Made changes, didn't go any faster. Track related.

[Dale FZ1]

^^ Tyres are bolt-on speed, without question.  The rubber I'd suggested is all a step up on what Dan currently runs, but slicks are a natural end point.  Depends on category rules - I think his class required treaded rubber?

Bars are a topic of debate/contention.  "Best" bar spec is relative to springs/shocks spec and they have to work together.  There's more than one way to get a desired result.

By way of example, my 33 currently runs a stock front bar.  The rear bar is removed.  Car isn't perfect, but it's got a workable/useable balance to the handling and last season it was one of the quicker things in its category.

[No Crust Racing]

9 hours ago, ch12matt said:

What weights 6/8?

Yep, 8kg front, 6kg rear. I looked into changing springs themselves but was advised not to do so because they are valved for those springs rates at factory. I could maybe get away with 7/5 but at what risk to the shock itself?
 

9 hours ago, Dale FZ1 said:

The "hard points" of the car haven't really changed from before/after.  ie. same weight, same max power, same rubber, same shocks/springs.  And the driver may have been a bit rusty?  Achieving a large number of laps at or near your previous best pace means the day wasn't a waste, and you'd have to take a positive from that.  Where your best pace sits relative to others is a different issue

 

Pic on the second tyre doesn't look great (LH front?) with that lateral cut/split across the face.  Make sure it's not heading towards a failure.

If you do get something new, try the RSRR, or a set of NT01 or AR1. If 9" rims and 255 rubber would fit without clearance issues, go with them all round. Get into the habit of monitoring and managing pressures.

If MCA are giving advice about what an S13 needs re: springs/shocks/bars, it comes from plenty of experience.  You  don't have to use their gear, but I would make the change without hesitating. But be certain that you are speccing the car for a purpose.  If you require any on-road ride quality it's probably going to need the lighter spring rates.  More important IMO, is balance front to rear.

Get a plate style LSD (eg Kaaz, Cusco) to replace the helical S15.

Aim to get your ride heights in a happy area.  MCA can give guidance about this point. It is fairly (ie. really) important, sets the suspension arm angles, not referring to the way the body looks or how much room there is between guard and tyre.

All of the above is about making the whole car "less wrong" and more mechanically suited for the job.

Now - chase your alignment settings.  What you used should be a reasonable starting point.

 

When you're at the track, be prepared to alter ride heights to address under/oversteer.  Don't just make small changes to the shocks and expect to feel something hugely different.  I generally try mid range shock settings both ends, then one end go full hard, full soft to feel the difference.  And repeat for the other end. You will quickly find useable shock settings from that.

 

 

Rusty? Get out

In terms of relative pace, There was 4tenths separating the top 3 cars in that class (Up to 4L/Road tyres). I beat an S15 with a 2871 on it and 315 rubber on the rear, so I think I was going "ok". Second place was an e30 who I pipped by 2 tenths for the win. 

No on road ability required, pure track car. Can't hurt ot try stock front bar as I still have it there and it's compatible with the new end links I bought. 

The helical diff WAS the upgrade from the standard VLSD, this is a budget race car so there will be no $1000 diff centre in this $5000 car. S15 diff was 50 and is solved my internal wheel flaring up. 

Will make some more drastioc changes to tyre pressure and camber and see what that results in. Will use these tyres up before buying new ones. 
 

4 hours ago, KiwiRS4T said:

If you can get a spare set of wheels and fit slicks that should help a lot. Rear sway bar needs to be heavier - if there is adjustment left on your existing one then do that otherwise go heavier... initially on the softest setting.

I have an  identical set of rims with the same staggered widths/offset but I don't want to go slicks as I'm 4 stud and would need like 18x10 rims to get the cheap slicks everyone else is running. 

Rear swaybar is stock s14  and the car is much happier with that versus the R32 GTR bar it had in it. Rear is nicely planted now. 

 

1 hour ago, Dale FZ1 said:

^^ Tyres are bolt-on speed, without question.  The rubber I'd suggested is all a step up on what Dan currently runs, but slicks are a natural end point.  Depends on category rules - I think his class required treaded rubber?

Bars are a topic of debate/contention.  "Best" bar spec is relative to springs/shocks spec and they have to work together.  There's more than one way to get a desired result.

