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ActionDan

Car too firm/skittish/struggling for grip.

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There's more to life then roll centre shit. You are missing so many things with your setup that are a bigger issue.

Edited by Stuss15

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You are seriously focusing on an ant in the corner and not the big picture.

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Everyone agreed I needed castor, the arms were stock, I got those. The RCAs were just a lucky acquisition, I needed ball joints anyway. It's not a big deal. Not expecting this to be a silver bullet at all. Relax a little.

 

There is clearly more than 1 way to make a car handle well. Suspension "experts" can't even agree on what spring rates should be in the car. All I can do is make some changes, go drive it and test, report back, make more changes. That's kind of how DIY motorsport works.

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What suspension experts? You are comparing an 86 and a Silvia. Throw a civic in the mix and that'll mess with you head cause they run heavier spring rates than us. Castor has nothing to do with roll centre. You need to address your coil over and setup of it. Do you know while your car is sitting on level ground where in the shock travel it's sitting. I've asked you several times to help you but you ignore it like it's irrelevant. Forget spring rates/swaybars and dampening if you are sitting at the bottom or top of your shock travel nothing else matters. Everyone that's tracked a Silvia can agree that spring rates as high as 8/6 to as low as 5/4 can work well.

Edited by Stuss15

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Spoken to MCA, Bilstien, JustJap, Pedders, Drummond Motorsport, BC themselves etc.

 

People who know more than me, including people on these forums. I have no idea why you seem so worked up, it's not your time/money, if I get it wrong and chew up some tyres, don't go as fast or maybe come off the track, none of that will affect you. I really do appreciate you trying to help but your approach is unnecessarily combative.

 

If I'm so far down the wrong path, and really all I'm doing is replacing some ball joints and putting castor arms in (which EVERYONE agreed was a good move - castor that is) maybe you should check out of this thread and pop back in when I've got some results, as it'll be a good month or two before I can test this stuff out.

 

Also looking at possibly selling the shocks and buying some MCA blues, but then we get back to talking swaybars as MCA advised there shocks on stock bars, nobody else agreed with that...

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Oh, droop/travel, no not sure, I'll take a look at the MCA website as you mentioned and see what I can work out there.

 

The car handled fairly well before the swaybars though and it's not dropped on it's guts low so I'm inclined to think that whatever the measurements, it's not "ridiculously" bad.

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Another factor is driver preferences. Dont discount that someone else may prefer their car to handle differently too. some people want to induce oversteer/understeer (either for preference or to mask issues with their driving) and that will play into their suspension setup.

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Josh from Mca is hung up on stock bars. What I'm saying is not combative. Unless you setup your shock stroke on your coil over it won't matter how good they are if your sitting on bump stops your fd. Josh from Mca has a base setting so when he sends you the coil over it's nearly spot on. This can appear to be a great upgrade, but for all you know your shocks were bottomed out on the bc giving you that limited grip feeling around the track. It's not my time or money, Its called giving a f and trying to help out from my track experience. There is reasons why a lot of tru trAck guys don't comment, it's because they are banging there head against the wall trying to get there point Across to help. When you setup a vehicle always put your coil overs in with correct bump and droop using the spring perch adjustment. Then adjust from the bottom to set height taking in to consideration the rake of the vehicle, this will not affect bump and droop. Rake on a Silvia seems to be 5-10mm lower in the rear. Don't mess with this too much. Once this is done get a wheel alignment and drive. Also set swaybars to soft as you are running higher spring rates and Adjust bars accordingly to reach the desired bLance of the vehicle. If you do all of this with the alignment as mentioned your car will be night and day difference. And you don't even have to spend bugger all money.

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I get what you're saying, and I can look at travel/droop etc, but the car felt night and day better before the bars went in, front is max soft, rear is not adjustable (25mm hollow R32 bar).

