1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

cut rear springs 1 coil

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Old Oct 22, 2003 | 11:26 PM
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cut rear springs 1 coil

Hey, today i cut my spare set of rear coils 1 coil on each spring, i didnt touch the front springs, its sits a little more level now and the ride hasent change much, its a bit stiffer, which i like.. its strange though, the pic i took makes my rear tires look wayy bigger than when i didnt lower the car.. im guessung because its more in the wheelwell..

i can guarantee 200 percent that these pics have not been chopped, i did crop them to make the image smaller and are original b4 and after shots of my car.....

tell me what you guys think
i know most of you are anti cuttng, but it did not bottom out at all and is alot stiffer.......
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Old Oct 22, 2003 | 11:40 PM
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This reminds me of this civic I saw....must have cut his springs...bouncing ALL over the place down Mulford. (Concrete road...wavy road) I laugh my *** off everytime I pass him.
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Old Oct 22, 2003 | 11:44 PM
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ok like i said, its not bouncy, its actually alot stiffer, and i didnt cut all 4 of my coils in half like the honda boys do... i cut 1 COIL of the back coils, thats it...
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Old Oct 22, 2003 | 11:46 PM
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Looks good. One coild shouldn't hurt anything. The problem with most people's coil-cuttin' is that they cut 2-3 coils off and then don't modify their bump-stops.

I'll be nipping 1/2 a coil off my fronts and 1 coil off my rears when I get a decent running FC...
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Old Oct 22, 2003 | 11:48 PM
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im contemplating nipping 1/2 a coil off the front, but then i would probably cut another half off the back to make it level, i dont like the "jacked up camaro" look

-greg
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Old Oct 22, 2003 | 11:53 PM
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I'd leave it at 1 coil...
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Old Oct 22, 2003 | 11:56 PM
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thats what i was thinking

-greg
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Old Oct 23, 2003 | 12:15 AM
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depends on what u mean by bouncing. suspension travel bouncing=shocks totally shot, stiff bouncing=car lowered to the point that it's sitting on the rubber bumpers.
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Old Oct 23, 2003 | 01:29 AM
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mmmm i am not against cutting , have you seen my white car??? your car looks much better
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Old Oct 23, 2003 | 01:30 AM
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thx robert.

Did you get my pm?

-greg
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Old Oct 23, 2003 | 01:30 AM
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Like I mentioned you just gotta keep from getting carried away...
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Old Oct 23, 2003 | 01:33 AM
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Originally posted by Gregs
thx robert.

Did you get my pm?

-greg
no i didnt get your pm.........
on the reat thoughg, remove the rubber bump stops... it will ride smoother, but dont tell anybody
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Old Oct 23, 2003 | 01:47 AM
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"no i didnt get your pm........."
alright, musta not went through..

i was pming you asking a price on a 48 and upper manifold for my 6 port..

-greg
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Old Oct 23, 2003 | 02:17 AM
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hmm i got it
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Old Oct 23, 2003 | 07:54 AM
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What did you cut them with? Did you do any grinding to flatten out where the spring seats? Looks very good - is see nothing wrong with cutting a coil if it's done right
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Old Oct 23, 2003 | 08:18 AM
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Nothing wrong with doing that Greg. I would trim the bumpstops though. As a check, you can put some clay on the perch and see if the bumpstop contacts it from hard cornering. Just dont run over any bumps during the test or obviously your results will be ruined.
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Old Oct 23, 2003 | 09:03 AM
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I would never cut load bearing coils.

have you considered these?

http://www.ground-control.com/?D=29b...85f81bae188263

scroll down and check the rear springs section...Eibach's that have 5 non-load bearing coils that can be cut to adjust ride level.
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Old Oct 23, 2003 | 09:08 AM
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Originally posted by Rx7carl
Nothing wrong with doing that Greg. I would trim the bumpstops though. As a check, you can put some clay on the perch and see if the bumpstop contacts it from hard cornering. Just dont run over any bumps during the test or obviously your results will be ruined.
Hehe.. that's funny, Carl. Don't hit any bumps in Spokane. There are more potholes in the road than there are stripes!!! Makes me wonder what the gas tax and everything else is going to!!??
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Old Oct 23, 2003 | 09:09 AM
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Gregs- Hey, did you cut the SE springs or your old stock ones?
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Old Oct 23, 2003 | 09:24 AM
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my car sits level with about a inch of fender gap.

