Shockabsorber 101

[lukits01]

Thanks SK, inverted or not do both designs look the same?

[Sydneykid]

Thanks SK, inverted or not do both designs look the same?

Nope, as previously posted

As you can see this design of shock has the more normal shaft diameter and hence is most likely for a double wishbone car. However it also has the larger diameter lower body indicating it is most likely a twin tube design.

The change in shock body diameter is usually the give away, not always, but most times.

cheers

[Beer Baron]

Ive always liked the brand and their line of zero coilovers,

which cusco coil overs did you have success with? And was it on a skyline. I have seen a few sets around lately, just curious as to what you liked about them.

[2rismo]

I know you dont want to dicuss brands specifically, but to what degree can the Whiteline/Bilstein shocks be modified to suit a drag racing application?

Specifically the front end.

Adrian

[Sydneykid]

I know you dont want to dicuss brands specifically, but to what degree can the Whiteline/Bilstein shocks be modified to suit a drag racing application?

Specifically the front end.

Adrian

Hi Adrian, simple question, complex answer.

With the large valve stack in a Bilstein giving a lot of flexibility in damping, I can revalve a shock to give those attributes for drag racing. At the same time, because of the valving sophistication, I don’t have to sacrifice too much, such that the car is not difficult to drive on the road. I can retain the high frequency bump valving suppleness so the car is not harsh on the bumps. There is also enough high frequency rebound damping to control the spring when driving around the road.

Keep in mind it’s not PERFECT solution for both worlds (road and drag), you would need quad adjustable shocks to achieve that. But that would mean spending 4 times as much money. So the revalved Bilstein solution is the best value for money.

Hope that answered your question

cheers

Edited September 3, 2006 by Sydneykid

[salad]

could we hear more about how valves effect handling/ride?

[RodMonsta]

besides the cons of twin tube design, what are the advantages?

[Beer Baron]

price.

[Fordy85]

I have bilstein's already in my car but my spring's aren't captive in the rear, do I need to go out and buy new shortened shocks or is there a way I can fix this while keeping my current shocks? If there is something that fixes it will it be detrimental to handling??

[siksII]

I have bilstein's already in my car but my spring's aren't captive in the rear, do I need to go out and buy new shortened shocks or is there a way I can fix this while keeping my current shocks? If there is something that fixes it will it be detrimental to handling??

you can buy 'helper' springs which u fit in under the springs u have to keep them captive. they look like this:

[Sydneykid]

price.

Check out the Group Buy for your model

cheers

[salad]

could we hear about how the valve design affects handling/ride?

such as how valves are designed to give good progression/digression

[Beer Baron]

Check out the Group Buy for your model

cheers

lol, you missed what i meant. the guy posting above me said:

"what are the advantages of twin tube shocks"

I answered:

"price" which as far as I can see is their only advantage.

whilst we are talking shocks. what are your thoughts on these, and any set-up advice. they are going into a 32 GTR. 270rwkw (meaty curve), Advan A048s. adjustable front upper arms, and castor rods, whiteline bars front and rear (adjustable).

Nismo G-attack R tune, Ohlins shocks. 20 X bump adjustment 30 X rebound adjustment giving a total of 600 settings. (YIKES!) All alloy shock.

also, care to use your experienced eye to hazard a guess at the srping rates? I'm guessing around 550pound or nearing 10kg?

also, I am currently running Bilsteins with Eibach springs and have been very happy with them. But I am keen to give these a go. Just hoping the dampers are good enough to properly control such hard core springs (should be though with remote canisters etc).

[Sydneykid]

whilst we are talking shocks. what are your thoughts on these, and any set-up advice. they are going into a 32 GTR. 270rwkw (meaty curve), Advan A048s. adjustable front upper arms, and castor rods, whiteline bars front and rear (adjustable).

Nismo G-attack R tune, Ohlins shocks. 20 X bump adjustment 30 X rebound adjustment giving a total of 600 settings. (YIKES!) All alloy shock.

also, care to use your experienced eye to hazard a guess at the srping rates? I'm guessing around 550pound or nearing 10kg?

also, I am currently running Bilsteins with Eibach springs and have been very happy with them. But I am keen to give these a go. Just hoping the dampers are good enough to properly control such hard core springs (should be though with remote canisters etc).

I have learnt (the hard way) not to guess spring rates. It's also a bit hard to see the wire diameter and 1 mm either way makes a big difference.

Ohlins make a good shock (in Sweden, not Japan) so they should be excellent. The best way to check would be to stick them on the shock dyno before you use them and have a good look at their damping curves. It's easy to pick the quality of the damping and it would also help with establishing a base line (where to start with the adjustments).

I know that you know this, but for other readers.............be very careful that you are not setting yourself up for an impossible task. Tuning double adjustable shocks is not simple, you can easily end up going around in circles and end up with worse than you have now.

