Handling woes

[shnazzle]

Some may have followed my posts about Dev's door shut bushes; in short, installing them has exposed my sh1t setup for what it is. Sh1t.

Somehow I got away with it before these things;the magic of body flex and compliance.

Lesson learned here is that chassis rigidity comes with the responsibility to make sure that you either handle the rigidity or build in compliance elsewhere.

So on that note; Can I please have your feedback on my setup and what you would change? I'm looking at the track boys for this.

Current setup and what I think is wrong:

Front
Team Dynamics 1.2 alloys
15 x 7.0 ET35 - 195/50/15 AD08R tyres
-0.4deg camber, 0.05deg toe in
Front strut brace
BC coilovers, 4kg, solid mount. Setting 5

Rear
Team Dynamics 1.2 alloys
16 x 7.0 ET45 - 225/45/16 AD08R tyres
-2.0 deg camber, 0.09deg toe in
Rear strut brace + stock brace
BC coilovers, 6kg,rubber mount, Setting 6

TTE middle brace
Dev's door shut bushes

Symptoms
- Back end feels very loose and breaks out easily. Not predictable
- Difficulty steering in. And when you keep pushing, the back end goes. General unbalance front/rear
- Snap back out of a corner. It wants to go straight, asap. Makes sense with the wider front track?
- before Dev's door shuts, a tendency to understeer on powered long bends, but generally felt well-balanced and easy to drive. Very stable back-end.

Guesses
- the front wheels poking out 10mm compared to the rear can't be good
-  2.0neg camber on the rear but 0.4neg camber on front would induce understeer. I'm debating whether I'm OK with that...I definitely prefer the 2.0neg rear camber.
- never done corner weighing. But is that really necessary on a non-track car? Although with all the bracing, light alloys, semi-track tyres and coilovers one could argue it is a track setup,hence should follow the same rules.
- loosening up the damping on rear coilovers, vs the fronts, may add compliance. So if I set the fronts to 10 and rears to 5 for example. Although that seems like it'd be adding compliance to mask an issue.
- at 90k miles, I probably need to do all of my suspension bushes. But as it's a daily, I really struggle with the thought of replacing them all with stiff poly bushes.

Thanks for your help guys

[Carolyn]

I think you've now managed to show up the fact that you're tyres are summer performance ones.  Can't imagine how else a little extra rigidity would have such a marked affect.

If you were nearer, I'd suggest a temporary swap-out with my all-weather ones.  Just to see.

[jvanzyl]

As per the other thread- refresh of the suspension bushes will restore driver/road connection, traction, braking and go-kart feeling..

Sent from my Moto G (5) using Tapatalk

[shnazzle]

I think you've now managed to show up the fact that you're tyres are summer performance ones.  Can't imagine how else a little extra rigidity would have such a marked affect.

If you were nearer, I'd suggest a temporary swap-out with my all-weather ones.  Just to see.

Makes sense but they seem to have been gripping fine through the same conditions over years.
If the tyres offer sufficient grip in the same conditions on one car setup and not another, which one is "wrong"?
Aside from the obvious fact that these aren't the optimal conditions for the AD08Rs

[Carolyn]

As Petrus has observed (and,somewhat Jason) it would seem that the more those tyres are used, the more the characteristic changes and they become less sticky in the cold.

Petrus (with his racing experience) reckons it's the heat cycles the tyre gets put through.

Is there anyone relatively close with some less 'racy' tyres that you could do a quick swap with?

It seems like a worthwhile experiment before you start spending dosh!

EDIT:  Jack's tyres have not had anything like the use yours have.  Good place to start?

[shnazzle]

As Petrus has observed (and,somewhat Jason) it would seem that the more those tyres are used, the more the characteristic changes and they become less sticky in the cold.

Petrus (with his racing experience) reckons it's the heat cycles the tyre gets put through.

Is there anyone relatively close with some less 'racy' tyres that you could do a quick swap with?

It seems like a worthwhile experiment before you start spending dosh!

EDIT:  Jack's tyres have not had anything like the use yours have.  Good place to start?

