Nook balancing a automotive has been a type of issues that appeared off-limits to the common automotive DIY fanatic.

Yow will discover a variety of digital scales from a pace store like Summit Racing; nonetheless, a ‘respectable’ set will set you again a minimum of $1,000, and a higher-quality set will value double that.

You need to use the toilet scale hack, the place you jack the automotive up and decrease it on a set of low-cost lavatory scales. I even tried this again in 2020 with Venture Tough, my ER34 Nissan Skyline GT-T, and had… reasonable success.

To do that appropriately, you could guarantee you’re engaged on a superbly flat floor. The automotive must be as degree as doable whereas on the scales –  i.e., on some form of platform – and also you want a solution to loosen up the arms after jacking the automotive as much as transfer the scales into place.

It’s fairly the dance, and there are a number of variables the place issues can go improper. One in all my scales broke resulting from going far past the utmost weight restrict of 130kg (286lbs).

So, measuring the burden in any respect 4 corners, making any changes, and having to carry out the entire circus once more made this method removed from sensible. It appeared like devoted digital scales had been nonetheless the one viable method.

Or Is It…

Quick-forward just a few years, and I found a YouTube channel known as SuperfastMatt. Matt’s movies are as humorous as they’re insightful, and one known as I Invented a Higher Option to Weigh Your Automotive. And it’s Cheaper, Too. discusses how you should utilize leverage and a little bit of math to calculate the burden at any given nook.

You’ve a supporting block wherein a beam rests on. The supporting block is a ‘X’ distances away from the toilet scale. You’d then place the tire on the beam, and that weight transfers throughout the beam to the size. The burden might be considerably smaller, which shouldn’t max out the size. If you already know the space from the supporting block and the space to the size, you may calculate the precise weight with the worth proven by the size.

Seeing that I nonetheless had my analog scales from the primary try and a workable platform I designed for aligning automobiles, I figured I’d let my inside engineer again out to play and provides this a shot. Earlier than going full ship, I made a decision to check it on a small scale with an previous battery from the household Honda Stepwgn.

I first weighed the battery to know my goal— roughly 9.8kg (21.6lbs). The decision on these scales go away rather a lot to need.

I subsequent created a platform that might have the beam degree with the toilet scale. I recorded the size (92.2cm). We’ll name this ‘L’.

Then I positioned the battery on the beam and obtained a studying of two.9kg (6.4lbs). Nice! I’ll name that ‘Fa’ for now. Now, to calculate the distances.

In contrast to the drawing, the drive of the battery isn’t a single level on the beam, thus I made a decision to take the common of utilizing a distance from in entrance of and behind the battery – one closest to the size (L2) and one closest to the supporting block (L1). I might subtract the 2 and divide it by 2.

(L2-L1) /2 = Lm

(39cm-15.5cm) / 2 = Lm

11.75cm = Lm

With what I’m calling ‘Lm’, you may subtract that quantity from L2 and get the battery’s ‘middle’ level of drive. I’ll name this worth ‘Lf’.

L2-Lm= Lf

39cm-11.75cm= Lf

27.25cm= Lf

With Lf now decided, I can divide it by the entire size of the beam. If you already know the space relative to the beam, you may divide that quantity by the burden on the size to calculate the burden. I do know it’s getting a bit wild right here…

Fl=Lf /L

Fl=27.25cm / 92.2cm

Fl=.2955

I discovered this on the full-size take a look at, however I attempted to maintain as many numbers after the decimal place as doable to extend accuracy. It does make a distinction. With Fl, we will lastly calculate the burden of F.

F= Fa / Fl

F= 2.9kg. / 2955

F= 9.81kg

That is an error of 0.10%, which greater than proves the accuracy of this mathematical take a look at. With this strong proof of idea, it was time to scale up.

Full Steam Forward

With Venture Tough able to go, I made a decision to do an alignment, as I might use the identical platform rig for the nook balancing.

For shaken, I needed to reinstall some OEM elements, which threw my alignment out of whack.

Bringing the automotive to my home from its storage spot was one of many sketchiest drives of my life. I adjusted my laser degree to degree the platform with shims.

I used to be now able to nook steadiness Venture Tough. I obtained my lavatory scale out and ensured the beam and platform had been degree…

…And instantly bumped into an issue. Though I had calculated that if my bar had been 184cm lengthy, I might have loads of area to drive on the beam and never max out the toilet scale, the burden deflected the beam a lot that it touched the bottom. Two extrusion bars weren’t going to work.

However how about three? Seeing that I had additional extrusions from numerous tasks at that very same 184cm size, I made a decision to attempt that earlier than chopping the beams to a smaller dimension. I used to be nonetheless afraid that if I had reduce the beams too brief and pushed too far on the beam, it could max out the size, and I’d danger breaking them.

Even with three beams in place, they nonetheless bowed like loopy. This wasn’t going to work. I then remembered that I might transfer the size nearer to the automotive and use a wedge piece of wooden for the beams to relaxation on to switch the load, successfully shorting the size of the beams. All I wanted to do was zero out my scale and check out it.

With my present size (L) now shortened to 108.3cm from 184cm, the beam hardly deflected and will proceed with the experiment. The studying on the size was 42.5kg (93.7lbs) (Fa).

It was now time to calculate the varied lengths as I had completed with the battery. Nonetheless, it was harder to inform the place the contact patch was on the beam. I used a small sq. ruler and slid it below the tire till it couldn’t transfer anymore, after which marked the beam. I did this for each side to get my L2 and L1 calculations.