Make sure that you put aside a test day just for getting to know what the shock adjustment does. Get a feel for what it feels like with minimum and maximum settings for both bump and rebound damping,

When I am training a new team (drivers and crew), I go through a sequence so that the driver can feel the differences and articulate those feelings to the crew. I usually start off with everything on minimum, tell the driver what settings I have used and then get them to do a few laps, then debrief. Everything on maximum, another few laps, debrief. Front on minimum rear on maximum etc etc. Work though the 4 possible min/max settings. Then I do a blind test, don’t tell them what I have done and see if they can feel the settings. Then we go through the processes of achieving the best settings for that car on that day.

With a crew of 5 and 1 driver that process usually takes the best part of a full day. That’s without getting into stabiliser bar settings, wheel alignment or spring rate changes. They just complicate the proceedings 10 fold.

So the usual warning, don’t go down this path (of adjustable shocks) unless you are capable of feeling for the right settings and are prepared to spend the time and money learning how to achieve them.

cheers

[Beer Baron]

thanks mate. the wire diameter of the rears is 13mm and the fronts are 12.5mm. I will do the proper measurements and put them up in your spring rate thread.

I am in two minds on putting them on the shock dyno. just testing them out at min/min max/max min/max max/min will be around $300 for the set of 4 (imagine the cost to test all 600 steps!!!). I was going to get it done, but now (being the tight ass i am) am leaning towards strap them on and put them on my bum dyno method.

I do have a little experience with adjusting 4 ways shocks. we used a set on the GT3 Cup Car which we ran for a year. Have to admit we were still a long way from being on top of things. With a varyable level of crew, that was just a core group of 3 (including driver and including me). but we did move in the right direction. beginning of the year we were regular top 10. by the end of the year we were getting podiums and regular top 6.

I am going to try and get to OP GP for a full day test which is a track where I have a fairly good feel for the car and will start out as you suggest. Maybe even start with the stock swaybars on then introduce my WL bars later down the testing track. or better to just jump in with the car the way it is now?

[Sydneykid]

thanks mate. the wire diameter of the rears is 13mm and the fronts are 12.5mm. I will do the proper measurements and put them up in your spring rate thread.

I am in two minds on putting them on the shock dyno. just testing them out at min/min max/max min/max max/min will be around $300 for the set of 4 (imagine the cost to test all 600 steps!!!). I was going to get it done, but now (being the tight ass i am) am leaning towards strap them on and put them on my bum dyno method.

I do have a little experience with adjusting 4 ways shocks. we used a set on the GT3 Cup Car which we ran for a year. Have to admit we were still a long way from being on top of things. With a varyable level of crew, that was just a core group of 3 (including driver and including me). but we did move in the right direction. beginning of the year we were regular top 10. by the end of the year we were getting podiums and regular top 6.

I am going to try and get to OP GP for a full day test which is a track where I have a fairly good feel for the car and will start out as you suggest. Maybe even start with the stock swaybars on then introduce my WL bars later down the testing track. or better to just jump in with the car the way it is now?

You don't have to do 600 shock dyno runs, you would boil the fluid anyway, as it takes a long time to cool down after each run. We usually do 3 or 4 runs, adjusting both bump and rebound at the same time. One each on max and min and one or two with the middle settings. That gives you an idea of the overall shape of the valving and the effective range of damping from the adjusters. I have never seen a dyno graph with every possible adjustment, it doesn't really tell you anything.

The $300 seems a bit rich, that's $75 per shock. Unless they don't have Skyline fittings for the shock dyno and are charging for making them up. Or they are charging for standing around while the shock fluid cools after each run. Who was that through?

If you have a bunch of settings (bars, alignment, spring rates) that you usually use for OP, then best to run through the shock testing as I outlined above with those settings in place. The usual rule (adjust one thing at a time) applies.

cheers

[Beer Baron]

Gary, what do you reckon would be reasonable (price wise) to have the shocks dyno'd, just 4 runs each shock, all 4 shocks? and where would you reccomend? If I could get it done for around half that $300 then I wouldn't think twice.

[Sydneykid]

Gary, what do you reckon would be reasonable (price wise) to have the shocks dyno'd, just 4 runs each shock, all 4 shocks? and where would you reccomend? If I could get it done for around half that $300 then I wouldn't think twice.

PM sent

cheers

[salad]

How do shocks manage to give different amounts of damping at different speeds? Is this similar to how Bilstein achieve digressive valving in some of their higher end shocks?

[Sydneykid]

Like all hydraulic devices, shock abosrbers are velocity sensitive. The higher the the velocity of shock movement (not to be confused with higher frequency) the more damping effect. That's without any valving steps. When you have multiple valves you can then modify that normal velocity sensitivity, either increase or decrease it.

cheers