Handling woes

[shnazzle]

Your suspension bushes may not necessarily 'look' bad but they're still 13 years and 80?k miles old.

Mine didn't look terrible and there wasn't any particularly noticeable play pulling on the wheels with the car jacked up. But there is a massive difference in the movement of new ball joints and inner tie rods. Admittedly the car has only moved in and out the garage since it was done but I'm sure it felt different.

You also don't need to polybush (if you think it's front related) - I got arms, droplinks, tie rod ends, a new inner tie rod and some misc bolts for less than £90 all in. Probably cost about that in tools lol

If you're passing by at any point you're welcome to try my stock wheels but given the brands on them I'm not sure it would be an objective test.

Funnily enough I did think of those arms that come with "stock" bushes. That's the only way I've seen a way to replaces bushes without going poly.

ARBs poly'd wouldn't be too bad.
So that leaves the rear

[Petrus]

Just for fun and perspective:
An entertaining CLEAR example of understeer going in and oversteer going out at 2:58

https://www.youtube.com/watch?v=csyCLFrs-5g

followed by FWD throttle lift oversteer.

[Petrus]

Buenos dias caballeros,

How are you getting on Shnazzle?

I cam back up into the mountains from the coast. It had rained on the coast, took the modern by pass and on the wide bridges crossed quite a few broad metal connections/drains. Looooooog sweeping corner, wiiiiiiide 5 lane smooth tarmac, not wet but moist. At around 130 km/h the car tracked giving confidence untill.... WOAHHHH... a metal connection;
I féél the chassis flexing and know I best NOT respond to what I think to feel.
It is more sound than actual jolt as the suspension is pleasantly soft but all four wheels stepped a bit outside, the rear ones also momentarily loosing forward traction and then finding it again. Basically nothing happens. The car literally shakes it off.  Íf I would respond, I would be late to the facts and upset the car, caúse it/me to loose it.
Modding the door into a chassis brace would change nothing as the air suspension in the tyres and the car suspension absorb the jolt. The chassis only flexes ´after the fact´. The féél however will be more violent, undampened by the chassis. Ditto any response by me.
I am só looking forward to bracing the door!!

[shnazzle]

Buenos dias caballeros,

How are you getting on Shnazzle?

I cam back up into the mountains from the coast. It had rained on the coast, took the modern by pass and on the wide bridges crossed quite a few broad metal connections/drains. Looooooog sweeping corner, wiiiiiiide 5 lane smooth tarmac, not wet but moist. At around 130 km/h the car tracked giving confidence untill.... WOAHHHH... a metal connection;
I féél the chassis flexing and know I best NOT respond to what I think to feel.
It is more sound than actual jolt as the suspension is pleasantly soft but all four wheels stepped a bit outside, the rear ones also momentarily loosing forward traction and then finding it again. Basically nothing happens. The car literally shakes it off.  Íf I would respond, I would be late to the facts and upset the car, caúse it/me to loose it.
Modding the door into a chassis brace would change nothing as the air suspension in the tyres and the car suspension absorb the jolt. The chassis only flexes ´after the fact´. The féél however will be more violent, undampened by the chassis. Ditto any response by me.
I am só looking forward to bracing the door!!

You know what? I think I'm getting used to it.
The steering in the front is quite direct now, which took some getting used to and caused me to oversteer. Not the car.

I won't be getting spacers. As that will induce more oversteer.
But, I will be keeping the rear damping lower than front and I'll change my rear toe inwards, front outwards a smidge, and a bit more front neg camber. I think that will work rather well based on what I'm feeling now.
I'm in no rush to do so though. I'm going to stick to damping for now and perhaps raise the driver's side front a couple of mm as I notice the steering is sharper one way than the other.

[Petrus]

perhaps raise the driver's side front a couple of mm as I notice the steering is sharper one way than the other.

Some manufacturers realise that their car will be driven with only the driver on board and compensate for this weight unbalance by fitting a harder front spring driver side.

It is a bit of a pet peeve of mine with light cars and I really have to switch it off when I get in and notice the one sided sag.

