Alphabettispaghetti
Club Member
Its funny how geometry affects everything. My 750kg kit car had 650lb front springs and had great ride quality.
When I asked how much, he new an exact price and I can't remember to the penny but it was just short of £1100.
I'll wait untill my top mounts arrive the pay them a visit to discuss the setup further. It's a company I would like to use as they have a good reputation and are right on my doorstep. In the meantime I'll get all the other bits for the suspention ordered which are:
Ground control top mounts.
Techno toys front/rear arms, tie rods, and bump stear spacers.
http://www.technotoytuning.com/media/products/z_conversion_05.jpg
I like this, was just thinking about some sort of rear end suspension conversion lots of late strong diffs and drive shafts about, incorperated with new suspension units, nice
Johnny said:but they don't seam to think preload is an issue and I also share that view.
Actually its not at all interesting... Its downright naive.Thats certainly an interesting take on things
Linear springs are the same spring rate no matter how much they are compressed. Almost all coilover systems come with linear rate springs. Linear springs are much better for sport driving, b/c they are much mroe predictable, and make tuning your suspension much easier.
You can only preload springs with threaded shock body coilovers.
To preload a spring, you compress it b/w the upper and lower spring perches by adjusting the lower collar with the spanner wrench.
With linear springs:
When you put the weight of a corner of a car (probably around 700lbs) over your spring it compresses to absorb that weight. With 400lb spring, it will compress about 1 3/4". So, if you start with the lower collar so that it is just tight enough to hold the top of the spring against the upper perch this would be 0 preload. Raise the collar 1 3/4", and you now have 700lb's of preload. (arbitrary #'s for the sake of illustration.) Since you have preloaded the spring, the same weight as the car's corner, when you put the car on that spring, it will not compress at all, and will simply sit on top of the spring. If you were to hit a bump, the force would still compress the spring the same amount it normally would if you had set the spring to 0 preload. Now if you set the spring to say 900lbs of preload, when you hit the bump (say its a bump that generates around 250lbs of upward force), the spring will compress much less b/c the spring is already beyond the load specified to absorb the bump. Since there is only 50lbs beyond the preload, the spring will only compress about 1/8th inch, and the car will likely be launched over the bump.
You will likely never ever preload a spring beyond the weight of the corner of the car it is on for that exact reason. Springs are there to absorb bumps, if there are any bumps at all, this is a bad idea.
What good is preloading the spring then?
It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. by preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep yourcar from bottoming out when cornering. You have to be careful though, b/c you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.
Thanks for the advice and yes I will go and see them once the top mounts arrive. They did say they would machine an adaptor to make a perfect fit for the shock. I'm pretty sure I'll go with them but a bit concerned about the spring rates they want to use. Price wise, they are about the same as others so not a problem there. I was sold on the AZ type but they don't seam to think preload is an issue and I also share that view. I don't have the time and fascilities now to do the work myself so getting someone to build a complete strutt is appealing too.
Up till recently that was what I was going to get but it does mean switching to 5 lug wheels which if your building a new project or fancy a wheel change at the same time would be my choice. Gabriel at TTT is also very helpful in dealing with your questions etc but this conversion will probably set you back an easy 3k before you convert your front hubs and a set of new wheels.