I want to bring it dow just a hair, then it would look perfect.

the 225s on the kosies in the rear should tuck nicely against the fender.
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Old Oct 23, 2003 | 09:53 AM
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Lower and stiffer is bad.

Let me know how it handles the first time you corner hard
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Old Oct 23, 2003 | 10:21 AM
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From: https://www2.mazda.com/en/100th/
Originally posted by peejay
Lower and stiffer is bad.

Let me know how it handles the first time you corner hard
what chu talking about, i need stiffer springs in the the back. turning in is a good thing

mike
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Old Oct 23, 2003 | 10:23 AM
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Cutting of the rear springs isnt bad...as long as you compensate for the stiffer spring rate up front to balance it out.
You do know what happens with our first gens handling when suspension is softer up front and stiff in the rear, right?
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Old Oct 23, 2003 | 12:34 PM
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Originally posted by RacerX7fb
Cutting of the rear springs isnt bad...as long as you compensate for the stiffer spring rate up front to balance it out.
You do know what happens with our first gens handling when suspension is softer up front and stiff in the rear, right?
No, what?
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Old Oct 23, 2003 | 12:36 PM
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The problem is, the roll center is Too Damned High in the back. As you lower the car, the roll center gets closer to the center of gravity. (The roll center on the stock rear suspension is the center pivot in the Watts linkage, it is a fixed location on the rear axle) This alters how much leverage the body has against the suspension when cornering loads work on the suspension.

Let's say the rear CG is 20" off the ground and the rear roll center is 12" off the ground at stock ride height. That means the CG and roll center are 8 inches apart. Now say the car is heavier ('81-up) and the rear end is an inch lower. Assuming the weight difference doesn't change the CG height in the bodyshell, now the distance between the two is 7". The body has less leverage on the suspension, its lever is 7" long now instead of 8" long. (One of the reasons why the heavier FBs have a smaller rear sway bar)

Now the car is aged and sagged another inch. 6". You cut a coil off. 5". <rleeermey> God damn, 5 inches. </rleeermey> Let's see what happens if the coll center is five inches away from the center of gravity. You're braking into a corner, the rear end lifts up, maybe back up to 6-7 inches or so. Then you are off the brakes and on the throttle a bit, compressing the rear suspension. Back down to 5ish. Hit a bump mid corner. 3-4 inches. 3-4 inches is roughly half of what 6-7 inches is. Do you see what that means? It means that the rear suspension's roll stiffness can roughly DOUBLE or HALVE in the space of one corner.

Isn't that what made early Corvairs so interesting to drive? Roll center changing radically in relation to the center of gravity, therefore causing the roll stiffness and therefore the car's handling characteristics to change radically? In the early 'vair suspension, the roll center moved in such a way that the roll stiffness went UP when the suspension went into droop. So you'd go over a rise and suddenly the rear suspension has mongo roll stiffness and you spin, slide into the dirt and flip, and Ralph Nader writes a book about it. We're looking at the SAME SITUATION in a lowered FB except it's the opposite, you hit a bump mid corner or do something else otherwise that compresses the rear suspension even a bit and suddenly it's like you have 300 pound springs back there. And around we go.

Back up at stock ride height, that same amount of suspension travel doesn't result in that high up a percentage change in CG. Maybe 50% or so difference maximum. Still not ideal, but why take a bad thing and make it worse by lowering?

BTW - The opposite happens in the front of the car when you lower. The roll center in the front is a mathematically calculated point based on control arm and strut angles. In a nutshell, as the car gets lower, the front roll center drops faster in relation.

So lower the whole car with no changes, and the rear end gets stiffer and the front end gets softer. Hmm, soft front, stiff rear, that is a guaranteed recipe for oversteer! Especially with such an unstable setup as having the CG and roll center so close together. That's why the aftermarlet lowering springs are about the same spring rate as stock in the rear, maybe a little SOFTER, yet the front springs are almost DOUBLE the factory rate.


Now you know why the racers ditch the Watts and get a Panhard - lowers the rear roll center. You need stiffer springs due to the increased leverage the body has over the suspension, but at least the suspension won't be changing its geometry so radically. Also why they there are spacers to fit between the steering arm and the strut... alters the front geometry so the front roll center is raised up.

Last edited by peejay; Oct 23, 2003 at 12:41 PM.
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