[Dev]

Most of these bracing modifications are generally in the feel category rather than actual suspension modifications like sway bars, struts and tires which actually make the car faster.  Having said that without feel you will be lost and will either input too early or too late, and that can make the car unstable and lower the preceived limits. Having a good sense of feel in my opinion is the magic sauce that makes the other upgrades work at the correct timing.   
   However with all modifications there are consequences and that is the more bracing you add the more weight you will tack on and then the car will suffer  a loss of nimbleness and might end up being sluggish or it can actually ruin the feel by being too stiff. 
You need to be judicious as well as conservative in your approach when applying modifications and at times you may need to pull something off.

[shnazzle]

Exactly the above.

So far, I've hopefully not added much weight.

Front strut bar - removed frunk plastics and bin lid. The strut bar is very light. Spare wheel out. Alarm bracket smaller

Rear strut bar - stock airbox and heavy piping removed and replaced with lightweight alu enclosed cone on much shorter silicone hose. May remove this though.
Toolkit removed

Coilover replacement with BC - each unit seemed a fair bit lighter than the stock units.

Exhaust manifold - 3kg saved by adding zero manifold
Cat - custom stainless cat will be lighter than stock.

Added weight:
Double din radio (front)
Small subwoofer (front driver side)
Piggyback ecu (center)
Door stabilisers (sides)
CG-Loc seat belt immobilisers (front driver side)
Lower mid brace

So, definitely a need to revisit the corner weighting, partially because I've also lowered the car and changed wheels/tyres from stock.

I think once you get to the point I have, you've well and truly messed with the stock setup and balance so really it's back to the drawing board.
Corner weighting, roll center adjustment (which I really need to do), alignment.. Hell, sometimes on a more spirited drive I wish I could adjust the brake bias a bit.

I enjoy all this. It's teaching me a lot about handling, mechanical grip, "feeling" the car, the physics of the car.
So, if I didn't do anything wrong, I wouldn't learn as much. So frankly I welcome my f-ups

[Petrus]

Hell, sometimes on a more spirited drive I wish I could adjust the brake bias a bit.

What would you like to achieve?

[shnazzle]

Hell, sometimes on a more spirited drive I wish I could adjust the brake bias a bit.

What would you like to achieve?

It's not a must-have by any means. But I've had the front lock up a small handful of times coming into a corner, unexpectedly,which then lead to basically not being able to steer obviously. Having a bit less front bias on dry days on grippy roads would let me play with that a bit.

As I said, that's something I've encountered maybe 3 times since ownership 2013. I'll never actually implement this Too much hassle and money for something I'm unlikely to use as most of the time it would be in stock config

[shnazzle]

Worth noting that those 3 situations arose (most likely) because of driver error. Not because I was driving 9/10ths on a public road.

Oh and as you might have guessed or seen from all my other posts over the years, I like tinkering and diving into the depths of things.
Keeps me off the streets

[Petrus]

What would you like to achieve?

It's not a must-have by any means. But I've had the front lock up a small handful of times coming into a corner, unexpectedly,which then lead to basically not being able to steer obviously. Having a bit less front bias on dry days on grippy roads would let me play with that a bit.

As I said, that's something I've encountered maybe 3 times since ownership 2013. I'll never actually implement this Too much hassle and money for something I'm unlikely to use as most of the time it would be in stock config

Did you fit a hard brake line kit yet? My appologies if I missed that.
It does not change the braking ofcourse but does improve modulation which is the most important property of the set up so the driver can brake to the max a given system is possible of.

[shnazzle]

What would you like to achieve?

It's not a must-have by any means. But I've had the front lock up a small handful of times coming into a corner, unexpectedly,which then lead to basically not being able to steer obviously. Having a bit less front bias on dry days on grippy roads would let me play with that a bit.

As I said, that's something I've encountered maybe 3 times since ownership 2013. I'll never actually implement this Too much hassle and money for something I'm unlikely to use as most of the time it would be in stock config

Did you fit a hard brake line kit yet? My appologies if I missed that.
It does not change the braking ofcourse but does improve modulation which is the most important property of the set up so the driver can brake to the max a given system is possible of.

Yes I have, a few years ago, and it did indeed improve things to no end for braking.
In fact, one of the 3 occurrences I mentioned, lead to me getting my HEL lines. It was on the Hartside Pass. I remember it well.

