Posted: Tue Jan 10, 2006 6:14 pm
Wally....what you are not getting from my posts...is that if the spring and damper combination is properly set up.....there should be little or no spring compression...just from sitting still. It should govern ride height.
More precisely said...and this is the crux of my posts concerning this....and is also getting back to the original thread........if you lower the spring height by lowering the perch....you are allowing even greater rebound travel...that that 1" or so of compressed rod length.
It WILL rebound the entire length of that excessive compression.
Thats a very uncontrolled reaction....that the stock type 4 already has way too much of.
Saying it controls ride height... may very well be be a misnomer. But by assuming it shouldn't...and ignoring what simply lowering the perch will do without shortening the strut rod....you will find out the hard way...what it causes. If the spring used were actually going to be softer...but longer....to maintain preload even when the too long strut rod over-rebounds...there would be no risk of damage to spring at all....but the pitch up on rebound will be unsightly....and hard to control at speed.
Can you control this? yes....with a very tight rebound stroke. Problem is...wthout fully adjustable (bi-directionally) cartridges....you generally get too much stiffness in the compression stroke as well. This breaks things. This can only be done really well....with a gas strut cartridge.
I applaud all experimentation that keeps these cars on the road. don't get me wrong at all! What I think would be even better than doing potentially damaging spring grafting.....is swapping in whole struts with cartridges whose damping rates match the pre-set compression level of the springs matched to them.
As an aside...you will notice that most quality factory adjustable spring perch systems that are used for the street...(see Bilstein)...use twin coils with two perches. Thats because this is the only way to get the progressive-ness...and maintain ride height and preload and rod extension to control rebound. Full race...depending on track type...most commonly uses single coils.
By the way...as noted..I already found a cartridge with a high rate of rebound control....awesome compression control...and the ability to work with slightly overcompressed stock blue coils. But...and this tells the complexity of valving....it only works in the low pressure gas version...not the high pressure gas version. The high pressure version is way overdamped. It breaks things
I weigh 185 lbs. Last night I jumped up onto the front bumper of my 412. It compresses about 1/2 ". No kidding! The rebound ...with so little energy took about 2 seconds to return to level. That is good balance. A very stiff front end...that takes speed bumps at about forty without a hitch...and without pitching from rebound.
Because its lowered about 7/8" lower than stock....and also has 2* more caster...which lowers the apparent front rake by about 1/2"...and add to that about 1.2" lower profile tires...and I am pushing about 2.5-3" lower than stock. The 7/8"....just brought it level front to rear from that nose high appearnce....which is not actually as high as it looks. What also adds a huge volume of apparent lowering...is when the rear drops down just slightly from the lower profile tires.
Just be careful how you lower. there is not much room in the control arm area...to play. There are significant geometry issues. also...and I know this from experience (as I have had mine lower than it is when I played with other struts like the 5000 cartridge)....lowering too much further than I have it already....without even lower tires...and even then (as anything belwoe a 55 series means the strut valving will no longer be correct).....has little added benefit. Some lowering of the 411/412 has large benefit. Too much does nothing more for the car.
The chassis rides to high on the wheels..the drivers position is high...and the "bubble roof"...is too high. Since you cannot "sling" the car much further down between its wheels...without seriously re-designing the front control arms....lowering too much simply impars suspension travel. Ray
More precisely said...and this is the crux of my posts concerning this....and is also getting back to the original thread........if you lower the spring height by lowering the perch....you are allowing even greater rebound travel...that that 1" or so of compressed rod length.
It WILL rebound the entire length of that excessive compression.
Thats a very uncontrolled reaction....that the stock type 4 already has way too much of.
Saying it controls ride height... may very well be be a misnomer. But by assuming it shouldn't...and ignoring what simply lowering the perch will do without shortening the strut rod....you will find out the hard way...what it causes. If the spring used were actually going to be softer...but longer....to maintain preload even when the too long strut rod over-rebounds...there would be no risk of damage to spring at all....but the pitch up on rebound will be unsightly....and hard to control at speed.
Can you control this? yes....with a very tight rebound stroke. Problem is...wthout fully adjustable (bi-directionally) cartridges....you generally get too much stiffness in the compression stroke as well. This breaks things. This can only be done really well....with a gas strut cartridge.
I applaud all experimentation that keeps these cars on the road. don't get me wrong at all! What I think would be even better than doing potentially damaging spring grafting.....is swapping in whole struts with cartridges whose damping rates match the pre-set compression level of the springs matched to them.
As an aside...you will notice that most quality factory adjustable spring perch systems that are used for the street...(see Bilstein)...use twin coils with two perches. Thats because this is the only way to get the progressive-ness...and maintain ride height and preload and rod extension to control rebound. Full race...depending on track type...most commonly uses single coils.
By the way...as noted..I already found a cartridge with a high rate of rebound control....awesome compression control...and the ability to work with slightly overcompressed stock blue coils. But...and this tells the complexity of valving....it only works in the low pressure gas version...not the high pressure gas version. The high pressure version is way overdamped. It breaks things
I weigh 185 lbs. Last night I jumped up onto the front bumper of my 412. It compresses about 1/2 ". No kidding! The rebound ...with so little energy took about 2 seconds to return to level. That is good balance. A very stiff front end...that takes speed bumps at about forty without a hitch...and without pitching from rebound.
Because its lowered about 7/8" lower than stock....and also has 2* more caster...which lowers the apparent front rake by about 1/2"...and add to that about 1.2" lower profile tires...and I am pushing about 2.5-3" lower than stock. The 7/8"....just brought it level front to rear from that nose high appearnce....which is not actually as high as it looks. What also adds a huge volume of apparent lowering...is when the rear drops down just slightly from the lower profile tires.
Just be careful how you lower. there is not much room in the control arm area...to play. There are significant geometry issues. also...and I know this from experience (as I have had mine lower than it is when I played with other struts like the 5000 cartridge)....lowering too much further than I have it already....without even lower tires...and even then (as anything belwoe a 55 series means the strut valving will no longer be correct).....has little added benefit. Some lowering of the 411/412 has large benefit. Too much does nothing more for the car.
The chassis rides to high on the wheels..the drivers position is high...and the "bubble roof"...is too high. Since you cannot "sling" the car much further down between its wheels...without seriously re-designing the front control arms....lowering too much simply impars suspension travel. Ray
) I have no direct e-mail connection when I hit that button...
