Traction issues when turning left

[Locutus]

Your adjustments are off. Your raised measurements on both sides should be identical.

[Magpie]

What is the length at full droop? I assume you mean raised?

The 30mm dif in length is the issue.

No you don't need a car corner weighted, however correct length dampers are required to make max use of suspension travel.

[pepejesus]

So I did some more measuring in better light. (also can not for the life of me get the rear swaybar end links undone)

You need to put an Allen key (5mm I think) on the end of the end link bolt otherwise the nut and bolt just spin around together. I spent a good 45 minutes shouting and swearing before I figured this out.

Also do what Magpie says - it's the only way to properly set the shock lengths.

[project.r.racing]

Spring perches on one side or off by 25-30mm. Should normally be an up to 5mm difference for corner and driver weights.

[Magpie]

Travel from Ride Height to full Droop - damper Length or Spring Perch
(L) 30mm
(R) 55mm

Whilst you only have 3mm difference in damper length at ride height, the difference grows to 25 at full droop. How much travel do you have at full compression? You have not measured the dampers at their extremes (full compression and fully extended).

This was my previous setup, the wheel contacted the body work well before it was fully compressed, hence less suspension travel. After doing the lengths properly I gained over 20mm of travel!
DSCN1988 by Eipeip, on Flickr

Full Droop Front
DSCN1987 by Eipeip, on Flickr

Full compression
DSCN1989 by Eipeip, on Flickr

As adjusted, to allow for bumpstops
DSCN1990 by Eipeip, on Flickr

Limit of damper on full compression, sans bumpstops/springs. Never had any rubbing to date!
DSCN1991 by Eipeip, on Flickr

[Roadrunner]

What is the length at full droop? I assume you mean raised?

The 30mm dif in length is the issue.

Is there a way to fix it without pulling the whole strut out as per your instructions earlier? (Don't have the time or the skills)

My thought is, jack car up,
Measure the distance from top plate to the bottom collar of the right strut.
Match this on the left side via the bottom collar (effectively raising the car but matching the droop on both sides)
Then adjust the left spring perch to set ride height?

But wouldn't this mean I need to lower the spring perch to lower the car to match the right side ride height? (remembering the left side is already extended 30mm more than the right) With how much decompressed the spring currently is, I'd worry about it coming un-seated/loose when jacked up. This seems to be the polar opposite to the drivers side.
Plus surely having now 60mm difference in pre-load left to right would effect the dynamics (or does this not matter not being a progressive spring?)
Or do I have that the wrong way around?

I guess I'm still a bit puzzled why the pre-load measurement is near identical when at full droop but massively different when on the ground. It's almost as if the left spring isn't compressing as much as it should with the weight of the car on it.

[Roadrunner]

Spring perches on one side or off by 25-30mm. Should normally be an up to 5mm difference for corner and driver weights.

But if I raise/compress the left spring perch to match the right (100mm at ride height) won't that raise the car?

[Magpie]

From previous discussions, been looking for the opportunity to complicate your post even further

Measure the distance from top plate to the bottom collar of the right strut - measure to the bolt in the suspension instead of the collar, may not be any difference but worth a check.
Back off the spring perch collar so that it becomes uncaptive when measuring the length as well as disconnect the sway bars.
Match this on the left side via the bottom collar (effectively raising the car but matching the droop on both sides) - yes droop is the important part
Then adjust the left spring perch to set ride height - yes

If you get any rubbing then adjust the length of the damper, however based on your information so far rubbing is not an issue. Further do not worry about the spring going un captive (this is another can of worms relating to helper/assist springs).

Hks Not quite, my understanding is

The spring only moves once the wight placed on it overcomes the preload placed on the spring

So at 0 preload
80kg give 10mm deflection to rest. So car now has 10mm of sprung suspension droop if the car weighs 80kg per corner

5m pre load
40 kg takes up the preload, 40kg pushes the car down 5mm. Car now has 5mm of sprung suspension droop at 80kg per corner

10 mm pre load
80kg take up pre load, no suspension movement. Car has no SPRUNG suspension droop. The wheel might droop further based on movement but it's not controlled by the spring.

10mm pre load
80kg takes up preload. 40kg dynamic loading give 5 mm of suspension bump from static but still no droop travel from static.

