joseph mitro

corner balanced my BMW E36 last night, and achieved a perfect 50.0% cross weight after two adjustments.

but the ride heights and rake are different from one side to the other.
for instance, left side rake is 5/8-6/8", while right side rake is 3/8".
And the LF is about 3/8" lower than RF. LF already has the most weight of any corner so I can't raise it anymore.

are these height differences irrelevant given the 50% cross weight?

Larry Herman

IMHO I wouldn't worry too much about the differences. They're not terribly bad. Could be that the car is a little twisted. The only way to know is to put it on a bench and have it checked. Any bushings in the suspension that could be collapsed?

joseph mitro

shouldn't be, they are all spherical bearings, no rubber anywhere.

my "measurement" of ride height is not super precise, so it's certainly possible the differences are not as big as they seem

PedroNole

Corner balance is more important than that little difference in the rake.

mark kibort

I think the rake comparisons are still pretty close if you are only 1/4" or so off.

If the cross weights are perfect, thats good, but if you can get side to side even as well, that is good too, especially up front. you could even fix the rake while gettting better side to side weights.
List the values and maybe we can make suggestions.

Greg Smith

It's normal, especially with cars that weren't designed ground-up as race cars.
Fixed.

fly2low

my guess, having spent $6k this winter to fix something similar is that you have a twisted body. Car now looks better - does not go faster

Veloce Raptor

Correct.

And ROFL.









Professional Racing and Driving Coach

CAM14

You did not go into detail on how you set your corner weights. Make sure your sway bars are disconnected, at least on one side, both front and rear. I’m assuming you’re adjusting your corner weight with adjustable spring perches. You can raise and/or lower your car without adjusting corner weight % by raising/lower the opposing corners the same amount. IE Left Front and Right Rear the same amount. And after every adjustment, roll the car off the scales, bounce each corner and then roll back on the scales. This will relive any bind in the suspension and tires. Lastly, as others said, a small variance is not uncommon on a street based car.

Slight change of topic, a 50% weight balance is a great starting point but might not be optimal depending on the track. For more Left had turn tracks, 50.5 might be better. You just have to test to dial in it.

Good luck and hope this help

Charles A. Toupin

Interesting info by Cam.

I like to assist when my mechanic does the corner weight. I will understand more the next time he does it!

C.

Cory M

Following all of the proper procedures I have had the same issue on a couple of production based cars, so I don't think it's vehicle specific or due to a bent frame. I didn't have the problem with the formula cars I've aligned (center seat, mid-engine). I think it is due to production cars having a less than perfect weight distribution from the factory, coupled with having the drivers weight offset to one side. If your car is light and you have a big driver you could be putting 10% of the total vehicle weight into the drivers seat. If you don't have ballast to move around then the only way to counteract that weight offset is to raise the passenger side to balance the load.

I have wondered about how big of an effect this has on your overall alignment, since the car is generally aligned with the ideal ride height then the heights are adjusted to balance. Adjusting the heights will change the static alignment settings, but I don't know how much that actually matters when you are driving the car and it's pitching, rolling, and yawing...

SAM DACOSTA

Last month I had my 964 Cabriolet 'corner balanced' and obtained a 50.7% cross balance but obtained a similar ride height/rake between sides. The rake is even better than it was before, as I always thought my front was too high, as compared to the rear. Here's what it looks like after;

analogmike

You can set the rake and heights really badly and still have perfect corner weights, corner balancing does not correlate to corner heights.

What you want to do, as CAM14 said, is to FIRST set the ride heights you want at each corner, with the sway bars off.

THEN you can do the corner balancing without changing the ride heights. You will find one diagonal is heavier than the opposite. Use the corner balancing formulas, not cross weights, for a car that is heavier on one side (most street cars) for better accuracy.

of course that's easier said than done, but if you are patient you can do it.

joseph mitro

ok thanks. I won't worry about it then.


I think what you're saying is the cross weight will not change, correct? the percentage of weight at opposing corners will change; but the cross weight will remain the same if opposing corners are lifted similarly.

my process is the standard protocol:
set starting ride height, disconnect sway bars, set alignment and tire pressures, corner balance with driver in car, ensure scales are completely level, shake car to level suspension, use adjustable spring perches, etc etc.

joseph mitro

let me see if i can remember the numbers from memory (using a ruler and rocker panels as reference):

LF - 9 6/8" RF - 10 1/8"
LR - 10 4/8" RR - 10 4/8"

weights I'll have to check at home

but by definition, corner balancing requires a change in ride heights. I'm not talking massive changes; only 1/8" to 1/4" to achieve the desired corner balance.