coilover adjustment

[MM89]

I just lowered the front by 10mm, by moving the lower perch higher
to close the gap between the thread. Re-installing the sussy exactly
the way it was before. The rear was not altered at all.

Since then steering has felt a bit loose and cornering a bit harder makes
it feel a bit understeery. Before and after driving around to let the sussy settle in. I have stiffened up the damper rebound by +2 (6 way adjustables) which has made the problem slightly better.

Just wondering what the cause is..

Should I lower the back too, will this bring the feeling back to what it was originally? Why?

I know I need a wheel alignment after adjusting the ride height. Could this be the cause of difference? Difference in toe and camber?

Any other reasons which I am unaware of?

[e240]

What sort of coilovers do you have?
Does it have seperate height adjuster or did you adjust the heigh using the spring perch?

[MM89]

they're coilovers from modproject
it's got the separate height adjuster below the spring
so i'm basically just reducing the thread length from the lower perch.
The spring is only just locked in, it hasn't been compressed whatsoever.

btw, i tried re-adjusting the front. The issue seems to be much improved
after the re-adjustment. I'm not sure whether this is the reason why it seems better now, but it is. The front height was out by 4mm between left and right. It is currently out by 1mm. Trying to make it as accurate as possible.

[aaronng]

Your front camber and toe might have changed after you lowered it by that 10mm.

[e240]

they're coilovers from modproject
it's got the separate height adjuster below the spring
so i'm basically just reducing the thread length from the lower perch.
The spring is only just locked in, it hasn't been compressed whatsoever.

btw, i tried re-adjusting the front. The issue seems to be much improved
after the re-adjustment. I'm not sure whether this is the reason why it seems better now, but it is. The front height was out by 4mm between left and right. It is currently out by 1mm. Trying to make it as accurate as possible.

Make it as accurate as possible. Be as consistent as you can when measuring and viewing the height on both ends to avoid parallax errors. It might feel lighter because you've unloaded the front and could take a while to settle.
Make sure when you've adjust the lower perch, you haven accidently loosened other parts like the spring perch etc. Now might be a good time to re-check the tension of the bolts.


But normally, lowering just the front puts more weight on the front, technically should reduce understeer but really depends on the entire scenario. e.g. You could still load the front to a point where it'll plow...

If you're still not sure, see your usual mechanic...

[MM89]

Bolts have all been torqued back to factory settings.
spring perchs have been measured to be at 198mm on L/R for front end
Everything has been checked thoroughly prior and after re-installing
the coilover unit.

The front camber and toe may indeed have changed from lowering
10mm. Will that play such a big effect on my situation where such slight
changes in these settings impact the feeling in such a big way?

[kongfu]

MM89 I highly suggest you go to Centreline suspension in williamstown..
They are the best in Melb...most of frequent track lovers go there. They normally take at least 4 and a half hours to do a proper wheel alignment and camber setting.
http://www.centrelinesuspension.com.au/

make sure you speak to Christ. he will look after you!

Also Glenn an aussie mate.

[MM89]

cheers for the heads up mate
you can call me mike if you want
MM89 sounds really =/
anyways had a look on their site, seems good to me
im assuming they're not going to be your standard
$65 bob jane wheel alignment if it's going to take 4.5 hours.
what does their process consist of? what's the difference in
cost?
<random>
just copped a $315 hit to the wallet today from parking in a
tow away zone. maybe i should have dropped it on the floor
so they can't get to any towing points to tow my car away,
then i'll do my wheel alignment.
</random>
but yeah give us a ball park figure. gonna be careful with the
coin i have left in the small bank account of mine.