By way of example, my 33 currently runs a stock front bar.  The rear bar is removed.  Car isn't perfect, but it's got a workable/useable balance to the handling and last season it was one of the quicker things in its category.

I'm happy with cheaper road tyres, so my thought was 255 RS-RR. Wider and newer/better compound. 255 is a stretch on a silvia clearance wise so it would be a little work just to get those under it. 

That was if I could get my other 9" rims from the second set onto the front (as the offset/disc type is not ideal, but I have the Gktech spacer kit so I have options). 

Otherwise I considered 235 Semis.


 

Edited June 6, 2017 by ActionDan

[Hadouken]

Rs-rr are good. For the close to the same money you can pick up nt01s.

Tyres make a huge difference.

If you put z221s on it would probably wipe a solid 2 sec off that time lol

[GTSBoy]

I agree with most of the sensible advice up above.  But keep in mind a couple of these points with ref the ARBs and you choice of camber.

If you stiffen the rear bar, then maybe the -3° you have at the front can stay.  But if you soften the front bar, think about reducing the front camber.  You are supposed to run more and more camber when the chassis is stiffer and stiffer because a stiff car stands the tyre up more.  A softer car compresses the suspension over the outside tyre instead of standing the tyre up.  A random thought associated with this is that the Federals are probably just too old, as has been said, and that they probably won't like the camber anyway.

[No Crust Racing]

27 minutes ago, Hadouken said:

Rs-rr are good. For the close to the same money you can pick up nt01s.

Tyres make a huge difference.

If you put z221s on it would probably wipe a solid 2 sec off that time lol

Anythign would be an improvement

10 minutes ago, GTSBoy said:

I agree with most of the sensible advice up above.  But keep in mind a couple of these points with ref the ARBs and you choice of camber.

If you stiffen the rear bar, then maybe the -3° you have at the front can stay.  But if you soften the front bar, think about reducing the front camber.  You are supposed to run more and more camber when the chassis is stiffer and stiffer because a stiff car stands the tyre up more.  A softer car compresses the suspension over the outside tyre instead of standing the tyre up.  A random thought associated with this is that the Federals are probably just too old, as has been said, and that they probably won't like the camber anyway.

Considered this, as the outside edge of the fronts has taken a beating which made me think it was rolling over too much as it was. Or is that just sidewall flex, not sure. 

[GTSBoy]

Yes, you probably need to try it again, get some video of the car in corner to assess* the roll and tyre angle and also get a IR pyrometer onto the tyres to see where they are getting hot.

*well, maybe help assess.

But, the other big thought mentioned by others above is the pressures.  Way low pressure like you had will lead to the sidewall collapsing, so your test conditions were probably ruined by that and maybe you shouldn't try to take too much out of the experience until you can do it again with more pressure.  Or better yet, new tyres and more pressure.

[No Crust Racing]

Hoping the photographer there on the day got some action shots. 

We'll see. 

 

 

[admS15]

New tyres, or your gonna be disappointed again.. I know the Dan in you wants to go quicker with what you've got first but you'll just be making yourself think your changes haven't been successful. You must fight the Dan within on this one and buy some new rubber.

[No Crust Racing]

I want to go quicker on the same rubber to prove that..

• Roll centre adjusters
• Castor Rods
• Subframe swap
• Diff swap
• Swaybar swap

Wasn't all for nothing. That's a lot of $$ and f**king around. 

I could swap in a bigger turbo, buy new tyres and go faster but it doesn't prove my backyard science about going faster through better suspension geometry. 

 

[KiwiRS4T]

Obviously better tyres will help but tyre pressures are critical. If you search you will see how with some means of measuring (probe is ideal but a cheap laser gun may do) you measure the temps as soon as you pull in and compare the centre of the tread (what's left of it!) with the outsides and alter pressures to fix (too tired to remember which way round it goes).

[No Crust Racing]

I've got a pyrometer, but the battery was flat and I left it at home

[djr81]

7 hours ago, ActionDan said:

Yep, 8kg front, 6kg rear. I looked into changing springs themselves but was advised not to do so because they are valved for those springs rates at factory. I could maybe get away with 7/5 but at what risk to the shock itself?

