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Vehicle Ride Height Adjustment / Settings
1. It is my first time adjusting the ride height. What ride height position should I set my car at?
If you are using standard springs, it is not recommended to lower the ride height very much. When lowering, stay within 30mm to 40mm. If you lower too much, the wheel arch and tires may hit. Front and rear balance should be the same as OE or 5 to 10mm lower in the front. For cars that already have a low ride height (Z32, FD3S etc.), if you lower by 10mm to 20mm will be sufficient. For any car, make repeated adjustments over time to find the optimal ride height for you.
2. If I mainly want to drive at the circuit, how should I set the spring rate and ride height?
You should increase the spring rate from the standard rate. It will also depend on the tires you use and the course you drive on. If you are using tires with good grip, the faster you go the centrifugal force will move and the amount of roll will increase. (If you increase the spring rate, the ride height will also increase, so please lower the lower seat.) When driving at the circuit, it is ok to lower the car until the tires nearly touch, but if you drive to the circuit, please abide by your local regulations. It is good to make adjustments to the front and rear balance by repeatedly driving and then adjusting by 5mm increments.
3. I wanted to lower the ride height by 30mm so I lowered the lower seat by 30mm. But the actual ride height dropped by 45mm. Why?
This is because of the lever ratio. The lever ratio is the stroke ratio between the shock absorber and the tire. Shock absorber – tire ratio is 1:1.5. For double wishbone types, the lever ratio is 1.2 – 1.7. For strut types, 1.0. For multi-link types, approximately 1.0 – 1.1.
4. Why is the front spring rate for the Mark II and Supra set so high, between 12k-18k?
This is also because of the lever ratio. The Toyota front double wishbone type has a lever ratio of about 1.6. If it were a strut type, the spring rate would only be about 5k to 7k. For the rear, the ratio is about 1.2. Other manufactures like Honda, Mazda also have models with high spring rates.
5. I purchased the SUPER STREET DAMPER and I intend to go to the circuit, so I increased the spring rate by 4k. I lowered the seat to the lowest position, but the ride height doesn’t drop very much. Why?
This is just because of physics. The spring rate and ride height depends on the vehicle’s weight. For example, if you have a lever ratio: 1.5, load at spring: 300kg and use 10k springs or 6k springs. The difference in ride height will be 30mm. Even if the lever ratio was 1.0, the difference will be 20mm. And of course, you need to adjust the seat position by the difference (e.g. 20mm). When dropping the ride height with high spring rates, you should change to shorter springs, or remove the helper springs. However, doing this will allow the springs to play and restrict use on public roads. (Short stroke is ok.)
6. I lowered my car very low, but the ride comfort is bad. What can I do to improve the comfort level?
It depends on the product that you use, but lower the ride height, less stroke can be secured, thus depreciating ride comfort. If you raise the ride height by 5mm to 10mm, you should be able to secure enough stroke and improve ride comfort. So please try.
7. I want to secure more stroke by cutting the bump rubber. How much should I cut?
If you compress the bump rubber, attached to the shock absorber, it will approximately be about 15mm. This compressed height is set at the minimum possible height, so if you tamper with the bump rubber, then the tire may hit the wheel arch, or the drive shaft may even hit the body.
When undertaking such process, the customer is fully responsible. Please take all precautionary measures, and make small changes at a time.
8. I often hear the ride comfort worsens as you lower the ride height, but if I raise the ride height, does it affect the ride comfort?
If you raise the lower seat lock to the highest possible position, the main spring will shrink, worsening the compliance with the road surface and ride comfort.
For this reason, we offer the maximum adjustable seat lock height for all threading type ride height adjustable shock absorbers.
9. I have HIGH.TECH springs on my car, but the ride height is not as low as I thought. Is the product defective?
There are some cases when the bushes get twisted during installation and the ride height becomes set a little higher. (When the suspension is fully rebounded, the screws on the installed part become loosened. The bushes become twisted towards the suspension’s rebound direction.) Rubber bushes are used in various parts of a vehicle’s suspension, such as in the lower installation points, the upper/lower arm installation points etc. When these bushes become twisted, it may make it difficult to lower the vehicle height. For all the suspension parts (moving parts such as the arm etc), loosen the installation bolts with the vehicle at 1G (when the vehicle is stationary on a flat surface). Lightly rock the vehicle a few times, then re-tighten all the bolts. This should straighten the bushes and return the ride height to its original position. If you drive when the bushes are twisted, you may hear some unusual squeaking sounds. Generally speaking, when installing our product, the arm maybe at a lower ride height than normal or set at a difficult angle. At this point, for the installed bushes, there is an extremely large amount of pre-load between outside and inside of the collar. It is necessary to remove this pre-load. On the other hand, in motorsport, this pre-load is taken advantage of by reducing the suspension over 1G, then re-tightening to set the car up even the slightest bit lower.
10. When looking at springs, e.g. S.TECH, spring rates are written like the following (2.9~5.5k). Does this mean that the spring rate can be chosen within the range?
This is what is called a “variable rate” and does not mean you can select the rate. The range shows the rate the spring may change while driving. It has the same effect as if you lined up the different rated springs all together. Variable springs are used for lowering the ride height and to prevent play. 1 variable spring contains the different rated springs. The spring rate range is quite large for most vehicles because the vehicle is compressed more, by the amount the helper spring would have filled.