Very true they haven't. But I'd have to swap them off the alloys as hers are different sizes. I'm not sure how enamoured she'd be with that She doesn't like me fiddling with Jack

As I posted elsewhere, I'm definitely considering moving to more all-weather tyres next time, as it is a daily. Or getting a set of stock alloys and putting something like Rainsports on for the non-summer months. That would resolve the grip issues. But it doesn't resolve the unbalance

[tricky1138]

As Petrus has observed (and,somewhat Jason) it would seem that the more those tyres are used, the more the characteristic changes and they become less sticky in the cold.

Petrus (with his racing experience) reckons it's the heat cycles the tyre gets put through.

Is there anyone relatively close with some less 'racy' tyres that you could do a quick swap with?

It seems like a worthwhile experiment before you start spending dosh!

EDIT:  Jack's tyres have not had anything like the use yours have.  Good place to start?

Very true they haven't. But I'd have to swap them off the alloys as hers are different sizes. I'm not sure how enamoured she'd be with that She doesn't like me fiddling with Jack

As I posted elsewhere, I'm definitely considering moving to more all-weather tyres next time, as it is a daily. Or getting a set of stock alloys and putting something like Rainsports on for the non-summer months. That would resolve the grip issues. But it doesn't resolve the unbalance

But if you swap the wheels between yours and Jacks, then you can see if it is indeed your ET wheels causing the issue?

[shnazzle]

As Petrus has observed (and,somewhat Jason) it would seem that the more those tyres are used, the more the characteristic changes and they become less sticky in the cold.

Petrus (with his racing experience) reckons it's the heat cycles the tyre gets put through.

Is there anyone relatively close with some less 'racy' tyres that you could do a quick swap with?

It seems like a worthwhile experiment before you start spending dosh!

EDIT:  Jack's tyres have not had anything like the use yours have.  Good place to start?

Very true they haven't. But I'd have to swap them off the alloys as hers are different sizes. I'm not sure how enamoured she'd be with that She doesn't like me fiddling with Jack

As I posted elsewhere, I'm definitely considering moving to more all-weather tyres next time, as it is a daily. Or getting a set of stock alloys and putting something like Rainsports on for the non-summer months. That would resolve the grip issues. But it doesn't resolve the unbalance

But if you swap the wheels between yours and Jacks, then you can see if it is indeed your ET wheels causing the issue?

Except for that hers are et35 at the rear and scrape the arches, as mine are not rolled like hers
I'd have to raise my suspension to make it driveable on et35

I guess what I'm looking for is someone to be able to look at the spec and go "aspect X looks fundamentally wrong" and then I'd change that.

I'm going to order 10mm spacers for the rear to cover up for my whoops on the wheel offsets. That's a must anyway I think. I'm not going to order two new wheels for the rear as I'm not Rockefeller

[Nvy]

As Petrus has observed (and,somewhat Jason) it would seem that the more those tyres are used, the more the characteristic changes and they become less sticky in the cold.

Petrus (with his racing experience) reckons it's the heat cycles the tyre gets put through.

Is there anyone relatively close with some less 'racy' tyres that you could do a quick swap with?

It seems like a worthwhile experiment before you start spending dosh!

EDIT:  Jack's tyres have not had anything like the use yours have.  Good place to start?

Very true they haven't. But I'd have to swap them off the alloys as hers are different sizes. I'm not sure how enamoured she'd be with that She doesn't like me fiddling with Jack

As I posted elsewhere, I'm definitely considering moving to more all-weather tyres next time, as it is a daily. Or getting a set of stock alloys and putting something like Rainsports on for the non-summer months. That would resolve the grip issues. But it doesn't resolve the unbalance

But if you swap the wheels between yours and Jacks, then you can see if it is indeed your ET wheels causing the issue?

Except for that hers are et35 at the rear and scrape the arches, as mine are not rolled like hers
I'd have to raise my suspension to make it driveable on et35

I guess what I'm looking for is someone to be able to look at the spec and go "aspect X looks fundamentally wrong" and then I'd change that.

