Sping Rates too Stiff?
Discussion
Hi All,
I've recently had Nitrons fitted on my car and the spec for them is 400 front and 325 rear sping, I imagine that rate is in lb/ft.
However, I feel that the car is stiffer than it used to be and really too stiff for everyday british roads. I travel a lot of B roads and am not doing track days.
I've turned the damping down to the point where the car now feels underdamped and it's skipping across bumps, but it's still too still, so am thinking I need to drop the spring rates by at least 25lb a corner.
Has anybody been down this road before? I don't feel like a 350 hp 1060kg car needs a choppy ride to feel like a sports car. Anyone else?
I've recently had Nitrons fitted on my car and the spec for them is 400 front and 325 rear sping, I imagine that rate is in lb/ft.
However, I feel that the car is stiffer than it used to be and really too stiff for everyday british roads. I travel a lot of B roads and am not doing track days.
I've turned the damping down to the point where the car now feels underdamped and it's skipping across bumps, but it's still too still, so am thinking I need to drop the spring rates by at least 25lb a corner.
Has anybody been down this road before? I don't feel like a 350 hp 1060kg car needs a choppy ride to feel like a sports car. Anyone else?
Some people seem to run stiffer than that. 400 / 350 is also a commonly provided combination.
I have been on 400 / 325 which is ok, but will be trying 375 springs on the rear shortly.
That still makes the rear quite a lot softer than the front due to the angle of the spring.
I have not found the ride too stiff with those rates and Gaz Gold Pro dampers. I have worked my way through a range of damper settings from firm to soft and should soon be able to let you know what difference the stiffer rear springs make.
I have been on 400 / 325 which is ok, but will be trying 375 springs on the rear shortly.
That still makes the rear quite a lot softer than the front due to the angle of the spring.
I have not found the ride too stiff with those rates and Gaz Gold Pro dampers. I have worked my way through a range of damper settings from firm to soft and should soon be able to let you know what difference the stiffer rear springs make.
Setup is everything! Geo etc.Walford, I don't know how you'd quantify it, I'm going slower than my other cars because of the jostle-y ride.
Targarama, glad it's not just me! I dislike the audi notion of a car needing to be stiff to be sporty. If the car is light it should be able to float more and still corner well.
To be fair, it is pretty mega on a smooth road, but there aren't enough of them around.
Targarama, glad it's not just me! I dislike the audi notion of a car needing to be stiff to be sporty. If the car is light it should be able to float more and still corner well.
To be fair, it is pretty mega on a smooth road, but there aren't enough of them around.
Walford said:
what you have to bear in mind is you don't have massive ground clearance, so limited travel, this is the nature of the beast, don,t compare the ride to cars running higher off the road
Don't think that's it. One of them is significantly lower (have to cross my driveway sideways) and it rides as well as the TVR.Maybe it's just the roads out my way, but I'm shocked at some of the spring rates mentioned here! How do your teeth not get shaken out?!
Does anyone know what the TVR standard rate is?
ChrisPap said:
Hi All,
I've recently had Nitrons fitted on my car and the spec for them is 400 front and 325 rear sping, I imagine that rate is in lb/ft.
However, I feel that the car is stiffer than it used to be and really too stiff for everyday british roads. I travel a lot of B roads and am not doing track days.
I've turned the damping down to the point where the car now feels underdamped and it's skipping across bumps, but it's still too still, so am thinking I need to drop the spring rates by at least 25lb a corner.
Has anybody been down this road before? I don't feel like a 350 hp 1060kg car needs a choppy ride to feel like a sports car. Anyone else?
I guess you are talking about the 46mm set, same as what I had put in last week as well as full geo. I had been holding off commenting on them until they break in and I get a chance to raise the car and play with the adjuster.I've recently had Nitrons fitted on my car and the spec for them is 400 front and 325 rear sping, I imagine that rate is in lb/ft.
However, I feel that the car is stiffer than it used to be and really too stiff for everyday british roads. I travel a lot of B roads and am not doing track days.
I've turned the damping down to the point where the car now feels underdamped and it's skipping across bumps, but it's still too still, so am thinking I need to drop the spring rates by at least 25lb a corner.
Has anybody been down this road before? I don't feel like a 350 hp 1060kg car needs a choppy ride to feel like a sports car. Anyone else?
But yes, I agree with you, so far they are way too stiff for the s
te roads we have. I'm not sure its the spring rates, I had similar rate increase on a s2000 (similar weight) and it was actually more comfortable than standard whilst vastly improved handling.
