Lowering Springs

[EarlyApex]

I went BRM 1" drop and have had them on for a couple of months. I love the look, no scraping or rubbing issues any where I drive so far. They did settle about a 1/4" during the first 500 miles. I made other changes at the same time so I can't say if by themselves they improve the handling. Bigger bumps result in a sharp jarring feel versus the stock springs. The install guide that came with the BMR springs did not mention trimming the bump stops whereas the Phadt 1.25" drop springs did have you trim them. I wish I had trimmed them as the sharp feel might be from hitting the bump stops. At some point I will take them apart and mod the bump stops but not for awhile since I just had the alignment done. Think a 1" front and 1.25" rear might give the best look with the gaps being more equal.

The biggest handling improvement came from replacing the front radius arm bushings (much improved steering feel) and the rear cradle bushings (got rid of the squirm).

[tw78911sc]

when you drop the springs regardless of the brand, aren't you preloading the swaybars as a result if you are using the OEM endlinks? If that is the case, the swaybars are actually influencing the overall spring rate, LMK

[Nor Cal ZL1]

Originally Posted by Orange Crush 1LE

Guys, one comment about lowering springs: When I had the coilovers installed initially, we dropped the car 7/8" front and 1-1/2" rear. Pete got on the phone with the shop and suggested they raise it up for optimal suspension geometry and handling. So I ended up with 1/2" drop front, 1" drop rear. Pete knows his stuff, so that's what I went with. It's working very well at the track. I get the rest of my drop by running 18's, which are 2.6" diameter smaller than the stock tires. So with that extra 1.3" drop, my total drop at the track is 1.8" front and 2.3" rear.

This^^^^
I don't know if the heights are different between the ZL1 and 1LE, but I checked the suspension under the ZL and the geometry will be screwed up if dropped below the numbers OC 1LE posted earlier. 1/2 inch in the front, and about the same for the rear if geometry is to stay correct. Below those numbers the travel arch will reverse and pull/push the camber reverse of the desired direction.

Stock the lower ball joint is below the body pick up point. This results is the following movements. Here are two examples of a right hand turn
As the LH suspension compresses the control arm moves up towards parallel with the body pick up point. This results in the ball joint end gets pushed outward due to the arch of travel. Pushing the ball joint outwards gains negative camber. The opposite action happens as the RH suspension extends on the other side. This results is more contact patch.

Parallel, or lower ball joint is higher than the body pick up point.
As the LH suspension compresses the control arm moves past or is above parallel. The travel arch is now pulling the ball joint in and decreasing the negative camber gain. The RH suspension extends and the travel arch pushes the ball joint out increasing the negative camber gain.
This is exactly opposite of what you want the camber gain/loss to be.

[tw78911sc]

does anyone make stiffer springs and keep the original ride height?

[Nor Cal ZL1]

Originally Posted by tw78911sc

when you drop the springs regardless of the brand, aren't you preloading the swaybars as a result if you are using the OEM endlinks? If that is the case, the swaybars are actually influencing the overall spring rate, LMK

No the sway bars are only loaded when there is a side to side weight transfer.

[Blownhotrodder]

I put LSR springs on mine.

[CrystalRedTintcoat]

Originally Posted by Nor Cal ZL1

This^^^^
I don't know if the heights are different between the ZL1 and 1LE, but I checked the suspension under the ZL and the geometry will be screwed up if dropped below the numbers OC 1LE posted earlier. 1/2 inch in the front, and about the same for the rear if geometry is to stay correct. Below those numbers the travel arch will reverse and pull/push the camber reverse of the desired direction.

Stock the lower ball joint is below the body pick up point. This results is the following movements. Here are two examples of a right hand turn
As the LH suspension compresses the control arm moves up towards parallel with the body pick up point. This results in the ball joint end gets pushed outward due to the arch of travel. Pushing the ball joint outwards gains negative camber. The opposite action happens as the RH suspension extends on the other side. This results is more contact patch.

Parallel, or lower ball joint is higher than the body pick up point.
As the LH suspension compresses the control arm moves past or is above parallel. The travel arch is now pulling the ball joint in and decreasing the negative camber gain. The RH suspension extends and the travel arch pushes the ball joint out increasing the negative camber gain.
This is exactly opposite of what you want the camber gain/loss to be.

NorCal: this is helpful. In other words lowering can create the opposite desired camber effect. Does an alignment solve that or are you saying more suspension work is necessary?

The most widely discussed and controversial of the three elements is camber. Camber angle is the measure in degrees of the difference between the wheels vertical alignment perpendicular to the surface. If a wheel is perfectly perpendicular to the surface, its camber would be 0 degrees. Camber is described as negative when the top of the tires begin to tilt inward towards the fender wells. Consequently, when the top of the tires begin to tilt away from the vehicle it is considered positive.