I'm going to order 10mm spacers for the rear to cover up for my whoops on the wheel offsets. That's a must anyway I think. I'm not going to order two new wheels for the rear as I'm not Rockefeller

You are miles away from the stock facelift setup.

Width 15″ x 6″
Offset = et45

to

Width 15″ x 7″
Offset = et35

Your rim will poke out about 22mm more thank before and that can very well unbalance your car. I think its best to have 20mm more rear to front on our cars so you would need a lot more than 10 mm spacer to make up for this difference.

Here is a calculator link with your settings:

https://www.willtheyfit.com/index.php?width=185&aspect=55&diameter=15&wheelwidth=6&offset=45&width2=195&aspect2=50&wheel_size=15&wheel_width=7&offset2=35

[Call the midlife!]

I think you've now managed to show up the fact that you're tyres are summer performance ones.  Can't imagine how else a little extra rigidity would have such a marked affect.

If you were nearer, I'd suggest a temporary swap-out with my all-weather ones.  Just to see.

Makes sense but they seem to have been gripping fine through the same conditions over years.
If the tyres offer sufficient grip in the same conditions on one car setup and not another, which one is "wrong"?
Aside from the obvious fact that these aren't the optimal conditions for the AD08Rs

"Through the same conditions over years" it's also 12 months since this time last year, age in the rubber might have pushed them past their usefulness.


Sent from my iPhone using Tapatalk

[shnazzle]

You are miles away from the stock facelift setup.

Width 15″ x 6″
Offset = et45

to

Width 15″ x 7″
Offset = et35

Your rim will poke out about 22mm more thank before and that can very well unbalance your car. I think its best to have 20mm more rear to front on our cars so you would need a lot more than 10 mm spacer to make up for this difference.

Here is a calculator link with your settings:

https://www.willtheyfit.com/index.php?width=185&aspect=55&diameter=15&wheelwidth=6&offset=45&width2=195&aspect2=50&wheel_size=15&wheel_width=7&offset2=35

Hmm yes I do seem to have done that wrong. You're right. My rear wheel sizes are stock but I did change fronts by quite a bit. I was comparing front to back. Not stock vs my setup.

One thing I don't get though is that if I use willtheyfit to compare front to back, it comes out with a poke difference of only 10mm. Wouldn't this then be 20mm?

[Nvy]

You are miles away from the stock facelift setup.

Width 15″ x 6″
Offset = et45

to

Width 15″ x 7″
Offset = et35

Your rim will poke out about 22mm more thank before and that can very well unbalance your car. I think its best to have 20mm more rear to front on our cars so you would need a lot more than 10 mm spacer to make up for this difference.

Here is a calculator link with your settings:

https://www.willtheyfit.com/index.php?width=185&aspect=55&diameter=15&wheelwidth=6&offset=45&width2=195&aspect2=50&wheel_size=15&wheel_width=7&offset2=35

Hmm yes I do seem to have done that wrong. You're right. My rear wheel sizes are stock but I did change fronts by quite a bit. I was comparing front to back. Not stock vs my setup.

One thing I don't get though is that if I use willtheyfit to compare front to back, it comes out with a poke difference of only 10mm. Wouldn't this then be 20mm?

You could go for square setup with 10 mm spacer but i had the same what you describe with square setup on a bit of slippery road - the rear will go out rly unpredictable out of nowhere. That made me spin at 60 km/h and smash all my wheels and front suspension, it wasnt very pleasant experience but at least the car was repairable. Good tires just mask the problems in my opinion because for example again on square setup the car is fine in the summer with AD08r but i doubt it will be any good in rain conditions. I have done only city driving and no track or any twisty roads yet. I will of course change the wheels setup if im going for anything more than that.

If you would like to take corners at speed and so on either dial in suspension differently - different springs rates/rollbars - or change the track of the car front to back. Im not a pro in these i just did a lot of reading, no real life experience tho. Except for the crash

[shnazzle]

You are miles away from the stock facelift setup.

Width 15″ x 6″
Offset = et45

to

Width 15″ x 7″
Offset = et35

Your rim will poke out about 22mm more thank before and that can very well unbalance your car. I think its best to have 20mm more rear to front on our cars so you would need a lot more than 10 mm spacer to make up for this difference.