[kongfu]

cheers for the heads up mate
you can call me mike if you want
MM89 sounds really =/
anyways had a look on their site, seems good to me
im assuming they're not going to be your standard
$65 bob jane wheel alignment if it's going to take 4.5 hours.
what does their process consist of? what's the difference in
cost?
<random>
just copped a $315 hit to the wallet today from parking in a
tow away zone. maybe i should have dropped it on the floor
so they can't get to any towing points to tow my car away,
then i'll do my wheel alignment.
</random>
but yeah give us a ball park figure. gonna be careful with the
coin i have left in the small bank account of mine.

hi mike they charge $120 inclusive GST for wheel alignment and camber setting.

Initially I thought they charge too much, but after I got my wheel alignment and camber setting done. OMG, completely different car. The handling of the car has been dramatically changed.

They did an awesome job to my car, I think it worth every cent I spent.

[aaronng]

4 hours? WTF? It usually takes 45 minutes, and that is to set front toe, rear toe and rear camber on mine at a Bridgestone tyre centre. They charge me $65 and I get to tell them what alignment settings I want.

Quality seriously depends on the operator who is doing the alignment.

[hisoka]

just copped a $315 hit to the wallet today from parking in a tow away zone.

WTF~~, is that how much the fine is for parking in a loading zone, i thought it was 50 bucks ?

[aaronng]

WTF~~, is that how much the fine is for parking in a loading zone, i thought it was 50 bucks ?

Tow away zone is not a loading zone. Tow away zone is like a clearway or parking in front of a fire station vehicle exit!

[e240]

Bolts have all been torqued back to factory settings.
spring perchs have been measured to be at 198mm on L/R for front end
Everything has been checked thoroughly prior and after re-installing
the coilover unit.

The front camber and toe may indeed have changed from lowering
10mm. Will that play such a big effect on my situation where such slight
changes in these settings impact the feeling in such a big way?

Ok, alot of people will disagree with what I say, but when I lowered my car by about an inch and a half, I didn't bother with a wheel alignment for over a year with no detrimental effects. It did get a little twitchy going into the turns but nothing major. For a while, I also ran with my front slightly lower than the rear - again nothing major, well, not on the street anyway.

Not very helpful there but its very hard to diagnose the problem based on description alone, there are so many factors to consider and different drivers have different feel.

if it does bother you so much, as many people have said, get to an alignment place and get everything set back to stock and then experiment from there.
It shouldn't cost you more than $100 and usually about an hour or less, unless of course you have camber kits.

On that note, unless you have camber kits, you can only adjust for Toe front and rear.

[MM89]

Tow away zone is not a loading zone. Tow away zone is like a clearway or parking in front of a fire station vehicle exit!

yeah i learnt the hard way...
at least i'll know for the future
but that was definitely a very expensive lesson.

[MM89]

Ok, alot of people will disagree with what I say, but when I lowered my car by about an inch and a half, I didn't bother with a wheel alignment for over a year with no detrimental effects. It did get a little twitchy going into the turns but nothing major. For a while, I also ran with my front slightly lower than the rear - again nothing major, well, not on the street anyway.

Not very helpful there but its very hard to diagnose the problem based on description alone, there are so many factors to consider and different drivers have different feel.

if it does bother you so much, as many people have said, get to an alignment place and get everything set back to stock and then experiment from there.
It shouldn't cost you more than $100 and usually about an hour or less, unless of course you have camber kits.

On that note, unless you have camber kits, you can only adjust for Toe front and rear.

Currently my rear is in fact approximately 1cm higher than the front.
So how much does this generally affect weight distribution?

I was thinking from what i retained from basic high school physics
that because the front is now lower, in the case of braking when coming
into a corner, more weight is distributed to the front end, applying more
stress on the front wheels and in the motion of turning in, it may possibly
cause more understeer?

Please correct me if I'm thinking totally in the wrong direction.

[aaronng]

Ok, alot of people will disagree with what I say, but when I lowered my car by about an inch and a half, I didn't bother with a wheel alignment for over a year with no detrimental effects. It did get a little twitchy going into the turns but nothing major. For a while, I also ran with my front slightly lower than the rear - again nothing major, well, not on the street anyway.

