Need a little help figuring something out

[83hurstguy]

I am a fan of the coil overs, for sure. If you go the ridetech route, we could install the same digressive valving in the front shocks that Lance has, which is a key reason it turns so well in the middle of the corners, when other cars are tight/pushy.

Thanks Ron. I probably shouldn't keep highjacking Lance's thread here, though this question may be pertinent to others interested. Looking at the budget, I'd be limited to single adjustable coilovers this year. The triple adjustables nearly double the price over the singles. What are your thoughts on having the singles vs waiting a year or more to swing the triples?

[Ron Sutton]

Thanks Ron. I probably shouldn't keep highjacking Lance's thread here, though this question may be pertinent to others interested. Looking at the budget, I'd be limited to single adjustable coilovers this year. The triple adjustables nearly double the price over the singles. What are your thoughts on having the singles vs waiting a year or more to swing the triples?

Hmmm. Good question.

I have raced a lot of series that only allowed us single adjustable shocks (as a cost control measure). We always choose rebound adjustable shocks of course. The reasoning is this:
* You can "tune" the compression of the suspension with springs.
* You can not tune the rebound of the suspension with springs.
* So if going single adjustable ... rebound adjustable shocks are the clear choice.

In racing, if the suspension is compressing too quickly, we simply change to a 25# stiffer spring ... and vice versa if too slow. But again, utilizing the adjustable rebound valving to control the extension of the shocks is major.

Double or triple adjustable shocks are preferred ... when budget is not an issue ... because you can adjust on the shock instead of changing a spring (to a degree). And, you can "fine tune" the compression rate in between spring rates.

So, Double or triple adjustable shocks are "nice" if you can afford them. Single adjustable shocks will achieve 80% of what you need to tune. Me? I'd buy the singles and rock on now. Your call.

[AutoX_a_Truck?]

I am a fan of the coil overs, for sure. If you go the ridetech route, we could install the same digressive valving in the front shocks that Lance has, which is a key reason it turns so well in the middle of the corners, when other cars are tight/pushy.

Hi Ron, I sent you a PM, but I am not sure if it went through but I also see you are busy starting a business. I have ridetech Triple Adjustable Coilovers on my Scout II, which uses a modified S10 front suspension somewhat similar to a g-body. I have aftermarket control arms and other components, but obviously my S10 based setup is currently less than ideal compared to some of the other high dollar stuff out there. When building my hot rod most of the parts and design fell into place based on what was available or what fit. My Dad and I recently mapped out the front suspension, which revealed slight differences side to side, probably from factory tolerances and 30 years of abuse. Anyway, without further hijacking this great thread, I have had a heck of a time trying to eliminate push in the middle of corners, particularly tight autoX corners. This thread inspired me and gave me hope that I might be able to wring quite a bit more out of my budget setup.

[Ron Sutton]

Hi Ron, I sent you a PM, but I am not sure if it went through but I also see you are busy starting a business. I have ridetech Triple Adjustable Coilovers on my Scout II, which uses a modified S10 front suspension somewhat similar to a g-body. I have aftermarket control arms and other components, but obviously my S10 based setup is currently less than ideal compared to some of the other high dollar stuff out there. When building my hot rod most of the parts and design fell into place based on what was available or what fit. My Dad and I recently mapped out the front suspension, which revealed slight differences side to side, probably from factory tolerances and 30 years of abuse. Anyway, without further hijacking this great thread, I have had a heck of a time trying to eliminate push in the middle of corners, particularly tight autoX corners. This thread inspired me and gave me hope that I might be able to wring quite a bit more out of my budget setup.

Glad you have "hope." If you want to discuss your numbers, set up & handling issues, start a new thread & PM me with a link.

[SSLance]

Ever since the first time I tried to do a "performance" alignment on my car, I ran into an issue getting all of the negative camber I wanted because my upper control arm bolts weren't long enough. Yesterday I remedied that situation.

Here's what the passenger side looked like with 0.6 degrees of negative camber...



See the back bolt there has no threads sticking out of the nut...we even took the washer out between the nut and the control arm to get every last bit we could out of it.