Here is a calculator link with your settings:

https://www.willtheyfit.com/index.php?width=185&aspect=55&diameter=15&wheelwidth=6&offset=45&width2=195&aspect2=50&wheel_size=15&wheel_width=7&offset2=35

Hmm yes I do seem to have done that wrong. You're right. My rear wheel sizes are stock but I did change fronts by quite a bit. I was comparing front to back. Not stock vs my setup.

One thing I don't get though is that if I use willtheyfit to compare front to back, it comes out with a poke difference of only 10mm. Wouldn't this then be 20mm?

You could go for square setup with 10 mm spacer but i had the same what you describe with square setup on a bit of slippery road - the rear will go out rly unpredictable out of nowhere. That made me spin at 60 km/h and smash all my wheels and front suspension, it wasnt very pleasant experience but at least the car was repairable. Good tires just mask the problems in my opinion because for example again on square setup the car is fine in the summer with AD08r but i doubt it will be any good in rain conditions. I have done only city driving and no track or any twisty roads yet. I will of course change the wheels setup if im going for anything more than that.

If you would like to take corners at speed and so on either dial in suspension differently - different springs rates/rollbars - or change the track of the car front to back. Im not a pro in these i just did a lot of reading, no real life experience tho. Except for the crash

I do see your point and it's something you see a lot on "track" cars. I.e. the wider rear track.
I don't really like the idea of spacers so I'm more tempted to go 10mm,which should have little effect on the bearings. At 20mm I'd need to see what kind of stress I'm putting on the wheel bearings

[Nvy]

You are miles away from the stock facelift setup.

Width 15″ x 6″
Offset = et45

to

Width 15″ x 7″
Offset = et35

Your rim will poke out about 22mm more thank before and that can very well unbalance your car. I think its best to have 20mm more rear to front on our cars so you would need a lot more than 10 mm spacer to make up for this difference.

Here is a calculator link with your settings:

https://www.willtheyfit.com/index.php?width=185&aspect=55&diameter=15&wheelwidth=6&offset=45&width2=195&aspect2=50&wheel_size=15&wheel_width=7&offset2=35

Hmm yes I do seem to have done that wrong. You're right. My rear wheel sizes are stock but I did change fronts by quite a bit. I was comparing front to back. Not stock vs my setup.

One thing I don't get though is that if I use willtheyfit to compare front to back, it comes out with a poke difference of only 10mm. Wouldn't this then be 20mm?

You could go for square setup with 10 mm spacer but i had the same what you describe with square setup on a bit of slippery road - the rear will go out rly unpredictable out of nowhere. That made me spin at 60 km/h and smash all my wheels and front suspension, it wasnt very pleasant experience but at least the car was repairable. Good tires just mask the problems in my opinion because for example again on square setup the car is fine in the summer with AD08r but i doubt it will be any good in rain conditions. I have done only city driving and no track or any twisty roads yet. I will of course change the wheels setup if im going for anything more than that.

If you would like to take corners at speed and so on either dial in suspension differently - different springs rates/rollbars - or change the track of the car front to back. Im not a pro in these i just did a lot of reading, no real life experience tho. Except for the crash

I do see your point and it's something you see a lot on "track" cars. I.e. the wider rear track.
I don't really like the idea of spacers so I'm more tempted to go 10mm,which should have little effect on the bearings. At 20mm I'd need to see what kind of stress I'm putting on the wheel bearings

I dont think 20mm is anything to worry about and even more if you can replace them yourself as they are cheap. I had 25 mm on my civic for a year and a half and it was fine.

Of course its best to have the right rims, i do have a set of 17x8 BBS forged(8 kg a corner) out of Evo 9 that im tempted to fit somehow but i dont think its happening unless i can somehow do 5x114 hub conversion and kill the arches

Offtopic you could try to look on facebook or some forums to trade your back wheels with somebody so you get the right thing say around ET 20-25

[Petrus]

First of all, PLEASE bear in mind that I have just about NO experience with the MR2. Thus évery single one of my observations is a generic one and should be ´reconfigured´ for the MR2 concept which is very specific: Per example; the mid engine, the relatively long wheelbase, it being relatively lightweight is neutral and easy on tires thus not putting a lot of heat in them. Less than with less neutral concepts, heavier cars. Just as an illustration of the MR2 being a bit specific. Same applies to the Lotus Elise and derivates. Beter look at earlier Elises than at any FWD hot hatch or BMW to name two other concepts.

