getting grip with your rear suspension

[s14seriesII]

ok so my car is lacking rear end grip

both coasting around a corner and under power it just slides, even in 4th gear it will roast the tyres

i had quite old semi slicks on the rear so this may be part of the issue but i still need a lot more grip

so who has done what ? roll centers, watts links, trailing arm lengths, positions and angles

[charged]

what springs are you running, do you run a panard now, how big a sway bar ? how fucked are the semis if they have gone through to many heat cycles and are hard they are next to useless

Go softer springs to start with, does it power down or is it turn in oversteer, roll oversteer?

[fantapants]

have a chat with josh young - he allways claimed his red toy was remarkedly grippy, but for the life of me i cant remember what he put it down to.

i know half the story was a dodgy pressure guage... reading 36 psi when it had like 28 psi or something. Mostly i think his came from pinion angle?

[Eircamae86]

Equal length 4 links with traction brackets would be a good start

[s14seriesII]

i have reasonably stiff springs suited to circuit use the tyres had been very well over heated previously
i am running 18mm rear sway bar maybe adjusted too stiff
running nagisa auto traction brackets on the most agressive setting with cusco trailing arms ( they are damn near the ground lol)

it has turn in oversteer, roll oversteer, and light throttle oversteer, and just wheel spin all the way through 3rd and is quite loose in 4th with 3.9 diff ratio

and still running stock panard rod in stock height location

[Konakid]

How much power do you have?

What width tyres are you running?

What spring rate are your springs?

[s14seriesII]

somewhere between 250 and 300rwkw.. havent been back on a dyno since the first tune at 18psi it made 205

225/50/15

about a 9.5kg with bilstein shocks

[Konakid]

wow!

you need 6 kg rear springs the difference will be huge.

obviously you realise that with that much power with live axle and 900kg's its always going to feel pretty slippery....

[ke70dave]

about a 9.5kg

in the words of adam savage,

well theres ya problem!

soften it up a bit!

if your shocks are adjustable, you can try softening them up, but failing that...new springs!

btw are you talking about an ae86 or an s14?

appears your talking about an ae86. so yer 9.5 is way over kill for anything. i have 6kg and i reckon its not grippy enough, get some standards and cut them, and see what you think. ask "ruiki" off here, he was getting amazing grip with 6kg front and just stocko rear. even had no sway bar at one stage.

also you mention you have a upgraded sway bar, stiffening up your swaybar will tend to decrease rear end roll, and thus "grip".

[s14seriesII]

ae86.. my s14 has shitloads of grip

hmm have tryed 5.5 in my road car and it still has no grip will try them in this when i get some new tyres as they delamed on the last lap..

problem is its about 3 seconds slower than the lead ip car down here and im not running the intake restrictor, new tyres will help a lot but not that much

[charged]

9.5kg springs would be like going to full roll stiffness, get some 6.5kg and work your way up, with that much HP you may want it fairly soft in the rear for power down and buy some new semis, the difference would be huge

[charged]

ae86.. my s14 has shitloads of grip

hmm have tryed 5.5 in my road car and it still has no grip will try them in this when i get some new tyres as they delamed on the last lap..

problem is its about 3 seconds slower than the lead ip car down here and im not running the intake restrictor, new tyres will help a lot but not that much

You would be speaking of Leighs car, a good turbo IP car doesnt make the power you make but would have a 100ft/lb or more of torque. Its a characteristic of a restricted turbo engine. It would actually accelerate a bit quicker than your.When the drags were open is SA Mark Short took his 120y sr20det powered IP car for a run at AIR and it ran a mid eleven, it only made 190 odd kwatw buts its torque what makes cars accelerate.

Plus leighs car has had plenty of development and he is a handy steerer

[Konakid]

agreed, id even try 5's in the rear with some new 225 tyres but to be honest it must be a very hard car to drive fast with that much power, i wouldn't be surprised if you ran faster times on your original 18psi!

You are delaminating tyres circuit racing, you shouldnt be letting them spin up that much, go easy on the loud pedal!

[s14seriesII]

the cars issue is more so that it has no real corner speed..

i have to turn in very smoothly and slowly and wait a long time after the apex to feed to power on..

power level is not an issue as the throttle is not an on/off switch

i will try new tryes, soft springs and softer sway bar or no rear sway bar and see what happens..
but have the feeling a watts link and correct roll centre is going to be a must.. who has played with changing the panard rod height ?