(L2-L1) / 2 = Lm

(20.5cm-1.1cm) / 2 = Lm

9.7cm = Lm

It wasn’t till I completed measuring every part that I noticed there was a better solution to decide the tire’s contact patch…

You possibly can press a bit of flat scrap wooden anyplace towards the tire and mark out the L2 and L1 of the tire contact patch utilizing the identical methodology. Amazingly, this methodology matched my numbers for the entrance tires (9.7cm) however was barely larger within the rear (10cm). These could be the Lm values used within the calculations.

Seeing that I can straight calculate Lm from the tire contact patch, my new equation is now this.

L2-Lm = Lf

20.5cm -9.7cm = Lf

Lf = 10.8cm

We now take Lf and calculate the drive relative to the space on the beam.

Fl=Lf / L

Fl=10.8cm / 108.3cm

Fl=.0997

Once more, hold as many locations as doable within the calculations. I saved the complete quantity on my calculator (0.099722992). Then, we will calculate the drive of the automotive at that nook.

F= Fa / Fl

F= 42.5kg.0997

F= 426.18kg

And identical to that, one nook is finished! Subsequent, roll the automotive again a bit, transfer the size to the following tire, drive up, and crunch these numbers.

When you get the dangle of it, every nook takes about 5 minutes. In fact, when you’ve got a number of scales and beams (I used to be nonetheless cautious and determined to not get extra beams to do that), you might do that entire course of in a single shot.

Listed below are the values that I got here up with after all of the calculations. In keeping with the shakensho, my Skyline ought to weigh 1,460kg (3,218lbs). I’m unsure how they obtained that quantity (moist, dry, full tank of fuel, and many others.), however I shouldn’t be too far off.

Think about a brilliant light-weight (learn: barely flimsy) FRP entrance hood, no spare tire, and some different bits right here and there, and the entire calculated weight is fairly rattling shut. Ideally, I might take Venture Tough to a spot the place I can drive and weigh the automotive, however that must wait till it’s handed its shaken inspection.

What can we do with this newfound details about Venture Tough‘s steadiness? A nook steadiness reveals your automobile’s weight distribution, which might then be manipulated to optimize dealing with. For individuals who are lifeless critical about getting the most effective lap time, you’ll manipulate this distribution by bodily eradicating weight or including ballast in strategic areas to get nearer to that ‘ultimate’ 50/50 distribution entrance to again and left to proper.

We will manipulate how a lot weight a nook receives by elevating or reducing it. Nonetheless, as one motion impacts all the opposite corners on the identical time, it isn’t doable to alter the entrance, rear, left, and proper weight percentages. So except I bodily take away, shift, or add weight, Venture Tough could have these values.

Entrance Weight % =54.06% 

Rear Weight % =45.95%

Left Weight % =53.23%

Proper Weight % =46.77% 

Observe: I didn’t simulate my physique weight (84kg/185lbs) or disconnect the sway bars. In good apply, you completely ought to do that when establishing a race automotive or a automotive with extremely stiff springs. Minor tweaks could have an even bigger impact, and also you don’t need unintended preload within the sway bars. Though Venture Tough has adjustable sway bar finish hyperlinks, and I’ve dialed them in for no preload, it isn’t a race automotive. We’re nonetheless doing this with lavatory scales no matter what number of variables we restrict.

What we can do is get our cross-weight to an excellent 50/50 scenario. At present:

(Entrance Proper (kg) +Rear Left (kg))  / Whole Weight (kg) = Cross Weight % 

 (351.83kg+340kg)  / 1439.27kg =Cross Weight % 

48.07% = Cross Weight % 

Anytime you’ve gotten a cross weight above 50%, you’ve gotten a wedge. Something beneath 50%, like Venture Tough, is a reverse wedge. Figuring out this, you may observe these guidelines to regulate the journey top to get nearer to a 50/50 distribution.

RAISING anybody nook will INCREASE the burden on that nook and barely have an effect on all different corners.

LOWERING anybody nook will DECREASE the burden on that nook and barely have an effect on all different corners.

Cross weight ABOVE 50% = DECREASE weight (top) on FR/RL or INCREASE weight (top) on FL/RR. – Wedge

Cross weight BELOW 50% = INCREASE weight (top) on FR/RL or DECREASE weight (top) on FL/RR – Reverse Wedge

Thus, I ought to work on growing the peak on the Entrance Proper – Rear Left or reducing the peak on the Entrance Left – Rear Proper. That is the place every part turns into hella-tedious. You additionally must determine how set you’re within the automobile’s journey top. Once more, the stiffer the springs, the stronger the influence minor changes will make. Nonetheless, if you’re lifeless set on how the automotive appears to be like, you might need to compromise that fifty/50 distribution.

And that’s so that you can determine. For me, as soon as I get Venture Tough again on the street, I’ll do that once more and goal to get that fifty/50 cross weight distribution. I additionally need to take a look at just a few extra suspension tasks and experiments.

This goes to point out that should you’re not afraid of a bit of little bit of math, you may unlock potential and information that might in any other case be locked behind costly tools. It did take some refinement, and this nonetheless received’t be as correct as an excellent set of digital scales, however not like my first try at nook balancing with scales, it was a hit.

Digital scales would nonetheless be glorious, although…

Ron Celestine
Instagram: celestinephotography