I think with suspension set up the first thing you have to do is decide what you want to do with the car.The way that the roads are starting to fall to bits where I live and the speeds I want to drive at a nice compliant suspension is fine, the rate that roll occurs is speeded up or slowed down by the damper settings as neil said by the time you have nipped through an s bend the two changes in direction occur very quickly and strong dampers will reduce roll,if you could control the damper settings on the move and very quickly you could stiffen the car up by just changing damping (hang on I think that that is how most constructors do it these days) I wish I knew what I am talking about ho hum, john
Standard replacement S2 Shocks Fitted!!
- Thread starter evoboy69
- Start date
evoboy69
New member
I really appreciate everyones advice.
I think I am just going to replace the anti roll bar bushes, castor mounts and get the alignment sorted.
I got really close to going down the KW3 route but by the time I added it all up, it was just too much to justify (Maybe next time around!)
My car is unlikely to hit the track anytime soon and I'm sure that if I were to improve the handling ability too much, I might start to become frustrated by a lack of outright horsepower.
I think I am just going to replace the anti roll bar bushes, castor mounts and get the alignment sorted.
I got really close to going down the KW3 route but by the time I added it all up, it was just too much to justify (Maybe next time around!)
My car is unlikely to hit the track anytime soon and I'm sure that if I were to improve the handling ability too much, I might start to become frustrated by a lack of outright horsepower.
Neil Haughey
New member
Audi have used electronically variable damping in some of their cars, I believe you can spec it on the TT for example, it uses a special fluid whose viscosity changes if you run a current through it the idea being that on the straights it stays soft but stiffens up as soon as you chuck the car about.
Fully active suspension was first on F1 cars many years ago and then promptly banned. In essence it didn't need springs at all but I believe they did have some amount of springing as a safety back up feature in case the hydraulics failed. Basically if you can have a set of damper like devices with electronically controlled valves backed by a high pressure pump and reservoir then you don't need springs or anti roll bars. There has been some fantastic research as well such as using little cameras or radar to map the road surface in front of the car and dynamically control the wheel movement in direct reaction to the upcoming surface. Expect ARB's and harsh ride quality to become things of the past in the near future, a bit further in the future and springs may well go the way of the dodo too. I believe the new McLaren road car has an active suspension systems, ISTR reading they have done away with the ARB's as just not needed any more. Interesting stuff.
Sorry all if I was a bit off hand last night, several guys made valid points but then contradicted themselves in the next statement.
Hi Neil,I was just joking,if you are really into the ultimate suspension you will end up going the active route,it is so easily set up for any road conditions or circuit it is the ultimate way to go,unless you are going to race seriously I would not advise anyone to nail their car down too tight ,if you want go cart type handling then do away with the suspension all together. I can remember when that aussie was racing for frank williams and they basically made the suspension solid,I think that having arbs that are too thick and spring rates that are too high for the road spoils a nice driving car, to get it right olso takes a lot of track time,all the best John.
Neil,
No problems. We all have off days.
Fully active suspension; yes, I have heard about it, and the ability to change the handling characteristics of a car at the touch of a button. Sexy stuff. I think it's a fluid which is affected by magnetic field, so the characteristics are changed by running a current through a coil around the damper.
However, I'm fascinated by the comments on springs. How did they do without them? Given that springs do a different job to dampers, why are they made redundant by having active damping? Surely there would still be a need for springs in the dynamic set-up? If no springs, how would the car ever get off its bumpstops?
Oli.
mik_ok
New member
Oli - there aren't any fully active systems out there at the moment - but the magnetic active dampers are becoming more common on high end stuff.
"Proper" active suspension used hydraulic rams. FastLane mag did a superb article back in the late 80's on a test mule Lotus Excel SE (at that time reknowned for it's superb handling/ride combo and obviously a direct 944 contemporary / rival) which was running a fully active test system for Lotus.
They drove it back to back with a std Excel SE and found it's abilities nothing short of remarkable - cornered flat as a pancake, and responded to road bumps by sensing them, immediately pulling the wheel upward, and back down as the bump was ridden over. By actively adjusting roll stiffness, you could also adjust under/oversteer bias to suit yourself, drop the ride height at speed, completely eliminate pitch & dive, and on one setting the car would lean into bends like a motorbike..... which by all accounts, took some time to get used to.
At the time they were using hydraulic rams powerful enough to flip the car over on its roof should you dump one side and apply full force to the other.