Negative camber is becoming increasingly more popular because of its visual appeal. The real advantages to negative camber are seen in the handling characteristics. An aggressive driver will enjoy the benefits of increased grip during heavy cornering with negative camber. During straight acceleration however, negative camber will reduce the contact surface between the tires and road surface.

Regrettably, negative camber generates what is referred to as camber thrust. When both tires are angled negatively they push against each other, which is fine as long as both tires are in contact with the road surface. When one tire loses grip, the other tire no longer has an opposing force being applied to it and as a result the vehicle is thrust towards the wheel with no traction.

Zero camber will result in more even tire wear over time, but may rob performance during cornering. Ultimately, optimal camber will depend upon your driving style and conditions the vehicle is being driven in.

Image of negative camber

[Nor Cal ZL1]

Originally Posted by CrystalRedTintcoat

NorCal: this is helpful. In other words lowering can create the opposite desired camber effect. Does an alignment solve that or are you saying more suspension work is necessary?

Hey OC, yes if the lower control arm position is compromised a solution is neccessary for optimum performance. If lowering springs have taken it out of the travel arch perhaps a longer ball joint, or an extender for the ball joint would work to get the lower control arm back into the correct position. Other than than a new control arm would need to be designed, or dropped spindles and heavier stock springs. Either would then need to be certified by load testing. Pedders was spot on with the advice they gave you.

Opps CrystalRed, sorry I thought it was OC1LE.

[Nor Cal ZL1]

Chrystal Red I read what you were trying to achieve and since you track you will concerned with the geometry at those drop levels. I would measure the distance between the control arm body rotational point to level ground, and the ball joint end to level ground. This will give you the difference, and how far you can go before the geometry reverses camber gain/loss. While you are under there you can visualize the travel arch as the control arm passes parallel, and the effect it will have on pulling the lower ball joint inwards. thus decreasing the negative camber gains.

I learned these things by making the mistake myself, and it took a bit before I had figured out what I had compromised. I did note the lowered the car did achieve faster lap times, but even with more static negative camber, less body roll, and stiffer suspension, the tires were still wearing the outside edge. The car also acted strange in slow tight corners, it would even hop the front end as the opposite camber gain/loss caused by reversed geometry resulted in the fight between the front tires. Dropped spindles were custom built, and the lower control arm geometry set back to correct solved everything and laps times improved much more.

A side benefit of the dropped spindles, was the roll center was also corrected, allowing softer springs and further decreasing understeer.

[Nor Cal ZL1]

Here is a shot that started the investigation. Here you can see how stressed the front driver side outer tire is, at this point that wheel is trying to go towards positive camber, instead of more negative.
Also note front the passenger side tire does not have full contact as the geometry is going negative instead of positive.

Also note how the tires look between the front and rear, the rear has the better geometry and better contact.

This is at Thunderhill.

[Apex Motorsports]

Originally Posted by RoaringV8

Do you think I would experience rubbing issues if I'm running a Wheel/Tire combo of 275/40/20's all around on the Apex lowering springs?

I'm looking to get lowering springs in the somewhat near future.

Originally Posted by CrystalRedTintcoat

Hello again fellas and gals. I've been doing some research. Which is best to buy and why?

Mainly a daily driver that doubles as a track car ...

$250.00
Detroit speed
http://www.detroitspeed.com/2010+F-B...p-springs.html
Lowers 1.5"
Front 220 lbs/in.

$255.00
Detroit speed
http://www.detroitspeed.com/2010+F-B...p-springs.html
Lowers 1.5"
Rear 425 lbs/in.

$266.95
Hotchkis http://www.hotchkis.net/2010_camaro_...l_springs.html
Lowers 1"
Front 210lbs/in
Rear 440 lbs/in

$300.00
Apex (Pfadt)
http://www.apex-speed.com/apex-motor...g-springs.html
Lowers 1.25"
Front. 225 lbs/in
Rear 425lbs/in

$250
BMR
http://www.bmrsuspension.com/?page=p...&productid=836
Lowers 1.0"
Front 220 lbs/in
Rear 460 lbs/in

Note: stock 1LE spring
Front 156 lbs/in
Rear 383 lbs/in

The spring rate numbers above for our springs is incorrect. When they first cam out in 2010 those where the correct specs but Pfadt changed them to 210 front and 390 rear a couple years ago.

[CrystalRedTintcoat]

@Apex Chase - noted and fixed. Thank you!

[CrystalRedTintcoat]

@NorCal thanks for the tips. I'll have to play around. Going to take the car to Custom Alignment and Brakes in Mt. View so and will see what they say too.

[Nor Cal ZL1]

Originally Posted by CrystalRedTintcoat

@NorCal thanks for the tips. I'll have to play around. Going to take the car to Custom Alignment and Brakes in Mt. View so and will see what they say too.

No problem. Let me know what you find out.