39 replies to this topic

[barrybethel]

Gedi Have you ridden in a standard n/a? Have you also ridden in an n/a equipped with the nitron kit? Do you know what the standard and nitron kit spring rates are? If not, then with the greatest respect I'm not sure you are best placed to judge. The problem is, I CAN now feel every imperfection and change in road surface. I will concede that my nitrons are not yet on the softest setting, but I will be very surprised if the ride becomes as good as standard when I try them on full soft. If what you say is correct, that spring rates have little impact on ride quality, why did Lotus not specify harder springs for standard? I think we all agree harder springs bring gains in ultimate road holding because of less weight transfer from one side of the car to the other. I think they didn't opt for harder springs because of the detrimental effect on ride. If there is no detrimental effect on ride, can you tell me what the down side to harder springs is?

[Thorney]

I've learnt an awful lot on this subject when developing the kit with Nitron, Guy (owner) knows more about suspension than anyone else I've met and he's the bloke who designs the VX GT car and numerous other racing suspension systems inlcuding Le Mans TVR racers. Barry, you're right in your analogy but out on one point. The springs are there to hold the car up but the moment and rate in which they react to bumps is controlled by the damping - the two really do act in unison. Long slow bumps (or long hard corners) the dampers control when and how the springs come into affect but the shorter harsher bumps (probably the ones you're referring to as they 'jar' the ride) are almost totally controlled by the dampers and they react to initial impact and not the spring. Think of dampers as gate keepers and the spring as the gate. The gate keepers see the bump coming and their reaction time is what determines how fast and how far the gate moves. Damping is adjusted in frequency and duration and it will always be a compromise between both this apsects. The clicks on the Nitron units control the size of the holes within the shaft on how much oil is transferred under use....the bigger the hole the more movement and the quicker the shock moves. Richard...I'm looking forward to setting your car up on the 27th and I'm surprised on the clicks issue as mine have got louder not quiter....but if the front of yours is bouncing try leaving the rear shocks as theare and softening the fronts off by 3 clicks (assuming you're back to standard).

[Thorney]

Gedi is pretty much right.....save for the fact that there is a limit how hard you can go on springs before the damping has little overall affect. If the spring is too hard then it simply won't move. Road cars are always a compromise, Vauxhall and Lotus have to supply a car that will appeal to the majority but without fail EVERY sports suspension upgrade Lotus have released has stiffer springs and softer damping.

[Jase_MK]

You guys have covered most stuff so I won't bore you all but I used to be well into this with mountain bikes and the principles are the same. Dunno what levels of adjustment you have on the Nitrons but all my bikes have had preload adjustment(partially compress the spring to adjust ride height and sometimes spring rate depending on whether the spring has a rising or linear compression rate), bound damping adjustment and rebound damping adjustment. One thing to watch out for is packing. People often think their springs are too hard when really the shocks are packing up. Say there is a series of 10 bumps close together. The shock compresses for the first bump but if there is too much rebound damping (i.e. the shock cannot expand quick enough) then things will not have settled before the next bump hits and compresses the shock even more. By the third or fourth bump your are riding on an almost fully compressed shock with no room for further compression and ll of a sudden things feel really hard. This can happen with the softest of springs, but is often mistaken for springs that are too hard. Remember, a damper is really simple. All it does is control the speed of the shock, nothing else. Oil flows from one chamber to another through litle holes. Your adjuster makes these holes bigger or smaller to control how fast that oil can flow. Genreally speaking, little damping gives a fast shock, ideal for small road imperfections but will feel harsh and bouncy on big hits. Lots of damping is ideal for big hits but will not repsond well and pack over small ripples. What levels of adjustment do you get on Nitrons? Do you have both bound and rebound damping adjustment, or just one adjuster that does damping in both directions? Also, can you preload the spring (I'm guessing that's how you adjust your ride height)?

[Gedi]

save for the fact that there is a limit how hard you can go on springs before the damping has little overall affect.

