Suspension Upgrade Journey
Part 7 - Upgrade Rear Coil Again
16th April 2003
Managed to get the TRD rear coil from the same AE86's racing half-cut, which I bought the front suspension off.
The TRD coil is 6.5 kg/mm confirmed by blue color coil with light green color dot. Nearly like my previous cut one round 6.66 kg/mm but higher in height.
The mech. install it without my top and bottom THICK rubber. Instead he used his normal thickness top rubber with transparent water hose tube rubber to be inserted onto the bottom of the coil one round to stop metal noise.
However after the complete installation with both rear wheel installed. We found the rear height is still too low. Therefore I ask the mech. to re-insert my bottom THICK rubber to overcome this problem.
Luckily this time the height off-set is correct. So case closed. I took the opportunity to reduce the rear absorber setting to no.5 from no.6
Ride Feel
PERFECT. I'm sure it is not, but my initial feeling until this moment of writing (3 days testing) still feels the same. Why?
In short, the rear and front feels as ONE.
Previously I could feel the front and rear have separate vibrating frequency / times / moments. I could always feel the front bump 1st then the rear (NOT IN_PHASE). I could also feel the front bump dies quickly (i.e. absorber manage to null quickly) while the rear bump is more. (i.e. absorber did not manage to null it completely in the 1st cycle)
But now, the entire car only feels one bump (IN_PHASE). Actually 2 bump jump / cycle after everyone 1 bump across. In short the coil's vibrating frequency is approximately 2Hz.
I dare to suggest this figure because I had the opportunity to drive around 600km distance across high-ways with many sections flat, some small bumps where I feel a good (1 bump / cycle only) in around 1/2 a second, this is because the road height sudden displacement is not deep enough to provoke a heavy force. While other deeper / uneven distance 2 (always 2 bump cycle) after each excitation.
I also took the liberty to count the number of bumps in 1 section time frame and they felt like 2Hz. Or very close anyway.
Regarding PHASE - they can never really be in_phase because the front and rear are always separated by 1.5 meters ???.
Anyway, however, as speed increase, the time at which the front and rear crossed the bump is closer.
Coupled with the effect of absorber absorption + the very nature of the car's mass contributing to the very coil's LOW vibrating frequency, they (the front and rear) waveform managed to ........ sync.
This is true in both theory and practical.
Anyway...................
Please come back again next time as I would like to discuss about suspension theory using mass, gravity and car's sectional / suspension's sectional issues.
Aftermath
I nearly forgot to mention. After the rear height is adjusted somewhat more correctly, where the front does not tilt up.
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The car feels more powerful. All gear shifts feels more torquey. Fuel economy increased a little.
I wonder is it because the car is tilting forward a little that the fuel flow is smoother? Don't think this contribute to fuel economy though???
Or is it the aerodynamic has improve a little, as I notice all the dead insect's essence trail on the wind screen now produce a very even ray from center outwards. Difficult to describe, hope can get pictures next time.
Or is it the theory about - easier to carry a load and push looking downwards versus pushing upwards???
Anyway....................
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