Proper ride height for Track

GSS138 · 12-22-2013, 10:56 PM

Well run as stiff and low as you can without bottoming out lol. Sort of tongue in cheek but true.

Lower CG = better, but you need(by the book) at least 2" of compression travel. up to 3 is better. So run as low as you can without hitting wheels and with 2" of travel left in the shock. That's kind of a "by the book" recommendation. But two infallible truths:

1. Lower CG always better.
2. 2 inches of shock travel required.

Not my rules, just quoting, but I understand these two rules.

Rusty · 12-22-2013, 11:27 PM

What is the suspension travel, front and rear? Shock travel, wheel travel?

RN SHARK · 12-22-2013, 11:59 PM

Sub'd. Lovin the info.

martin82 · 12-23-2013, 12:50 AM

My car was too low all the bit own braces bolts are nicely grounded down, lca also hit the track a few times lol. Not sure exactly what I raises it up to now but working well.
I kept breaking undertrays on track as well

03threefiftyz · 12-23-2013, 05:44 AM

Quote:

Originally Posted by BGTV8

These springs are close to those that the Z34 NISMO RC ships with and are what I would expect as a start for road-racing on slicks - or sticky R-spec's - with large front bar (1.25" or maybe 1.5" hollow) and a small rear bar, but only when the suspension bushes are stiffened right up.

I'm not sure why you'd consider this to be a handful on a road-race circuit unless you reckon it would be too twitchy given the stiffness in the suspension - but our circuits here in Australia are (relatively) smooth - there are a few (like Wakefield Park in NSW and Sandown in VIC) that are bumpy, but the really quick ones like Phillip Island are quite smooth and reward driver committment and a stiff chassis.

Anyway, back to the OP - beware running the car too low, suspension arms need to remain relatively flat and you need enough "bump" to avoid bottoming under braking and bumps which will make the car lock wheel(s) and dart/break-away with little warning

RB

I was referring to the set-up on my car would be a handful on a road course, it is just not set-up for high speed turns.

As far as the other poster who wrote lower CG=Good...well, yes in of itself, lower CG is good, but the Z33/Z34 roll centers start to go from meh to really meh once you get below about 1.5" from factory.

Easiest way to figure out how to spring a car is via frequency, which is easy enough to calculate using your corner weights, motion ratio and spring rate. There is a more involved means of calculating frequency, which involves chassis strength, bars, etc, but the above will suffice.

IMO, every off the shelf spring kit is going to be much to soft. They are made with a strong compromise to ride quality. That said, really good shocks will make even a 700-800lb spring entirely tolerable on the street.

03threefiftyz · 12-23-2013, 05:46 AM

Suspension travel =the amount of bump (compression) the shock has before it bottoms out. Unless you are using a lot of spring or ride on silky roads, you are going to want more than 2". The old rule of thumb 2" is really more geared towards true, single purpose track cars. In fact, formula cars often work on less than 1" of bump travel these days since most have a dedicated spring for aero load. I have run up close to 3" on BIG bumps with 1000lb springs for reference.

Mike · 12-23-2013, 09:46 AM

Quote:

Originally Posted by martin82

My car was too low all the bit own braces bolts are nicely grounded down, lca also hit the track a few times lol. Not sure exactly what I raises it up to now but working well.
I kept breaking undertrays on track as well

me too. never bottomed out the suspension when I was that low, but I did grind the flanges on my exhaust flat and all the bolts that held the undertray on too.

martin82 · 12-23-2013, 01:14 PM

I actually bottomed out the front left suspension if I hit the berms very hard but that was mostly due a bad corner balance, once fixed I didn't bottom out anything either.

cossie1600 · 12-23-2013, 03:29 PM

How mucha re you guys lower than stock?

GSS138 · 12-23-2013, 04:07 PM

I doubt you will find anyone much lower than 1.5" in the front and probably more like 1.25". I have been told we usually end up slamming our upper control arm into the body before we run out of suspension travel if you go much lower.

Also 03threefiftyz mentioned that below 1.5", the Roll Moment starts to get thrown all out of whack as well. I am not sure how to measure that personally but I am sure he speaks from experience.

That Voodoo spindle + camber arm that someone posted from Sema a few weeks ago would solve that problem and potentially allow you to go even lower. I can only imagine what they are going to charge for that part though.

martin82 · 12-23-2013, 04:43 PM

this was the lowest, no idea on how much vs stock

GSS138 · 12-23-2013, 05:01 PM

Your coils have 9 or 10" springs Martin?