 

The big difference is noticeable tyre where on the out side edge of the tyre front and rear, I could just add camber but that would reduce traction under power and braking. I was told camber will be shit now with bars and stock castor so I got castor arms to help that. Ball joints needed replacing, the RCA's just means the LCAs will be more parallel than they were, all agree that's a good thing.

 

This is just another step towards faster lap times.

 

I defs need to read about the shock travel/droop stuff though, I think I adjusted my ride height from the base, I "think".

Edited by ActionDan

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Had a read about the droop/bump travel and height adjustment stuff, I honestly cannot remember from which end I adjusted it.

 

I understand now why it should be adjusted from the spring base.

 

What I do know is the car doesn't foul anything under full compression. tyres don't hit anything and suspension arms clear everything.

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If you add more camber it won't affect braking around -3 and what you gain in corner speed will far out weight any braking loss. Really need to add -.5 degree all round. It's not really about fouling on stuff that josh goes on about. He is talking if you wanna slam ya ride. Adjust from spring to set bump droop then adjust from bottom to set height. If u do what has been mentioned your car will be sorted.

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So you think all of my handling issues are simply height adjustment being done incorrectly?

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Balance is always an issue. Can't remember if I posted here or not, but having whiteline front / stock rear on my car felt worse than stock front / rear. Running whiteline front / rear now and there is so much more feeling mid corner than with stock front / rear. Have not done a single timed lap ever in this car, though.

 

With spring rates - you can not compare different cars. It means different things. Even comparing R32 and S13 is pointless, as the fronts are double wish bone vs. macpherson strut. The spring has less leverage in comparison, so comparisons are irrelevant. You'll see a lot of JZX cars with 14/12kg spring rates, but they're double wish bone front and rear, and the seemingly huge spring rate still handles more comfortably than an s13 on 8/6kg.

 

Valving will make a huge difference with changing springs. Otomoto said with HSD's you can't change springs by more than 2kg without having the shocks revalved to suit. Racepace in melbourne make a lot of money by revalving tein coilovers for GTR nerds... Regardless of quality control, the BC coilovers are mass produced, and the valving will be vague to take into account the spring rates, the large range of height adjustment, and the "32 points" of damper adjustment. You might see top dollar coilovers having 3 or 5 damper adjustments, but even then, you want the valving suited to the springs, the height, etc. No coilover off the shelf will give your s13 with specific suspension setup, absolute precision in cornering.

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BC said the same re spring rates, i was going to change rates I think I'd just buy the MCA blues with 6/4 standard.

 

Rear brs, whitelines S13 bar is 20 or 22mm and solid I think, the R32 bar is 25mm hollow which i think someone worked out as being roughly 19mm solid.

Edited by ActionDan

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Pretty sure some of the grip guys I was talking to a while back said the Whiteline front gtr rear bar combo wouldn't work very well and it was better to just go whitelines at both ends

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Changing coilovers from BC to something close to the same price range isn't going to make much difference to lap times. I wouldn't bother until you've maximised your driving.

Make sure your shock travel/droop is set up properly. Fix the front caster issue.

Maybe put stock swaybars back in if that caused the tyre wear issues. Just change one at a time if the balance isn't what you want.

Don't overthink everything. Change the simple things and drive the car!

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Pretty sure some of the grip guys I was talking to a while back said the Whiteline front gtr rear bar combo wouldn't work very well and it was better to just go whitelines at both ends

 

Source?

 

 

Changing coilovers from BC to something close to the same price range isn't going to make much difference to lap times. I wouldn't bother until you've maximised your driving.

Make sure your shock travel/droop is set up properly. Fix the front caster issue.

Maybe put stock swaybars back in if that caused the tyre wear issues. Just change one at a time if the balance isn't what you want.

Don't overthink everything. Change the simple things and drive the car!

 

Did you see my clip? My driving is maximum :D (I posted that clip with sideways stuff ups to show what happens after the limit is reached)

 

I do feel like the car is not a little bit of a limiting factor, more so the tyres actually, I feel comfortable going faster and want to, but the "grip" available won't allow it.

