If your shocks are too "hard" then they will not allow the spring to recoil fast enough after the compression. We have found this with the race cars, running adjustable koni's. If we wind on too much rebound, the car gets"sucked" down to the ground, because the spring can not push the shock out fast enough.

This sounds kind of cool, but in reality it limits the suspension travel siginificantly, and gives a VERY hard ride, as the spring is already compressed somewhat when you hit the next bump.

What you want to do (in my oppinion) is select a spring rate that is comfortable, and then select a set of shocks which will "control" the oscillation of the springs. Any good Suspension shop should be able to help you with this. Alternatively...... go for the adjustable koni's .... I found them to be great.

cheers Datman55. what spring rate would be good for a sweet road cruzing 1200? I want the same feel that you get in a new non sti WRX - real firm but not overly harsh, i dont want to bounce around and bruze my kidneys on every bump (like my coupe) but i HATE cars that sag and wobble. would 20% stiffer and shocks to mach be good?
stiffer?
lighter?
Cheers

One of the things that contribute to an unpleasantly hard ride is spring "stiction" What happens is that the manufacturer places low friction rubbing blocka at the ends of the spring leaves where they rest up against the leaf above. After some miles & years, they wear out & the leaves rub against each other. This gives a lot of interleaf friction & the rust between the leaves does not help. This means that a certain amount of "jolt" is required before the leaves begin to move. Thats stiction.


Datman is right, if the release of energy that is stored in the spring is too slow, on a rough surface, at quick speeds, it feels like the suspension is being "sucked" down. Not much fun.


For stock ride height in a street vehicle, then stock spring rates should be OK, but as the suspension gets lower, the spring rate should be stiffened up a little. The spring rate is the pressure that is required to compress a spring a measured distance. Lets use 1 inch as an example.


If your spring needs 100lb's to compress it 1 inch & you have 4 inches of travel, then it would take 400lb's to cause that spring to bottom out. Lets lower it 2 inches. It would be desireable to make this spring have a new rate of much closer to 200lb's per inch so that it still takes 400lb's of force to bottom out over the reduced distance of 2 inches of travel. Thats why lowering blocks suck & cars lowered this way will bottom out a lot more. The stiffened spring rate makes for a harsher ride, but hey, theres no free lunch. To get a benefit in one area, you pay for it in another.


If you are going to pull the rear springs out during a rebuild [recomended] then have a reputable spring works reset them to the ride height that you select, assuming that lowering is on the agenda, & see if Nissan still supply these friction blocks. They are NLA for 1000's but it's lucky that i bought 2 sets for my sedan many years ago & i still have 1 new set available for my coupe.
If they are not available, then the spring works will more than likely have some generic replacements.


I recomend Urethane bushes when refitting the springs & if the shackle pins are pitted, try to get new ones. The trick is to allow the spring to work with an absolute minimum of friction so that it can do it's job properly. The shock then controls the ride quality by controling the rate at which the spring returns to the static ride height. I set mine so that it returns to ride height from a dip that compresses the suspension about half or more of it's travel in one move. By that i mean that it does not rise above static ride height & drop down again. Do this test at speeds that you are going to drive at MOST of the time.


It seems to have worked well for me. It's not the cheap way, but it is right way to have your car ride & handle well. Do it on the cheap, & you will need to do it all over again to fix it right. Poor man pays twice.
Chris

Damn it 89mm, this was going to be a short reply.

i printed this out, so i can read it over teh next few weeks lol

but yeah very informative !

89mm
With the exception of special purpose shocks, i have been of the belief that ALL double action shocks had much less damping on the compression stroke, than on the extention stroke. Many cars had single action shocks that had NO damping on the compression stroke. Even the poverty pack EA Falcon of the early '90's had single action shocks.

The one car that i DO remember for it's shocks was the early 50's Austang A40. By the time these things had a few miles on them, many had shocks that did not work at all. Since the shock was a structural part of the suspension [top wishbone] it was a major, & expensive, job to replace, & many wern't. It was always funny to watch one pull up at the lights or a "halt" sign & watch the front end bobbing up & down for what seemed like minutes after the car stoped.
The best part about those good old days is the fact that they are over. Bring on the good new days.

chances are the Monroe shocks are not the cause of the hard ride. I've heard alot of things said about Monroes, but never that they are too hard. But even a standard 1200 has a harsh ride.

A set of variable rate front coils combined with the shocks you've got will absolutely transform the car. Best ride/handling compromise you'll find for the 1200. Did you get Holden Gemini's (Opel Kadet) in NZ? Front coils out of them can be used for this purpose - they're the same diametre as 1200 coils and are variable rate. They have to be cut, but if done sensibly can remain captive at full extension, and once you drive it you'll wonder why aftermarket spring manufacturers don't make em like this for the 1200!

Cheers L18_B110.
My girlfrinds father is going to sell his golf (fully worked mk1 1800) and buy a Kadet for his next project and more than likely he'll biff the front springs and get heaver ones so I should be able to get them for free! Sweet.
Ive been thinking heeps about the rear suspention setup and thanks to you guys Ive decided to take the springs out (shocks are already out) and finish the resto on the rear end. Once thats finished I'll get the springs reset 1- 2 1/2 inchs lower, with nolithane bushes and put the monroes in coz there free and if I need to replace them I can do it up on jacks (real easy) and I'll get adjustable konis or spax.
Cheers
Quinn

no the topic of bushes Ive been quoted $120 for just the rear set of nolithanes. Last week I was at a plastics factory and I noticed they had a poster for industrial bushes so I told the guy about my car and asked if they make them to order, he asked how many I wanted and how big they were and then gave me a rough quote for $120 - $160 for the whole car!! Its like nolithane but better, it has 100% memory harder than rubber comes either slightly harder than nolithane or slightly softer depending on which grade you choose. ANd it garenteed because its used in heep of industrial stuff, I cant rember the name started with a 'I' maby.
I'll keep you posted, Im going to get a sample made in the next few weeks.
Quinn