Handling Challenges

[GraemeI 41]

Sounds fair Lauren - I do the same thing myself, and tbh, if you're happy with how it's handling, then leave it like that

I am going to get mine 'checked' tomorrow so will see what the outcome is.

[Deacon 1357]

1 hour ago, Lauren said:

...I was wrong... 

Bloody hell. @rob275 this should be stickied surely! 😂😂😂

[GraemeI 41]

42 minutes ago, Deacon said:

Bloody hell. @rob275 this should be stickied surely! 😂😂😂

Happens to all of us at some time or another, some more than others, so I just learnt to live with it  

[GraemeI 41]

Well, it’s still a mystery.... Toe was slightly off at the rear, but not by miles (see the Before column in the first image).  Tony said they often have way worse, particularly if people have been doing Time Attack or airfields, as it rips the toe out of alignment...

He has now set it up with some toe out at the front, and toe in at the rear to see if that helps.  Everything else checked out within reason assuming I don’t want to go full track attack and the car still needs some tyre and bearing life on the road   He checked all the components and checked for anything being loose or broken and nothing there, so that’s something eliminated, if not closer to the answer....

I haven’t really tested it yet, but on the one roundabout I pushed it a bit, the back came round very easily again, so it’s still more lively than I would expect, so there is a mystery for sure.  Front feels a bit more remote and has lost a little feel, but is definitely quick to turn in now, and is stable in a straight line, so will continue testing it to see what it feels like.

Of more interest to me was the left/right misalignment, even if only very slight, plus the slightly different wheelbase side to side - suggests someone did something unnatural to the car at some point.... 

*scratches head*

FWIW, this looks difficult to read, but is really simple   First (Before) column is as it says.  Middle (Target) is also what it says - before they start the work, they enter the target figure and range, so this is just a record of that - probably not totally necessary, but does give a reminder of what was being aimed at.  Lastly, the Actual column is what it says too - the actual readings after the alignment.  We had agreed not to touch the camber for now, but that is the next option.

 

This next one shows contact patch n the road for the front wheels - too little comes as a result of high camber of course - great for track, not so much for road  

 

This one is simply track and wheelbase - concerning the left and right don't tally!  Confirms the second image showing the left to right offsets.

 

Edited January 12, 2018 by GraemeI
Updating some info :)

[KevinA 695]

Wonder if it's worth putting a set of different tyres on for a comparison, I have various types on wheels if you want to play around sometime.

[GraemeI 41]

1 hour ago, KevinA said:

Wonder if it's worth putting a set of different tyres on for a comparison, I have various types on wheels if you want to play around sometime.

Really appreciate the offer Kevin, thank you. I really need to drive it a bit more with the new settings to understand what it is (and isn't) doing, and can then take it from there.

Tony suggested I try another car to see if it's me, which is 100% logical, but Colin eliminated that already I think - he has driven enough of them to know what's right and what's not

 

[Lauren 2259]

It's weird that difference in the wheelbase side to side. I suppose we don't often see this measured as the print outs I get don't show that. It's a tiny amount though with the diagrams hugely exaggerating that. I would say though given that at this time of year the roads are often fairly greasy and the road temperature will be low, the car is always more lively at the rear than you will experience in the summer. Only tonight coming across a roundabout and accelerating (not hard) in second gear I went a bit sideways, but I guess I'm just used to it. No problem, but it's something that happens with greater frequency than it will in a few months time. So maybe it's just a case of allowing for this, which is what I do. 

I guess you don't know the full history of your car and who knows whether it's had a whack somewhere that has ever so slightly moved one or some of the mounting points for the suspension, but I guess you'll never know. 

[GraemeI 41]

3 hours ago, Lauren said:

It's weird that difference in the wheelbase side to side. I suppose we don't often see this measured as the print outs I get don't show that. It's a tiny amount though with the diagrams hugely exaggerating that. I would say though given that at this time of year the roads are often fairly greasy and the road temperature will be low, the car is always more lively at the rear than you will experience in the summer. Only tonight coming across a roundabout and accelerating (not hard) in second gear I went a bit sideways, but I guess I'm just used to it. No problem, but it's something that happens with greater frequency than it will in a few months time. So maybe it's just a case of allowing for this, which is what I do. 

I guess you don't know the full history of your car and who knows whether it's had a whack somewhere that has ever so slightly moved one or some of the mounting points for the suspension, but I guess you'll never know. 

+1 good reason for owning the car from new I guess

It is a small amount, but 4mm total difference in the wheelbase side to side, suggesting something happened at some point, but as you say, I will never know...

I am definitely conscious of the fact that the weather, temperatures, road surface and road conditions all affect the handling so am not expecting dry summer handling   I do allow for it, and have been for the last 6 months, but what is frustrating is when an expert tests it and doesn't want to run round the track at, or even near the limit - then you know the unpredictability is a problem, and it's not 'just a bit loose'.  