Even with smaller rams, no-one has got power consumption down to the point where it is feasible - from either a performance-sapping, or fuel consumption perspective.
Hence the current magetic dampers are becoming so popular - takes very little power to adjust their damping properties and provide a large degree of active response, without being fully active. As you suggested - you still need conventional springs (or air springs) with active dampers.
"Proper" active suspension used hydraulic rams. FastLane mag did a superb article back in the late 80's on a test mule Lotus Excel SE (at that time reknowned for it's superb handling/ride combo and obviously a direct 944 contemporary / rival) which was running a fully active test system for Lotus.
They drove it back to back with a std Excel SE and found it's abilities nothing short of remarkable - cornered flat as a pancake, and responded to road bumps by sensing them, immediately pulling the wheel upward, and back down as the bump was ridden over. By actively adjusting roll stiffness, you could also adjust under/oversteer bias to suit yourself, drop the ride height at speed, completely eliminate pitch & dive, and on one setting the car would lean into bends like a motorbike..... which by all accounts, took some time to get used to.
At the time they were using hydraulic rams powerful enough to flip the car over on its roof should you dump one side and apply full force to the other.
Even with smaller rams, no-one has got power consumption down to the point where it is feasible - from either a performance-sapping, or fuel consumption perspective.
Hence the current magetic dampers are becoming so popular - takes very little power to adjust their damping properties and provide a large degree of active response, without being fully active. As you suggested - you still need conventional springs (or air springs) with active dampers.
Neil Haughey
New member
Very much so. I reckon in some ways if you have active dampers and active ARB's (like on some beemers) then its probably job done for a road car. ISTR the F1 car with active suspension (was it Lotus or Williams? I am sure it was Lotus that first developed it but as said above Mansell also had it in the Williams) could do as you say above and jack up the outside of the car on turn in to a corner, pretty mad stuff. Mid corner it looked completely flat.
944 man
Active member
I disagree that ARBs reduce the independence of independent suspension assemblies: ARBs arent directly interconnected. Between the assembly mounting and the body mount/bushing, they act as a link only. Theyre manufactured in one piece only for economy and simplicity of integration.
Of course: all suspension is a mixture of compromise and black art... [
]
Of course: all suspension is a mixture of compromise and black art... [
]Neil Haughey
New member
Well they are not perfectly rigid if that is what you mean however if the ARB is not stiff enough to compress the spring on the other side of the car then its effectively useless i.e. just like adding a torsion bar. Thus any practically useful ARB will reduce the independence of the suspension to some degree even if its only small. There is a school of thought that says ARB's are an admission of failure on the part of the chassis designer, not something I really agree with as they can be used to cleverly tune a cars dynamics.
As for the black art thing it seems most agree on that. I am convinced now that our MX-5 has the rear roll centre wrong, not the sort of mistake you would expect from a major motor manufacturer of one of the best known sports cars. It squats a lot coming out of corners but on the way in the rear suspension not only feels very firm it seems to suffer from a touch of roll oversteer, even with only 160 Bhp you just can't get on the throttle early like you can in a 944 with another 50+ Bhp.
mik_ok
New member
What Neil said.
The whole point of ARBs is to transfer (some of the) suspension load incurred during cornering from the loaded side to the unloaded side ~ ergo your independant suspension is no longer fully independant.
This feature is great for reducing cornering roll, but when you hit a bump on the left hand side of the road, the suspension compresses and the ARB transfers that compression load to the right hand side also. This compromises the ability of the suspension to soak up bumps / holes.
evoboy69
New member
Today was a good day for my 944 S2, Today I had 968 Front Wishbone Castor mounts fitted and a full Geometry check carried out. What a transformation!
If you read back to the start of this thread you will recall that after refreshing all the worn Struts with new OEM equipment, I was a little disappointed with the result. Today everything has come together and the handling is transformed!
If you read back to the start of this thread you will recall that after refreshing all the worn Struts with new OEM equipment, I was a little disappointed with the result. Today everything has come together and the handling is transformed!
If you want active suspension then this is amazing, particularly towards the end. This is pretty old though and as far as I know development went no further.
(look out for the 911 too for added Porsche content!)
http://www.youtube.com/watch?v=eSi6J-QK1lw
(look out for the 911 too for added Porsche content!)
http://www.youtube.com/watch?v=eSi6J-QK1lw
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