Keep in mind that be weight of the car acts in the opposite direction (downwards) on the spring compared the force of the preload (upwards).




Sent from my iPhone using Tapatalk

Please note; this does not include angular correction for shock orientation. This is purely looking at a weight acting on a spring with and without pre-load

Sent from my SM-N9005 using Tapatalk

[Roadrunner]

Haha Thanks Magpie, that actually makes sense. (and you are correct, I have no issues with rubbing at the current ride height)

Should I be concerned that there is such a difference from side to side though? Since I have never touched the spring perch, was this always like this and I'm only just noticing it, or is there something broken (spring or damper) with the coilover? Trying to remember the past few years of playing with alignments and heights and my memory is telling me every time I have checked ride height, the passenger rear has been higher, but not certain on that.

Just checked another NB with same coils and set up and it also measures equal each side top to spring perch measurements at full droop and at ride height

[RS2000]

At ride height:
Top plate to spring perch:
Left: 130mm
Right 100mm

Soo....why the difference in my rear shocks? Why does one spring compress more than the other when lowered.....

I think the problem lies here.
For one spring to compress more than the other, you either have different loads or different spring rates. Stuffed spring?
Spring preload has NO effect on the loaded spring compressed length (as the calcs in Magpies post proves ie 19+10 = 29)
A shock absorber does not support vehicle weight (unless jammed) & I wouldn't think the arb could cause that much load difference.
It should be easier to disconnect the arb at the bar (ie link top joint), than at the suspension arm.

When measuring ride height, the only really accurate place is at the inner lower suspension pivot points. When I set these the same side to side from the floor, the pinch welds to floor & guards to floor are all over the place - but my car could be bent!

[project.r.racing]

Spring perches on one side or off by 25-30mm. Should normally be an up to 5mm difference for corner and driver weights.

But if I raise/compress the left spring perch to match the right (100mm at ride height) won't that raise the car?

Not if you adjust the shock foot at the same time also. That is why there is two adjustment locations.

Just make sure the springs match also in length. And also the sway bar is not bent, (as in link bolt holes match up etc).

[Roadrunner]

Starting to believe there is some serious shenanigans going on.

Have a look in this pic from 2 years ago.

Both sides, distance from perch to base are identical. Ride height back then was equal all round but slightly higher than now. I have played numerous times with ride height in small amounts over time (only by the lower collar, never the perch) but I'm remembering always having to lower the rear left every time I measured it. After a number of adjustments, now the rear left is as low as it can go and is bottomed out in the bottom housing.

Silly question, but is it possible for a spring to expand/stretch? I would have thought if the spring 'failed' it could compress/sag.
The perch collars are locked tight. I don't believe they have moved under their own will.

Also noticed I didn't used to have wear marks on the right hand side of the swaybar bushes where I do now, but that could just be the amount of track days I've been doing since this photo.



The car goes in tomorrow for front brake seals to be done, I will get him to undo the rear swaybar links while he has it. I can not budge them no matter how much penetrating oil and swearing I throw at it

[project.r.racing]

The sway bar moving laterally and loosing some paint is normal.

[Magpie]

If you get up to QLD on day I'll see if we can arrange a dodgy day for you

Always adjust height by the spring perch and not the lower collar!

All things being equal, the spring will be compressed by the same amount by the weight on that corner. The spring perch collar is then moved up/down to change the height, the spring will always be compressed by the same amount (unless you change the weight on that corner) no matter where it is in the vertical plane.

The damper length collar will also change the spring perch height, HOWEVER it will also change the damper length which in turn changes the amount of suspension travel.

[Roadrunner]

Ok so I've got tomorrow off work so I will tackle this with all the advice given. Mechanic cracked/undid and re-tightened the swaybar bolts too so I can actually remove it from the equation all together too.

Just for arguments sake, if adjusting the coilover body length to the same as the right doesn't allow the wheel to drop as much as the right, Is it safe to disconnect the bottom coilover bolt (that connects to the control arm) to check that the whole left assembly actually drops as far as the right? (ie to check nothing is binding/limiting travel in the control arm etc?)
Even at full droop its not under tension pushing down is it??