So i have the hookups with eibach, and i was wondering what the difference is between all their products. like their springs or camber kit?
what exactly is the differenece? whats bettter? Thanks.

 

Springs of any make have almost nothing to do with handling assuming the stiffnes vs weight ratio matches the vehicle.
Lowering creates problems unless the camber and toe curves and static numbers are returned to oem by adjustment or after market parts.

Unfortunately the OEM frame attachment locations are fixed and when you lower you change the SHAPE of the curves, this can cause weird handling as the curve is no longer CENTERED after lower [kind of like when the vehicle is fully loaded with passengers trunk and gas and body is down by 1-1.5".

 

so springs are just for the lowered look??

and you need a camber kit to readjust it to OEM standards to drive better?

 

A camber kit makes the static alignment look correct but the problem is not sitting still it is as the suspension moves while driving.

Using oem alignment numbers after camber, toe, caster kits is just a feel good but nonaccurate solution............duh it meets oem numbers must be ok........WRONG!

When you lower [or raise] you need to change the body pick up points by the same amount [impossible for somethings]...........why they make tie rod end spacers to keep the rod angle correct for accurate steering [no toe bump steer].

The whole lowering thing is [has been] a fad to get peoples money.

Disclosure: I installed Eibach's on my 1990 Q back in 1994 and still have then on BUT over the years I've spent multi thousands to correct for the problems lowering caused.

I estimate the spring change cost me an extra $4,000 over 15 years........tire wear, suspension correction pieces, extra shock wear........4 years instead of 5 year life.
I get things free and wholesale so it would cost the typical owner much more.

 

So installing an aftermarket camber kit and using oem specs to correct the problem of inner tire wear is a good idea even if the car is stock???
If the oem numbers are wrong, what do we use??

 

OEM published numbers are actual misalignment numbers created by oem from actual measurements at speed. The engineers come up with alignment numbers that create the best conditions at 55 mph going straight [ZERO TOE and mild negative camber].

Tires are designed to operate at -0.5> zero> +0.5 degrees of camber!
As the suspension rolls the rubber bushings and the tire sidewalls compress resulting in A MORE POSITIVE CAMBER thus more negative INITIAL neg CAMBER is require if you want to not exceed the +0.5 degree camber limit for tires when turning.

If you set front at -0.7degrees camber it is expected that body roll will not change camber more than 1.2degrees result in +0.5.

Suspension are designed to become more negative as the springs compress below and expand above OEM DESIGNED RIDE HEIGHT. This is the builtin camber gain curve!

Large caster angles are used to increase camber gain per 1" of body roll

A normal OEM design is ~~~ 0.5 degrees of camber change per inch of travel away from normal ride height.

This means as the nominal -0.7 rolls 1"[~~0.3G] it gains -0.5 because the tire and bushings go positive by -0.7 + -0.5 =~ -1.2 or 1.7 in total to +0.5 tire limit.

2" adds another 0.5 totalling -1.0 degrees
3" adds another 0.5 totalling -1.5 degrees

At 3" body roll roughly 0.9G the -0.7 + the -1.5 is 2.2 + 0.5 = 2.7 degrees of range to keep tires at no more than +0.5 degrees of camber.

The amount of sidewall roll varies by tire size and brand and model so using different than oem tires affects this calculation.
http://autoracing.suite101.com/artic..._camber_angles
http://www.tamparacing.com/forums/ch...er-change.html

 

Obviously a street car owner cares about tire wear vs a racer who expects to change tires at every race.

If lowering a street car actually improved handing beyond just the steering feel of handling by a non professional driver it might be worth it but it doesn't.

Simple to calculate the changes lowering creates in tire load weight transfer CG/track width x G x opposite weight.

Now Eibach progressive rear springs are a special case in that they stiffen up as the body rolls compressing them 1">2" >3"................if you calculate correctly they can do good or very bad things if you don't.

They progressively decrease understeer and may go thru neutral and then into oversteer in wet conditions during sudden [non smooth] steering actions [panic or just not professionally trained].

