Suspension Lifetime
09-25-2003, 01:07 PM
#16
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Hi Joey,
You're right, I didn't explain myself very well. I didn't mean to suggest that the turn in was less precise, in fact the handling is very throwable, but mid corner imperfections do bizarre things to its handling that tend to make the car hop or skip and twist as you load up into a corner at lower speeds.
It kind of feels like the car is correcting itself constantly but I suspect that the front suspension just cannot cope with what's going on at lower speeds. On the other hand, with higher speed cornering, the car goes in fast and stable and comes out faster with very few side effects. At 100-120mph+ you can throw the car around with quite unbelievable ease and reassurance, and that's something I would never do on standard suspension.
The springs and dampers were replaced at the same time and the roock coilover system is (supposedly) highly regarded, JZM state that this bouncy behavior is normal for this setup. Wouldn't mind trying someone Else's at some stage to compare.
With regards to comparing standard suspension to lowered progressives. There are many different progressive springs rates out there and some are considerably stiffer than others. Although I don't actually know what rates Roock use, the H&R coil-over progressive springs (which I believe roock use) are quite a lot stiffer than Eibach Pro-Kit progressives which are actually initially softer than the factory springs;
Eibach 964 Pro-kit springs
Front 82.6-250 lbs/inch
Rear 188-256 lbs/inch
H&R 964 Coil-over Springs
Front 250-285 lbs/inch
Rear 265-285 lbs/inch
H&R 964 springs
Front 190-255 lbs/inch
Rear 220-265 lbs/inch
so perhaps it's not surprising that your experience has been an improvement in ride. Good to get your opinion though, thanks.
Ade.
You're right, I didn't explain myself very well. I didn't mean to suggest that the turn in was less precise, in fact the handling is very throwable, but mid corner imperfections do bizarre things to its handling that tend to make the car hop or skip and twist as you load up into a corner at lower speeds.
It kind of feels like the car is correcting itself constantly but I suspect that the front suspension just cannot cope with what's going on at lower speeds. On the other hand, with higher speed cornering, the car goes in fast and stable and comes out faster with very few side effects. At 100-120mph+ you can throw the car around with quite unbelievable ease and reassurance, and that's something I would never do on standard suspension.
The springs and dampers were replaced at the same time and the roock coilover system is (supposedly) highly regarded, JZM state that this bouncy behavior is normal for this setup. Wouldn't mind trying someone Else's at some stage to compare.
With regards to comparing standard suspension to lowered progressives. There are many different progressive springs rates out there and some are considerably stiffer than others. Although I don't actually know what rates Roock use, the H&R coil-over progressive springs (which I believe roock use) are quite a lot stiffer than Eibach Pro-Kit progressives which are actually initially softer than the factory springs;
Eibach 964 Pro-kit springs
Front 82.6-250 lbs/inch
Rear 188-256 lbs/inch
H&R 964 Coil-over Springs
Front 250-285 lbs/inch
Rear 265-285 lbs/inch
H&R 964 springs
Front 190-255 lbs/inch
Rear 220-265 lbs/inch
so perhaps it's not surprising that your experience has been an improvement in ride. Good to get your opinion though, thanks.
Ade.
09-25-2003, 01:23 PM
#17
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Hi bill,
Effectively all 964 suspension is Coilover. ie. the spring is mounted around the shock as a single unit which is then installed into the car.
It's a marketing thing that manufacturers seem to call their high end 964 suspension "coilover" - when they combine a fully threaded body shock with hand matched springs and sell it as a system.
Yes - dampers are another name for shock absorber, or shock or strut.
Uprated shocks in most cases does mean stiffer, and the valves inside the shock absorber can be changed for both initial compression and also rebound (returning to rest).
Ade.
Effectively all 964 suspension is Coilover. ie. the spring is mounted around the shock as a single unit which is then installed into the car.
It's a marketing thing that manufacturers seem to call their high end 964 suspension "coilover" - when they combine a fully threaded body shock with hand matched springs and sell it as a system.
Yes - dampers are another name for shock absorber, or shock or strut.
Uprated shocks in most cases does mean stiffer, and the valves inside the shock absorber can be changed for both initial compression and also rebound (returning to rest).
Ade.
09-25-2003, 01:36 PM
#18
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Bill,
I think you've got a pretty good undestanding of the terminology and characteristics of progressive springs. Yes, damper is the Brit term for shocks and it's actually a better one. That's what shocks do ... they dampen spring oscillations.
