What is corner weighting

[genolan]

What is corner weighting, I see it all over the forum and I don't understand what it is. Also I have a Backdraft so please target your responses toward this vehicle. I live in North Jersey so who would do this or is it a easy DYI project.

[Detroit Bill]

Corner weighting is putting each tire on a scale and trying to get the pressure on each tire the same or very close front to back. Because of the nature of coil over shock adjustment you can get it out of wack when adjusting the shocks pre-load and ride height.

A race shop locally would be able to help you. The scales are around a grand.

[Bernica]

It is adjusting all 4 corners of the car while on 4-corner scales to establish an even weight distribution front to rear and corner to corner. You should be in the car when it's done (or put your equivalent weight in drivers seat) and most guys do it with 1/2 tank of gas or so. Much debate on this site about it, but for me and many others it made a noticeable difference in handling.

[Tommy]

Here's the classical way of describing it for the non-technical. Imagine a four legged table on a flat floor with all four legs the exact same length. If the table weighs 40 pounds and the weight of the table is evenly distributed, the foot of each leg will be carrying 1/4th of the weight, or 10 pounds. Now imagine that you saw a quarter inch off the bottom of one leg. The table will rock back and forth between the short leg and the one opposite it, with most of the weight being carried by the other two legs. You might find, for example, that the short leg is carrying no weight, the one opposite it is carrying 8 pounds and the other two legs are carrying 16 pounds each.

If the distribution of weight in your car AND the suspension settings are not optimized, your tires may not be carrying equal weight. Thus, when near the limits of traction (e.g., hard acceleration, braking or cornering), a tire carrying lighter weight may break loose before another. This will happen sooner if the corner weights are not balanced, and it may cause the car to change direction (left or right spin).

[patrickt]

Just skip to the last post of this lengthy thread: Best way to adjust rear coil overs for proper height on my SPF

[cycleguy55]

Originally Posted by patrickt

Just skip to the last post of this lengthy thread: Best way to adjust rear coil overs for proper height on my SPF

Direct link to the post patrickt referenced: Best way to adjust rear coil overs for proper height on my SPF

[Bernica]

Originally Posted by patrickt

Just skip to the last post of this lengthy thread: Best way to adjust rear coil overs for proper height on my SPF

I knew you would show up for this one Patrick!

[genolan]

Thanks all now it makes sense. The chair legs did it for me. Any idea what a speed shop would charge to do this?

[azsprint6]

Just to clear this weight distribution thing, when adjusting 4 corners weight transfers in an X pattern. The following numbers are just examples. If you raise the LR 2 turns it adds 20Lbs to LR and RF. Equal amounts are subtracted from the RR and LF. Get the same results with tire pressures by lowering the RR it will add weight to the LR and RF. If your car weighs 1200 in the front and 1200 in the rear NO adjustment will change this. The only way to change front to rear distribution would be to cut something off the front and weld it to the rear. Example, if you raise the rear equally 2 turns that is all you've done-raised the rear.

[wrogers55]

Disconnect both sway bars before you start the process.

[Dwight]

[WardL]

I adjusted my SPF to the recommended ride height and when I checked the corner balancing it was spot on. I have never driven my Cobra with the corner balancing off by much so can't comment on the improvement made.

[genolan]

Any idea what a speed shop would charge to do this?

[redmt]

Originally Posted by genolan

Any idea what a speed shop would charge to do this?

Not many speed shops can do it. You'll have to find a race type suspension shop for that. I charge around $100.00 for setup and weight check and hourly after that. You should look to spend a couple hundred and up.

[NRP/MN]

I have corner balanced sedan type road race cars. The method used was to match the cross weight of the RF/LR to the weight of the LF/RR. This does not yield equal weights on thr RF/LF or the LR/RR. The target is to achieve similiar cross weights to create a neutral chassis balance durng aggressive cornering. Example-a higher weight percentage on the RF/LR cross favors left hand turns. Keeping the cross weight similiar generates a setup that turns right and left with similiar handling characteristics, no oversteer or understeer when turnng right or left. However this is all fine if your spring and sway bars are perfectly chosen as they also impact "tight or loose" Performing this on a Backdraft may be a pain the #%ss as you only have coil over adjusters on the front. The rear spring is conventional (seperate from the shock). This would require spacers placed under the spring. In addition to balancing the cross weights, you also have to maintain correct ride heights, not as easy as it sounds. This can be a half days work. In addition our scales are on setup stands that are laser leveled with each other. The surface of the shop floor is not accurate to do this.

[NRP/MN]

I should have added this is done with driver or similiar weight in vehicle and sway bars disconnected. It is almost mandatory to have some form of adjustable sway bar link to reconnect without disrupting the scale work performed.

[Bernica]

Originally Posted by NRP/MN

In addition to balancing the cross weights, you also have to maintain correct ride heights, not as easy as it sounds.

Bingo!
I had one shop try it years ago and although in their minds they had it balanced, the ride height was all messed up. As stated above, not as easy as it sounds. You are wrestling with two variables. Height and balance.

[patrickt]

Originally Posted by Bernica

Bingo!
I had one shop try it years ago and although in their minds they had it balanced, the ride height was all messed up. As stated above, not as easy as it sounds. You are wrestling with two variables. Height and balance.

I would rather set the corner weights than set the valves. Provided you have a flat garage floor, and the nice digital weight scales, you just put sand bags in the seat, loosen the sway bars, and take your time with the coil over adjustments. There's no magic to it, you can let your mind wander, and you're never going to get it perfect anyway. You can go as slow as you want, it's impossible to accidentally break anything, screw anything up badly, or drop a tool down your engine. It's really a nice little weekend job.

[FatBoy]

It possibly needs re-stating that you're not trying to get all four wheels to show an equal weight. If you have a front or rear weight bias, no amount of corner balancing is going to change that.
Instead, the idea is to get the sum of the weights of the diagonal wheels to be equal i.e. LF + RR = RF + LR.
As Pat just said, it isn't rocket science, but it can be frustrating and you'll be surprised how little adjustment you need to make a big difference to the registered weight.
Get your ride height and tyre pressures set first though before you start messing around with the corner weights.
You really need to have all four wheels on the scales at the same time i.e. one under each wheel. You can't just weigh one corner at a time because you'll chase your tail forever.

Paul

[csx4017]

Here is an interesting site with some very good technical information. The first Cobra on the weight sheet is mine with 160# of fuel and a 165 # driver. I have a 46.5% F and %53.5 R bias. They have been at many Good Guys car shows with their 4 corner racing scales. They do it for no charge and provide you with a 4 corner print out. The real work is getting the cross corner weights adjusted as Patrick has indicated.



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