I took the control arm loose and used a C-clamp to press the bolt out of the frame. Here is the factory bolt and it's new replacement side by side. The new bolt is a class 10.9 12mm x 1.75 70mm long, about 15mm longer than the stock bolt.



The rest of the parts for the day



I had the inner fenders out because of my body bushing swap project so I figured it was the easiest time to do this as well but I'm not ready to do a new alignment at the time, so my plan was to just put shims back in place to set the alignment back where it was for now.

I put the bolts in the frame and then ran nuts down and snugged the bolts up tight. I ordered bolts fully threaded because I wanted to be able to use nuts to hold the bolts in place. I then put a couple of washers on the bolts and a shim or two to get the thickness that matched the stack of shims I took out.



It took some finagling to get everything in place as I had to hold the UCA in place (still attached to the spindle), run the bolts in, start the nuts and run them down as they drew the bolts through the cross bar. The cross bar would not go over the bolts once they there bolted to the frame first due to the headers.

Lots of thread available now for any adjustment I might need...



Snugged up tight



Before I put the inner fenders back in, I went ahead and did the driver side as well. I've never ran out of threads on this side, but figured just in case...might as well do it now.



On the back bolt, there weren't enough shims to make up the thickness of the nut so I left it out. When it comes time to align it like it needs to be, if there is room then for a nut I'll put one in.

[Ron Sutton]

Looking Good Lance.

Now that you have solid body mounts & more UCA adjustability ... what's next ?

[SSLance]

Pretty much ever since I have had this Quick Performance 9" rear axle, I have fought the passenger side axle seal (or the lack thereof) leaking rear end gear oil. QP uses a Moser Billet Torino style (big Ford) axle end and Moser axles with sealed bearings pressed on them. Their thought is the sealed bearing will stop the gear oil from leaking...it doesn't.

I finally learned that there is a step down inside the end that a National part #473229 seal fits into so I picked a couple of them up last week. Here is what the axle end looks like.



and here is what it looks like with the seal pressed into place.



ID of the seal is 1.5" which matches the axle. Sure hope it works...

I cleaned a LOT of leaked gear oil up today. And I just LOVE the smell of gear oil.

Also put a new E-brake cable on the passenger side and test drove the car.



Everything feels pretty good but it was hard to make a comparison with those old stock size tires on the car, need to get my new rims cleaned up and sealed and some new rubber on them then really take it for a shake down run.

[SSLance]

Now that you have solid body mounts & more UCA adjustability ... what's next ?

Well... The test drive went okay, glad the car is back down on all fours again. First time I've driven it on stock sized rubber in a while though, that was entertaining!!!

I think I'm about ready to four corner scale the car and see if the springs need any adjusting... Then I'll get my Joe's Racing camber\caster tool out and work on the alignment a bit more. Should one of those be done before the other? Or does it not really matter.

I won't have my new tires on my aluminum rims for a while yet, so I plan on doing both with my stock tires on since they are all four the same size. The tires I have on my aluminum rims are staggered in both width and height and the new tires will be the same on all four. Still working my way around what's best to do there in the meantime.

I know I'll be able to adjust (fine tune) the alignment specs after I get my new tires in and mounted, but not sure if I'll still have scales available then.

Once the four corner weights and alignment is set, then all I have left to do is some interior add ons, a good cleaning, and a nut and bolt check on everything again and I'll be ready for race season to start.

[SSLance]

Last weekend I adjusted my front end alignment, bolted my aluminum rims and good street rubber (for now) to the car and did some extensive test driving on the street. I had an interference issue with the drive shaft loop I had to correct right away, a light raise in body height and a 2 degree lowering of the pinion angle was the cause and a couple of washers used to space the loop down was the cure.

I put a bit too much static camber in the car and the steering got pretty heavy. Was surprised how that camber added more of a heavy feel than the large amounts of caster I have added before.

I went from -0.6 camber \ +9.25 caster to -1.6 camber \ +8.75 caster

When I get back under the car I'm going to pull a shim from each of the front UCA bolts and try to take the same amount of camber out of each side while increasing the caster to try to get it back over +9.00 degrees.

