My Lowered 96 Chevy Beretta!

[Kyle Anderson]

If the suspension at stock ride height has 4 inches of travel, and the stock spring has a constant of 100 lb/in, then the spring will absorb up to 400 lb of force before the suspension bottoms out.

If the stock spring is then cut so that the resting height is the desired 2 inches lower, then there is 2 inches of suspension travel left. The spring constant is roughly equal to the old constant multiplied by the length ratio, so the spring can absorb only 250 lb of force before the suspension bottoms out.

If a 2 inch lowering spring with a spring constant of 200 lb/in is fitted, the spring will be able to absorb 400 lb/in before the suspension bottoms out, as was the case with the stock spring.

While I do agree that cutting the stock springs doesn't raise the spring rate enough, your example does leave out some key points:

1. Original length of the spring is needed to determine the new spring rate.
2. Cutting the spring 2 inches shorter doesn't lower the car 2 inches. The increase in spring rate means it now takes more weight to compress the spring, so the change in ride height (assuming a 1:1 wheel rate) will be less than 2 inches. The more you cut, the less of a lowering effect it will have.

Cutting springs is fine if you know the effects:
-New spring rate? Is it high enough to not bottom out the dampers, cause suspension bind/interference, or cause wheel to body interference?
-Free length, and will the spring have preload when installed?
-Will the spring stay seated properly when installed?

[theSLEEPER]

I honestly have been wanting to lower the front more, but I know that's past being safe since I won't have to compress the springs to reinstall the strut... Thus no preload.

[lolwut]

Airbags. Come on, do iiiiit

If every thread you start is this epic I'm auto-subscribing now. Even Kyle got in here and posted lol

[DTMAce]

Thanks for posting weights guys. I'm not sure what's making your car so heavy Jon. Maybe the bigger motor and the 4t60e which IS a heavier trans?

I'm going to sound off on the fuel mileage issue as related to fuel pumps too.

Just because a few guys manage better mileage does not mean their pumps are weak. It's a POSSIBILITY , but usually a weak pump results in WORSE mileage not better. Not sure where that idea got implanted but it's complete mis-information, which is sadly, becoming a norm any more....

Well, Jon got that from experience. He was getting really good gas mileage with his older red beretta, well better than anyone's average, but found his pump pressure was low due to a weak pump. He replaced the pump and his MPG went back down to expected norms for our type of car. I happen to agree with the theory behind this as well, despite doubting that in the case of the Z its more how I drive it, rather than the pump, but with that being said, I don't see the same mpg with the base that I did with the Z. However its also nearly winter, and I always get lower mpg in the cold, so till I can run a better comparison next summer, I don't know for sure that there is much of a difference between the two due to how I drive.

MPG is based on how much fuel you consume as you drive. So if you are starving your engine for fuel, you will burn less. Its simple physics. Atomization may play a serious factor in performance of the engine, but I doubt it will impact the mpg as badly as performance. My theory there is, (as an example) if you squirt one ounce of fuel into the chamber well atomized, vs one ounce of fuel that did not atomize well, its STILL one ounce of fuel that you squirted that stroke. The engine may have a better bang and burn more of the fuel when atomized well vs not, but you still used an ounce. This is assuming a consistent fuel pressure for both examples. Now with less fuel pressure you have less atomizing, but you are using less fuel per stroke. If you lower the pressure of a garden hose, what happens? It takes longer to fill the bucket. Its not going to fill it faster!

Anyway, that's what makes sense to me. But you can argue that all you like. I don't mind.

[woody90gtz]

Jon must be talking weight with driver. Mine is just over 2900lbs with me in it though.

[theSLEEPER]

If it ends up being fuel pressure, I'll have to install an adjustable regulator to lean it back out.

Lean running motors make more power. More power, while using less fuel is a plus in my book. I'm very doubtful that I'm going to hurt the motor running it lean while using 100hp max...

[scd88ga]

So hard, I'm trying so so hard Jon! lol

[theSLEEPER]

Airbags. Come on, do iiiiit

If every thread you start is this epic I'm auto-subscribing now. Even Kyle got in here and posted lol

Does anyone run airbags? What I would REALLY like is just a taller and softer spring. Something that would lower as much as I need but still remain tight.

[berettaboi]

i knew a guy who had hydraulics on his 93 gtz quad 4 in my city. it was cool, that was 10 years ago, and it was different. i would love to have an air bag suspension on my car, but that involves money and fab work for mounting. there are air struts available on line i think i have come across at some points... that is an easier alternative, but not quite the same.

there have been a few air bag suspension beretta's. Jengtz (jensgtz?) was one that i know of. years ago i think i remember hearing that car is stuffed in a garage somewhere...

[Chad91GTZ]

If it ends up being fuel pressure, I'll have to install an adjustable regulator to lean it back out.

Lean running motors make more power. More power, while using less fuel is a plus in my book. I'm very doubtful that I'm going to hurt the motor running it lean while using 100hp max...

Seriously?

Hope you like valve jobs.


Secondly, cutting springs. Fitment and rotation and spring rates and force loads and chassis load and bump stops and x's and y's and all that math aside......

Think of how much heat you put into your spring when you cut it.

As someone with an expensive college education in metallurgy and manufacturing, cutting a spring with a saw or torch or whatever is about one of the stupidest things you could ever possibly do. Jon your posted information was great, but NOTHING in that really matters. Because unless you used a shear to cut that spring, that is all bogus math.

There is SIMPLY NO WAY IN THE REALM OF MATHEMATICS, PHYSICS OR STATISTICS that you could ever accurately measure what your spring rate would be on a spring that you have cut using a method that imparts work heat into it. Why?

Because you are changing the molecular structure of the metal, and therefore, in the simplest terms possible, all bets are off. There is no way to tell accurately with what you have available to you in your garage how you have worked that material, and what type of characteristics it will have. Coil springs are tempered AFTER they are wound. Saying that you see no issue with cutting a coil spring basically is you saying you have no idea how coil springs are made, which is fine I suppose. Im just trying to help. You ruined a set of springs. End of message.

[DTMAce]

I honestly don't think he cares. He says it works fine for him, and its already done. But its all good to know for future projects.

[Kyle Anderson]

If every thread you start is this epic I'm auto-subscribing now. Even Kyle got in here and posted lol

I don't post often anymore. Really, look at this place. Way too much drama for such a small group...

What I would REALLY like is just a taller and softer spring. Something that would lower as much as I need but still remain tight.

What you really need is a shorter, stiffer spring with adjusters. Take a look at what Ground Control has to offer.

Jengtz (jensgtz?) was one that i know of. years ago i think i remember hearing that car is stuffed in a garage somewhere...

Funny you should bring up that car. I e-mailed Jen Palmer about 2 years ago. She had long since sold it and wasn't much help, but she knew it had stuck around the St. Louis area. It actually ended up on a used car lot at one point and was listed for sale online. Mindy had seen the car and was able to give the owner my contact information. I spoke with the new owner over a brief phone call, but he didn't sound too interested in selling. Somewhere around here I still have his number.

[Chad91GTZ]

I dont care if he cares. He will care when his springs snap at 70 mph. Or maybe he wont, as he dives off the road out of control and into a ditch or a telephone pole or some soccer moms minivan full of kids.


Whatever. I'm not telling anyone what to do.

Also, whatever method of figuring gas mileage, you're doing it wrong.

[scd88ga]

you're doing it wrong.

[DTMAce]

Also, whatever method of figuring gas mileage, you're doing it wrong.

Who? I'm simply using Fuelly... lol