[Konakid]

hmmm.

have you got a front swaybar?

get a 24 to 27mm if running an 18mm rear bar.

what front springs do you have? they may be too stiff also.

[s14seriesII]

yes 24mm have adjusted it as stiff as it goes

the car feels very compliant on the track and has quite a lot of suspension movement like nearly 2 inches of compression.. and more on the front

the front end could even go stiffer as its just got so much grip its not funny..

[Simon-KE70]

i'd be running softer then 5kg's... try something like 4.5 kg's and quality shocks. will go a LONG way to getting grip.

[s14seriesII]

the only thing better than bilsteins is d.m.s ?

[charged]

the only thing better than bilsteins is d.m.s ?

The best shock is only as good as its valved, Im presuming the bilstein has set valving for compression and adj bump. A lot of guys that I know that run bilsteins have slightly heavy compression with a softer spring. We run Koni on all our 4 ip cars and they are great plus the distributor in Adelaide knows what he is talking about and gives great service. We tried a set of bilsteins on the nephews IP car and it went backward, valved wrong and the after sales service was rubbish

There is plenty of better featured shocks than bilsteins Proflex, Penske just to name two

[Hokey]

slydar played with his panhard mount in his current maybe previous 86?? and also ran equal length trailing arms. stock ke springs and r1r's seem to work for leigh pidwell haha

[DRFTR86]

leigh also runs 70 psi cos the r1rs are to grippy according to him

[Simon-KE70]

they are grippy but no he doesnt run 70psi

[LittleRedSpirit]

Quite simply remove the rear swaybar and go for a lap.

[Simon-KE70]

that works for corners but not for straight line grip

[driftke70]

id be dropping the psi in your tyres below 35,
getting your diff nose pointed down,
stiffer shocks, softer springs,
and ease off the front sway bar.

[s14seriesII]

id be dropping the psi in your tyres below 35, i run 30 to 32 cold in semis
getting your diff nose pointed down, its been both up and down now straight
stiffer shocks, softer springs, deffinately dont need stiffer shocks but softer springs will be tryed temperarily
and ease off the front sway bar softer front sway bar will exagerate the problem if the rear is too stiff

sorry for my vague question,
but im more after what ppl have done with there panard rod mount heights, whos fitted watts linkage's, and who has changed there trailing arms angles and mounting heights.. more than just simple traction brackets as i already have these

[DRFTR86]

leigh also runs 70 psi cos the r1rs are to grippy according to him

from the conversation i had with him at status tuning, he ran 70 psi at a DA round because of his low power output, he had to much grip and couldnt get the tyres to spin hence the 70 psi, im sure he doesnt run that pressure all the time, but that was one of his attempts to lose some grip

[driftke70]

softer front sway bar stops the the rear end pushing onto a rigid front, and allows the front to absorb some of the action from the rear end.

[s14seriesII]

softer front sway bar tends to increase front grip and loosen the rear end.. i need to go the other way..

-after doing some calculations and my rear roll centre is about 3 inches too high

[munki]

before you lower your rear rc 3 inches take a look if you need to raise your front rc first. a good rule of thumb is to have a lower rear rc when doing circuit work on live rear axle cars.

[af300e]

softer front sway bar stops the the rear end pushing onto a rigid front, and allows the front to absorb some of the action from the rear end.

Softer front swaybar promotes oversteer. Ie. the opposite of what is desired in this case. This is pretty basic chassis tuning knowledge.

What you say might be true if the rest of the setup is super fucked up. 9.5kg springs in the rear is pretty fucked up.

The general consensus in the thread is pretty much on the money.
Softer rear springs and,
Less/no rear swaybar.

I know an engineer who ran an rx3 making around 250hp as a grip car. He found the best setup was
Stiff front end (both swaybar and springs),
Soft rear springs, and
No rear swaybar.

It might be worth having a look at some of the chassis tuning books available. Carroll Shelby had a good one and there was one called "Competition Car Suspension, Design, Construction, Tuning" but I can't remember who wrote it.

Here are some guidelines:

A softer front bar:
1. Increases front chassis roll.
2. Increases front grip or traction, while decreasing rear grip or traction.
3. Slower steering response.
4. Increases off-power steering at corner entry.


A stiffer front bar:
1. Decreases front chassis roll.
2. Decreases front grip or traction, while increasing rear grip or traction.
3. Faster steering response.
4. Decreases off-power steering at corner entry.