Chassis act like suspension. Same thing the side wall of the tyre. To some extend same thing rubber bushes and stabeliser/torsion bars.
OEM spec is a finely tuned optimum for a wide range of ´sporty´ use on public roads conditions.
It is with good reason that most manufacturers tailor a model to the market. Hence more than just emision spec. differences.

See the OEM spec. as a chain with all links as strong as any other.
The moment the user changes óne link that will put different stresses on other links.
Take a stiffer of softer sidewall. This will change directional stability and roadholding. The latter is more important than the former. The latter sets the limits of the traction, the grip. This is why higher end sports cars with far more expensive high tech suspensions have more traction with all else the same; same weight/layout/tyres.

Stiffening the chassis has akin effects:
Ever jacked up one corner of a an average 5 seat hatchback? You can jack it up a lóóóng way befor another corner gets off the ground.
Now install a full roll cage, lower(stiffer) suspension and see how this effects the ´roadholding´ of the other three.

As a perspective: ´In the old days´ there were only diagonal ply tires with hight sidewalls. The contact path flexed a lot as did he high sidewalls hence the tire pressure needed to be high yet the tire still acted as air suspension.
When Michelin invented radial tires ALL changed and to keep now not absorbed vibrations from the occupants, rubber bushes needed to be incorporated in the suspension, which in its turn introduced designed flex. Etcetera. The chain see?!

Right now oversteer versus understeer.
The generics are rather simple and by and large apply to any vehicle. Just more or less acute depending on the weight bias/ engine location et al.
This is extensive as it gets simplified:

http://www.morpca.org/drivers-education-guide/understeer-oversteer/



As to the MR2 mk.3 there is the electric power assisted steering. It works a treat but is almost fly by wire; does not give the best of feed back in the steering wheel.
Snazzle is in the situation that many things have been changed with a confusing combined result. It is not óne thing leading to the behavior and it will not be magically sorted by changing óne thing.
Changes however must be done one buy one, well documented and best MEASURABLE thus under ´controlled´ conditions. Seat of the pants, the ´feel´ is important to document too but not measurable.
When making a change don´t exagerate as that may introduce other effect masking what you are doing. Don´t be too subtle either as you do want to measure sómething.
If I would be experiencing any of the issues Snazzle describes, I would try get more info, feed back and temporarily ´switch off´ the power steering.
As I understand it is fairly simple to do by connecting the two hydraulic lines at the pump side, creating a closed loop.

@Snazzle; with or without power steering; try tyre pressure first. One directon at one end only. Then a bit more. Now go the the other way.
Return to where you started and apply to the other end.
Well, ´first´no. Fírst choose a test section of road, a test route.

Will be interesting to see how you fare.

[james_ly]

What's your ride height? If you've lowered it a lot, this will have impacted the suspension geometry. Unfortunately there's not much information I've found on this.

However I suspect the main problem is AD08s in cold conditions. I've noticed on track that lightweight cars are more affected by cold temps than heavier cars, as they can't get tyre temperature (and goes the other way on a hot day where the GTRs etc cook tyres fast).

Anyone know if you can buy standard rubber bushes anywhere?

[james_ly]

Oh and RE balance... mine is like that. Set up in the dry to be quite pointy, but it's ultimately got more grip than power, so it will be neutral or understeer under power. On cold, wet tarmac however, limited traction, so corner exit it's pretty lively. Even though the chassis is the same in both conditions.

[1979scotte]

I vote tyres what is your manufacturers date and when did you fit them?
Am sure you would benefit from a new bushes etc but start with tyres.

[shnazzle]

Love this club


1) I haven't changed anything to my setup in a good while and it's been aligned to 0.00deg as it is, without the bushes.

