34 replies to this topic

[jules_s]

Ok,

 

A somewhat thorny subject of late, suspension is.

 

So I'll throw this one out there for (hopefully) the views of the various people in the know.

 

I just found this courtesy of Partidge/Pidgeon; and tbh I didn't realise the OEM NA springs were so 'soft'

 

VX220 NA = 234 / 268 lbs/in = 42 / 48 N/mm VX220 Turbo = 275 / 315 lbs/in = 49 / 57 N/mm (estimated value) VX220 Spax kit = 250 / 350 lbs/in = 45 / 62 N/mm VX220 NA Nitron kit = 375/450 lbs/in = 68/ 82 N/mm VX220 Turbo Nitron kit = 375/475 lbs/in = 68/ 86 N/mm VXR = 300 / 340 lbs/in = 54/61 N/mm (estimated value) Oehlins = 350 / 400 lbs/in = 63 / 72 N/mm (estimated value) -------------------------------------------------------------------------------------- S1 Standard = 185 / 220 lbs/in = 33 / 39 N/mm S1 LSS = 228 / 285 lbs/in = 41 / 51 N/mm S2 Standard = 228 / 285 lbs/in = 41 / 51 N/mm S2 LSS = 250 / 325 lbs/in = 45 / 58 N/mm         

 

 

So why do we all run so hard springs these days? I must confess, I just changed to GAZ and really didnt ask any questions...and prefer them to OEM.

 

However, the chap building my suspension took one look at the rates and commented they were/are (far) too hard for my road only use.

 

He's now weighed everything, measured everything applied the necessary math to achieve a sensible CPM and he's suggested 250f/300R...which doesn't seem a million miles away from S2 fed territory.

 

Any thoughts as to why we have veered so far to the firm side of things? I've read Chris_uk's wishbone thread so I'm somewhat wary here

[Bumblebee]

These suspension threads are getting confusing....for me anyway lol as there seems to be loads of different variations

Edited by Bumblebee, 10 June 2013 - 10:33 PM.

[jules_s]

Same here, to an extent.

 

I've just read 20 or so threads on Seloc (loads on there - near none on here) about the subject; and all i've got is harder=better for track so must be better for everybody.

[Nev]

I reckon softer for our potholed roads (as a vague rule) is better IMO. I remember following you down near Tormarten on those twisty roads and my stiffer suspension was certainly not helping.

 

As with any aspect of tuning a car, you have to tune it towards what type of driving and roads that you personally use it on. This is something I think a lot of people don't think about, it's too easy to get swept along by what companies say, as at the end of the day they want to sell you stuff, regardless of whether it suits you/your car/your driving style.

 

I'd be interested to see how your can handles on the country roads after this Jules, probably really well at a guess

 

Just for reference, I have 450 lb on the front, 600 lb on the rear, as advised by Chris Randal. This setup is genuinely great on flat/good tarmac, however on a bumpy road it is correspondingly poor.

Edited by Nev, 11 June 2013 - 06:39 AM.

[JimmyJamJerusalem]

I think people go harder as they are looking to do trackdays too.

 

Look at standard VX spring rates.275/315 - Fine for road and if anyone has driven on standard shocks when they were new and pliant (most standard are ruined these days) then they will say how good the drive is!  A decent anti roll bar at this point makes for a great road going drive!  You start adding components like ARB's though, a remap here or there, some sticky tyres and all of a sudden the wimpy standard rates are struggling and your car's pitching and rolling around like a good un.  This is where the cornering force guys step in.  They keep the spring rates down and control the body roll with clever ARB setups.  Makes for a nice drive on the road.  Personally some standard spec coilovers and a decent arb achieve a similar result here for less ££

 

track work is where the big mix up comes in.  If you're looking to go on track regularly then you want a tighter flatter car and the only real way in my opinion is to go the spring rate route.  But how far to go...?  I've got 550/700 on mine, Scuffers and co more like 900lb+ (not sure exact rates) but I wouldn't recommend these sort of rates until you're confident to push hard!!  MAXR and GeorgeBC both have the same shocks as me and both push as hard and both love them.  George even uses his on the road

 

So for the track day driver who's looking to develop their skills and want a shock that will take them there I always recommend around 400/550-450/600.  This will still be a good road shock and allow you to enjoy your car but yes on the ragged edge when you are pushing the car hard through poorly surfaced roads then the car will not manage the bumps as well as a car down on 300lb odd springs (assuming it's damping is decent) but that sort of driving (I hope) is quite rare!  For such a small loss on the road the benefits on track are far greater and your car will be flatter and more confident on track than the same lightly sprung car.

 

Personally I ran 450/600 for two years on my road and track going VXR and I found it awesome!  I drove it all the time on the road and never found it compramised at all. 