A softer rear bar:
1. Increases rear chassis roll
2. Increases rear grip or traction, while decreasing front grip or traction.
3. Less on-power steering.


A stiffer rear bar:
1. Decreases rear chassis roll.
2. Decreases rear traction, while increasing front grip or traction.
3. Faster steering response in high speed corners and chicanes.
4. Increases on-power steering.

[s14seriesII]

before you lower your rear rc 3 inches take a look if you need to raise your front rc first. a good rule of thumb is to have a lower rear rc when doing circuit work on live rear axle cars.

have taken this into consideration.. going to see how the rear peforms this weekend as raising the front r/c has been on a list of things to do but can hopefully wait for the time being as i cant use the normal bolt in rca's so crossmember modification was always planned :)

[Jase86]

What you say might be true if the rest of the setup is super fucked up. 9.5kg springs in the rear is pretty fucked up.

:thumbup:

..fix this first before worrying about anything else - no other changes are going to work properly until you go softer spring rate in the rear. Just look at other local quick cars and you will find that rate is way too stiff!

[Medwin_3sGTE_AE86]

Hate to say I told you so Mark..... :rolleyes:..... Who am I kidding, I love being right (who doesnt!) :hehe:

For those who dont know, I was having a heap of issues too, rear end just too taily. It wasnt so bad that it was uncontrolable, but for what I built my car for (track, tarmac grip) it wasnt on par with what I wanted.

So, I spoke to real people who have actually done things in motorsport who actually know real facts and figures, (read, not the bunch of forum warriors who's only claim to fame is the ability to spend more time on the net than working on or driving their car, yet profess to know everything there is to know), and their advice was simple, softer rear end setup = more rear end grip.

9.5kg/mm rear springs! :hehe::gah: Mark, you may of as well welded the rear end solid. Yeah, in your s14 they might be alright (yes, we all know about the 'quick as IP guys around basky with the drift setup' story) but the s14 weighs a bit more in its fat arse than the 86. I dont know the weight of the s14, but my guess would be that the 86 has only 2/3 (if that) the weight acting on the rear suspension as the s14 does, therefore a 9.5kg in an s14 would be compareable to a 6.5kg in the rear of an 86.

Not that you're going to listen to anything I or anyone else on here says, but I can tell you that my initial (rear) setup was with custom made 4.5kg/mm springs, whiteline adjustable swaybar on the softest setting and that was far too stiff. Changed to standard springs and no sway bar, world of difference. Equal length trailing arms trialed, tested and setup, and pinion angle calculated and adjusted so it was in the optimum range and the improvement was again, unbeleivable. Redesigned front end, springs and adjustments in shocks, played with setup on whiteline adjustable sway bar, and the thing is great.

If you're so naive to run 9.5's in the rear, I cringe to think of what the front is set up with (14kg/mm?!) and no doubt set at a height for maximum wank factor, which consequently has no practicality what so ever as it has no room for suspension travel. Wank factor might be great, but you're not going to get it to handle like an IP car with no travel.


Softer front swaybar promotes oversteer. Ie. the opposite of what is desired in this case. This is pretty basic chassis tuning knowledge.

What you say might be true if the rest of the setup is super fucked up. 9.5kg springs in the rear is pretty fucked up.

The general consensus in the thread is pretty much on the money.
Softer rear springs and,
Less/no rear swaybar.

I know an engineer who ran an rx3 making around 250hp as a grip car. He found the best setup was
Stiff front end (both swaybar and springs),
Soft rear springs, and
No rear swaybar.

Funny that after talking to people and testing and tuning different setups, I ended up with that ^^^ exact setup. You wouldnt beleive the amount of criticism I received when I first suggested softening up the rear to induce more grip.


:thumbup:

..fix this first before worrying about anything else - no other changes are going to work properly until you go softer spring rate in the rear. Just look at other local quick cars and you will find that rate is way too stiff!

Thing is Jase, Mark seems to think that because he 'ran as quick as the IP guys on the drift setup' in his s14, that the rates used in the 86 being the same as the nissan will provide the same characteristics. That, and that if he let it slip to any of the NS guys that he'd softened up his suspension setup, his wank factor ranking within the tas drifting circles would plummet. :hehe:

[driftke70]

9.5kg/mm rear springs! :hehe::gah: Mark, you may of as well welded the rear end solid. Yeah, in your s14 they might be alright (yes, we all know about the 'quick as IP guys around basky with the drift setup' story) but the s14 weighs a bit more in its fat arse than the 86. I dont know the weight of the s14, but my guess would be that the 86 has only 2/3 (if that) the weight acting on the rear suspension as the s14 does, therefore a 9.5kg in an s14 would be compareable to a 6.5kg in the rear of an 86.




not to mention an irs setup is acting more so on one spring at a time than a live axle rear end, and the lever effect produced by various arms.