The car drives real well, is vibration free, and it just felt good to be behind the wheel of it again. I stuck my GoPro under the front and checked out the frame flex under some side to side cuts made at about 45-50 mph and here are the results.





So it looks like to me from this video that with just the new PolyGraphite #1 bushings clamped down tight, the frame doesn't want to slip back and forth under the bushings like with the old wore out rubber bushings...it just kind of tilts side to side just a bit.

Those were some pretty hard cuts back and forth at about 45-50 mph. Not really the total force that the frame will see under an extreme autocross corner, but probably close.

If the top of the frame is secure against the core support and not moving side to side and the bottom of the frame is moving just ever so slightly, that has to drastically correct the steering input feel during cornering.

I'm wondering how a beefier brace designed such as the Speedtech brace or the SC&C brace would help in tightening up the little bit of frame twist still evident (or if it should even be a concern to me right now)?

[Ron Sutton]

If the top of the frame is secure against the core support and not moving side to side and the bottom of the frame is moving just ever so slightly, that has to drastically correct the steering input feel during cornering.

I'm wondering how a beefier brace designed such as the Speedtech brace or the SC&C brace would help in tightening up the little bit of frame twist still evident (or if it should even be a concern to me right now)?

As you know, even full frame cars are flexi-flyers without additional support & bracing. I say "as you know" because you saw how much the frame sagged in the front when lifted on a 2-post lift.

Chassis rigidity plays such a big role in performance. You definitely want to improve it where you can. The challenge becomes:
a. Finding products that work well. (like your bushings made a huge diff)
b. Or, making them (like braces, reinforcement items, etc.)
c. Not adding a ton of weight in the process.

I think the Speedtech is 1.5" tubing & the SC&C is 1.25". I'd lean towards the stiffer version .

[SSLance]

Tyler, how much does your front suspension travel under hard braking? Is it more of a typical stiff spring autocross setup or a high travel\ low roll setup like we are steering my car towards?

I know it sits pretty low in grid, but never watched it close enough on the track to see how far it travels.

[AutoX_a_Truck?]

I believe that my front end would be considered a “Tweener” setup. Taking actual shock travel measurements at an event or by simulating event conditions is a priority once the weather is better. But for now I can only estimate based on videos, pictures, and jouncing the front end that my front shocks can compress and extend about 2.5” each way.

I have a few holes for adjustment in my motion ratio, but the current setting is approximately a .578 ratio so I think that would mean almost 4.25” of compression travel at the wheel? That’s with the 4.1” stroke coilover (10.125” compressed & 14.225” extended) running a 10” tall 2.5” ID 450 lbs/in spring.

I have the long stroke coilovers on the rear, but the axle bottoms out on the frame notch after just 2” of compression. That’s with the 6.9” stroke coilover (13.125” compressed & 20.025” extended) running a 12” tall 2.5” ID 150 lbs/in spring.

I have managed to scrape the front cross member (4 ¼” static ride height) on a few occasions, and I had to slightly raise the ride height with the Scout II body compared to the truck body to keep from ripping my rocker panels off.

I wish I had my own set of corner scales, but I do not so in the past I have had to rely on borrowing a set from a local racer for a small fee or using the ridetech booth at shows. The only time I have corner scaled the setup with the Scout body was using ridetech’s scales at a show. An accurate race weight with driver was 2,805 lbs, but the front to rear split was not accurate because the scales were not 100% level but slightly downhill. Based on this, I think 1,460 lbs on the front and 1,345 lbs on the rear are good ball park estimates. I hope to get more accurate numbers soon.

I am also battling a somewhat high scrub radius due to running an 11” wide wheel with just 4.25” backspacing. Using the method in post #77 scrub radius measured 4 13/32”

Finally, the S10 spindle steering arm geometry has always annoyed me because it’s front steer and the arm is actually angled forward toward the centerline of the front of the frame because the tie rod must clear a tire (for small diameter stock style wheels) or in my case the wheel itself. Moving the tie rod end outward any further will require shortening the steering arm at least an inch or two so that it can clear the rim lip and barrel, but I have not quite been able to determine whether this is feasible or not.