[Petrus]

/quote]
Yes I have, a few years ago, and it did indeed improve things to no end for braking.
In fact, one of the 3 occurrences I mentioned, lead to me getting my HEL lines. It was on the Hartside Pass. I remember it well.

Then basically Patrick you have all the modulation you need 
If wánt to, if only for confidence sake, you could achieve more rear bias with different pads; the same brand and type in one grade softer at the rear than at the front.
Personally I would not modify the genreic road condition set up for an exception.

[shnazzle]

/quote]
Yes I have, a few years ago, and it did indeed improve things to no end for braking.
In fact, one of the 3 occurrences I mentioned, lead to me getting my HEL lines. It was on the Hartside Pass. I remember it well.

Then basically Patrick you have all the modulation you need 
If wánt to, if only for confidence sake, you could achieve more rear bias with different pads; the same brand and type in one grade softer at the rear than at the front.
Personally I would not modify the genreic road condition set up for an exception.

No indeed. I shan't

[Petrus]

And?  How is it goin? Getting used to it?

I am looking só foward to stuffing them in.
Expecting quite a transformation now 

[shnazzle]

I'm quite comfortable with it now to be honest, but it's been quite cold and wet so truthfully I won't be 100% comfortable until summer comes

Also a bit more tramlining on the rear. But that's always been there to some degree. Especially after -2 rear camber

[Ardent]

Just for fun and perspective:
An entertaining CLEAR example of understeer going in and oversteer going out at 2:58

Enjoyed that.

[shnazzle]

Just to revisit this. 
It's an odd thing. I've had a good push a couple of weeks ago. Perfectly dry and sunny warm weather. 
Very obvious UNDERsteer. Came around a long-ish bend and the car just wouldn't come in. 
The front was dragging the car out. Very obnoxious.
So, rear unsettled when wet, but when pushing it, understeer for days. The rear being unsettled has changed with fresh AD08Rs on the rear. 

So before big suspension changes take place I want to try;
10mm spacers rear. Rear toe in a bit for straight line. Front camber to -2 with 0 toe.

After that, it's koni inserts into my BC coilovers or something along those lines. The damping on the BCs really does degrade very quickly over time. It seems to be crap at first, then goes sweet, and then dreadful 

Having driven a few cars with stock suspension now, I'm actually leaning towards moving to a more stock setup.

[Petrus]

Me not like.
Please try change ONE thing at a time.

Also, go back to THE one and only basic:
Going through a corner, centrifigal force pushes the car to the outside and the grip of the rubber prevents that, with the limit being the amount of adhesion.
ANY other force on any of the tyres will lower the the amount of adhesion availeble to counteract centrifugal force.

On the mid engined MR2 with rear bias weight distribution, slight load shifts or steering changes will affect the above mentioned balance noticably. The resulting oversteer/understeer needs be taken back to the basics and to individual aspects if you want to address it.

Additionally the oversteer/understeer is both tyre ´slip´; the creep of the rubber itself while maintaining adhesion ánd actual slip, a % of drift becasue of going over the limit of adhesion.
An example:
Inflating a tyre a bit will stiffen it and reduce the creep of the rubber itself: Inflate the front ones a bit and it will result in less understeer.
Adding a bit negative camber ot a front tyre that has a reduced contact patch because of centrifugal forces, will give more adhesion and thus reduce thát slop = also reduce understeer.

Now add the effect of driving forces. Accellerating or decellerating will not only add forces directly, it will also shift the weight load on all four of the tyres.

I have found the this MR2 to be very, véry sensitive to the latter. To both the accelerating/decellerating and weight shifts.

[shnazzle]

I see what you're saying but my logic is as follows:
1) my front track is wider than my rear. That's jusr wrong regardless. Hence spacers. I messed up on alloy purchase. 
2) rear - 2 camber with front - 1 camber will induce understeer. So either reduce rear or increase front. I like the corner grip that - 2 rear gave. So going with changing front
3) I didn't toe the rears in enough when I had my last alignment, so straight-line stability suffered a bit. Not massively 

I used to be able to push through the same corner much harder than I cna now. Which tells me I messed something up.

[Petrus]

I used to be able to push through the same corner much harder than I cna now. Which tells me I messed something up.

So start with making a list of what changes you made and write the effects of those; both the theoretical and what you perceived, behind them.

