Corner balance, any tips? Options

[tradisrad]

I am going to corner blance my 914 in the next week or so and I am looking for any tips that my help.

I picked up a set of Mad Racing scales, a Longacre caster/camber gauge and toe plates off of CL for $200. After I purchased said items I could not find a lot of info on the Mad Racing scales:



I did find that folks don't like these scales especially when compared to the Longacre digital scales. It also seems that there is a question about repeatability and accuracy with this type of scale. But they are what I have.

So, I would appreciate any advice on using these scales as well as the camber/caster gauge & toe plates.

My suspension set up is:
Elephant Poly Bronze x 4
GPR front bar
Stock torsion
Upper front monoballs
150lb Eibach springs w/ ground control
Bilstein shocks x 4
Turbo tie rods & bump steer.

[SirAndy]

I am going to corner blance my 914 in the next week or so and I am looking for any tips that my help.

You're looking for 50/50 cross weight and close to that in front/rear balance.


- Break tie rods lose in the front and the trailing arms bolts in the rear if you are planning to do a full alignment.

- 1/2 to 3/4 tank of gas

- Full drivers weight in the drivers seat

- Disconnect any swaybars

- Roll the car on the scales

- Set ride-height roughly where you want it

- Fine tune height using the scales until you are happy with the cross weights

- Lock in steering wheel in center position (two wooden poles cut to length work great for this)

- Set camber (and caster if needed)

- Set toe

- Tighten the tie rods and trailing arm bolts

- Reconnect the sway bars

- Go for a drive


I think that's it ... (IMG:style_emoticons/default/idea.gif)

[tradisrad]

Andy, Thanks. I hope it is as easy as you make it sound.
I am not sure if I am going to do a full alignment. Rich at HPH said that my alignment should not be thrown off too much. I will check camber/caster & toe before and after to see what changed.

[SirAndy]

Rich at HPH said that my alignment should not be thrown off too much.

I wouldn't do without an alignment after a corner balance ... (IMG:style_emoticons/default/shades.gif)

[jjackson]

In our experience-corner balancing after alignment is wrong.Corner balance then align.Backwards makes a real poor handling car unless its close to balanced now.Sir Andy is correct.Sounds like bad advice form Rich.J

[tradisrad]

Should I bring my car back to the specs that it is currently set at after I balance? (I dont have the specs with me at work)

[jjackson]

Should I bring my car back to the specs that it is currently set at after I balance? (I dont have the specs with me at work)

Yes.I've seen several cars corner balanced after alignment-including my own in a quest for better handling.(20 plus years ago).In every case the handling was worse.Sometimes dangerously worse.Some friends did this recently before atrack day-clock don't lie.J

[strawman]

I used a similar "fulcrum-based" lever system on my old MR2 CSP autocross car with good results. I'd echo what Andy says and agree with JJackson that it is an iterative process.

One thing to keep in mind is that you need as close to a perfectly flat measuring area to get good results. I started by parking the car in the center of my garage (to allow for lots of space around it to work on things), and marking 1-foot squares for each tire contact patch. I then used clear tubing & water to check the flatness of the four contact patches; I used 1/8" vinyl floor tiles to prop up the low spots in my garage. I then went back and painted the squares onto the floor using a vinyl tile and spray paint. Then I built ramps out of 2x8 wood so that I could drive onto the lever pads after making each change to ride height and alignment (you'll end up doing this repeatedly, since a change in ride height changes alignment and vice versa).

I plan to use the same system for my teener when it is done (someday!).

Geoff

[r_towle]

If you dont have rear threaded perches, you can only really use the front to corner balance the car.
It wont be perfect, but you can make it ride a bit better...certainly better than nothing.

Do get an alignment after you setup your height and corner balance.

Rich

[tradisrad]

I spent some time last weekend playing with the corner balance on my car, the I put my tool away and went climbing in Yosemite.

First I have always thought that the car sits a little lower on the right rear than it does on the left rear. There is/was a 1/3" to 1/2" difference between the fender and rim from the left to right side; the left side having the larger gap. I have no reason to believe that the car has been wrecked or that the chassis is tweaked in any other way and the suspension points look great.

To get my corner weights more even I had to raise the left rear and this helped with the weights, but it exaggerates the distance between the rim and fender even more than it was and the car appears to sit crooked.

Also I found that adjusting the front torsion bars had little to no effect on distrubiting the weight of the car.

This all leads me to a few more questions.
1. is it possible that my car is not square from the factory and that is why it has the difference in height between the rim and fender?
2. why did adjusting the torsion bar have no effect on distributing the cars weight?
3. Once the corner balance is complete will the car sit even (I dont think so, but I have to ask) and how uneven can it be?