There is nothing wrong with changing the springs by 1kg/mm without adjusting/changing the shocks.  There is no risk to anything.

If you are understeering soften the front and/or stiffen the rear.  If the car is too soft as a whole but has some traction then feel free to stiffen the rear.  If traction is poor and it has enough spring in it overall then soften the front.

Also grippier tyres fix everything.  Don't try to tune the car on flogged out rubbish tyres.

[No Crust Racing]

BC told me no don't do it. 

What makes you say different than the manufacturer? 

[admS15]

16 hours ago, djr81 said:

 

Also grippier tyres fix everything.  Don't try to tune the car on flogged out rubbish tyres.

This

[GTSBoy]

1 hour ago, ActionDan said:

What makes you say different than the manufacturer? 

I would guess the fact that many people have changed springs on BCs without the world burning down afterwards.

From my perspective, I would suggest that any "adjustable" damper like is in a BC should be able to swallow a 15% spring rate change (like going from 6 to 5 kg).  If it could not, then you would rightly declare them to be SHITE and should never consider using them.  I mean, an off the shelf, non-adjustable Bilstein damper will swallow a massive range of different spring rates.....because quality design and manufacturing.

[No Crust Racing]

At $95 per spring, is it worth the gamble?

$380 for springs plus maybe get 6-700 for these coilovers and I'm on my way to just buying new/better BCs with better springs or a bit more for MCA blue ($50 extra to choose spring rates). 

 

 

[GTSBoy]

I would not be changing springs until all the other things have been tried and tested.  After that, then your question above becomes worth considering.  Keep in mind also that the spring rates are really about keeping the wheels on the ground when handling the bumps on the surface that you drive on.  If the car is riding properly, then there would be no reason to change the springs in order to change the handling balance.  You could do that with the auxiliary devices (bars, tyre pressures, alignment, etc).  So if you work through the other things we've talked about, spent some more time in the car happier with the balance, you will then be able to concentrate on the question of whether the overall spring rate is right at each end (purely bump handling), before considering whether to change those and then have to go through the effort of balancing the car again.

[No Crust Racing]

Sound advice. 

[djr81]

1 hour ago, GTSBoy said:

I would guess the fact that many people have changed springs on BCs without the world burning down afterwards.

From my perspective, I would suggest that any "adjustable" damper like is in a BC should be able to swallow a 15% spring rate change (like going from 6 to 5 kg).  If it could not, then you would rightly declare them to be SHITE and should never consider using them.  I mean, an off the shelf, non-adjustable Bilstein damper will swallow a massive range of different spring rates.....because quality design and manufacturing.

It is not necessarily the quality of the damper that allows the spring rate to be changed.  The "optimal" damping rate is proportional to the square of the spring rate.  What does that mean in actual meaningful terms?  If you double the spring rate you need to change the damping rate by 41%. So for a 10% spring rate the damping rate changed by 5%.  For any given bump/transient condition are the damping rates within 5% of what may be optimal. No. Nor will they ever be.  So change your spring rates as much as you like up to +/- 40 to 50% of the original rate (On the assumption you started near where you should be)

7 minutes ago, GTSBoy said:

I would not be changing springs until all the other things have been tried and tested.  After that, then your question above becomes worth considering.  Keep in mind also that the spring rates are really about keeping the wheels on the ground when handling the bumps on the surface that you drive on.  If the car is riding properly, then there would be no reason to change the springs in order to change the handling balance.  You could do that with the auxiliary devices (bars, tyre pressures, alignment, etc).  So if you work through the other things we've talked about, spent some more time in the car happier with the balance, you will then be able to concentrate on the question of whether the overall spring rate is right at each end (purely bump handling), before considering whether to change those and then have to go through the effort of balancing the car again.

I would be changing springs.  Doing so is one of the easiest, cheapest and most effective tuning methods there is.  Second only to chucking some more neg camber at the front end.  You can make big changes to poorly handling cars with small changes in spring rate. It is easy to figure out if the car has enough spring in it.  With an 8/6 combination on an Silvia you aren't going to be much off anyway.

[djr81]

3 hours ago, ActionDan said:

BC told me no don't do it. 

What makes you say different than the manufacturer? 

Have done it a bunch of times on my car and made improvements each time.