Tyre age and (lack of) traction

[Lauren 2259]

45 minutes ago, Innersphere said:

They are fitted correctly - i.e. the Outside (Exterior in this case) is on the outside of the wheel all the way round.  The rears are more worn than the fronts (surprise surprise!), but still have 3mm.  Should still not be spinning from every junction and trying to slide round every roundabout (unintentionally anyway!).

Toyota gave the car the all clear so I am back to square one.  Suppose it's new tyres then, just to be safe!  Save these for track/drift days - lol  

You don't want to go under 3mm for the rear as they really tend to aquaplane at speed in heavy rain when they get low on tread. Sounds like you're better off swopping the rears to the front or getting a new set of tyres, but perhaps something better than the Goodyears. NS2-R's are definitely not what you want. 

[Captain Duff 79]

I really don't think it is your tyres. I've had Eagle F1's (on standard rims) on mine for a couple of years and have never had an issue with them (other the first couple of hundred miles of scrub in, but that is common with most new tyres), in fact I really struggle to get the car to misbehave such is their grip and confidence on corners so I've been very happy with them (I don't do track, which is the main reason why others on here who do will caution against them as they are not track orientated at all). So while 3mm tread is getting a little low on your rears (I would be doing a diagonal swap with the fronts) they should be ok and not be doing what you describe so I would be looking elsewhere for a reason for the issues you describe. A proper 4 wheel alignment is always worthwhile every couple of years so I would be doing one of those - Align my car

[GraemeI 41]

Thanks Church - input gratefully received!

Just as a newbie, are OEM twins the BRZ/GT86 pair? And then DD & Track - Daily Driver and Track test?  I like to check I am understanding correctly  

I don't the lowering, but the ride and handling should not be compromised by it.  Showa are 15/15mm F/R and Ohlins 20/15mm F/R which sounds ok.

Showa seems difficult to get hold of and would be another experiment, and the Ohlins are just downright expensive and I still have no way of knowing if they are right for me. Is it just me, or is that too much to splash out because it 'should' be right?   

I see they measure the spring rates in N/mm - stock (from other threads) is about 3kg/mm or 29.4 N/mm which is less than the Showa (35/40) , but seems like it should still be ok for some compliance.  It's a lot lower than the TEIN seems to be set by default 59/59 or 49/59 for Lauren's example  

Sorry for all the spam - hopefully I am getting there, albeit slowly! 

[GraemeI 41]

21 minutes ago, Captain Duff said:

I really don't think it is your tyres. I've had Eagle F1's (on standard rims) on mine for a couple of years and have never had an issue with them (other the first couple of hundred miles of scrub in, but that is common with most new tyres), in fact I really struggle to get the car to misbehave such is their grip and confidence on corners so I've been very happy with them (I don't do track, which is the main reason why others on here who do will caution against them as they are not track orientated at all). So while 3mm tread is getting a little low on your rears (I would be doing a diagonal swap with the fronts) they should be ok and not be doing what you describe so I would be looking elsewhere for a reason for the issues you describe. A proper 4 wheel alignment is always worthwhile every couple of years so I would be doing one of those - Align my car

Thanks for the input.

I am trying to make sense of it as I wouldn't think the alignment would affect pulling away from a standstill and they slip nearly every time I pull away (and I am bearing in mind it's wet at the moment, so it's barely 1/4 throttle at most).  It even does it in the dry and the front pushes on at fairly low speeds, which could be alignment.  I am going to get the alignment checked regardless, but it doesn't seem like that would be the issue for the rear tyres?

Anyone have any idea how much the standard geometry would have changed with the different wheels/tyres and spring lowering?

I think the fact the car has had the tyres around End 2014 (Mid September 2014 at the earliest as that was manufacture date), and has only done around 11k miles since then which means it has been sat doing nothing for some months in the last year to two - surely that must have affected them negatively?

[Lauren 2259]

If the car has been lowered and you haven't had the geo reset or the previous owner didn't bother, then that's is a prime thing to get sorted. Do that first I would say. Tyres that have been sitting on a car and not used don't tend to fare so well. Get the geo checked first though. 

[Church 209]

Innersphere: yup. Heard gt86/brz "family" in general referred as "twins" many times on related forums (technically it leaves out USDM/Canadian Scion FR-Ses though), so started myself to refer them such often too. And you also got DD right, many use that abbreviation for daily driving or daily driver for short.

As for Ohlins .. if comfort is what you're after, they should be ok. It's track that some other alternatives with stiffer springrates may fit better if used with grippier tires & if seen more side-Gs then what one may see during DD, if driving within legal limits & not like hoon

[GraemeI 41]

41 minutes ago, Lauren said:

You don't want to go under 3mm for the rear as they really tend to aquaplane at speed in heavy rain when they get low on tread. Sounds like you're better off swopping the rears to the front or getting a new set of tyres, but perhaps something better than the Goodyears. NS2-R's are definitely not what you want. 

Thanks Lauren

Like all forums, differing opinions abound, so all good   Seems the NS2-R's are very track focused which is not what I am after right now, so I think I will try out the PS4's and see how I get on, as I don't fancy aquaplaning front or rear tbh!

