Nook balancing a automobile has been a kind of issues that appeared off-limits to the common automotive DIY fanatic.
Yow will discover a variety of digital scales from a velocity store like Summit Racing; nonetheless, a ‘respectable’ set will set you again not less than $1,000, and a higher-quality set will value double that.
You should use the lavatory scale hack, the place you jack the automobile up and decrease it on a set of low-cost toilet scales. I even tried this again in 2020 with Venture Tough, my ER34 Nissan Skyline GT-T, and had… average success.
To do that appropriately, you will need to guarantee you might be engaged on a wonderfully flat floor. The automobile must be as degree as attainable whereas on the scales – i.e., on some type of platform – and also you want a option to loosen up the arms after jacking the automobile 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 flawed. One in every of my scales broke as a result of 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 system removed from sensible. It appeared like devoted digital scales had been nonetheless the one viable strategy.
Or Is It…
Quick-forward just a few years, and I found a YouTube channel referred to as SuperfastMatt. Matt’s movies are as humorous as they’re insightful, and one referred to as I Invented a Higher Option to Weigh Your Automotive. And it’s Cheaper, Too. discusses how you should use leverage and a little bit of math to calculate the burden at any given nook.
You’ve got a supporting block through which a beam rests on. The supporting block is a ‘X’ distances away from the lavatory scale. You’d then place the tire on the beam, and that weight transfers throughout the beam to the dimensions. The burden might be considerably smaller, which shouldn’t max out the dimensions. If you understand the gap from the supporting block and the gap to the dimensions, you may calculate the precise weight with the worth proven by the dimensions.
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 interior 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 depart lots to need.
I subsequent created a platform that might have the beam degree with the lavatory scale. I recorded the size (92.2cm). We are going to 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.
Not like the drawing, the pressure 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 dimensions (L2) and one closest to the supporting block (L1). I’d 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 ‘heart’ level of pressure. 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 whole size of the beam. If you understand the gap relative to the beam, you may divide that quantity by the burden on the dimensions 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 realized this on the full-size check, however I attempted to maintain as many numbers after the decimal place as attainable 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 check. 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’d 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 automobile 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 toilet 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’d have loads of house to drive on the beam and never max out the lavatory 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 further extrusions from numerous initiatives at that very same 184cm size, I made a decision to strive that earlier than slicing the beams to a smaller measurement. I used to be nonetheless afraid that if I had minimize the beams too brief and pushed too far on the beam, it could max out the dimensions, and I’d threat 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 dimensions nearer to the automobile 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 dimensions was 42.5kg (93.7lbs) (Fa).
It was now time to calculate the assorted lengths as I had executed with the battery. Nevertheless, it was tougher to inform the place the contact patch was on the beam. I used a small sq. ruler and slid it underneath 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 thing that I noticed there was a better option to decide the tire’s contact patch…
You possibly can press a bit of flat scrap wooden wherever in opposition to the tire and mark out the L2 and L1 of the tire contact patch utilizing the identical technique. Amazingly, this technique matched my numbers for the entrance tires (9.7cm) however was barely increased within the rear (10cm). These could be the Lm values used within the calculations.
Seeing that I can immediately 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 pressure relative to the gap on the beam.
Fl=Lf / L
Fl=10.8cm / 108.3cm
Fl=.0997
Once more, preserve as many locations as attainable within the calculations. I saved the whole quantity on my calculator (0.099722992). Then, we will calculate the pressure of the automobile at that nook.
F= Fa / Fl
F= 42.5kg.0997
F= 426.18kg
And similar to that, one nook is finished! Subsequent, roll the automobile again a bit, transfer the dimensions to the subsequent tire, drive up, and crunch these numbers.
When you get the hold of it, every nook takes about 5 minutes. After all, in case you have a number of scales and beams (I used to be nonetheless cautious and determined to not get extra beams to do that), you can do that complete course of in a single shot.
Listed here are the values that I got here up with after all of the calculations. In accordance 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.
Consider a brilliant light-weight (learn: barely flimsy) FRP entrance hood, no spare tire, and some different bits right here and there, and the whole calculated weight is fairly rattling shut. Ideally, I’d take Venture Tough to a spot the place I can drive and weigh the automobile, 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 exhibits your automobile’s weight distribution, which may then be manipulated to optimize dealing with. For individuals who are lifeless critical about getting the perfect lap time, you’d manipulate this distribution by bodily eradicating weight or including ballast in strategic areas to get nearer to that ‘excellent’ 50/50 distribution entrance to again and left to proper.
We are able to manipulate how a lot weight a nook receives by elevating or reducing it. Nevertheless, as one motion impacts all the opposite corners on the similar time, it isn’t attainable to vary the entrance, rear, left, and proper weight percentages. So until I bodily take away, shift, or add weight, Venture Tough can have these values.
Entrance Weight % =54.06%
Rear Weight % =45.95%
Left Weight % =53.23%
Proper Weight % =46.77%
Be aware: I didn’t simulate my physique weight (84kg/185lbs) or disconnect the sway bars. In good observe, you completely ought to do that when organising a race automobile or a automobile with extremely stiff springs. Minor tweaks can have a much 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 automobile. We’re nonetheless doing this with toilet scales no matter what number of variables we restrict.
What we can do is get our cross-weight to a perfect 50/50 state of affairs. 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 will have a cross weight above 50%, you will have a wedge. Something under 50%, like Venture Tough, is a reverse wedge. Understanding this, you may comply with these guidelines to regulate the trip top to get nearer to a 50/50 distribution.
RAISING anyone nook will INCREASE the burden on that nook and barely have an effect on all different corners.
LOWERING anyone 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 rising the peak on the Entrance Proper – Rear Left or reducing the peak on the Entrance Left – Rear Proper. That is the place every thing turns into hella-tedious. You additionally must resolve how set you might be within the automobile’s trip top. Once more, the stiffer the springs, the stronger the affect minor changes will make. Nevertheless, if you’re lifeless set on how the automobile seems to be, you might need to compromise that fifty/50 distribution.
And that’s so that you can resolve. For me, as soon as I get Venture Tough again on the street, I’ll do that once more and intention to get that fifty/50 cross weight distribution. I additionally need to check just a few extra suspension initiatives and experiments.
This goes to point out that when you’re not afraid of a bit little bit of math, you may unlock potential and information that might in any other case be locked behind costly gear. It did take some refinement, and this nonetheless gained’t be as correct as a great set of digital scales, however in contrast to my first try at nook balancing with scales, it was successful.
Digital scales would nonetheless be glorious, although…
Ron Celestine
Instagram: celestinephotography