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So you think all of my handling issues are simply height adjustment being done incorrectly?

 

I'm saying if you don't understand bump and droop and haven't set it then there is a very good Chance you have no shock travel either cause you are bottomed out or to high in the travel. This will cause the car to push or oversteer skittishly in your words. I can't repeat myself anymore. Running missed matched swaybars is near impossible to get it to work. The white line pair is what you should use to fine tune it, n start them all on soft. Once again, all of this is irrelevant unless you have correct bump and droop. N just to repeat myself again, run more camber. Bars, set droop/ bump and 5mm rake with .5mm more camber will be gold. Just do it an tell us how f**kn great your car is. Also we can play a game, measure your hub to guard on front and rear on one side. Lift the car on that side an take the measurements again with the wheels in the air and I'll be able to work out if your bump and droop is terrible.

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More likely high, it was not lowered much at all and if it was bottoming out I'd feel it, have been enough full sik cars mashing bump stops to know. Worth checking though and good advice.

 

Re camber, interesting to note that to get it even required more adjustment on one side than the other, and if I recall correctly from my 33 back in the day, it was because the hub was bent. That is. I'll only be able to adjust it a little more on the rear as one camber arm will run out of adjustment before the other.

 

Rake was set at 5mm last time we did height, I remember that being the measurement we had decided on. Hub to guard in the front from memory was 345mm, but I'll have to double check as I also recall adjusting them at one point as the driver side front was locking under brakes prematurely due to corner weighting issue.

 

I genuinely do appreciate your assistance, but please tell me you don;t work in anything to do with customer service...

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Your biggest gains will come from changing tyres.

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For sure neil, but given how much tread is left on these and what second hand tyres are worth I might as well use them up before I go drop another few dollars on rubber, we all know how not cheap that is...

 

I'm going to try and source a whiteline rear bar as well.

Edited by ActionDan

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If his car was setup well then better tyres would help. Rsrs are a great tyre. And just as fast bald so don't stress about that.

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Out of curiosity can you measure your hub to guard on front and rear on one side. Lift the car on that side an take the measurements again with the wheels in the air and I'll be able to work out if your bump and droop is ok?

Edited by Stuss15

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Yep when I get a chance. Got a car being delivered and people coming over to look at stuff for sale.

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If it isn't lifting tyres then the droop won't matter. Also if it doesn't have tender springs you can make it have more droop without the spring falling out. This is if the springs have no preload.

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Mca springs are loose at full droop. Josh says it doesn't matter unless your in a rally car. It's not so much about lifting a wheel, it's about having the wheel flowing freely in its travel over bumps underload.

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pretty sure they also use a 45mm spring retainer?

 

Was as out before. Full droop on front passenger is 369mm

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So, removed the whole hub as I couldn't get a good swing at the ball joint to split it from the LCA.

 

While it's all out I was thinking I could slot the LCA inner mount 5mm or so, gain some camber and get a little extra track.

 

Any issues with doing this?

 

The other thing I considered was how I match that in the rear, I have a little extra camber adjustment left that might get me the camber I need, but I can't slot the LCA mounts the same way as they are boxed and there;s nothing to work with. The other issue was if I add track up front I need to add it out the back too, slip on 5mm hub centric spacer or something?

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Also what are your thoughts on needing after market traction rods?

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Your getting way to caught up on setup.

You just need to drive, I highly doubt you've got the most out of your setup or can even consistently lap within a tenth which will give you a read on if your developing in the right way anyway?

Your driving is aggressive, it means you are aggressive on inputs and probably over driving it a fair bit.

 

Everyone is going to have their own theory on what works and what doesn't. You'll never get a straight answer because everyone drives different, prefers different things and setup will change depending on conditions, the track and also the driver.

I would get onto the track, get considerable laps and track time and fix the one wheeling diff.

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