I'm gonna go a bit into it because I've got a few minutes because I'm sure this sh*t gets asked all the time. Don't mean to sound like I'm preaching here, I'm no suspension expert but I think I know a bit about this stuff. And I'd rather say things that can be understood by the n00bs at the risk of sounding a bit patronizing to some more experienced guys. Everyone's at different levels but I wish I heard all this sh*t when I was 14 and trying to sort out the parrotted bullshit/myths/biased opinions from the truth, like "lowered cars need lowered shocks" and "cutting springs is dangerous" from what I'm about to say:
Eh, chopping springs is alright for low. But it does soften the springs 'cause you reduce the spring rate somewhat.
Imagine a coil spring is a torsion spring that has been wound into a coil. Making it shorter makes it stiffer... there's an inverse relationship (when you exclude any non-live coils/wire in the spring) between springrate and length of wire/free length of spring, assuming of course the spring diameter, wire diameter, wire material etc are kept constant.
The only way you can modify a spring in a car without increasing the springrate is by 'compressing' it, and a severely 'compressed' spring can bind coils so it should really only be used for small adjustments when you don't have adjustable seat positions for your springs (adjustable coil-overs do obviously have that feature) and you're already happy with the loading rates/stiffness.
So... the Sunny wagon... I know nothing about Sunny wagons but my guess would be they have a strut front end and a leaf sprung live axle in the back? As I hinted at above, I don't know where you're at but I'll just spell it out in some detail anyway.
Front first: The coils are probably open one end and closed and ground flat the other end, that's the way all of my cars have been but I'm sure there are exceptions to that. (If they're closed both ends, get custom springs made, if they're open both ends, that's alright but unless you can turn the seat around on one end you're gonna need to chop exactly a full coil at a time which is probably a pretty coarse adjustment! hahaha). So yeah, chop em - as Wisey said. Unless you have a few spare springs lying around, you probably wanna go a fraction at a time. Think of the velocity ratio between the wheel and the spring - in my car when the wheel moves up an inch, the spring only gets compressed about half an inch because of the cantilever - the spring is about half way between the pivot points of the suspension arms and the centre of the wheel so it's a 1:2 velocity ratio. Also once you pull a spring out of the car and you go to measure it up you need to keep in mind that it's decompressed - you're measuring its "free" dimensions. You can either measure the distance between coils at ride height before you take it out (if you can access it) to work out its compressed length or you can just guestimate. Cutting springs does make them stiffer but the springrate increase won't transform the car in a hurry unless it comes with a lot of coils you're willing to dispose of. However, just having a car lower to the ground gives it a stiffer 'roll resistance' (i.e. like having a bigger swaybar) because the centre of gravity is closer to the ground, and that's properly significant. But if you wanna drive the car hard you will probably end up wanting stiffer springs and stiffer shocks that you'll need to pay for, but without chopping the springs and experimenting first, you won't learn anything - and you won't know what kinda springs you'll actually want in the end without spending money on a few different sets.
For an example, if you want the car to sit two inches lower (50mm) and the pitch (distance between coils) is 40mm out of the car, assuming a velocity ratio of two, you would probably wanna chop about 2/3 or 3/4 of a coil off.
You can also chop excess off the spring and make up a spacer to sit on either end of it to compensate for the 'excess' that you cut off, then the springrate increases. But to do that you need a deep spring seat on the closed end of the spring to keep it all captive (often doable on double wishbone front end cars) and unless you have access to the tools etc to make it easy you're probably better off just getting some coils made up with thicker wire diameter or a larger pitch (less coils at the same free length = higher springrate and less chance of binding) because you're just guessing what you want anyway. I have done it once and it worked okay but making the spacers was a pain in the arse.
Alright this is getting out of hand and I CBF talking much more. Rear quickly: Read my 260C thread - I removed a leaf from the leaf-spring pack in the rear end and that made it softer and lower, and I made up a little plate to compensate for the missing length and it acts like a tiny lowering block for fine-adjustment in the ride height which can be useful. You might end up needing to get new leaf springs made up or your pack reset, or some people try flipping leaves but I haven't done that myself.
As has been said, make sure you shocks aren't stuffed because that will make a huge difference. And anyone who tells you that you need 'lowered shocks' for a lowered car is making a gross over-generalization. If your bump stops remain as they were and the car's shocks bottom out before the car hits the bump stops, that's no good regardless of what the normal ride height it. And honestly most shocks won't bottom out until very late anyway (i.e. past full bump). Lowered shocks in a lot of cases are just something that doesn't really have any merit that's easy to flog off to people who don't know any better.
Check your toe adjustment on the front end after changing the ride height. Old cars normally have woeful bump-steer so the toe will go up the sh*t when you lower it.
Don't hesitate to ask me moar if you can put up with more of my preaching haha
Register
Login
FAQ
Search
![[ img ]](http://img.photobucket.com/albums/v471/Nebuchernezzer/DatsunSilviaSig.jpg)