Depends on the car model too. On mine, when I lowered it by 1 inch, the rear camber went out to -4 degrees, V8 supercar in reverse style!

[hisoka]

Tow away zone is not a loading zone. Tow away zone is like a clearway or parking in front of a fire station vehicle exit!

ohh ok lol thanks,

[Bowzer]

they're coilovers from modproject
it's got the separate height adjuster below the spring
so i'm basically just reducing the thread length from the lower perch.
The spring is only just locked in, it hasn't been compressed whatsoever.

btw, i tried re-adjusting the front. The issue seems to be much improved
after the re-adjustment. I'm not sure whether this is the reason why it seems better now, but it is. The front height was out by 4mm between left and right. It is currently out by 1mm. Trying to make it as accurate as possible.

We recommend you add some pre-load to the spring so that there isn't too much free play between the perches this will help give your car are more predictable feel especially when your going over bumpy roads. Also you might find there is less noise as a result.

[JohnL]

But normally, lowering just the front puts more weight on the front, technically should reduce understeer but really depends on the entire scenario. e.g. You could still load the front to a point where it'll plow...


Imagine looking at your car from the side, now imagine lowering the front (or rear because this is the same except in reverse if you change rear height on it's own rather than front height), now imagine a point that approximates the CG (which will be forward of the middle of the wheelbase on a FWD car).

As the front lowers the CG will move in an arc centered on the points where the rear wheels touch the ground, and as a result the CG will move down and forward, and this wil cause the CG to both lower and move forward (i.e. change front rear weight distribution with more weight on front wheels and less on the rear).

Note that the degree to which the CG lowers will be less than the degree to which the front was lowered because the CG isn't at the front axle line but further back between the front and rear axle lines, however the CG lowering will be significant depending on how far the front was lowered, more so the further forward the CG is.

However, because of the angle (much more horizontal than vertical) of the line drawn from the rear contact patches to the CG (the rear contact patches being the points around which the CG moves in an arc when the front is lowered), the degree to which the CG moves forward (and as a result how much the front / rear weight distribution changes) when the front is lowered will be very very minimal and as a result will be of no practical consequence, i.e. lowering the front will make no discernable or significant difference to the front / rear weight distribution nor to the handling balance as affected by the front / rear weight balance.

Any change in handling balance as a result of lowering the front will be a result of the CG lowering, and / or camber changes etc, not as a result of any change in front / rear weight (which will be an insignificant change, even with a substantial change in front height).

On a related note; body roll does not cause a significant change in lateral weight distribution either, because the degree to which the CG moves laterally within the plane defined by the four contact patches as a result of body roll is highly insignificant (though real).

[e240]

fine if static,

and then you need to add acceleration, braking and cornering to the equation, and sometimes braking&cornering or acceleration&cornerning and ..well, braking&acceleration..LOL.

and then you add terrain features as well...

[JohnL]

fine if static,

and then you need to add acceleration, braking and cornering to the equation, and sometimes braking&cornering or acceleration&cornerning and ..well, braking&acceleration..LOL.

and then you add terrain features as well...

There is still no significant direct affect (static or dynamic) on front / rear weight balance when you lower (or raise) one end of the car, other than what will occur dynamically as a result of changing the CG height (associated with a ride height change). There may be indirect affects associated with potentially increased accelerations (lateral and / or longitudal) that might occur as a result of changing CG height or any associated camber changes etc...

[MM89]

Hey guys, i'm back again!

Seeing this thread isn't TOO old i decided to ask more questions
since it's regarding the same topic and i was also the thread starter..
By the way, I believe these coilovers from modproject are identical
to the Skunk2 Pro-C coilovers.