I don't think I've ever heard of linear-specific shocks--they're usually characterized by compression and rebound values--but maybe a real expert can clarify. As others suggested, grab a ride with someone and see what feels right to you. Then let us know what you decided on and how it turned out.
Hey Ade,
That's very good informatin. Yes, I agree that the low spring rates for the Eibachs are behind the smooth ride. At speed, they're also pretty decent but require just a bit of patience to avoid unsettling the car.
Yes, I've heard many good comments about the Roock setup and I'm surprised by your experience. I would've expected that combo to keep you glued to the tarmac. Someone else on the board has this setup--you may want to do a Search to locate the owner.
I think you've got a pretty good undestanding of the terminology and characteristics of progressive springs. Yes, damper is the Brit term for shocks and it's actually a better one. That's what shocks do ... they dampen spring oscillations.
I don't think I've ever heard of linear-specific shocks--they're usually characterized by compression and rebound values--but maybe a real expert can clarify. As others suggested, grab a ride with someone and see what feels right to you. Then let us know what you decided on and how it turned out.
Hey Ade,
That's very good informatin. Yes, I agree that the low spring rates for the Eibachs are behind the smooth ride. At speed, they're also pretty decent but require just a bit of patience to avoid unsettling the car.
Yes, I've heard many good comments about the Roock setup and I'm surprised by your experience. I would've expected that combo to keep you glued to the tarmac. Someone else on the board has this setup--you may want to do a Search to locate the owner.
09-25-2003, 01:43 PM
#19
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Location: Toronto
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Ade
What does "fully threaded body shock " mean? Are we talking only about the shock absorber in which case the only threads I've seen on one are at the top of the ram shaft (i.e. the shiny chrome rod section which moves up and down). The other end (i.e the body of the shock absorber?) is usually connected to the controll arm and has a hole to accept a bolt in order to secure it the the control arm. I've noticed the standard coilovers on the rear of my car now, has a thread section (i.e which has a spanner nut and is adjustable) which the body of the shock absorber goes into - are you talking about this? This adjustment if adjusted up to the top could increase the ride height if the shock absorber is not at the upper limit of its' travel. If the shock absorber is at the upper limit of its' travel and one adjusts this spanner nut up to the top the spring will compress more and create a stiffer ride because the sping is being preloaded?
Sorry for all the questions
Bill
90C2
What does "fully threaded body shock " mean? Are we talking only about the shock absorber in which case the only threads I've seen on one are at the top of the ram shaft (i.e. the shiny chrome rod section which moves up and down). The other end (i.e the body of the shock absorber?) is usually connected to the controll arm and has a hole to accept a bolt in order to secure it the the control arm. I've noticed the standard coilovers on the rear of my car now, has a thread section (i.e which has a spanner nut and is adjustable) which the body of the shock absorber goes into - are you talking about this? This adjustment if adjusted up to the top could increase the ride height if the shock absorber is not at the upper limit of its' travel. If the shock absorber is at the upper limit of its' travel and one adjusts this spanner nut up to the top the spring will compress more and create a stiffer ride because the sping is being preloaded?
Sorry for all the questions
Bill
90C2
09-25-2003, 01:55 PM
#20
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Regarding an earlier question, John, here's how one person modified a later, RS part to his 90 C2:
Details can be found in the tech session of John Miles' wonderful 964 site. There are complete DIY articles with pics.
Details can be found in the tech session of John Miles' wonderful 964 site. There are complete DIY articles with pics.
09-26-2003, 07:42 AM
#21
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Hi Bill,
A 'fully threaded body' shock has a longer machined thread (all the way down the body of the inner strut) which is used to carry the lower spring perch. The standard shocks (and Bilstein HDs) have a shorter (say 1-2 inch) threaded section. A longer threaded section gives you more flexibility in lowering and corner balancing the car. For example the roock coilover kit even lowered to Euro RS spec still has about 2+ inches of thread left below the Perch with H&R progressive springs.
Ade.
A 'fully threaded body' shock has a longer machined thread (all the way down the body of the inner strut) which is used to carry the lower spring perch. The standard shocks (and Bilstein HDs) have a shorter (say 1-2 inch) threaded section. A longer threaded section gives you more flexibility in lowering and corner balancing the car. For example the roock coilover kit even lowered to Euro RS spec still has about 2+ inches of thread left below the Perch with H&R progressive springs.
Ade.