If the spring is too hard then it simply won't move.

Thats what I mean. For the spring to control the the ride quality, it would have to be so hard, that it wouldn't move, thus completley removing the role the dampers play of absorbing shocks.

[barrybethel]

Thorney & Gedi I agree that damper rates do have an effect on ride quality. My point is that when the spring rates are much harder, even with adjustable dampers on the optimum setting for ride quality, the ride will be less comfortable than if the car had those dampers but standard rate springs. If this were not so, then will someone please tell me why harder rate springs weren't specified by Vauxhall in the first place? As I have said before, I think the reason is because harder springs = worse ride. If I am wrong, then there must be some other reason why Vauxhall/Lotus thought harder springs were a bad idea. There must be a downside. What is it?

[JasonS]

Does any get problems with theirs losing clicks?  I once had to set the car up on guesswork due to not hearing the clicks on the rears and it seemed to suck up the bumps like a rolls.  Have'nt been able to match this even on the lowest setting.

My front offside doesn't make a clicking noise any more when rotated to go softer, but I can still 'feel' the clicking points though. I put some WD40 above the adjustment ring last time I played with it to remove some grit that was preventing it from going full hard, so maybe it'll be clicking next time I try it.

[Thorney]

Thorney & Gedi

I agree that damper rates do have an effect on ride quality. My point is that when the spring rates are much harder, even with adjustable dampers on the optimum setting for ride quality, the ride will be less comfortable than if the car had those dampers but standard rate springs.

If this were not so, then will someone please tell me why harder rate springs weren't specified by Vauxhall in the first place?

As I have said before, I think the reason is because harder springs = worse ride. If I am wrong, then there must be some other reason why Vauxhall/Lotus thought harder springs were a bad idea. There must be a downside. What is it?

Harder springs don not neccesarily mean harder ride asuming you soften off the damping to compensate.

The reason Vauxhall/Lotus don't spec them as standard is two fold:

1. My previous reason about needing to cover widest segment of customers, some wanting soft and some wanting hard

2. Standard suspension is non adjustable and too soft a spring would be just as bad in the handling stakes.

My whole point on this is that the Nitrons (and any other adjustable suspension) DO allow a softer ride than standard, just because the rings are harder does not mean it HAS to be a harder ride.

Trust me, play around with the settings....you can make a difference.

[streetboy]

My understanding of this is that the spring rate controls the range of movement, and the rebound/dampening controls the speed at which this movement occurs.

[goofballs]

A harder spring almost certainly gives a harder ride. Irrespective of damper settings. Damper settings are there to gather the stability of the car after the initial shock has been registered. This is the logic behind dual spring upgrades, where a softer spring is placed on top of a harder spring. When travelling in a straight line over bumps the car will be supported by the smaller softer spring. As soon as the car corners the softer spring collapses completely and the car rests on the harder spring. This gives the car the benefit of a harder spring when cornering, and the softer spring when travelling in a straight line. Nice little setup, worked a treat on my integrale. cheers

[streetboy]

This is the logic behind dual spring upgrades...

There is a theory that the standard rear springs on the VXT could be improved with more progressive bump stops - the soft spring compresses under acceleration to put weight over the rear wheels but excessive suspension travel sits on the bump stops and stiffens the ride.

Very similar to a dual spring rate solution.

[goofballs]

ooooh.... progressive bump stops, MA LOINS ARE BOILING. I had some modified bumpstop put on my integrale, essential when lowering the car and allow the car to drive a lot faster over a bumpy B-road, without having the car hop all over the place. Saying that I have never had a problem with the VXT and suspension travel on the rear. cheers

[barrybethel]

Goofballs Thank the Lord! an ally! Thorney I still think you're wrong mate. I agree with Goofy. I might read up on suspension theory to prove the point but for the moment I can't be arsed. I am confused about your last post though. You say Vauxhall didn't specify harder springs o/e because "...needing to cover widest segment of customers, some wanting soft some wanting hard". If you are correct, that ride quality is not adversely affected by v. hard springs, then why would Vauxhall specify softer rate springs to satisfy (presumably) the "some wanting soft" element? I fear your argument defeats itself. If harder springs dont affect ride quality then they could have had rock hard springs and medium rate dampers. Everybody would be happy and the car would roll less meaning less weight transfer and more grip. A no-lose situation! The second point you raise to answer the question why Vauxhall didn't spec harder springs as standard doesn't answer that question at all. It talks about why they didn't spec softer springs - which as far as I can see is completely irrelevant.