2) happy to try 20mm spacers. We had 30mm spacers on our Audi (were already on there) and that never did any damage for years so.. Should be OK. Finding someone willing to sell those exact wheels, in that colour, in that specific size for my size is a very very unlikely scenario. So spacers is infinitely more realistic.

3) tyres were put on last year and had a build date of 2018

4) I hear what you're saying about the tyres but I can't help but feel that's not the issue. I "feel" a fair bit of the car and it's not the lack of grip I'm dealing with. I'm used to the AD08Rs having little grip in the cold and wet. It's the fact that before i was able to work with that. It communicated very well when I reached the limits of what they'd do in those conditions. And now they're not. Now they're just snapping. It feels a lot like a rubber band. I turn in, turn in and the car feels tighter and tighter to turn. Then all of a sudden, snap and the back end goes.
Whereas before it was turn, turn, feel it start to slip, compensate (speed, angle, etc) , keep turning, all good.

I don't know how else to explain it other than that the car feels like it's 80/20 front to back. Even on very shallow and slow corners, I feel like I'm much further forward in the car. I don't feel like I'm centered. The whole weight balance seems off.
Obviously that's not the case, so something else is making it feel that way.

Also, the rear losing grip doesn't explain why the front now feels like a chore to get around a corner.


... Lastly... I can't believe I'm having these discussions after sticking some blocks of nylon in my door shuts. Wtf.

[Carolyn]

Take them out and see if it's really them?

[shnazzle]

Take them out and see if it's really them?

Will do. Will get some more double-sided tape. But I drove home from work, ran straight in and got the bushes, put them on within 15 mins tops and headed straight out for a test run and noticed things immediately. So, I'm not sure what else could have changed in the 15 mins it stood on the drive

I noticed it first on the first right-hander through our estate (literally the first time you turn the wheel after pulling away) when I got a bit close to a car on the outside of the bend, as the turn-in was not as expected.
When I got on a straight later, I swirved the car left and right and I remember grimacing a bit. Now bear in mind at this point I was all "yippee this is great!", so having a moment where I grimaced isn't good.

[Call the midlife!]

I'm going to be the one to say it...
How's your subframe?


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[shnazzle]

I'm going to be the one to say it...
How's your subframe?


Sent from my iPhone using Tapatalk

Absolutely smashing. And also unlikely to have changed in the 15 mins I was on the drive as well haha. Good thinking though. I only replaced it about a year and a half ago

[jvanzyl]

Did I mention suspension bushes?... not sure if I have... but no really... it's your suspension bushes! It's the ONLY thing left and I kid you not, you're probably looking at nice flaky rubber by now and the extra rigidity everywhere has now found them to be the weakest point, which I think explains the lack of linear change or "snap" as you call it...

[Petrus]

I'm going to be the one to say it...
How's your subframe?


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Absolutely smashing. And also unlikely to have changed in the 15 mins I was on the drive as well haha. Good thinking though. I only replaced it about a year and a half ago

OK, so you have actually already located the ´cause´; the door stabilizers.

Now have a look at

http://trdparts.jp/english/image2012/doorstabilizer_graph.jpg

With the door stabilized, the steering angle response becomes more direct.
In other words; the same steering input should see you to the inside of the corner quicker.
Since it is ceterus paribus we should assume that it is so.

Can you do a objective test?
Wrap a drift style yellow/bue/red/green/whatever tape around the top centre op the steering wheel.
Find a stretch of straight highway and do a ´slalom´ with the dotted line with the driver side front  wheel.
Do same on a more lane round about.
Watch carefully how much steering input you give and how the car responds.

Take the blocks out and repeat.

What is different?

Repeat with the blocks refitted if needed.

It can very well be perception and you ´doing´ it, subconsciously compensating:
Steering in, oops feeling, subconsciously compensating out and then getting insecure, leading to tenser arms adding to a twitchy ´car´ feel.
On motorcycles it is só easy for the rider to be the ´issue´. Done that mááány times befor getting my brain/muscles reprogrammed to a change. Took Jorge Lorenzo a year and a half