[GraemeI 41]

Thanks for the explanations Church.  I don't mind a bit of roll in a car, particularly on the road - it can sometimes help with feeling what is coming next as you can feel the chassis loading up.  Besides, I try to avoid driving like a hoon on the roads - I save that for my karting  

Makes sense Lauren - going to get it checked today too if possible.  Previous owner did seem particular about the car so doubt he missed it, but still want it checked  

[Lauren 2259]

Graeme, something to bear in mind is that when you put lowering springs on you will need camber bolts on the front and offset bushes on the rear or adjustable lower arms in order to get some camber adjustment. Stock settings have very little camber and a lack of camber on the front has a lot to do with the understeer it sounds you are experiencing. There rear like the front has no provision for camber adjustment so you need to add it. Lowering will generally increase the camber on the rear, but you need to check what it's at. 

Ideal settings for the road are 2 degrees negative on the front and 1.75 on the rear. You may not achieve that on the front with camber bolts though. 

[Church 209]

Lauren: wrong. If one puts camberbolts in both holes (spc lower, whiteline upper hole), at stock height -2.2/-2.3 with just camberbolts is common (from my own experience too). Or some -2.5, if lowered. So if just -2 wanted - perfectly doable with just bolts.

Pitty it's still below what i want (as for track use i need at least -3 front but still keeping rubber topmounts for NVH, so for a while i thought that i have to choose between camber i wish or NVH of pillowball camberplates ), so next thing i'm going to try - add whiteline's positive traction kit bushings (adds +0.5 caster) and powerflex eccentric bushings (supposedly +/-1 camber. Real life will show if that much possible and if it will sum with camber from camberbolts. Parts ordered, sometime later this month will install those bushings).

[Lauren 2259]

Fair enough, Church. I've never used camber bolts as I already have coilovers with pillowball mounts. 2 degrees negative is plenty enough for track in all honesty. You don't need to go to to three degrees. Just go with pillowball top mounts, there's a bit more NVH but you get used to it and better feel to boot. Castor is less important as it is less relevant on higher speed corners. 

[Church 209]

If i get explicit wear/ripping (or was right term "clipping"?)  of tire outside when driving on track when camber was just -2.2 (and in honesty, that's where 2/3rds of tire thread i spend, despite relatively much lower mileage vs dailydriving), then it's clear sign of insufficient camber even without pyrometer checks. I'm cheap penny pincher, so it pained my heart to change out tires with ripped almost to cord outside, while there was still lot of thread left at tire center/inside edge.

From what i saw from threads related with HPDE/track, most commonly mentioned numbers were "starting with -3 front", "don't think about even wear if not at least -3", and many mentioned something like -3.2 from their alignment numbers they were using. From what i tried now with temporary camberplates back again (camberplates & +camberbolts, for now dialed in -3 front camber total (there is still range if i need to), indeed tire wear on track got much better. Unfortunately on local (very bad) public roads NVH increase with camberplates is close to unbearable on some type of bumps/roadholes (you might not have such issue @UK with probably better road state), hence my wish to somehow get that camber at lower mount only (as whiteline Com-C not an option .. they tried few revisions to fix common bearing binding in them, but finally gave up and delisted twins from being compatible with those). At some point i considered slotting of struts, but then found out Powerflex bushings (PFF69-801G or PFF69-801GBLK (later is of "black" line, of stiffer material), which i'm going to try with high hopes. If they won't net -3 together with bolts .. well, at least adding caster with whiteline bushings also may add a bit to that static camber also dynamic camber with wheels turned. Even if slight .. every little bit counts, lol

[Lauren 2259]

I think it depends a bit on which tyre you use. I get some wearing of the outer edge if that's what you mean by 'clipping'? But it doesn't really impact on how many miles I get out of the tyre and they wear evenly enough for it not to be an issue. I'm not really a 'penny pincher', but even with some wear on the outside shoulders of the front tyres they're still good for 20K miles, so it doesn't mean I need to replace the tyres any sooner due to wear on the outside edge. 

[Church 209]

My tires looked something like these (except it was not so much as these white cords, but more like fine metallic brush sticking out of rubber). At point of cord showing through i decided to stop risking using them further, they might blow after all . But - that's the reason why i want that camber, for whole tire to work and work longer. More grip and more life from very same tires. Even initial -2.2 was improvement over stock, grip wise (i could take turns at almost 10kmh faster vs stock 0 camber), grip bias wise (due more camber then in rear there was no understeer anymore), and wear wise a bit too, but i want to dial in optimum alignment once and for all, and then just keep changing wearables of tires & brakes. For now it comes together with NVH problems.

[Lauren 2259]

I'm really confused how that can happen and that badly. Unless your track surface is really bad, or you're doing hundreds and hundreds of laps. I do get some amount of wear on my outer sidewall, but it's nothing to worry about. My tyres take track work well though. What tyres are you using? 