Currently they are set to 10 out of 24 clicks (delivery settings).... when I get round to adjusting the they will go straight to 5 and binary search settings from there... but I am worried about this because iirc you should not have shocks set at their limits of adjustment either way, but these may be different.
The current positives are that the cars heading stays totally true when going over bumps, I have confidence it its handling now where previously there was none. This may be mostly due to the geo setup provided by dreadnought garage.
If they dont work when setting the adjuster way down they they are going back for revalving and springs or whatever.
edit: by similar rate I meant similar relative increase.
Edited by SergSC on Friday 3rd May 22:41
Serg,
actually, it's a 40mm set. Had new rear bushes and full geo at Str8six when the dampers were fitted and it has transformed the handling. Car tracks beautifully now, nice balance and great grip in the corners, and nice stability on braking and turn in.
It just feels like the springs are too stiff. The car was set up with 12 clicks front and 11 back (out of 24). I've softened if 3 clicks all round and it's slightly better, but now get the feeling that it's underdamped, pogo-ing slightly.
Glow worm, thanks! My car is a June '05 (so pre august) Tamora with (I think) Green and White spings so maybe the same rate as the Tuscan and if so it looks like they were fully HALF the rate of the nitrons!
actually, it's a 40mm set. Had new rear bushes and full geo at Str8six when the dampers were fitted and it has transformed the handling. Car tracks beautifully now, nice balance and great grip in the corners, and nice stability on braking and turn in.
It just feels like the springs are too stiff. The car was set up with 12 clicks front and 11 back (out of 24). I've softened if 3 clicks all round and it's slightly better, but now get the feeling that it's underdamped, pogo-ing slightly.
Glow worm, thanks! My car is a June '05 (so pre august) Tamora with (I think) Green and White spings so maybe the same rate as the Tuscan and if so it looks like they were fully HALF the rate of the nitrons!
Edited by ChrisPap on Friday 3rd May 21:59
glow worm said:
Because the geometry is different between a Sag and a Tuscan I don't think you can compare them.
The TVR values are a lot lower than aftermarket sets now supply.
I have been told that TVR used softer springs and quite a lot of pre-load on the spring, but am not sure how that effects things.
how many miles have you put on them so far? Ive done about 120, but have been told they can take 500 miles to breakin and soften a bit... then again Ive also read reports that this theory is bs.
To correct myself when comparing with my s2000, I went up a similar % increase in spring rates on an s2000 and got better comfort and handling, I guess because it was much better damper... but there more variables so hopefully somebody who knows better can chip in and educate better. I guess the actual sr number you get on different cars depends on how much leverage the suspension arms can apply so I guess the sagaris has more because of this and then some...
To correct myself when comparing with my s2000, I went up a similar % increase in spring rates on an s2000 and got better comfort and handling, I guess because it was much better damper... but there more variables so hopefully somebody who knows better can chip in and educate better. I guess the actual sr number you get on different cars depends on how much leverage the suspension arms can apply so I guess the sagaris has more because of this and then some...
Sevenman said:
I have been told that TVR used softer springs and quite a lot of pre-load on the spring, but am not sure how that effects things.
That doesn't sound right. Certainly on my Tamora originally there was no spring pre-load. I only correct your information so as to not go down the wrong path, not sure who told you that, maybe it's for a different model. As you wind tension on to a spring, it is supporting a greater degree of load, however much weight it would take the spring to compress the same distance. So if you put 250kg on a spring to compress it 1 inch, then by adding that much preload, you will need to add 251kg of weight to that spring before it will move. but when it does move, it will only take the rate of the spring to move it. so if it's a soft spring it will still be soft once you overcome the pre-load. It's a nice idea, but to make it work you need to compress the spring against a stop in it's rest position, and that would be the droop stop. But if that were the case when you jack the car up the wheel would come off the ground instantly, not stay on the ground for the first inch or two of jacking- like my car did and still does.
SergSC said:
how many miles have you put on them so far? Ive done about 120, but have been told they can take 500 miles to breakin and soften a bit... then again Ive also read reports that this theory is bs.
To correct myself when comparing with my s2000, I went up a similar % increase in spring rates on an s2000 and got better comfort and handling, I guess because it was much better damper... but there more variables so hopefully somebody who knows better can chip in and educate better. I guess the actual sr number you get on different cars depends on how much leverage the suspension arms can apply so I guess the sagaris has more because of this and then some...
I've done over 600 miles so far.To correct myself when comparing with my s2000, I went up a similar % increase in spring rates on an s2000 and got better comfort and handling, I guess because it was much better damper... but there more variables so hopefully somebody who knows better can chip in and educate better. I guess the actual sr number you get on different cars depends on how much leverage the suspension arms can apply so I guess the sagaris has more because of this and then some...