@ 1. Agreed BUT be aware that this does not affect the front scrub radius you changed, although it affects mainly stability, not understeer/oversteer,

@ 2. You should not have more negative camber than necessary to restore a by distortion reduced contact patch.
As on the MR the rear is heavier and the sidewall higher, the tyre distortion tends to be larger. Through tighter corners, the steering angle of the front adds a force thus distortion.
Too much negative camber for the available traction; cornering forces, redúces the contact patch.

It is só easy to completely loose track of the actual set up and thus where to go to.

A good comparative list remains:
http://www.morpca.org/drivers-education-guide/understeer-oversteer/
but it has to be seen in the context; see my reservation concerning negative camber.
Do read through the whole list and try project it on the basic; centrifugal force vs. traction.

The ´take a different line´ is very sound one and shoul be read as enveloping all driver´s style. In mý case it made a world of difference and I am stíll coming to grips with the behavior of this mid engined gem: Just this very weekend concluded that Í am ´causing´ the recently experienced understeer in tighter corners.

[H1GRM]

I have been following this thread with interest. The link from Petrus has it all down to a fine art. I remember something like this in a booklet many years ago from the BRDC, I used to do hill climbs and sprints and then had a couple of seasons on the track before the money ran out.

However, unless you are competing, please remember these limits and the subtleties being discussed are way beyond driving on the roads (at least in the UK @Petrus)

Stay safe chaps. Greg

[Ardent]

Facinating read.

[Petrus]

However, unless you are competing, please remember these limits and the subtleties being discussed are way beyond driving on the roads (at least in the UK @Petrus)

Buenos Greg; point taken.
HOWEVER; if the political correctness rules than we need a non public sub forum for all this and related.

Bottom line:
- A bit more or less negative camber, more of less tyre pressure, a bit wider rims even oversized ones, are not going to lower the availeble traction só much that legal speed centrifugal forces surpass it.
- Within the framework of indicated maximum speeds, there will never ever be more than the lightest understeer or oversteer on dry roads with an MR2 Spyder even on El Cheapo tyres.
- Rain on worn shiney roundabouts excepted.

The link I gave is for the reference framework. Without proper understanding of the basics and the principles, ány modding is per definition going into unknown territory.

Right, now for road legal advice;
1,  Push less and you woes will go away.
2.  Change the AD08Rs for rubber with a wider/lower temp. range befitting the driving mentioned under 1..




 

[Petrus]

For those keen to learn, to understand the art of setting up a vehicle there is an intersting write up on the model development of the first gen. Honda NSX:

As found by the automotive press such as Car and Driver in their September 1997 issue's comparison of "Best Handling Car for more than $30K", the NSX, due to its mid-engine layout and rear-end link travel, was susceptible to a sudden oversteer condition during certain cornering maneuvers.
While this condition rarely occurred during normal driving conditions, it was much more prevalent on race tracks where speeds were much higher.
To address the problem and improve the NSX-R's cornering stability at the limit, Honda added one aluminium bracket under the front battery tray and added one bracket in front of the front radiator to add more chassis rigidity replacing the entire suspension system with a more track oriented unit, featuring a stiffer front sway bar, stiffer suspension bushings, stiffer coil springs and stiffer dampers.

The standard NSX has a somewhat rearward bias in its spring and bar rates, where the rear was relatively quite stiff versus the front.
This means that the lateral load transfer distribution, or the amount of load that is transferred across the front axle versus the rear while cornering, is rather rear biased. This can make the car quite lively and easy to rotate at low speed, but during high speed cornering, this effect becomes more pronounced and could be a handful to manage.
To reduce the tendency to oversteer, Honda fitted softer rear tyres on the NSX.

For the NSX-R, Honda reversed the spring bias, placing stiffer springs on the front suspension along with stiffer front sway bar.
This shifted the load transfer stiffness balance farther forward, resulting in more rear grip at the expense of front grip; this had the effect of decreasing the oversteer tendency of the car, making it much more stable while cornering at high speeds.

Overall, the NSX-R utilises a much stiffer front sway bar along with stiffer springs than the standard NSX (21.0mm xt2.6mm front sway bar :F 3.0 kg/mm—R 4.0 kg/mm for the NSX versus F 8.0 kg/mm—R 5.7 kg/mm for the NSX-R).