple Beam Balance

And there's no reason that you wouldn't do this on a 4 cylinder, 5 cylinder, 12 cylinder. Makes no difference.

The only weights that you are missing is the rotational assembly, and that's what a rotational assembly balance is for. Hence why this is a statically balanced reciprocating assembly as outlined in the post.

You want to come in and hem and haw and a proven method that saves you real cash dollars, please atleast do it with some relevant, and truthful information. Thanks.

I have seen Phil N Ed do this DIY Engine Balance and helped him install these piston assembles in his wife's convertible last year.



This engine was the smoothest running engine I have heard running so far..................................

It maybe only accurate to the hundredth of a gramme, but for us NON Wealthy Sprint, Swift and Geo drivers, it is something an average guy/gal can afford......................

_________________
Dale

1985 Chevy Sprint Mk1 G10 5 Speed Sky Blue