57 replies to this topic

[cyberman]

Also, you can see my progressive Eibach spring in the picture.

Clipping_point

That progressive spring looks interesting. Do you have them all round? What is the effective spring rate at different compressions? You mention Eibach - is this a standard product for them or a special that you had made to your spec? How do you find it works in practice?

I am just working out a sequence of upgrades for my VXT and suspension is the unresolved area. Rising rate springs feels like a very interesting element of the solution.

Kind regards - Ian Douglass

[Thorney]

Whatever you do make sure you replace springs and dampers at the same time - they work in unison, just changing the springs would probably make it worse.

[goofballs]

Thorney, Eibach sell a range of suspension options. One of them, is the springs on their own, these are recommended to be used with the standard damper and will have been specifically tested or designed to complement them. Eibach, off the shelf springs are one of the best upgrades to make on any car, for handling purposes. cheers

[cyberman]

Eibach, off the shelf springs are one of the best upgrades to make on any car, for handling purposes.

Goofballs

Thanks for your input.

I have had a quick scan of the Eibach website and see they offer a ProSport kit for the Opel Speedster. However the technical data is not available. Even the wheel spacer kit they want to sell has no dimensional information. I have emailed the suspension department asking for the relevant data. As and when it appears I'll post it.

They don't seem to suggest they have a UK agent. Anybody know of such?

The website emphasis seemed to be on how sporty it will look lowered and widened. I suppose there is a market for that. Just wish they would tell of the spring length, wire thickness, internal diameter, rate, progressive characteristic etc.

Kind regards - Ian Douglass

[Thorney]

Eibach do good stuff...no argument there. As a cost effective upgrade they'd be good I'm sure. I just don't want anyone to think bolting on a set of progressive springs will be a magical cure dats all.

[goofballs]

I certainly agree with that, handling at the expense of ride quality is a very tricky nut to crack. A more cost effective handling upgrade (with no adverse effect to ride quality) would probably be a more aggressive geometry setup, utilising the full negative camber capabilities of the Lotus setup. For geometry I would recommend Scared Stiff or, if you've got a deep pocket, my own specialist, Racing Technologies in Putney. cheers

[clipping_point]

That progressive spring looks interesting.  Do you have them all round?  What is the effective spring rate at different compressions?  You mention Eibach - is this a standard product for them or a special that you had made to your spec?  How do you find it works in practice?

Yes, it is Eibach progressive springs but only in front. Rear they are "normal" but from the same ProKit. The ride is the same, but the car is lower. Will see soon how it is on a race track rally .

The cost was only £100 so I just bought it to test. Looks better tho!!

Edited to say that I try to post a picture, but it doesn't seem to work .

Edited by clipping_point, 09 March 2004 - 02:41 PM.

[clipping_point]

Tried again to post a pic. NO SUCH LUCK! Are the camber shims 1 mm thick as Ricky says? Ricky? Anyone? ..cos tomorrow I´ll start grinding the steering arm. You see I have -1,3°/-1,7° L/R measured camber with ALL shims removed

[Steve Crisp]

Hi, It might be an idea to take off more than you need, and then add shims to bring it back to where it should be. That way you'll have adjustment either side of the "correct" setting? Steve

[clipping_point]

Yeah, I think I'll start out taking off 2 mm equal to about -1° or so.

[caleebra]

According to EPC, shims are either 1mm or 3mm...

[clipping_point]

According to EPC, shims are either 1mm or 3mm...

Great! Thanx! No I feel safe cutting the 2 mm´s.

[caleebra]

No probs... good luck I hope you are good with power tools however

[Ducati996Senna]

Lotus go to great lengths to set the steering geometry into their chassis. Okay each car may be different however the optimum is to have the wheel/tyre upright. The object of the exercise is to reduce to a minimum the change from +tive -tive camber during suspension travel and body roll. Unequal length wishbones are the best compromise to this and building in excess of negative front camber will cause: a) car to be difficult to maintain in a straight line changes in geometry during cornering which will not place the wheel/tyre at its optimum angle. Excessive negative camber seen on some race cars is a compromise. Be mindful of problems with braking as the wheel will not have its full tread on the road surface. I suggest you read a number of suspension tuning books before you undertake this project.

[barrybethel]

Duke All good points I agree, but if the machining proposed results in a worse handling/slower cornering car then more shims can be added to bring it back to standard. It would be good to do back to back tests against the clock on a track to settle the argument.....

[clipping_point]

Lotus go to great lengths... OK but then they obviously build the cars with such reknowned poor quaility so you have to machine it to get it to the original specs. My problem is that the camber isn´t the same L/R. The caster is 0,5° wrong aswell but the same L/R

Edited by clipping_point, 12 March 2004 - 08:01 AM.

[goofballs]

Duke is correct when he says that dialling in negative, can cause more problems. This is why the person who is doing this has to be a very capable racing car tuner with a good previous history of triumphs on the circuit. Even tuners with engine upgrading capabilities suffer from setting up suspension poorly, leading to oversteer snappiness, a very fidgety setup that leads to camber hunting, or setups that make the car understeer heavily because the rear is gripping more than the front. It is not all about negative. A person needs to understand the characteristics of toe and castor settings. I would not recommend anyone to test out their settings until they find ones that are suited, because there will come a time where a person will get thrown off the road (normally in the wet) when they have dialled in some very poor geometry settings. However, where I disagree with Duke is the fact that a wishbone setup like the VX does not benefit from changes of geometry including an increase in negative as one of the many changes. There is more than enough proof on the forum that the people who have their car geometry set ny a proper race tuner will be able to benefit from the full and adjustability of the setting. My car is a perfect example. It doesn't hunt camber anymore than standard, and now that the tyres have worn into the camber that has been set, it will brake as hard as before. The only price you pay is the fact that the inside of the tyre will wear slightly more than the outside. The setup on my car does not look like a BMW in the Kumho series, the adjustability of the VX will not allow extreme race style adjustments on the camber. And I don't think this is what clipping_point is looking to do. cheers

[clipping_point]

Well said! However a small adjustment, knowing that even Lotus use different settings on different products, does not feel risky. The standard N/A setup provides a heavy understeer, suitable for an inexperienced driver. This was a contrast, I think, to the Elise Mk 1, which was really hard to drive because of oversteer. Several owners here have said that Scared Stiff have succeded in improving the behaviour by minor geometry adjustments. My own experience showed that removing ALL shims in front eliminated the understeer, but instead a slight oversteer could occur in extreme situations (wet race track). The problem is that the setup as delivered from Lotus different L/R. I want to correct this in order to run perhaps -1,5° camber on BOTH sides

[goofballs]

Although I don't know the settings on my car when my tuner set it up, I certainly know that the front has slightly less negative than the rear. And this would make perfect sense, the VX as standard has -0.06 on the front and -1.48 on the rear. Bearing in mind the car hasn't got any form of traction control it would be wrong for you to begin at the same setting for front and rear. You should try increasing the negative on the front and rear by the same, and then experiment by increasing the front a little. I am way out of my league on this one, however, the setting you propose will give you a very snappy oversteer. Don't forget, the engine is in the rear, the front will turn in very easily due to its lightness (and therefore will need less help from an extreme negative setting). On a front engined car it is the opposite, the extra engine weight at the front will make the car very hard to turn in (because the weight of the engine being shifted from going straight). The lighter rear will have less of a problem. Therefore, on a front engined car the front is dialled in with more negative than the rear. Look at the Kumho series BMW cars. cheers

[clipping_point]

The plan is to use -1,3/-1,3° in front and increase it slightly back as well, maybe -2,0/-2,0° cheers