Scale levelling process

[Daryl DeArman]

I leave my simulated driver weight installed for the entire alignment process, certainly doing corner weights. My corner weight numbers without driver weight are massively different

Yep. Let's say that with your driver your desired corner weights are: 250 250
350 350


You obtain that and then remove the 160# driver from the equation, and unladen the corner weights are:

220 200
300 320

Now your cross weight looks out of spec (48%), your splits across the front is out of whack (20# diff) but when you put that driver right back in the car you're back at your 50% cross and 0# split across the front. Your set up could be duplicated without the need for the driver by going for the 220 - 200, 300 - 320 set up.

Same thing with alignment---if you run -2.5 camber with driver that might be -2.25 w/o, toe might change from .125" out total to .09375".

I would not even bother to check them, for any reason.

Fair enough. More than one way to skin a cat.

[DaveW]

I leave my simulated driver weight installed for the entire alignment process, certainly doing corner weights. My corner weight numbers without driver weight are massively different, and I would not even bother to check them, for any reason.

I agree. That's why I put all that weight on the car for setup. But if you're talking about biasing weight side-side, the driver weight doesn't really affect that since that weight is very close to being laterally centered.

[Daryl DeArman]

I think something is being lost here in my poor explanation. Allow me one last attempt. Here's the hypothetical:


Dave's hot set up is measured and called "Setup Dave"

We then don't do a damn thing but remove the driver weight from the car.

We now record all the scale and alignment readings and call that "Setup Unladen".

Next time we arrive at the setup platform we set up the car, unladen with "Setup Unladen".

It's the exact same setup with half the hassle.




_________________


If you measured your camber to be -2.5 at ride height and then measured it at full droop to be +2.5, and didn't change a damn thing you could set your camber at full droop at +2.5 and be golden. It will be -2.5 at the same ride height.

[problemchild]

Yes, I understand the concept ..... whether because of preloads, intentional crossweight, or stiction issues, my cornerweights change dramatically with and without driver weight. My inconsistency seems to be consistent on any of my cars. With driver weight applied, I get consistency and repetition throughout multiple sessions through an event, and can see differences by tire wear. My cars seem to work pretty well and my drivers rave about the consistency of my cars handling.

I would not consider setting cornerweights without simulated driver weight. That would be a waste of my time. Running 3 cars at an event, perhaps on the pad as many as 6 times each per event, I need to be very efficient with my time.

[DaveW]

Yes, I understand the concept ..... whether because of preloads, intentional crossweight, or stiction issues, my cornerweights change dramatically with and without driver weight. My inconsistency seems to be consistent on any of my cars. With driver weight applied, I get consistency and repetition throughout multiple sessions through an event, and can see differences by tire wear. My cars seem to work pretty well and my drivers rave about the consistency of my cars handling.

I would not consider setting cornerweights without simulated driver weight. That would be a waste of my time. Running 3 cars at an event, perhaps on the pad as many as 6 times each per event, I need to be very efficient with my time.

I think you are a magician with your setup abilities - so there is no way I can argue with you on this.

[Purple Frog]

Greg, I think you can take that to the bank.

[Daryl DeArman]

my cornerweights change dramatically with and without driver weight.

Yep, and the farther apart the drivers' CoG and the cars' CoG the more different they will be. The greater the drivers' weight the more they will change as well. Irrelevant how much they change with regards to this exercise.

My cars seem to work pretty well and my drivers rave about the consistency of my cars handling.

[problemchild]

I think, at the very least, you need enough weight to overcome the spring preload.

[DaveW]

I think, at the very least, you need enough weight to overcome the spring preload.

My thoughts exactly - I don't use preload, so that's not quite as important. But other things depend similarly on having the bellcranks, for instance, at their proper operating angle. VD's have highly-increasing front bellcrank motion ratios, and if you're not close to the position they will be at on the track, your setup can be off significantly.

[Rick Kirchner]

I believe what I was seeing was the weight CG vs driver CG situation.

[Daryl DeArman]

Apparently, not only am I bad 'splainer using my written words I'm not understanding what I'm missing.

Why would preload, bell crank angle or any other widget or doohickey matter one iota IF we make no adjustments to them between our laden/unladen process?

(A) Set up the car on platform with driver.

(B) Remove driver.

(C) Touch nothing and record all alignment and scale readings.

(D) Replace driver.

A and D scale and alignment readings will be the same unless you have other problems.

If I set up the car as measured in (C) and then insert driver I will have the same setup I had in A and D.




Maybe some are assuming that I'm implying the desired cross weight and alignment targets/goals are the same laden/unladen, they won't be. Not sure what I'm missing in my explanation or understanding of the counter argument.

[Brandon Dixon]

Apparently, not only am I bad 'splainer using my written words I'm not understanding what I'm missing.

Why would preload, bell crank angle or any other widget or doohickey matter one iota IF we make no adjustments to them between our laden/unladen process?

(A) Set up the car on platform with driver.

(B) Remove driver.

(C) Touch nothing and record all alignment and scale readings.

(D) Replace driver.

A and D scale and alignment readings will be the same unless you have other problems.

If I set up the car as measured in (C) and then insert driver I will have the same setup I had in A and D.




Maybe some are assuming that I'm implying the desired cross weight and alignment targets/goals are the same laden/unladen, they won't be. Not sure what I'm missing in my explanation or understanding of the counter argument.

With preload and droop limiting you could make massive changes to the car and the unladen weights would look identical. For instance, if the car is on the droop limit on the pad w/o the driver, you could add as much preload to that one spring without any change to the measured load at the pad. Then if you add the driver and the car compresses past the preload on at least one corner the weights would look different.

[Daryl DeArman]

With preload and droop limiting you could make massive changes to the car and the unladen weights would look identical.

Ah, got it! Thank you.

What happens if/when people run more preload than the driver weight will overcome? Are they scaling car with droop limiters removed and then replacing droop limiters at a known installed length? If droop limiters are integral to coil-overs what are they doing? Running less preload than driver weight?

[Rick Iverson]

Yep. Kirchner, build an inexpensive platten. I have plans for the one I built, if interested.

I sent you the plans

[Rick Kirchner]

Many thanks!

[Rick Iverson]

Robert, part number for the Harbor freight ramps, please.

My shop floor has drains all over the place. A nightmare ot set up four Longacre scales on the floor. Not a level spot anywhere. Built this rig with adjustable feet on the four ends of the rails (2"x2"x1/4" wall alum.). Just used a SmartLevel (Already had that camber tool) to level the rails (end to end). Then sent the two trays (3"x3"x 1/4" alum angles with 1/8" alum plate between.) on the rails. Used the SmartLevel to get both trays level side to side while on the rails. All easily done with the adjustable feet. DONE. Tape measures with a sticky side (God love Amazon) were taped to one rail for easily locating the trays for correct wheel base, and then one tape each put on the trays for easily setting the Longacre scales on the tray for various front & rear tracks. The adj. feet on the scale pads need not ever be touched again after a one-time leveling them all the same height and level front-back and side-side. Then added some gizmos on each end to hold a string. $400 vs. a $4,000 store bought rig. Oh, Harbor Freight ramps.