Corner balance!

[ClickClickBoom]

Ok,
I bought an Intercomp scales for fire sale prices. Too cheap to pass up! The '75 got crunched, buddies wanted to borrow them, ect. Well I decided to take them for a spin since after 2 years of ownership, I never had done anything other than plug them in and check for operation, the dog did in fact weigh 66 lbs with a distinct forward weight bias.
I got El Chup jacked up, load cells in place and weights noted with a 3/4 tank of gas.
The front tires were almost 275lbs different, wholly schnikes! Rears were relatively close. Total weight was around 2650ish. The PO's kid fancied himself a mechanic, when I bought the car I noticed the ride height at the front was off a bit and inspected the front pan area closely for possible damage, finding none, I figgered the kid had jacked around trying to "lower" the car, since the front adjusters are so obvious. Well I broke out the 11MM socket and started to get the ride height sorted out, after I added 160 lbs in weight bench weights to the drivers seat. I was able to get the ride height on the front to 25.5 ish left and right and the L/R front balance to about 65lbs difference, with the LF being heavy. I went to the rear and found that the wrench requirement to adjust the ride height was crazy 36MM and 24MM on the inside, but hey everybody has 24 and 36 MM thin wrenches in their box right? Not me! Driving into town I spied the Snap -On truck at the local mechanic and decided that this was gonna hurt, bad. Seems that 36MM and 24MM are on different wrenches, bought a whole set, who needs to pay the mortgage anyway? Well I ran out of time and couldn't use the wrenches on the rear, but with the PO's lowering effort trued up the car now tracks true and straight at hands off on the freeway and the steering is much lighter and accurate.
I am looking forward to finishing the corner balance with the rear being able to be adjusted as well, except I will put 200 lbs in the seat to counter my fat butt and get this one even closer!
I will say the the corner balance while mysterious and often not cheap, must be one of the most ignored maintenence procedures. The effect on the handling is dramatic!
Hola
Eric

I will follow up with final impressions after the full corner balance is finished!

[Craig_D]

Interesting, glad you wrote that up.

[80-911SC]

great write up ...

now your scales are going to make you very popular ...

You could throw a weigh in on a weekend ... I am close enough to go if you decide ...

[dshepp806]

Now: alignment will be needed, right??

Nice find!

Doyle

[ClickClickBoom]

Originally Posted by dshepp806

Now: alignment will be needed, right??

Nice find!

Doyle

Not yet, I retained my bubble camber gauge from the BMW 2002 days, but my magic string pier blocks and strings went into the deck project. With nothing more than some construction discards, a cheap British camber bubble gauge and some welded up steel scraps for toe in adjust my '74 2002 Beemer traced true enough to go hands off at 110.
The Pcar with real adjustments will adjust faster! Once I get the Elephant 22/28s and "Chuck Tuned" Bilsteins and the real corner balance done, I will add the Turbo Tie rods and then "find" some new pier blocks and string and do a full on proper alignment. Don't need no stinkin' computer alignment machines!
Hola
Eric

[micheloaks]

Am interested to understand the process of corner balancing and 'pier block' alignment better as I have begun to strip down my suspension in readiness for some ER goodness.

Once all together I would like to see if I can do the CNR balance and alignment Without resorting to some of the local shops.

Any greater details and pics would be appreciated. Cheers Michel

[ClickClickBoom]

Michel,
The corner balance requires scales, the actual type is not critical. The devil is in the set up and execution for the particular use. A level surface is required Beyond that its, how much time the execution will take. Alignment is a little more complex, the Smart Strings is a slick, smooth concept that has been used for years, in fact, in the airplane world the symmetry check is part of the Annual Inspection on more than a few planes, so for cars its just a symmetry check with measurements and a few conversions from distance to degrees. Realize, how you achieve the factory dimensions is truly unimportant, different techniques will determine how much time is spent. For me time is only relative when I am paying for some one else's, I can afford to use caveman tools and processes. The pier blocks are placed outside the shadow of the cars perimeter in general position. Using the symmetry method find the centerline of the car and locate the blocks accordingly. I then triangulate the blocks using basic geometric techniques. I then determine the height of the centerline of the wheels and use scraps of wood nailed to the pier blocks to achieve the proper height. Pull strings and confirm symmetry with a tape measure. Its then a simple process of measuring front and back of the wheel rims to determine toe in and using the bubble camber gauge to determine camber.

Smart Strings:
https://www.pegasusautoracing.com/group.asp?GroupID=SMARTTOOL

Bubble camber:
Intercomp Racing Bubble Caster Camber Gauges 102010 - PowerSportsPlace.com


Details:
Amazon.com: How to Make Your Car Handle (9780912656465): Fred Puhn: Books

Intercomp:
http://www.intercomp-racing.com/category/Alignment_Equipment.cfm

Pier blocks and string:
You figger that one out

The difference between this method and using a $15K machine is time and some measure of total accuracy. I can get my car within the factory +/- specs so that is close enough for me. I got my Intercomps on eBay for $500.00, looked brand new without a scratch. My bubble camber gauge came from England, so I am sure that you could source any and all via the internet and have them ship down under. Sorry no pics, when I am in the zone, distractions like cameras are not even thought of, and to be quite honest it wasn't until this forum that I thought anyone would be even remotely interested. When I have tape measures and calculators out even my dogs eyes glaze over, much less any human within a 20 mile radius.
eric

[RSTarga]

One important point of corner balancing often forgotten, is to disconnect the roll bars. Otherwise you'll get false readings. One side on each bar will do.