[10000rpm]

^^^
Roffle, Lmao..

Geez Mr medwin, you just love starting a shit fight...:S

Have to agree with what you say though...:thumbup:

From my own experience, I have found a softer bum gives more grip, not sure if the total removal of sway bar is helpful though...I would at least run the standard one...

Regards

Scott

[s14seriesII]

haha good to see your back medwin, i was almost begining to miss your short essay style replys :)

anyway i will keep running ridiculas springs rates but i will try something as low as a 5.5

that is all i will keep you all posted when i find some rear traction :)

[Simon-KE70]

i run 4.5's in the back of my car and it's used for drift, its still on the too stiff side IMO

[driftke70]

i run 4.5's in the back of my car and it's used for drift, its still on the too stiff side IMO

from what i have seen this thing seems to be a good balance of power, grip and lean.

[Simon-KE70]

i never ran 10 rears dave, running whiteline rear bar and TRD front bar. seems to work well, front seems to be a little stiff as it picks up inside wheel during scando's lol

[ae71neo]

What shocks in the rear Simon?

[Simon-KE70]

TRD blue long strokes.

may look into changing these rear shocks tho... im not all that happy with them

[ae71neo]

Ah ok. Yeah im looking for shock upgrade in mine too.

[Simon-KE70]

was 12 and 6 lol, only cause the 12 springs were free and i was on a real tight budget, but with the cusco SW20 MR20 shock it ran real well and drove great. still, not the best hahaha

i want to upgrade the TRD blue long strokes..what should i go?

[driftke70]

will be good to hear about these bilsteins, as im planning my suspension pieces together at the mo and am tossing up between a few combos, got my heart set on hts though.

[Simon-KE70]

are these off the shelf bilstines dave?

maybe chuck me a set to trial ;) i'm doing a private day at lala soon and will be taking a variety of susp parts with me to swap and change on the day to see what works and what REALLY works.

[ae71neo]

Looking forward to the results!

[driftke70]

nothing beats seat of the pants testing,

Can anyone see any improvements that i could make in my setup?

Front 24mm bar,
sigma lca
40mm rca
xt130 strut, cut spaced hts'd
8kg ( i had 8s and they were a little stiff, but i think the smidge more weight of the 3s and w55 will make it a good choice)
pillowball tops
rose jointed castor arm with braced mounts,

rear equal length 4 links,
nose a SMIDGE below horizontal,
5.5kg (f series)
hts dampies
18mm adjustable swaybar (whiteline)
adjustable pan
custom rca, about 15mm.

car is braced with 10 point and various other braces,

tyres are 195 60 14 semis up front
185/195 60 14 on rear depending on rims fitted at the time, in something with a bit of tack not adrenalins unless i feel i need them later,

i will be running my sway bar on the medium side of things, shocks will be firm in front, moderate in the rear, (moderate being probably stiffer than what agx go to)

my driving style uses alot of weight transition and not so much hand brake or clutch kicking.

i know i will probably end up changing stuff other than the shocks but, i was thinking maybe a slightly smaller front sway bar

[Dave]

the new design monotube blisteins sound gd with the new valving and heat protection technology etc. Was going to sell my trds and try these but then found out that the new designs had softer compression than kybs, which most people didnt like the feel off. I could be wrong though.

Pending feedback from David @ ajps :)

[s14seriesII]

ive found mine can still go harder in the front

im running 24mm sway bar with even shorter adjustment holes and stiffer than 8kg springs but when i lift the front r/c up it may be stiff enough

obviously the rear in mine still needs to be sorted but it was kinda thrown together with what i had at the time have jic coil overs to go in the rear hoping to get bilstein to make inserts for them

[driftke70]

im a bit odd with my setups, i tend to drive off the rear of the car, like i wouldnt mind running standard sway bar on the front, i would like a softish rate in the front so i can still get some sort of rise and fall to move weight around

same with when i ride motos, bars real swept back, sit on the back of the seat and just keep the front wheel skimming,

[s14seriesII]

8's with 24mm adjusted right up will be good then just depends on shock choice and valving as to how fast/much weight shift u get under brakes and steering etc and if u keep your front r/c low this will also make the front dig in and feel soft

[driftke70]

i still like to get a decent signal from the front end, thats why i dont always like alot of castor, it sort of shrouds the message sometimes.