[UMI Tech]

Hey Tyler.

Side note: I know if you showed up at my oval track shop with your truck you'd be welcome to my scales anytime.

ramey

[SSLance]

During the tail end of last season's racing after the installation of Stage 2 of Ron's setup on my car, one thing that kept holding me back from really experiencing the true results from all of our work was having unequal or inadequate tires on my car. On the street I was running smaller (245/40/17s) brand new BFG Rivals on the front and wore out 275/40/17s Nitto 555s on the back and to try to equal things out and get a bit more traction on the autocross course I was running race used cast off 275/60/16 Hoosier A6s on all four corners.

Racing with the Hoosiers allowed equal grip on all four corners and they stuck pretty well, but the size of them, especially being mounted on 16" wheels wasn't the most optimum solution either, plus towards the end of the season I'm certain they had been cycled a few too many times and were giving up grip as well.

I was looking for a 200 TW tire to run on all four corners since I'll be racing in the Classic American Muscle class this year on street tires, but the options were limited because of my 17" rims and I wasn't too fond of the idea of replacing all of my wheels just to open up my tire choice.

I finally decided to buy two more 17x9.5" wheels that match my current wheels and four Falken 615K 275/40/17s and I'll run all four of them for a square setup during my race days this upcoming season. Having the same wheel and size of tire on all four corners will help me keep their wear even by allowing rotation plus help with shock setup. Also, I still have my 8" rims with the almost new Rivals on them that I can mount on the front for street driving to help reduce the wear on my Falkens. This is the first time in over a year that I'll have a brand new set of matched tires with equal grip on all four corners of the car. I got the tires mounted up last Friday and installed over the weekend. I was able to get a little bit of road testing in and man, what a difference new tires make. I can't wait to get to a Test N Tune to really dial in the shock settings with the new gription on both ends of the car and really begin to feel what this car will now do.

Here are some comparison shots of the old vs the new, first one shows the old Hoosier A6 on the right and the new Falken on the left.







As you can see they are very similar in overall size, the actual tread width on the Falken is about a half inch wider than the Hoosier. The huge difference is in the sidewall height. I'm betting that these Falkens will grip just as well as the Hoosiers did at the end of last year. I know already that the street manners are a big improvement with them.

Here are a few more pics of them installed on the car.







Other projects also completed in the off season to address deficiencies found with the car last year include replacing all of the 28 year old wore out body bushings with new PolyGraphite bushings (and repairing two frame mount holes), repairing a leaky rear axle seal, replacing the power steering pump and adding a PS fluid cooler, and extending the front upper control arms bolts to allow for better front alignment specs to be reached. I also replaced all of the front brake components while upgrading the calipers to Afco 2.75" piston units and the pads to EBC YellowstuffR.

The car is roadworthy once again and I still plan on four corner weighing the car to fine tune the coil over spring heights for proper weight balance and putting it on a digital alignment rack for one final fine tuning of the alignment before our first event April 6th. There is talk of an opportunity for a Test N Tune possibly in the next few weeks where I'll dial in the ridetech Triple Adjustable shock settings to work with the rest of the off season enhancements...then I am looking forward to a season of racing the car without having to deal with a different setup in the car at nearly every event. .

I plan on working on the driver more this year than the car...I'll keep everyone posted on how that goes during the year.

[SSLance]

So all of the rest of my pertinent off season improvements are done now and in place so now it's time to fine tune the corner weights.

Ron if you have time and check in on this thread, can give me (us) a quick overview of what I should be looking for and the best plan to achieve the results we need? I'll most likely be heading to a friend's shop and borrowing his scales and floor jack, so I'll weighing and making the adjustments there.

I don't imagine that it will be a big deal, the car was pretty even side to side the last time I weighed it and I haven't changed much weight wise since.

I'm assuming say the LF and RF are 1075# and 1025# respectively, I would tighten or raise the RF spring adjuster a bit, effectively putting more pressure on the spring and more weight on that tire? Where I'm a bit unclear is how the rear weights play into this equation (wedge)?

Or is it more of a scenario of looking at all 4 corner weights and then figuring out which one to raise or lower to make both the front and rear balanced side to side?