 

Nev's right in that you should look at what you want from the car and spec your shocks accordingly.  I always go through customers exact needs when speccing the right shock to them and have had no complaints yet

 

Just my 2p's worth

[jameso]

IMO this is why the CF set up is so good for people that use it on road and a moderate amount of track - allows you to run much softer springs and still have less roll on track. I have SIGNIFCANTLY more rear traction since moving to the softer springs - and less roll than I had before. Then you also have a lot of front to rear grip adjustability and can easily alter the handling balance of your car from understeer to neutral to oversteer to suit your style and needs on a particular day. However I appreciate it's not cheap, and many of you don't like a rear ARB

[JimmyJamJerusalem]

I've driven JG's car on the full CF setup on track and it was great.  I was able to push nice and hard and really enjoyed the drive but it's not for the track driver that really wants to develp their track driving to the n'th level as it's the equivilant of hard springs on a bumpy road in reverse if that makes sense.  On track it's just a little too soft no matter what you do to it

 

That's why it's down to preferance. 

 

If you prefer perfect road, a little soft on track --  then go soft springs, CF etc

If you prefer perfect track, a little hard on roads -- then go harder sprung setups etc

 

It's much a muchness but is a little cheaper to go the hard spring route, lighter and ultimately on track better performance hence why the faster track cars opt for this.

[BlueVX52]

VX220 NA Nitron kit = 375/450 lbs/in = 68/ 82 N/mm is the above refferring to nss or ntr or is that the standard pring rate fpr amy off the shelf nitron? all interesting reading for me as ive just gone from standard to second hand nss the difference is already amazing and ive nit even had the full geo set up yet or fiddled with the rebound settings. Dan

[siztenboots]

NTR , NSS did not exist back then

[BlueVX52]

oh so this is refferribg back to when the vx first came out...misunderstood!

[Paulus H]

Sense and objectivety in a spring thread - I must be tripping!

 

Paul

[jules_s]

I think people go harder as they are looking to do trackdays too.   Look at standard VX spring rates.275/315 - Fine for road and if anyone has driven on standard shocks when they were new and pliant (most standard are ruined these days) then they will say how good the drive is!  A decent anti roll bar at this point makes for a great road going drive!  You start adding components like ARB's though, a remap here or there, some sticky tyres and all of a sudden the wimpy standard rates are struggling and your car's pitching and rolling around like a good un.  This is where the cornering force guys step in.  They keep the spring rates down and control the body roll with clever ARB setups.  Makes for a nice drive on the road.  Personally some standard spec coilovers and a decent arb achieve a similar result here for less ££

Cheers for that Jimmy old chap And everybody else, certainly food for thought I rather gather my Gaz are 300F/350R my problem with going 250/300 would mainly be my non existent memory of what the car was like when I got it Still, I think I'm going to jump in with both feet given the cost involved and the near zero chance it'll ever see a track in anger

[Paulus H]

Sounds like a plan! Let us know how you get on. Kind regards Paul

[nicollow]

I had the standard 375/450 Nitrons and it was a bit tiring for street use. Ive since changed to 325/400 and its lurvely, really pleased with it. Its what Elise Parts spec for spring rates is it not?

[JimmyJamJerusalem]

Not sure, standard fast road NTR setup is 375/475.  I've never known anyone go softer than that to be honest.  nicol, you're geting old

[nicollow]

Not sure, standard fast road NTR setup is 375/475.  I've never known anyone go softer than that to be honest.  nicol, you're geting old

 

I got rid of the Larini and stuck the OEM backbox on cos it was too loud. You are right, I hate you for it, but youre right

[Exmantaa]

Elise 111R "Zolder" Bilsteins: 47,4N/mm front and 65N/mm rear (271/371)

 

These felt better with the std 2,2 shocks up front and I used lowering brackets to get a decent ride height.

[alexb]

Thread resurrection, as this has to do with spring rates and this thread has all the right info. I'm trying to set up my Speedster using some standard suspension guidelines. One of which is that rear ride frequency should be about 10% higher than front. This is to reduce excessive pitch: front hits a bump first, the rear a little later. Front and rear frequencies are therefore out of phase and difference between the two, causing the pitch, is minimized if rear ride frequency is about 10% higher than front. So far the theory. When I calculate ride frequencies for all of the above combinations of rear and front springs, ride frequency at the back is always lower than the front however. 

 

The 10% is just a guideline and I can imagine that Lotus broke it for higher purposes as suspension is always a compromise. But anybody has an idea why?

 

*********************************************************************************************************************************

 

Examples:

268 rear and 234 front (standard NA): 1.4 Hz rear, 1.5 Hz front

350 and 300 (my current springs): 1.7 Hz and 1.6 Hz

600 and 450 (highest mentioned above): 2.1 Hz and 2.1 Hz

to get to 10% difference, something like 550 - 350 would work

 

What I used for the calculations:

- car weight: 890 kg split 40% front, 60% rear (according to some numbers I got from people who corner weighted their car)

- driver 70 kg, split 60% front, 40% rear (no jokes please)

- left and right 50% split (OK, not true, but good enough for government work)

- unsprung mass rear 30 kg per corner, front 25 kgs per corner

- wheel/spring ratio rear 1.32, front 1.43

 

From the above you can calculate the sprung mass (fair approximation at least) per corner and from that, the wheel/spring ratio and the spring rate you calculate the ride frequency per corner. Would be good if someone checked that too.

[ghand]

Just to throw a spanner in the works, what happens when you throw progressive springs into the mix as a lot like me have them now.

[siztenboots]

Just to throw a spanner in the works, what happens when you throw progressive springs into the mix as a lot like me have them now.

 

you end up in a hedge backwards ?