[s14seriesII]

ah ive always found more caster = more feel/feeback
but try to keep camber and caster close to square eg 4 cast'. 3 camb' you end up with the outside wheel when drifting close to square with the road when on opposite lock..
which is really the essance of running camber and caster :)

[driftke70]

yeah i had that dialed in my previous build, which you can see in my sig, just when you have low op lock situations and your not packing 250hp (16v) it felt like the front wheels would want to straighten, not so much that they wernt tracking, but you felt more of it trying to straighten through the wheel and your knees than you felt how much grip they were getting, how much of a 4 wheel drift was taking place, was in the inside wheel slightly dragging or what ever.

One thing i hated and dialed completely out of my car is the sensation of the rear end pivoting off the front end.

all my experience driving have been in wierd situations, so its hard for me to draw comparisons, like ive had a fair bit of seat time in an sr20det clubman, and that certainly is one car that steers off the rear, a fair bit of time in an mx5 which was almost neutral but slight oversteer, easily the best setup standard car ive ever driven. For the last few months ive been driving an 07 hilux 2wd and you can really get some serious 4 wheel float into corners and i love it, but fucking hate no lsd.

[s14seriesII]

yeh maybe a bit of toe out is needed ? i always set mine at about 2mm out for skids but it ends up at 5 to 10 after riding the inside ripple strips

heres a pic of what my outside wheel camber/castor is like at nearly full lock..

http://www.ae86drivingclub.com.au/dcimages/1/0/1/4/14864.jpg

[driftke70]

http://img200.imageshack.us/img200/575/post15141196951659.jpg

[driftke70]

funny you should mention toe changing, i used to be a wheel aligner at a tyre shop and had my car up at least once a week, and when i had standard control arms in with rubber bushes in it used to move a wee bit, but once i put sigma arms in and ground the bushes back so they fitted nice and snug, after that it seemed to change much less, it might have something to do with greater angles in the triangulation of the arms and control arms and stuff but yeah, thats what happened, also more castor seems to keep it in line.

[Konakid]

Toe out makes the car MUCH more oversteery and twitchy, that could be one of the biggest factors in the oversteer.

Id recommend:

0 toe
+3.5 castor
-3 camber
new rear tyres
4.5kg springs
7kg front springs
stock rear swaybar
24mm front that you currently have

Should make a fair bit of difference compared to your old setup.

[s14seriesII]

for grip i change to 1mm total toe in and reduce camber to 3.25 neg

[driftke70]

i always ran mine ALMOST zero, like when you look at it on the wheel aligner it looks zero, but when you line it all up and take a good look it is just out, helped me sleep at night.

basically what kona kid should see you right, said before but slicks on the back arnt the best when they are new never mind once they have had a cycle,

[s14seriesII]

running zero toe or close to it makes the car too wandering under power the front just has no direction espesh down the straight at high speeds

[Konakid]

let us kno what you change and how you go dude.

[bigm]

http://img200.imageshack.us/img200/575/post15141196951659.jpg


what caster and camber settings where u running in that pic? if you can remember?

thats ideal!

[driftke70]

sigma arms, -3.5 camber + 3.2 castor

[bigm]

thanks mate
looks like a winner for my wheel alignment

[s14seriesII]

ok so not grip driving but for yesterdays drift practice day i changed to 6kg springs and softened the rear sway bar to softest setting and raised the rear about half an inch to make up for the softer springs under loaded conditions same height as previous...

had heaps more grip for drifting can get over 90 deg to the track on entry and still grips up nicely still lacking in straight line but im also running a bit more power again and changed to a 4.3 diff ratio at the same time keen to see what its going to do to my lap times as the new semi slicks on the rear made a good difference aswell

[Konakid]

Good to hear it improved, id use some 4kg springs in the rear for grip laps, will help with straight line power down.

What front springs are in it at the moment?

[s14seriesII]

the rear is soft enough will adjust the rear sway bar up one notch for more circuit work it has ok drive in straight line but the trailing arms are on quite an angle (down at the back) i think equal length is a must do going to be getting close to 300rwkw and 225 semis just dont put that much power down