And how close to balanced side to side should I be looking to get it? With all four corners adjustable, will I be able to dial the weights in to a gnat's arse side to side no matter how unbalanced the car is to start out?

Looking forward to your input on this when you have some free time.

Thanks,
Lance

[Norm Peterson]

Lance - it's probably better if you can adjust each of all four corners a little than to try to do it all at one corner. This results in smaller changes in geometry and available suspension travel if nothing else. You'll be increasing corner weight at two diagonally opposite corners and decreasing it at the other two.

You can't alter the left side (or rear) percentage of total weight unless you physically move stuff around.


Norm

[Ron Sutton]

Lance - it's probably better if you can adjust each of all four corners a little than to try to do it all at one corner. This results in smaller changes in geometry and available suspension travel if nothing else. You'll be increasing corner weight at two diagonally opposite corners and decreasing it at the other two.

You can't alter the left side (or rear) percentage of total weight unless you physically move stuff around.


Norm

Agreed.

.

[Ron Sutton]

So all of the rest of my pertinent off season improvements are done now and in place so now it's time to fine tune the corner weights.

Ron if you have time and check in on this thread, can give me (us) a quick overview of what I should be looking for and the best plan to achieve the results we need? I'll most likely be heading to a friend's shop and borrowing his scales and floor jack, so I'll weighing and making the adjustments there.

I don't imagine that it will be a big deal, the car was pretty even side to side the last time I weighed it and I haven't changed much weight wise since.

Looking forward to your input on this when you have some free time.

Thanks,
Lance

Hi Lance,

Glad to help …
Let's start with getting the scales level & located properly to achieve accurate numbers. I use a what is called a scale platen to roll the cars on that has been leveled in every direction & locked down. Most guys don't have access to something like this, so let's talk about how to properly scale a car on the garage floor.

Tip #1: Take your time & get this right. The info that comes out of this is only as good as the accuracy of the scaling.

Tip #2: Yes, 1/8" is a big deal. I've seen garage floors off 1/2".

Getting the scales ready ...
a. Find spots on the garage floor to match the track width & wheel base of the car. IIRC yours is 108" wb … 58.9" front track width … and I don’t remember the rear track width but figure it out. Place the scales in a rectangle on the floor, dead center to those measurements.

Using a laser pointer or long, straight, non-bowed, stiff piece of tubing, make sure the scale pads are square to each other. Use blue masking tape to outline the four sides of the scales ... in the exact location they need to be on the floor. Now, during the process, when you knock scales around, you can always go right back to the correct spots.

b. All 4 scale pads need to be at the exact same height.
Using a laser level or long, straight, non-bowed, stiff piece of tubing & a level (digital is preferred as it will be more accurate) ... determine which pad is highest. Then using 16"x16" vinyl floor tile squares (Home Depot?) ... and thin pieces of 16"x16" sheet metal of different thicknesses ... shim the low pads to match the height of the tallest pad.

c. You want the pads themselves to be level too. So if the floor dips so much it causes a scale pad to sit at an angle, you may want to pick another spot, or put shims under the low end.

You want to end up with the scales:
* Centered for track width & wheelbase
* Level & level to each other
* Square to each other & outlined with tape

Grease Plates:
Anytime you jack & lower the front suspension, the tires will "bind" from rubber friction on the scales. This will sometime move the scales ... sometimes not. But it will always give you false ride height & scale numbers. So you need to prevent this "tire bind."

Make four square pieces of thin sheet metal somewhere around 12"x12" to 15"x15". I use .040" thick aluminum, because we have it around the shop often. Put a fine, thin, even film of grease on one side of two plates. Lay another plate on top of the greased up plates ... and you have two sets of "grease plates."

Lay these centered on top of the scales for the front tires.

Now you can move the scales (shims & all) out of the way ... roll the car into place so the tires are centered in the tape squares ... jack one side (or one end) of the car up & place the scales in their tape boxes ... repeat on the other side (or other end).

In the real world, the car never ends up centered and the scales and/or grease plates are out of their boxes. Jack & move stuff until the scales are in their boxes & all four tires are centered on the scales & grease plates.

