Suspension Upgrade Journey

Part 3 - 911 Zentrum Absorber Testing

5th April 2003 

They are visited to test the effectiveness of the TRD absorbers.

911 Zentrum 

Dimiliki oleh Roadsafe Auto Services Sdn Bhd - 477772-H

address changed

Employee Jeffery's Mobile +60(12)366-2910

email them

The car is driven up the Sachs Absorber Tester. It test left and right independently. 1st front then finally rear.

All coils are original KE70 20 years old. Front and rear is around 2 kg/mm. These estimations are based on theoretical calculation from measurements of coil wire thickness, actual central coil diameter and numbers of active coils.

Front absorber has compression of 236kgf with 112kgf rebound. Rear is on setting no.8 with unknown compression and rebound. Setting no.4 gives 83kgf compression and 32kgf rebound.

and the results: -

From the physical machinery test and from the print out results, I conclude the system test the entire suspension on each car's corner at "static" load. i.e. basic idea of up down, no momentum / motion forward, backwards or sideways. Does not take into account G forces or air pressure push "down-force" etc.

  1. The print out shows a "time domain" response. 
  2. From the time lapse signal / waveform, one is able to find or see resonant frequency(s).
  3. One can also see how the absorber nulls the resonant(s). 
  4. Did it null it or not?
  5. Or did it null the wrong frequency?
  6. That part that it null is it enough?, too much? or too little?
  7. etc

If someone take his stock suspension for a measurement, then modify it and measure it again and keeps all the records. Plus knowing the modification specifications like coil's kg/mm, absorbers compression's kgf and rebound's kgf. Then one could study the performance not only by feel of driving, but also "see" it's performance / response technically on paper. 

What scientist and people like Bill Sherwood call this "quantitative" comparisons. Not little boys simply play play..............

This is why I try to obtain as many technical information / specifications as I can, as well as obtain actual measurements. To give an edge on product understanding to better fully utilize it's potential / limits.

Talk about limits, knowing all these things also make sure you don't go overboard and get into trouble by asking too much from each items. Taking care of them ensures longer lasting enjoyment. :)

Anyway, after we obtained the results, the service personnel gave a brief explanation about the graph and mentioned my rear is not stable, where it warble allot. We confirmed that :) [see they knowwwwwww]

Bill Sherwood sat in the passenger seat before and felt something wrong the1st time. Bill ask me what was the setting on the rear absorber and I told him no.8. Bill reply saying that's too high and that's the "thing" that causes the problem. So he asked us to reduce it to say 4. Bill did a quick push on the car and let it rise to equilibrium and found that the absorber setting is a bit too soft. So we increase it up to 5 and he tested it again. Now it is a bit too hard. Bill said 4.5 would be perfect. But hey,,,,,, we don't have 4.5 so 5 will do :)

In short of time - Basic suspension theory: -

  1. coil govern vibrating frequency
  2. absorbers null it either fast or slow

Serious racers can use this test to allot benefit. :)

Aftermath

After the rear absorber is on setting no.5 the entire drive / ride feels is much better. In fact very good and I dare to take corners from an angle previously felt un-safe. I felt the response or simply put it the car telling me it's OK to go faster :). investment paid of :)

  1. Upgrade Rear Absorber to TRD
  2. Upgrade Front Absorber to TRD
  3. 911 Zentrum Absorber Testing
  4. Shopping
  5. Front Rear Suspension Re-work
  6. Coilovers and Camber Adjusters
  7. Upgrade Rear Coil Again (serious theories) - more like serious bullshxt now :)
  8. Upgrade Rear Absorber Again
  9. Wheel to Hub - CENTERER

 

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