Having used the previous setup for about a month or so now, i'm kind
of chasing a better setup. I think the suspension can be to tuned to
handle better. The previous setup was slightly biased towards a wank
factor; a little too low and a little too stiff. Not much shock absorbing
was going on; hence for some roads that are a bit more harsh, handling
did not benefit much and 1st gear was a must when it came to speed
bumps, once again being too stiff and too low. Scrubbing and wierd
noises at full lock. I just wanna bring that to an end. The plans was
for this car to handle like a dream. Now I'm trying to chase that.

(all meausrements in mm)

LF | RF
-------
LR | RR


PREVIOUS SETUP

Ground - Wheel Arch

578 | 583
---------
595 | 600

Thread Length

43 | 50
-------
66 | 60

Spring Length

198 | 198
---------
195 | 194

Complete C/O assembly
385 | 390
---------
404 | 404

Damper Rebound setting: 3/6 All around



CURRENT SETUP

Ground - Wheel Arch

601 | 601
----------
601 | 601


Thread Length

70 | 70
--------
70 | 70

Spring Length

195 | 195
---------
190 | 190

Complete C/O assembly

408 | 408
---------
405 | 405

Damper Rebound setting: 3/6 All around



As you can see, the figures have become consistent throughout now.
Steering feels lighter, like what i was experiencing before, but
not understeery. What I mean is that the initial turn in
feels too light? Is that a good thing? I think I could imagine
myself with a tighter steering wheel feeling as it seems to be
more predictable.
Apart from that, no scrubbing, ride is firm, not overly stiff.

What I don't understand is why the spring length in the rear being
5mm less than the front and c/o assembly being 3mm less in the rear
as well still gives the same ground to wheel arch measurement.
Maybe I measured it wrong. The rear does LOOK lower from the eye,
so I shall further investigate into that.

My question is, how can i further improve the settings of this
set of coilovers? The springs in the front are 3mm shorter and
springs in the rear are 5mm shorter. Has this in theory made
much of a difference? I can't exactly feel it for myself because
i've changed the thread length too, which may have added to the
effects?

By improving the settings/setup I'm generally referring to a
street setup. In the case of Melbourne roads, I would assume that
you would need sufficient shock absorbing, yet I still want enough
stiffness to tackle the corners without booty roll. How can I set
for a more solid turn in as well? For track, I would imagine the
setup to differ in many ways. So that can be attended to when
the day comes..

Comments and suggestions much appreciated.

[outatime]

man those numbers are complex.. just measure the distance between the locking perch to the base of the coilover. Mine is set to 38mm at the front and 60mm at the back. with that setup, the back is 2mm higher than the front. it gives my car a good stance, handling, and free from scraping.

[MM89]

man those numbers are complex.. just measure the distance between the locking perch to the base of the coilover. Mine is set to 38mm at the front and 60mm at the back. with that setup, the back is 2mm higher than the front. it gives my car a good stance, handling, and free from scraping.

i'd like to make sure that everything is as perfectly level as can be.
hence why i measure the spring lengths as well as the thread length
between the perches.

38mm front 60mm rear ? i dont quite understand how that only makes
2mm difference. are there also differences in other parts of the coilover
between front and rear?

[outatime]

38mm and 60mm are the distance between the lock perch and thread base of the coilovers.. then with the car on a level ground, i measure the distance from the base of the wheel lip up to the edge of the fender. measurements are 527mm at the front and 529mm at the back.

[MM89]

i see..so you actually remove the whole lower component of the coilover that
connects to the control arms and measure to the base of the thread.
Considering 527mm and 529mm does not include the bottom of the tyre
making contact to the floor, i'm guessing it would be approximately the same
as mine; as you saw from previous posts, mines currently sitting at 601mm F/R
from the ground to the edge of fender. (random) is that your car in your dp?
looks quite low and there doesnt seem to be much wheel gap in between.
is that me or am i seeing things or whats the sitch? :)

is there any particular reason why you measure from the base of the wheel lip
to the edge of the fender? is that a standard that is used or is it simply a point
where you prefer measuring from? reason why i ask is because i'm unfamiliar with
the methods that are used to measure suspension dimensions etc