Prepping the car:
a. Put the fuel level in it you plan to compete with.
b. Air the tires up to the pressure you plan to compete with, or at least the same.
c. Put weight in the driver seat to match the driver's weight with helmet & gear.
d. Make sure the tires are dead true straight ahead. If you have toe-out, make sure both are evenly toed out.
e. For now … unbolt one side of the sway bar linkage, on both front & rear bars, so they don’t affect our numbers.
f. Mark a spot on the frame at all 4 corners where you will measure ride height … and measure ride height before you start. Write them down.

Now, you can read the scales & see where you are. Write these numbers down, before you start making adjustments. I suggest you write down all your ride heights, adjustments & scale readings (with dates) from those changes and keep in a file folder. You'll need the info someday.

Ok … before we make any adjustments … are the car's ride heights level side to side? If not, we need to fix this & the weights together. Never tweak on the adjusters to “hit a scale #” without keeping the ride heights correct. I prefer to get the ride heights even side to side … and the desired rake front to rear … then tune on the adjusters to achieve my scale numbers.

Here’s how …assuming your ride heights are even side to side:
• If you need to add cross weight (make the LR & RF heavier) adjust the spring adjusters to raise the LR & RF … and to lower the RR & LF … by the same amounts.
• In other words if you turned the spring adjusters to raise the LR & RF by 1 full turn … turn the spring adjusters to lower the RR & LF by same 1 full turn.
• This will keep the ride heights “pretty close”.
• When you get down to the gnat’s eye, you’ll need to tweak them individually … but not by much.
• We almost always keep the ride heights level side to side for road course & autocross competition. There are exceptions, but not worth discussing here.

I'm assuming say the LF and RF are 1075# and 1025# respectively, I would tighten or raise the RF spring adjuster a bit, effectively putting more pressure on the spring and more weight on that tire? Where I'm a bit unclear is how the rear weights play into this equation (wedge)?

Or is it more of a scenario of looking at all 4 corner weights and then figuring out which one to raise or lower to make both the front and rear balanced side to side?

And how close to balanced side to side should I be looking to get it? With all four corners adjustable, will I be able to dial the weights in to a gnat's arse side to side no matter how unbalanced the car is to start out?

We only care about the numbers with the driver ... unless it's going to be a drone.

So for discussion sake, let’s say the scales read ...
LF 1075# RF 1025#
LR 900# RR 900#

Results:
3900# Total weight
53.85% Front Weight Bias
50.64% Left Side Weight Bias
49.36% Cross weight or “wedge”
* As a “standard” tuners add up the weights of the LR & RF for a percentage.


This is where tuners differ. Some will adjust the spring adjusters to achieve 50.0% cross weight.

That would look like this:
LF 1062# RF 1038#
LR 913# RR 887#
* Remember, check your corner ride heights.

Results:
3900# Total weight
53.85% Front Weight Bias
50.64% Left Side Weight Bias
50.00% Cross weight or “wedge”

The problem with this strategy is the heavier left side weight will make the car roll less & have more grip on left hand corners & roll more & have less grip on right hand corners. An ideal solution would be to physically move weight from the left side of the car to the right side of the car.

Because ultimately an autocross or road course track car will perform best if the side-to-side weight bias is 50/50 … and the cross weight is 50/50. But for many street cars, that is not practical. The best “compromise” solution that will produce the best handling (if the left side is heavier) is to run less cross weight than 50%.

I’d love to tell you the formula is XYZ. But in reality, every car is a bit different. I do however have a proven rule of thumb. And that is the cross weight & left side weight need to add up to 100.0%. So if the car’s left side weight (with driver) is 50.64% … then we need to reduce the cross weight from 50.0% to 49.36%.

Hey wait a minute … that’s where we started in this example. Yup … the 50.64% Left Side Weight Bias & 49.36% Cross weight kind of balance each other out. It’s just an experienced starting point. Because you have other factors in your car that may make it have more grip one direction & less grip the other.