When comparing Sags to other T cars, the leverage of the wishbone (wider track) and the inclination angle of the dampers both have an effect on required spring rate.
Not sure what to make of your s2000 experience. Did you really double the spring rate and find it better?
ChrisPap said:
Not sure what to make of your s2000 experience. Did you really double the spring rate and find it better?
yep standard 2008 s2000 was f280 r294. Upgraded shocks were meister Zeta R at woping 560lb/in. But it wasnt just me, every other report felt the same about these well regarded shocks. What I dont know though is if the oem set was buggered (24k) as I was 2nd car owner and dont necessarly know what a good oem set is like.Your spring rates aren't excessive so unless you've got the wrong springs fitted by mistake which are much stiffer than 400/325 then the springs aren't likely the cause.
It sounds much more like the damper build you have (for whatever reason) has too much high speed piston resistance, so I would be sending the dampers back to nitron for testing (however electric dyno rigs like the industry standard SPA dyno can't truly replicate proper high speed piston movements as seen on bumpy roads, you need an uber expensive hydraulic rig for that and I dont know anyone who has one of those ..).
However, if they test out as ok, or even if they don't, I would be asking for a compression curve on the damper that is more digressive than the one you have at the moment. The higher speed piston resistance is controlled off the valving and the bleed adjuster has little effect on that, so adjusting your bleed valve won't solve the issue you are experiencing I don't think, so you need to bring down the high speed resistance without changing the lower adjustment range of the bleed valve. This will still give you the handling tunability that you get when you adjust the lower piston speed ranges off the adjuster, but reduce the resistance of the damper when you meet a choppy road and are asking the piston rod to move quickly.
Hope that makes some sense. If you need any more info please message me.
It sounds much more like the damper build you have (for whatever reason) has too much high speed piston resistance, so I would be sending the dampers back to nitron for testing (however electric dyno rigs like the industry standard SPA dyno can't truly replicate proper high speed piston movements as seen on bumpy roads, you need an uber expensive hydraulic rig for that and I dont know anyone who has one of those ..).
However, if they test out as ok, or even if they don't, I would be asking for a compression curve on the damper that is more digressive than the one you have at the moment. The higher speed piston resistance is controlled off the valving and the bleed adjuster has little effect on that, so adjusting your bleed valve won't solve the issue you are experiencing I don't think, so you need to bring down the high speed resistance without changing the lower adjustment range of the bleed valve. This will still give you the handling tunability that you get when you adjust the lower piston speed ranges off the adjuster, but reduce the resistance of the damper when you meet a choppy road and are asking the piston rod to move quickly.
Hope that makes some sense. If you need any more info please message me.
ChrisPap said:
That doesn't sound right. Certainly on my Tamora originally there was no spring pre-load. I only correct your information so as to not go down the wrong path, not sure who told you that, maybe it's for a different model.
As you wind tension on to a spring, it is supporting a greater degree of load, however much weight it would take the spring to compress the same distance. So if you put 250kg on a spring to compress it 1 inch, then by adding that much preload, you will need to add 251kg of weight to that spring before it will move. but when it does move, it will only take the rate of the spring to move it. so if it's a soft spring it will still be soft once you overcome the pre-load. It's a nice idea, but to make it work you need to compress the spring against a stop in it's rest position, and that would be the droop stop. But if that were the case when you jack the car up the wheel would come off the ground instantly, not stay on the ground for the first inch or two of jacking- like my car did and still does.
Information came from a TVR Specialist, but it isn't something I am sure about and have never seen for myself. Given the spring rates are 1/2 those used in aftermarket kits, it makes sense that something is a bit different, could be damping. As you wind tension on to a spring, it is supporting a greater degree of load, however much weight it would take the spring to compress the same distance. So if you put 250kg on a spring to compress it 1 inch, then by adding that much preload, you will need to add 251kg of weight to that spring before it will move. but when it does move, it will only take the rate of the spring to move it. so if it's a soft spring it will still be soft once you overcome the pre-load. It's a nice idea, but to make it work you need to compress the spring against a stop in it's rest position, and that would be the droop stop. But if that were the case when you jack the car up the wheel would come off the ground instantly, not stay on the ground for the first inch or two of jacking- like my car did and still does.
You could imagine the pre-load effectively negating some of the weight of the car and then the spring being used for extra compression at the lower rate. But I would also have thought that it could cause problems under extension. If we knew the lengths of original springs that might help.
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