03threefiftyz · 12-23-2013, 06:15 PM

That would be a really tall spring. I use 7" up front and 6" in the back..

martin82 · 12-23-2013, 06:18 PM

not sure I'd have to look up specs, if I had to guess 6 or 7"

SPOHN · 12-23-2013, 07:42 PM

Quote:

Originally Posted by cossie1600

How mucha re you guys lower than stock?

I believe I'm at an inch. I'm now on 18's so I have more clearance there and I've have raised my car little by little over the past year so I feel I'm near a perfect height for my coilovers. First of the year I'm going to be ordering and custom setup. I want higher spring rates and valved to properly.

12-22-2013, 10:56 PM	#16 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Well run as stiff and low as you can without bottoming out lol. Sort of tongue in cheek but true. Lower CG = better, but you need(by the book) at least 2" of compression travel. up to 3 is better. So run as low as you can without hitting wheels and with 2" of travel left in the shock. That's kind of a "by the book" recommendation. But two infallible truths: 1. Lower CG always better. 2. 2 inches of shock travel required. Not my rules, just quoting, but I understand these two rules. SPOHN likes this. __________________ Current Mods: Vorpal Weapon +5.

12-22-2013, 11:27 PM	#17 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 68 Posts: 35,220 Drives: 2011 Nismo GM 6M Rep Power: 2684438	What is the suspension travel, front and rear? Shock travel, wheel travel? __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

12-22-2013, 11:59 PM	#18 (permalink)
RN SHARK Track Member Join Date: Jun 2011 Location: Delafield, WI Age: 44 Posts: 618 Drives: 09 370Z, 14 SRT GC Rep Power: 35	Sub'd. Lovin the info. __________________ ___________ '09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare '14 SRT Grand Cherokee; '08 TL Type-S

12-23-2013, 05:46 AM	#21 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	Suspension travel =the amount of bump (compression) the shock has before it bottoms out. Unless you are using a lot of spring or ride on silky roads, you are going to want more than 2". The old rule of thumb 2" is really more geared towards true, single purpose track cars. In fact, formula cars often work on less than 1" of bump travel these days since most have a dedicated spring for aero load. I have run up close to 3" on BIG bumps with 1000lb springs for reference. Last edited by 03threefiftyz; 12-23-2013 at 07:33 AM.

12-23-2013, 04:07 PM	#25 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	I doubt you will find anyone much lower than 1.5" in the front and probably more like 1.25". I have been told we usually end up slamming our upper control arm into the body before we run out of suspension travel if you go much lower. Also 03threefiftyz mentioned that below 1.5", the Roll Moment starts to get thrown all out of whack as well. I am not sure how to measure that personally but I am sure he speaks from experience. That Voodoo spindle + camber arm that someone posted from Sema a few weeks ago would solve that problem and potentially allow you to go even lower. I can only imagine what they are going to charge for that part though. __________________ Current Mods: Vorpal Weapon +5.

12-23-2013, 12:50 AM	#19 (permalink)
martin82 A True Z Fanatic Join Date: Nov 2011 Location: los angeles Posts: 2,636 Drives: 12 Nissan 370Z MB M6 Rep Power: 20	My car was too low all the bit own braces bolts are nicely grounded down, lca also hit the track a few times lol. Not sure exactly what I raises it up to now but working well. I kept breaking undertrays on track as well

12-23-2013, 01:14 PM	#23 (permalink)
martin82 A True Z Fanatic Join Date: Nov 2011 Location: los angeles Posts: 2,636 Drives: 12 Nissan 370Z MB M6 Rep Power: 20	I actually bottomed out the front left suspension if I hit the berms very hard but that was mostly due a bad corner balance, once fixed I didn't bottom out anything either.

12-23-2013, 03:29 PM	#24 (permalink)
cossie1600 A True Z Fanatic Join Date: Jun 2009 Location: californee way Posts: 5,380 Drives: 370, Leaf Rep Power: 30	How mucha re you guys lower than stock?

12-23-2013, 04:43 PM	#26 (permalink)
martin82 A True Z Fanatic Join Date: Nov 2011 Location: los angeles Posts: 2,636 Drives: 12 Nissan 370Z MB M6 Rep Power: 20	this was the lowest, no idea on how much vs stock

12-23-2013, 05:01 PM	#27 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Your coils have 9 or 10" springs Martin? __________________ Current Mods: Vorpal Weapon +5.

12-23-2013, 06:15 PM	#28 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	That would be a really tall spring. I use 7" up front and 6" in the back..

12-23-2013, 06:18 PM	#29 (permalink)
martin82 A True Z Fanatic Join Date: Nov 2011 Location: los angeles Posts: 2,636 Drives: 12 Nissan 370Z MB M6 Rep Power: 20	not sure I'd have to look up specs, if I had to guess 6 or 7"

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