I did a search on strut modifications, and I just needed a little clarification. If I cut the struts and put in new inserts, what insert works best to put back in it?

Here is what I am trying to talk about. Are there a variety of inserts that I could put in?[img]http://datsun1200.com/modules/myalbum/photo.php?lid=257[/img]

You cut the strut to suit the desired insert.

You will need a KYB/Bilstein/Koni parts book to determine what insert you wish to use, before determining the strut diameter and strut tube dimensions.

By shortening the strut, you are changing your front suspension geometry, which will raise the roll centre, and make the car handle worse. So if you don't understand front suspension mechanics, I'd keep away from this sort of modification.

If you must..

Stick to the Nissan models to choose from.
There are 2 widths of strut tube, and up to 5 different tube lengths.

So it depends what struts you are shortening. It also depends what sort of upgrade you are looking at. Anything from a slightly heavier car will work well, to keep the car flat.

Chris

Dattodude,

Thanks for the help. I understand some about suspension geometry, but what exactly does it do to the geometry that makes it handle worse? Just caster and camber or bump steer? I figured if the car is lower to the ground it would handle better. Like I said, I don't know a whole lot about it.

Actually, lowering the front lowers the roll centre, which generally isnt a bad thing...
The problems start when you go crazy, and the arm that connects the bottom of the strut to the crossmember is higher at the strut end.
This gives a very low roll centre, but sadly gives positive camber change with body roll.

To fix this, you put a spacer between the steering arm, and the bottom of the strut, so that the bottom arm sits more or less parallel to the ground (It's a compromise between your personal roll centre preference and getting a good camber curve)

Lowering the car lowers the centre of gravity, Yes. But most well sorted cars have a roll centre that equals the centre of gravity. By shortening the struts the roll centre actually rises, and the centre of gravity lowers.

That's what those strut spaces for, lowering the roll centre.

I have cut my 180B struts to fit smaller Z-car inserts, and when it's on the road, I will be playing around with several different sized strut spaces that go between the strut and the balljoint. I will report on the results.

I'm not a racing expert, nor a suspension expert, my opinions are theoretical.

Cheers,
Chris

here's the pic.
I did this to increase suspension travel. The car was already lowered about 1.5in before. My lower control arms are level with the ground. I know this is not ideal, but whatever, progress here is slow.
If you can imagine making a left turn, the car leans or rolls to the right. As the right side compresses, the control arm swings up and in (from level), decreasing camber. This decrease in camber plus the decrease from body roll = a right front tire not perpendicular to the road. And it only gets worse the harder you take a turn.
Am I right? or close to right? I've read all the books but don't have real world experience.
From what I experienced with this mod, the geometry did not change. It changed because I lowered the car.
PS- the KONI and Tokico adjustable cartridges for the same year and model Jetta do not fit in the stock strut tube.

I'd be interested in ferals thoughts on this matter.

240z inserts are what is in my old mans sedan. the standeard stanza inserts werent working and there was no travel so he cut down the tube and put in 240z inserts. but it wasnt cut down that much!!

Shortening the strut while maintaining constant lower arm angles with spacers, keeps the roll centre the same height while lowering the CG.

You can vary the front roll centre by using different thickness spacers or by changing the strut angle on adjustable tops.

Depending on preference, front roll stiffness is usually kept quite high to minimise arm angle changes, while the rear roll centre is raised and lowered to unload the inner rear tyre on solid rear axle cars. If you have an LSD then lower roll centres on the rear are the go to get the best times.

The best part about shortening the strut is that you gain extra suspension travel before the strut bottoms out, allowing more compliant suspension and better road holding.