[outatime]

no need to remove the lower component.. you can actually measure it with the wheel off. what i mean by thread base is the small bump where the thread ends.. i'll see if i could put a pic..

yes that's my car.. there's a 1.5 finger gap between tire and fender. enough for the car to go through all sorts of humps and driveways without any hassles.

i didnt include the bottom of the tire because it could be unevenly worn or the tyre pressure arent the same. that's the proper way to measure it. well that's how I was told by a RalliArt Suspension mechanic. surely he cant go wrong. the 2mm advantage at the back is hardly noticeable and it compensates if the petrol tank is full or if passengers are at the back.

[JohnL]

Steering feels lighter, like what i was experiencing before, but
not understeery. What I mean is that the initial turn in
feels too light? Is that a good thing? I think I could imagine
myself with a tighter steering wheel feeling as it seems to be
more predictable.


The 'tight' steering feel you're after is a function of the caster angle. Increase caster as much as possible and the steering will feel much more positive and 'connected' to the tyres. The steering will also become somewhat heavier, but not a problem with power steering.

You'll also improve the 'steered' camber angles, i.e. as you steer the outside wheel will gain additional neg camber (relative to the body) and the inside wheel will gain positive camber (or lose neg camber depending on the static camber angle from which you begin). Both of these affects will tend to help keep the front contact patches presented more 'squarely' to the road as the body rolls.

[string]

Exactly how low are you? If you're getting close to the bump stops then I'll bet your problem is the front roll centre location. Increasing the front roll couple relative to the rear will result in worse steering feel, especially on turn-in; a feeling of perpetual understeer and tyre-rollover - sound familiar?

Also I am curious as to why you are trying to get the ride heights identical left and right on each axle. You only want to do this if each of corners holds identical proportions of the sprung weight. This is unlikely even on a modified race car let alone a stock civic. The only way you'll get it right is to get the car on scales and corner weight it. The other method is funnily enough, what you did in the first place which is to set each spring's perch to the same height - the sides won't sit even if they don't have the same weight on each tyre (very likely) but the side with less static weight will deflect the spring less, causing it to be higher than the other side and thus take more of the sprung weight.

Aligning each fender the same will give you false confidence of the car's left/right consistency

[MM89]

so how should the springs/perches be set?
i dont have much clue where to start from.

the car is now raised and im guessing has
taken some excessive strain off the bushings,
control arms etc. steering is lighter, but
i'm still trying to figure out what johnL mentioned
in regards to the increased castor causing a
more positive steering wheel feedback.

[JohnL]

i'm still trying to figure out what johnL mentioned
in regards to the increased castor causing a
more positive steering wheel feedback.

Increasing caster also increases what is called the 'trail', which is the distance from the point at which the steering axis intersects the road to the centre of the contact patch (a little simplistically put). Trail increases as the steering axis is tilted further backward (i.e. increase in caster angle), or moved forward relative to the wheel without increasing caster.

Imagine a shopping trolley wheel (i.e. a 'caster'). These have a great deal of trail (but despite their common name, zero caster angle) because the steering axis is a long way in front of the contact patch, and the more trail the stronger the tendency for the contact patch to remain directly behind the point at which the steering axis intersects the road as the wheel rotates. The contact patch 'trails' behind the point where the steering axis interscects the ground.

In essence, the longer the trail the more strongly the contact patch will 'want' to position itself directly behind the point at which the steering axis intersects the road (as wheel rotates), and the more force will be required to cause the contact patch to move away from this position (because of trail, when steered the centre of the contact patch not only turns but also moves laterally, more so with more trail).

This increases the strength with which the steering self centres, and increases the force required (inputed at steering wheel) to steer away from the straight ahead positon. Steering resistance will be felt more strongly and more immediately as the steering wheel is turned away from straight ahead.

There are other affects of caster assiociated with increased steering weight, but they aren't as strong and I dion't have time now to describe them.