So driving it hard in autocross competition & tuning it are what I suggest to achieve optimum balance for your car. More cross weight (heavier loaded LR & RF) will add grip turning left & free the car turning right. Less cross weight (heavier loaded RR & LF) will add grip turning right & free the car turning left.

You … and everyone with adjustable spring heights … have the ability to fine tune this and achieve the best balance.

After you scale it, post your numbers & let’s discuss it.

[SSLance]

I have secured the use of a set of scales and plan on 4 corner weighing my car once again (this time properly, at my own shop not in a hurry) in a couple of days. I had to go find this post to print out the instructions again so I thought I'd bump it up just in case anyone else might need it once again.

Hi Lance,

Glad to help …
Let's start with getting the scales level & located properly to achieve accurate numbers. I use a what is called a scale platen to roll the cars on that has been leveled in every direction & locked down. Most guys don't have access to something like this, so let's talk about how to properly scale a car on the garage floor.

Tip #1: Take your time & get this right. The info that comes out of this is only as good as the accuracy of the scaling.

Tip #2: Yes, 1/8" is a big deal. I've seen garage floors off 1/2".

Getting the scales ready ...
a. Find spots on the garage floor to match the track width & wheel base of the car. IIRC yours is 108" wb … 58.9" front track width … and I don’t remember the rear track width but figure it out. Place the scales in a rectangle on the floor, dead center to those measurements.

Using a laser pointer or long, straight, non-bowed, stiff piece of tubing, make sure the scale pads are square to each other. Use blue masking tape to outline the four sides of the scales ... in the exact location they need to be on the floor. Now, during the process, when you knock scales around, you can always go right back to the correct spots.

b. All 4 scale pads need to be at the exact same height.
Using a laser level or long, straight, non-bowed, stiff piece of tubing & a level (digital is preferred as it will be more accurate) ... determine which pad is highest. Then using 16"x16" vinyl floor tile squares (Home Depot?) ... and thin pieces of 16"x16" sheet metal of different thicknesses ... shim the low pads to match the height of the tallest pad.

c. You want the pads themselves to be level too. So if the floor dips so much it causes a scale pad to sit at an angle, you may want to pick another spot, or put shims under the low end.

You want to end up with the scales:
* Centered for track width & wheelbase
* Level & level to each other
* Square to each other & outlined with tape

Grease Plates:
Anytime you jack & lower the front suspension, the tires will "bind" from rubber friction on the scales. This will sometime move the scales ... sometimes not. But it will always give you false ride height & scale numbers. So you need to prevent this "tire bind."

Make four square pieces of thin sheet metal somewhere around 12"x12" to 15"x15". I use .040" thick aluminum, because we have it around the shop often. Put a fine, thin, even film of grease on one side of two plates. Lay another plate on top of the greased up plates ... and you have two sets of "grease plates."

Lay these centered on top of the scales for the front tires.

Now you can move the scales (shims & all) out of the way ... roll the car into place so the tires are centered in the tape squares ... jack one side (or one end) of the car up & place the scales in their tape boxes ... repeat on the other side (or other end).

In the real world, the car never ends up centered and the scales and/or grease plates are out of their boxes. Jack & move stuff until the scales are in their boxes & all four tires are centered on the scales & grease plates.

Prepping the car:
a. Put the fuel level in it you plan to compete with.
b. Air the tires up to the pressure you plan to compete with, or at least the same.
c. Put weight in the driver seat to match the driver's weight with helmet & gear.
d. Make sure the tires are dead true straight ahead. If you have toe-out, make sure both are evenly toed out.
e. For now … unbolt one side of the sway bar linkage, on both front & rear bars, so they don’t affect our numbers.
f. Mark a spot on the frame at all 4 corners where you will measure ride height … and measure ride height before you start. Write them down.

Now, you can read the scales & see where you are. Write these numbers down, before you start making adjustments. I suggest you write down all your ride heights, adjustments & scale readings (with dates) from those changes and keep in a file folder. You'll need the info someday.

Ok … before we make any adjustments … are the car's ride heights level side to side? If not, we need to fix this & the weights together. Never tweak on the adjusters to “hit a scale #” without keeping the ride heights correct. I prefer to get the ride heights even side to side … and the desired rake front to rear … then tune on the adjusters to achieve my scale numbers.

