Ride difference between cut springs and coil overs...

[ZMONSTR]

I have a restored 260z with cut springs.  The car bottoms out a fair bit and in general doesnt like bumps in the road.  I am attaching a pic to let you see the current stance and cut springs

 

I have the OK from SWMBO to upgrade a few things to the tune of 3k or so.

 

So I am looking at coilovers and new seats.

 

Based on reading here, it doesnt seem to matter what you buy for coilovers..you get about the same thing.  My question is are coil overs going to improve the handling of bumps, or at least stop the bottoming out with the same stance?

 

Thanks

 

 

[74_5.0L_Z]

If you lower the S30 and do not significantly increase the spring rate then you will most likely experience bottoming of the suspension over bumps.

 

On a lowered Z, the benefits of coil-overs come mostly from the availability of different lengths and rates of springs, and from the additional clearance between the strut and wheel.

Read the sticky regarding sectioning struts. 

 

To properly lower a Z car the struts must be sectioned, you must install shorter inserts, and you must have decent bump stops.

[BluDestiny]

Lowering a Z can also be detrimental to handling if you go beyond what the suspension geometry is meant for. 

 

So going with Stiff coilovers will help you from not bottoming out, but will be a more jarring ride. 

[jacky4566]

Cutting springs is only suitable for hillbilly racing. Adding to 74_5.0L_Z's response if you cut the springs the ride will be very bouncy since at the top of travel the springs are just floating. This can be scary if you hit a bump at high speed.

[JMortensen]

Dan mentioned the bumpstops, but I'd like to reiterate: Energy Suspension polyurethane bumpstops are not good. They're way too stiff. Get some decent ones from Koni or FatCat Motorsports or someplace else. They should be a foam bumpstop, sometimes they'll even have a spring rate listed. They're taller, and you will engage them more often, but that's OK, because they're not stupid hard like the ES ones.

If you're going to section the struts, figure out if you have a 240 or 280 chassis (260s were split). If you have a 240 chassis, you could section the rears an inch or inch and a half to try and even out the travel with the front end. If you have a 280, you can swap 240 insulators (or 280 front insulators) and skip sectioning the tubes in the back.

[OMONLA]

Lowering a Z can also be detrimental to handling if you go beyond what the suspension geometry is meant for. 

 

So going with Stiff coilovers will help you from not bottoming out, but will be a more jarring ride. 

What spring rate will you recommend "BluDestiny"?

[74_5.0L_Z]

What do you want to do with the car?

 

Are you auto-crossing, drag racing, or just driving?  How are the roads where this car will be driven?

Is the car structurally sound or is it really rusty?  Does it have a cage or any structural reinforcement?

Are you planning to run camber plates or use the stock isolators?

 

My car has a lot of structural reinforcement.  I autocross and road race.  My front springs are 500 lb/in and are 8 inches tall free length.  My rear springs are 400 lb/in and again 8 inch free length.

 

You have to consider rate and free length when selecting springs and while you are placing the coil-over sleeve on the strut.