Too much rear sway bar is bad with progressive rear springs in wet conditions.

 

A lowered car should have less roll providing you change everything else to match (ie lower cog). So it will definately have something to do with handling which may be negative if not followed through with the rest of the needed package.

On my other car part of this package is the transmission and engine mounts (fwd). I could see some of the same issues with my Infiniti as well (awd).

 

When you lower the center of gravity bt 1": that is 1/60 improvement vs stock in weight transfer. As you can see that's 1.5%. Tires are not perfectly linear why we use 1% as the typical measured improvement.

Body roll has little to do with measured handling it does confuse non engineers and non professionally trained drivers. Don't confuse steering wheel feel with the real world.

What's important is to maintain all 4 tires in the -0.5 > zero> +0.5 camber under turning load.

Easy to calculate transfer weught load by how far the vehicle loads and compresses springs x spring rate as installed not published rate.

If a vehicle rolls 3" on 150 pounds per inch as installed springs then the weight transfer is 450 pounds, changing the load on tire by 5-10 pounds is not significant.

 

Body roll has to do with handling not to be confused with steering wheel feel. Lowering a car by 1" doesn't translate to a cog of the same amount since it is a vector. In fact you can lower a car and raise the cog by tossing out excess weight which is often done at the same time.

What is important is how you lower it. You need to maintain the suspension geometry for handling purposes and you also need to maintain it in relationship to the driving assemblies. What needs to be considered is that what you are trying to do is lower the body treating it as a separate enity. What you really are doing is lowering parts of the suspension and then having to compensate for the rest. On my other car which is FWD part of this compensation is to raise the engine/transmission assembly to maintain the same halfshaft angles to prevent wrapup. Caster, camber, toe in/out, shock curve, etc. all come into play and with most lowering projects compensation is usually in the form of compromises rather than ideals.

From an appearance standpoint with the Infiniti the negative in appearance is the wheel wells. The radius of the opening now makes it appear like it has larger gaps on the sides when lowered. For this reason I think the best lowering jobs for appearances are ones that include a fender modification to go with the lowered body. Another option is the illusion of lowering by essentially bringing 'down the sides'. No compromises and since the projects are usually for looks only may actually be cheaper than doing a lowering job correctly.

 

From an appearance standpoint is for ____________? Why would any automobile engineer worry or consider looks vs performance?
I expect that 90% of the inexpensively lowered newer cars actually handle WORSE than stock because they were so optimized to begin with for magazine tests.
Measured G limits and slalom with professional drivers. Especially once the tires are differentially worn across the tread patch.
Excess camber causes excess heat which hardens the excess worn portion of tread.

 

Every car is built with compromises of a multitude of factors, appearance, performance, economics, etc. A senior engineer would be intimately aware and involved in all of these.

I would believe overall they handle worst as well. Maybe some improvements in some areas, but if one was to take in all driving situations for a stock car I would believe a typical lowering job results in poorer handling.

To me what most would be equally satisfied with from an appearance standpoint is the illusion of lowering which has been done many times while maintaining basically stock suspension configuration.

 

^ how do they get thata illusion?

 

One example is larger wheels. This makes the wheel wells look fuller even if the overall stock diameter of the combination looks the same. One issue however is that rarely do those that go with larger wheels consider the effect these may have on braking due to the change in location of the rotating mass.

You can 'bring down the sides'. That is skirts, changes in fender radius, and so on. Front and back bumpers changes including lips will make a car look lower without changing anything on the suspension geometry. Even slight paint fading tricks around stock fender wheel openings can change the apparent height of a car. Something that used to be used a lot that has recently made a modest comeback is simple two tone paint schemes, some of which are not really readily apparent. Consider how some convertibles look with the top up and the top down. My 64 Merc Parklane convertible (which really is almost on the ground) looks a lot lower with the top down. It is purely an illusion, but that is really what matters when it comes to an appearance item. With an Infiniti you will see a little of this effect with simple window tints on certain colors.

 

The smallest lightest strongest wheels that will fit and clear the brakes is always the best. If any type of performance is a consideration.