[JP911]

Just in case your Snap On guy takes returns. These work like a charm: 15 Piece Metric Service Wrench Set

[Jack Olsen]

I spent part of my afternoon doing a 'poor man's corner balance' with 16 Ikea bathroom scales on a very-definitely-not-level garage floor. I got the platforms themselves level, though -- which I hope at least puts me in the ballpark.

[ClickClickBoom]

Originally Posted by JP911

Just in case your Snap On guy takes returns. These work like a charm: 15 Piece Metric Service Wrench Set

Oh we'll,
I have my airport rollaway filled with Snap-On tools already, I like the feel of them, I am sure they hold their value as well.

[pwujszuf]

I can do the CNR balance and alignment Without resorting to some of the local shops.

[James Brown]

OMG jack, that has to be the DIY of the year!!! how close did you get

[McLaren-TAG]

Originally Posted by Jack Olsen

So what was your interaction like with the checkout girl at IKEA when you showed up to the counter with 16 bathroom scales?

[ClickClickBoom]

Originally Posted by McLaren-TAG

So what was your interaction like with the checkout girl at IKEA when you showed up to the counter with 16 bathroom scales?

Even more importantly, what was her reaction when you returned them?

[Jack Olsen]

Thanks. I got within 10 pounds on the diagonal weights. I figured fine-tuning beyond that was probably wasted time.

The Ikea checker didn't bat an eye. They probably see some very strange stuff.

[afterburn 549]

Chuck, I have done the same thing...........ONLY thing is i am wondering about the "stiction"..
Not rolling on and off the scale to get things to settle .........
.................................................. ...............
I lay a wake at night
with corner weights and plights
I see them
nightmares of scales
calibrations
chewing on my nails

[Walt Fricke]

Jack - that is flat out hilarious.

A bunch of my buddies and I got together 10 or so years ago and bought a set of "real" corner balance scales. Turns out none of us use them more than once a year, if that, so it worked out great. But the overall cost per person wasn't high. And the convenience factor of not having to read 16 scales and so on would seem to be pretty high.

Do those weight transfer platforms you welded up have adjustable feet?

If so, that does give me an idea. My garage floor is not level. Not far out, pretty much all in one plane, but not level. I've used various thicknesses of thin board to create level pad sites, but getting it just right is tricky and time consuming, and has to be redone each time. If I made square steel tube tire cradles which spanned front and rear tracks, and had adjusters on each end, I could level the front one and the rear one, and forget about how true the scales themselves were.

I know all the literature says you want all four scales in the same, dead level, plane, I am of the view that getting it completely to that point is not needed. As long as the scales are all in the same plane, and that plane isn't tilted more than, say one degree, your corner weights should be so close to what they would be if the tilt was zero degrees as not to matter. We all know there is a certain amount of noise in any corner balance from "stiction" of suspension parts and so on. The scales are so sensitive that reaching out the driver's window to adjust the scale readout on a tray outside will alter the readings. Getting within 10 pounds of your target is close enough. Getting within five consistently is excellent. Changes due to fuel consumption probably are greater than that.

The reason I don't think the angle of the plane matters too much if the tilt is small is this: When a car is tilted to one side, that side will weigh more because the center of mass/gravity of the car has moved to that side. But a one degree tilt moves the CG but a tiny bit (0.4" if CG height is 24"), so on an SC with a front track of 53.9" and 500 lbs on each front corner, the one degree tilt would add 3.7 lbs to one side, and subtract it from the other (if I did my math right - maybe the weight should be double that). If you got the difference down to the resolution of most digital levels - 0.l degree - the difference would be 0.37 pounds.

With the wheelbase being much larger than the track, the effect of having the rears higher than than the fronts, or vice versa, during weighing would be a bit less than half as much as a front tilt, so getting side to side level at each end ought to be good enough.

Since I don't have ramps, and thus have to jack the car up to get it on the scales anyway, putting something under the tires isn't an extra burden.

[Jack Olsen]

Yes, Walt. The feet are threaded, and I welded in nuts on each corner so I can get each platform level and also on the same plane as the other platforms.

My first try involved notched 4x4s, but that was a disaster -- the car fell off them at one point. So I swallowed my pride and sprang for some adjustable feet.



It seems like support ramps could move the scales even higher, which would give you easier access to the underside of the car for adjustments. I'm spoiled, in that the lift makes it easy to raise it up, adjust, and then lower it right in the same place over and over again. I've also got coilovers front and rear, so height adjustment is quick and precise.

[JQ911]

Does one have ball park cost for corner balancing? Is 250 to 400 range just about right? Then a 4 wheel alignment is gonna cost me 165. Found a shop in millburn, nj who's familiar with air cooled classics vw and pcars.