[GraemeI 41]

6 hours ago, Lauren said:

Graeme, something to bear in mind is that when you put lowering springs on you will need camber bolts on the front and offset bushes on the rear or adjustable lower arms in order to get some camber adjustment. Stock settings have very little camber and a lack of camber on the front has a lot to do with the understeer it sounds you are experiencing. There rear like the front has no provision for camber adjustment so you need to add it. Lowering will generally increase the camber on the rear, but you need to check what it's at. 

Ideal settings for the road are 2 degrees negative on the front and 1.75 on the rear. You may not achieve that on the front with camber bolts though. 

I see I fired up another interesting discussion

My results are in and they are not very pretty.  I am still about 90% sure the issue I am having is not alignment but rather the tyres, but the alignment sure isn't helping the rear of the car.  The front is still pretty acceptable (toe needs fixing) and seems like an intentional setup (using camber bolts), but the rear is just broken and has no adjustment available. See attached image for fun evidence

Going to chat to Toyota to see their suggestions and if nothing useful, will probably be looking at some camber arms.  Any suggestions on those? The ones I have seen are:

http://www.fensport.co.uk/parts/toyota/gt-86/zn6/chassis-tuning/gt86-swave-rear-camber-control-arms-pair/ with 

http://www.fensport.co.uk/parts/toyota/gt-86/zn6/chassis-tuning/gt86-swave-rear-toe-control-arm-set/

OR

http://www.fensport.co.uk/parts/toyota/gt-86/zn6/chassis-tuning/gt86-control-arm-lower-and-adjustable-toe-control-arm-kit/

 

Appreciate your time and energy put into the responses, so thank you all

[Church 209]

Don't know, maybe track specifics, or cheap tires i usually got, or my lacking driving skills or all of the above. Most often times i've been to small tracks (made for karting) with slow awg/max speed & tight/slow curves, eg. this or this, ones that are 95% driven in 2nd gear :). Only this year i got to "real" track too. (of course none of these videos are mine, just something googled up on those tracks).

[Church 209]

Innersphere: WTH with camber on left rear? Have you heavy hit something with it? Most probably that s the culprit, or rather that much difference from right.

As for adjustable rear LCAs, i'd suggest cheapest stock-alike like Whiteline/Eibach/SPC clones, or if budget is plentiful, - Velox's with STX bushing (and lights beam adjustment bit).

Imho you don't need rear aftermarket toe arms. Toe is adjustable on ours both front and rear. Camber on stock twins is which is not adjustable. Adjustable aftermarket toe arms usually are needed only for cases, where stock adjustment range is not sufficient.

[GraemeI 41]

Great question Church...  I wish I knew WTH....  I have only had the car for just over a week and I haven't hit anything, so who knows before that

Do you mean LCA's like this then?

http://www.amber-performance.co.uk/product.php?xProd=26532

How about the ones I linked - they look like a more sensible adjustment to me - similar to the Velox ones, but not as expensive

 

[Church 209]

Yeah. These Eibach/SPC/Whiteline ones are almost 1:1 as stock from stamped steel, with exception of bolt with eccentric washer ring on it at wheel end. And they happen to be the cheapest ones for ours. (it may not matter for you at UK, but here in LV adjustable LCAs are not MOT-legal, so "stock looking" is big bonus ).

As for "higher-end" choice .. Velox published (as often does) development process. Like simulating design and removing material only where it's not needed, and they actually subjected those LCAs on special stand to repetitious bending tests to ensure durability/strength at least on par with stock. I haven't heard such tests done/performed on other LCAs on market, thus if getting some of those blindly, then only from bigger profile vendors that often work closer with OEMs, not from some small shop that may just quickly weld or cut from billet something somewhat of needed dimensions or just using extra thick metal to compensate lack of effort. I'd also get only ones with STX compatible bushings, not with pillowball ones, and ones that should work at stock height too, not ones meant for extreme lowering of car.

[GraemeI 41]

Ok, thanks.  My thoughts were if I am spending £216 on a set of the cheapest, why not spend £380 and get ones that are more easily adjustable, but my logic could very easily be faulty as it's been a VERY long time since I last modified any of my cars....

Your explanation makes good sense and I haven't done enough research or have enough knowledge about this market space or the vendors to have a valid view.

Sometimes I hate being the newbie - lol

 

Edited August 9, 2017 by Innersphere
Added explanation

[Church 209]

Take everything with grain of salt. I by far am no expert and just sharing my subjective views that may as well be completely wrong and not everything i say is backed by facts or own experience.

I'm newbie too, just lurking in forums about things that interest me a bit longer

[GraemeI 41]

LoL   Good to know I am not alone then  

[Lauren 2259]

Your toe is just terrible, it's all over the place. Things like this will be the likely cause in all honesty. The car isn't tracking straight at all. It's not going to feel good. 

As for adjustable rear lower arms, I have the SPL ones. Billet aluminium and things of beauty. Undoubtedly the best you can get. They are rose jointed too. £540. A lot of money, but they are just a lovely bit of kit. If you could you would, I reckon.

[GraemeI 41]

Hahaha - well put - terrible indeed!  

I didn't want to try sort the toe till I get the camber sorted otherwise I will have to do it all again.  As for the SPL LCA's, they are just a bit past my threshold of want vs need   If you weren't getting those, what would be your next best option?