[Thorney]

I'm not saying harder springs do not equal a harder ride, I'm just saying harder springs on their own do not necessarily mean a harder ride HAS to occure as soft springs with very hard damping would be harder. Anyway the point is a bit moot at the moment......I did suggest you mess around around with the Nitron settings lets talk after you've done that.

[barrybethel]

In the interests of fairness I'll post again with my impressions when I've tried the Nitrons on full soft - prob end of next week.

[cyberman]

Look, when it comes to ride, its all about transmitting forces to the sprung element (i.e. chassis). These forces result in accelerations in the chassis. As the deflection of the suspension and the chassis are coupled through the spring, and the whole combo has to absorb the energy inserted by a bump, the relative deflections will vary dependent on spring rate and sprung / unsprung weight ratio. A stiff undamped spring will deflect less than a soft undamped spring. Ergo, more energy is transmitted to the chassis and it is transmitted faster. More energy translates to more "ouch" factor. However, please don't try this, as undamped springs tend to resonate and the induced motion can be quite sickening. Damping is more than desirable and hugely modifies the behaviour of pure sprung system - thank the lord. By winding the bump resistance up on a damper (and on friction dampers you can lock them up totally) you will slow the compression of the spring. The wheel still has to go up over a bump. If the spring/damper system is not compliant the car goes up or the suspension bends. Winding bump resistance up thus has a similar effect to a higher spring rate in terms of transmitting the initial tranche of energy to the chassis. As the suspension becomes absolutely rigid you get to feel everything. The interaction between spring / damper sprung / unsprung weight is reasonably complex but can be modelled pretty well. The subjective consequences are as variable as the bums that sit on them. BTW, I have wondered what the VXT would be like with rising rate springs. This is where the spring is wound so that as it is compressed the coils rest on each other progressively effectively shortening the spring and therefore stiffening it. It lets you have a relatively soft spring rate for ride absorption but hardens up under the sort of compression track days introduce. Its a more sophisticated version of the various 2 stage systems suggested above (bump rubbers, dual springs etc). Rising rate was becoming popular about the time I stopped experimenting with cars and I never really followed through. Fully active suspension supplanted them shortly after. Is anyone still using them? I have wondered if the extra precision required in manufacture caused rather low yield and made them too expensive. Prima facie it seems a good idea. Kind regards - Ian

[barrybethel]

Just read Cybermans post. Wow. Far too technical for me. As promised though I can now relay my initial impressions of the nitron kit on full soft damper settings. The difference between near - full hard is enormous. The car does actually ride ok on the road on full soft. Not as soft as standard but still liveable with. Of course on the twisty stuff it feels more tied down and generally better than standard. For a while I was worried the nitrons had ruined the car for road use but now I am very happy with them. I have the best of both worlds, a great handling road car that is turned into a track weapon when I wind the dampers up and put the oz's on. The car also looks a lot better that bit lower. For what it's worth I would definetly recommend them.

[Joe-Turbo]

I dont think I will take mine on track, not for some time any way, my insurance is high enough, is there any point getting nitrons for just road use

[Thorney]

Barry........I'm glad you got the chance to play around with the settings, just goes to show that suspension is a very personal thing and only way to get it right for everyone is to make them adjustable. Nitrons transform the car on or off the road (ie track) IMO.

[Guzzler]

For what it's worth I would definetly recommend them.

Thanks for coming back with the update.