Ok I will throw in what I know from my single seater racing experance. First off a bone jarring ride not only pounds your kidneys but it also kills the cornering speed on your car. I can't tell you how many student cars I get into at track days and almost immediately ask" do you have the shocks full stiff" A really stiff set-up will make the car very skatey - it will feel fast because it gives instant feedback but it will slide a lot earlier than a softer set-up. If the wheels are not be able to follow undulations in the road then the tires aren't on the ground so they are not building any grip. Further when you watch Indy car races or F1 and it rains the team soften the car up to build mechanical grip. A friend of mine is the leading Triumph GT 6 racer in the country and Kas Kastner who raced for Triumph is always telling him to run the car slightly softer than what feels racey. Same as if your car is so soft it bottoms if you car is to stiff it will efffectively bottom out when the wheel makes a sudden movement , so that wheel as no grip. For the sake of argument if you have four 7 inch wide tires you have 28 inches of tire on the ground , if one does nothing for a split second you have 21 inches of tire on the ground. If this occurs two or three times in a corner then obviuosly the car will go slower. If you have ever driven an unloaded full size pick up down a wash board gravel road you know what overly stiff suspension does.This is no different then setting your car up to oversteer. Oversteer is fun but it's slower than a car with a hint of understeer.(Alain Prost's words not mine)
Now with all that said buy good quality shocks , springs and a matched set of sway bars. You need to match all the suspension components to each other to get the most out of them. You can use parts form the wreckers as long as the work together. The C-sedan set up that is on this pages works very well and it is essentially what I use. 7/8 front bar , 1/2 rear with Tokico strut inserts and a set of old non-gas Koni adjustables. (The Koni shocks work well for fine tuning and Koni will still service them). I cannot remember the spring rates but the springs are straight out of the NISMO catolog. So remember bone jarring is just as bad as the car bottoming.

My $0.02 Tom Grossmann

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Stiff ride? It doesn't take a lot of kidney jaring ride to change ones tune on that one.

Dattodude seems to be right on the money with his post. The suspension is supposed to work FOR you, not AGAINST you, & excessively stiff springing takes all the fun out of it.

Im not 100% sure abuout what governs/dictates the roll centre yet so if someone wants to have another go Im all ears. Its been mentioned that spacing the wheels out improves it ,and I was wondering a mate of mine used 910 bluebird
front struts which make the wheels stick out further this is a good thing, yes? I have been slowley acumulateeeeeeeeing the parts to copy his set up , does anyone know of the pluses or minuses of making changes to the ackerman of the front steering? The reason I ask is because to usethe bluebird strut legs Ive got to use 310 sunny steering knuckles and lower arms/ balljoints If the arms are different lengths (I havent checked yet) thats easy to fix but if the sunny lower steering knuckles are different it could get hard. My mates car was a track only job so he cut and welded his but mine will see some street use and Im not that game

The suspension needs some movement.

And you'd be surprised with no suspension how the smallest pothole will send you off the track.

Stiff shocks and soft springs are good. But having no suspension, or having the car bottom out is the worst thing.
Most people have never put good quality shockers in their cars, and "go overboard" with ideas to improve things. Start with good quality HD sports shocks and VR rated or ZR rated 50-60 series tires. Cheap tires means cheap handling.

The extra leaf is a great idea. I did reverse eye extra leaf springs on the rear of my old 1200/CA18DET sedan..it felt much better to drive. But with more than 120kw at the wheels, you may need to look at installing tramp rods, slapper bars or re-engineer the rear end like I'm doing.

Chris

You should not require a rear anti roll bar ,if you want the 1200 to handle neutrally ..If you require oversteer fit a rear anti roll bar .. the larger rear Bar the more oversteer

Rollcenter height dose effect Body roll ..the closer you get the roll centre height to the Cars centre of gravity the less the car body will roll over .. To change the front roll center height you use spacer blocks(mac pherson strut ) Between the steering arm and the strut leg
.. To change the rear roll centre with a solid rear axle it gets a bit harder as the roll centre is usally the center of the axle and Dosent change when you change to lower ride height on the rear unlike the front rollcenter which dose change with ride height ..So to change the rear height you require a watts link with a adjustable pivot point .. The pivot point height changes the Roll center height . it is best to use as softest spring rate as" Possible ", As this a allows the tires to follow the bumps and irregularities in the road a higher percentange of the time ..
Anti roll bars are usally THE last Tunning Aid adjustment you would use after you get your spring rates .Roll centres and alignment dialed in .
This informatiom relates to a acheiving maxium cornering power
..NOT ride comfort ..

Would it give the best handling to have stiff springs\shocks and sway bars? (I dont really care how unpleasant the ride is).
Car will only be used on seal. Also what do you think about putting an extra leaf on top upside down in the rear to reduce axeltramp?

I've had similar cars (Mustang) with stiff springs + soft rollbars, and another with soft springs + stiff rollbars. I preferred the soft springs and stiff rollbars. It felt better to me going around corners, plus the ride on smooth pavement was much nicer. It had a monster front swaybar that reduced roll to imperceptible. It would corner faster than I dared. The stiff-springed car was a police pursuit model and felt more conventional in the handling department, and probably held the road just as well, but just felt less confidence-inspiring. On the other hand the stiff rollbars were *bone-shattering* offroad (or on uneven pavement).

But as dattodude says, it is complex science. I'm not sure the same would work on a Datsun 1200 because the rear springs are already fairly stiff, partially due to the light weight of the car.

great reply dattodude!!!

Soft springs are better... I may be wrong but heres what I think.

Springs support the car, Shockies control the rate of movement of the suspension both in compression
and rebound. HArd springs reduce the amount of mechanical grip a car has (No good)

Imagine a car with solid conections (no springs) the car would follow every single bump. This is what increasing spring stiffness begins leading to.

In a datsun, fitting a rear sway bar will increase the amount of understeer!!! This is because the swaybar increases the grip level of the rear tyres.

Swaybars compensate for cars that have a buggered up "roll centre".

Most cars when you lower them, actually increase the body roll as the roll centre moves further away from the centre of gravity. If you move the centre of gravity down, then the sway bars aren't so important. It's complex science! And for most people, it's so confusing they just don't think about it.

Lowering a car lowers the centre of gravity, but without other changes, the roll centre exponentially moves away from the centre of gravity. Which means lowering most cars (without stiffening sway bars) actually increases body roll.

So if you want to lower a car, you also need to stiffen the sway bars, and change the spring rates. Otherwise adding strut spacers on the bottom of the struts, is mostly to help "roll centre" issues. It's not for many of the reasons that people sell them.

Chris

Shocks and springs are for pothole recovery..good suspension geometry and (including swaybars, panhard rods, watts linkages) are for handling.

Why do offroad cars have high springs?
1. for suspension travel, but the other good reason is that:
2. it keeps the centre of gravity below the roll centre, meaning that when you go hard around a corner, the shocks/sway bars don't have to work hard to keep the car flat through a corner..

Hey I was at the local reckers and I found a Nissan silvia s12 ( old square 80s one) and I was checking it out for parts when I decided to take the rear swaybar off just for sh*ts and giggles and if it was going to cost more than $20 Id leave it at the counter. It was $9 so i took it home and it will fit a 1200!!
I dont think I need it because Ive already got stiff rear springs and it would stiffen up things to much but I also have a sedan with standard rear springs. I'm wondering what, other than stiffen up the back, does a swaybar do? is it better to run soft springs with a swaybar or stiff springs with no swaybar?
what do they realy do?
Cheers
Quinn