I saw pictures of Andys car when he corner balanced it and mine looks a little like his does from the rear and to the best of the knowledge my car has not been wrecked. http://www.914world.com/bbs2/index.php?sho...=50515&st=0

I'll post the weights and changes this evening. I dont have the info at work.

[SirAndy]

1. is it possible that my car is not square from the factory and that is why it has the difference in height between the rim and fender?
2. why did adjusting the torsion bar have no effect on distributing the cars weight?
3. Once the corner balance is complete will the car sit even (I dont think so, but I have to ask) and how uneven can it be?

1. I highly doubt it ...

2. You do know that to increase weight on a corner you have to *RAISE* that corner? It's somewhat counter-intuitive at first and a lot of people try to go the other way.

3. If the tub is straight, it will sit even left to right but probably not front to rear.


(IMG:style_emoticons/default/bye1.gif)

[Borderline]

There's another theory of corner balance that I read about. Instead of equalizing the sum of the opposite corners, the theory is to put the same percentage of wt. on the left side front and rear and right side front and rear. Hard to put into words. If the car has 55% of it's wt on the left side(based on total wt), then the left front wheel should have 55% of the front wt and the left rear wheel should have 55% of the rear wt. I like this method as it seems to result in the front corner wts being closer to each other. That gives better braking performance. FWIW (IMG:style_emoticons/default/smile.gif)

[tradisrad]

after a few weeks time and sorting out some suspension issues (front shock bottomed out) I reattempted to corner balance my car.

What I have found is that with my low spring rates (150lbs) and stock torsion bars I have to radically change the ride heights to get the weight to shift around (with my 180lb butt in it). I had to drop the drivers side more than two inches. But w/o me in it the car is close to balanced.

I don't want to increase my spring rates or torsion bars to get the car to balance with me in it. I've been told that higher spring rates make the weight shift with less change to the ride height.

I though that I could just balance the car w/o me in it and call it good. Is this a reasonable idea? The car is going to be only used for the street and I probably don't need to bother with the corner balance at all. But I've got the scales and alignment tools and I want to use 'em.
thanks
-Rob

[sean_v8_914]

did you have slider plates under each wheel?

[tradisrad]

slider plates?
I have a set of 4 scales, arms, balance plates. With one under each wheel. Like the picture above.

[McMark]

If you jack up the car, you need to roll the car to let the suspension settle or have some sort of 'slider plate' that will allow the tire to move any direction freely. The idea is that when you jack up the car, the suspension droops. When the suspension droops the wheel move slightly inboard. When you let the car back down, the tires hit the ground and GRIP and you end up with the tires effectively holding the rest of the car in an artificially high position. Rolling the car back and forth relieves that tire grip and lets the car settle, or having a low friction surface that will negate the tire friction.

[tradisrad]

Thanks Mark.
The lever arms for the scales do have rollers on them and they roll side to side under the car; with one set of wheels on the ground and the other set on the scales. Do the wheels on the lever arms act as "slider plates" and negate the tire friction?
I'll take pictures next time I have it set up.

[sean_v8_914]

square metal plate about 15 x 15 on top of similar plate with lube in teh middle
one goes under each wheel
wheels on a 914 do not move up and down whlie trackign teh same tire patch

[sean_v8_914]

rubber bushings and this sweep conspire against good readings

[tradisrad]

i've got elephant poly bronze on all 4 corners and there is no binding. the lever arms roll out from under the car when loaded & the car can rock back and forth on the balance plates; I also bounced on all 4 corners in a effort to settle the car. My results seem repeatable.

the problem I am finding is that with me in the car I can't balance it with my low spring rates.
w/o me in the car my weights were:
lf=496 rf=480
lr=568 rr=560
total 2104
I am sure I can dial this to be perfect and shift more weight up front, but it was not the goal.

put me in the car and the weights change:
lf=556 rf=508
lr=644 rr=572
total 2280

in order to lighten the left side of the car I found that lowering the left rear yielded the best results and I got minor results from lowering the right front. With this I still had a 50lb difference side to side on front and rear with the weight being on the driver side. The car sat like a lame duck (sorry no pics, it was embarrassing) with the left rear being some two inches lower than the right.

I believe the inability to shift the weight w/o having a jacked up stance is due to the low spring rates. I think if I had 300# springs I'd be able to balance, but they would kill my hemorrhoids.

Hence I think it may be in my best interest to balance the car w/o me in it. It will look/sit decent and may exhibit a minor improvement in handling (like I would really notice!).

If it is possible to balance my car with my current springs & t-bars and not have it sit totally crooked please help me!