At least with yours, you know it's sideways for a good reason with the toe out , and is probably predictable and controllable.  Mine, not so much - lol   

[KevinA 695]

When did you notice the change, how did the car feel at Cadwell for instance?

[GraemeI 41]

10 minutes ago, KevinA said:

When did you notice the change, how did the car feel at Cadwell for instance?

Great question!  It’s been like that since I got it - trip home after picking it up, it got sideway in 3rd gear on the straight going up the A41   I then got the alignment checked and camber was all over, so bought adjustable LCA’s and new PS4’s, followed by a full alignment, all within first 2 weeks.

Car was much better than it was, but Cadwell was still interesting   Most exciting was mass oversteer before  turning into Gooseneck because I didn’t brake way early and the back just let go because it’s a slight turn coming in. I turned it down again after that, and got as fast as I could without coming off, which is why if you look at the times, my last two were within hundreths of each other, but a good 8.5s off yours!  

I put it down to a lack of talent at the time as I accepted the ‘fact’ (according to most people) that the 86’s have a flighty rear end.  It still never felt right to me, which is why I booked thr 1/2 day with CAT Driver Training - either to learn how to drive the car properly, or confirm it wasn’t right before I spent money on coilovers etc.

Sadly, the latter was confirmed - i.e. it just isn’t right....  Now I am kind of stuck with what to do next, but will test the new settings a bit more before thinking about that too much.

[GraemeI 41]

Yay, success!  After the suspension mods, the issue has been resolved!  Went to visit Colin Hoad at CAT again and he did a test drive of the car and it has been cleared of it's previous affliction!  It seems to have been slightly 'over-cured' though and now resists oversteer at all costs which was not the intention!  Now to tune some oversteer back into the car

 

[Church 209]

What was the fix?

And regarding oversteer, my choice would be to lessen understeer not via reducing grip in rear, but adding grip in front.

[GraemeI 41]

Just now, Church said:

What was the fix?

And regarding oversteer, my choice would be to lessen understeer not via reducing grip in rear, but adding grip in front.

Not exactly sure what fixed it tbh, but I replaced my suspension with some TEIN Flex A's (+EDFC) with a complete geo setup, including changing the caster at the front end by rotating the coilovers.  This gave more front end and feel in the steering too which is a good thing   Something in there fixed it, so all good.

100% agree on getting more front end rather than reducing rear grip!!.  My intention is to spend some time tuning it to get max grip all round, probably with a slight understeer bias.  This is only because on track I trail brake which loosens up the rear anyway, so will ideally make it neutral to slight oversteer, as I quite like steering with the brake and throttle.  Will make road driving a bit more boring but tbh, I drive like a grandparent on the road anyway, so it will rarely affect me.

All in theory mind you - still got to work out how

[Church 209]

I doubt caster being at fault. How caster may impact handling - with what force steering wheel tends to return to center, and some dynamical camber gain with turned wheels. In most cases weirdness in camber or toe (wrong settings or unevenness side to side) is what sets handling off (assuming no problems with tire pressure or that no weirdness with sway bar modding or (if adjustable) damping adjustments on coilovers).

As for oversteer/understeer bias .. even if going for most common performance alignment numbers i seen chosen on these cars (negative camber by half degree more in front then in rear, zero camber front, slight toe-in rear) car still should be slightly understeer biased. Just less biased then with stock alignment. As for overall camber .. it should be chosen on amount of tracking one does, as to where most of tire wear happens. With just one or two trackdays per year it makes sense to compromise track max grip/wear evenness. With 10-15+ trackdays per year it may make sense to compromise a bit daily driving, as track is where 3/4ths of tires will be worn down

[GraemeI 41]

I didn't think it was the caster, just mentioned it as the other major change.

I am doing about 6 of the Sprint Series rounds this year (if the plan works out  ), and maybe a track day or two, so with that in mind, camber is up in the front to 2.5 and rear to 1.75, neutral toe front, 6' rear toe in. Not massively different to before, mostly the front up, but obviously with new springs and dampers.

Still learning the EDFC adjustments and trying different settings to work out most effective for road and separately for track.  Once I have that figured out, I will consider if need any ARB's or other changes to help.

[Church 209]

To me preferable camber was about extra 0.5dg front for wished bias, i kept it such with interim alignment of -2.3/-1.8 and still use (gone for more track oriented -3/-2.5).

I know that EDFC is very powerful system rising suspension capabilities .. but i'd hate to spend too much time fine tuning/tinkering/dialing it. Lot of flexibility may mean also ability to dial wrong. As my insensitive butt dyno and inconsistent driving would prevent me from objectively gauging impact of changes, i probably would have gone with whatever settings/modes some more experienced/knowledgeable in suspension and this system suggest and just kept driving it instead rather adjusting myself to car.

[GraemeI 41]

My driving is pretty consistent so I am sure I will work it out eventually - plus I plan some seat time with a professional suspension tuner to make sure