Here’s how …assuming your ride heights are even side to side:
• If you need to add cross weight (make the LR & RF heavier) adjust the spring adjusters to raise the LR & RF … and to lower the RR & LF … by the same amounts.
• In other words if you turned the spring adjusters to raise the LR & RF by 1 full turn … turn the spring adjusters to lower the RR & LF by same 1 full turn.
• This will keep the ride heights “pretty close”.
• When you get down to the gnat’s eye, you’ll need to tweak them individually … but not by much.
• We almost always keep the ride heights level side to side for road course & autocross competition. There are exceptions, but not worth discussing here.





We only care about the numbers with the driver ... unless it's going to be a drone.

So for discussion sake, let’s say the scales read ...
LF 1075# RF 1025#
LR 900# RR 900#

Results:
3900# Total weight
53.85% Front Weight Bias
50.64% Left Side Weight Bias
49.36% Cross weight or “wedge”
* As a “standard” tuners add up the weights of the LR & RF for a percentage.


This is where tuners differ. Some will adjust the spring adjusters to achieve 50.0% cross weight.

That would look like this:
LF 1062# RF 1038#
LR 913# RR 887#
* Remember, check your corner ride heights.

Results:
3900# Total weight
53.85% Front Weight Bias
50.64% Left Side Weight Bias
50.00% Cross weight or “wedge”

The problem with this strategy is the heavier left side weight will make the car roll less & have more grip on left hand corners & roll more & have less grip on right hand corners. An ideal solution would be to physically move weight from the left side of the car to the right side of the car.

Because ultimately an autocross or road course track car will perform best if the side-to-side weight bias is 50/50 … and the cross weight is 50/50. But for many street cars, that is not practical. The best “compromise” solution that will produce the best handling (if the left side is heavier) is to run less cross weight than 50%.

I’d love to tell you the formula is XYZ. But in reality, every car is a bit different. I do however have a proven rule of thumb. And that is the cross weight & left side weight need to add up to 100.0%. So if the car’s left side weight (with driver) is 50.64% … then we need to reduce the cross weight from 50.0% to 49.36%.

Hey wait a minute … that’s where we started in this example. Yup … the 50.64% Left Side Weight Bias & 49.36% Cross weight kind of balance each other out. It’s just an experienced starting point. Because you have other factors in your car that may make it have more grip one direction & less grip the other.

So driving it hard in autocross competition & tuning it are what I suggest to achieve optimum balance for your car. More cross weight (heavier loaded LR & RF) will add grip turning left & free the car turning right. Less cross weight (heavier loaded RR & LF) will add grip turning right & free the car turning left.

You … and everyone with adjustable spring heights … have the ability to fine tune this and achieve the best balance.

After you scale it, post your numbers & let’s discuss it.

There have been some other goings on with my new setup while getting it ready for the SCCA Nationals this coming weekend. I'll update the class more a bit later on when I get some time. It's been interesting for sure...

[SSLance]

Thanks Ron, that gives me a better understanding of what I'm gunning for here.

So cross weight or wedge is always LR + RF / total weight and the goal is to get the cross weight % plus the left side weight % to add up to 100%.

We have a private autocross test n tune scheduled for next Monday the 17th on an asphalt parking lot where we'll have a full course set up with timing equipment and all day to make runs, make changes, and see the effects on the times.

We then have a test n tune at MCC where we run our normal events on April 5th the day before our first official event on the 6th.

Hopefully I can get it weighed and primarily adjusted this week before the first tuning session, then test for left vs right turn grip there. I've got the ride heights set exactly where we like them and the fronts and rears are even side to side already. Hopefully it doesn't take too much adjustment from there.

Do the shock settings matter when weighing? Should I have them set at the race settings or is it okay to weigh it with them set on the street settings? Since I'm borrowing the scale setup (and will most likely do it at my friend's shop) I'm hoping to get it done as quickly as possible to keep the hindrance level to a minimum for him. Busy time of the year here for sure with everyone trying to get their race cars ready for the season.