Suspension advice needed

[grannyknot]

My 240Z has been lowered by p/o with Tokico illuminas shocks and 180-190lbs springs, great handling but brutally hard on my old injured back. I would like to keep the lowered stance but get a softer ride.

The guy at a local Z specialty shop recommended doing coil overs (to keep the lowered stance) but use softer 140-150lb springs to soften up the ride.

Does that sound like a good plan?

Thanks,

Chris

[John Coffey]

Your ride issue probably has more to do with the shocks and suspension travel then the springs. Turn the Illuminas down to 1 and see how that goes. Also, check how much bump travel you have before the car is on the bump stops. You should see at least 2" of shock shaft before the bump stops hit the top of the strut tube.

[jmortensen]

Agreed 100%. Your springs aren't too stiff, you're hitting the bumpstops.

I would add going to softer springs with coilovers just means that you'll be on the bumpstops more. Your choices are to section the struts to gain more bump travel or to raise the car up.

You're basically driving around near the bumpstops as it is. Many newer cars do this as designed from the factory, and different bumpstops can have a HUGE effect on comfort. Check with FatCat Motorsports and see what they have for you if you don't want to change out the springs or section the struts. New bumpstops are going to be your cheapest option. I would think this would probably be the one for you, but you might check with them before ordering: http://fatcatmotorsports.com/FCMstops_46.htm

[grannyknot]

Guys, I might not be using the right terms, I thought coil overs and sectioned struts were the same thing. Sectioned struts is what has been recommended to me.

John, I have 1 as the setting, brutal! So as Jon says it might be the bump stops, I'll check and see if they are there or not. How do I check how much bump travel I have, is it as easy as measuring between top of shock and top spring?

Chris

[Walter Moore]

One would hope that the PO at least replaced the bump stops. My Z didn't have them when I bought it, and I had already replaced the strut inserts before I discovered that they were supposed to be there. I had to open the struts back up to install bump stops. So making sure that you have bump stops is a good first step.

I will have to let the racers explain if there is a difference between sectioned struts and coil-overs. After reading this I am not sure:

http://www.arizonazcar.com/coilover.html

The thought of using a chop saw on my strut housings gives me pause...

Personally, my 240Z has OEM springs and it rides pretty hard. Keeping a lowered stance and getting a soft ride may be mutually exclusive objectives. If you make it work I bet there are a lot of people who will want to emulate your setup.

[beermanpete]

Guys, I might not be using the right terms, I thought coil overs and sectioned struts were the same thing. Sectioned struts is what has been recommended to me.

John, I have 1 as the setting, brutal! So as Jon says it might be the bump stops, I'll check and see if they are there or not. How do I check how much bump travel I have, is it as easy as measuring between top of shock and top spring?

Chris

Sectioning the struts and installing coil overs is not the same thing. However, they are commonly done at the same time. Technically, the car came from the factory with coil overs. When the car gets "coil overs" installed it is to use 2 1/2" dia. springs and threaded preload adjsuters. This allows ride height adjustment and room to adjust the camber (if camber plates are also installed). Sectioning the struts restores bump travel that would otherwise be used up lowering the car.

To check the bump travel look up into the wheel well while the car is on the ground and look to see how much of the damper rod (the bright shiny part) is exposed. You should be able to see if the bumps stops are installed at the same time.

If the bumps stops are missing you might get enough improvement just from putting some in. Our car was missing the bump stops and it was pretty harsh when it bottomed out. When we replaced the springs and shocks with the Tokico lowering springs, HP shocks, we put in new bumps stops and it is much smoother.

[grannyknot]

Had a look this morning and there are no bump stops installed, I can't check the bump travel as the engine is out and the car is being striped for restoration. So, I'll get some bump stops in place when I put it all back together and see how that feels before I go any further.

Thanks for the advice.

Chris

[grannyknot]

The Tokico springs in the front are labeled 5020F the rear are 5020R. I just checked the Tokico site and these springs aren't offered for a 240Z so I have no idea what their weight is. I checked Tokico's search function for the part number but it just said "no results" . p/o told me they are 180lb but I have found lots of half truths in his discriptions.

Anyone recognize the part # 5020

Thanks,

Chris

[Zed Head]

I have a set of the 5020's for my 280Z. That's the car they're sold for. The rears are installed, the fronts are cut stock springs (haven't installed the Tokicos up front yet). I have KYBs and no bump stops (didn't think about them until it was too late for the one day job). I've not bottomed and the ride is great.

The FSMs show a pretty big difference in spring qualities, 1972 (all I can find) vs. 1978, Rear Axle -

280Z 15.43 inches long, 8.5 active coils, 128 lb/in spring constant

240Z 14.5 inches long, 10.65 coils, 104 lb/in constant

Hard to compare mounted qualities without knowing the preload (space between the spring perches on the struts) of the 240Z strut compared to the 280Z strut. But it doesn't look like those springs are designed for the 240Z. It's a lighter car for sure.

Just found this link also. It doesn't give the 5020 number but John Coffey in Post #3 does describe different springs for the 240 vs. the 280. Looks like you have the stiff 280 springs on your 240. Might be the problem. http://www.classiczcars.com/forums/thread36261.html

Edit - Post #9 describes a 240Z with 5020's as like a gokart, very stiff but handled great, couldn't handle a pothole though. Kind of like what you're describing. It's the springs...

Edited November 26, 2012 by Zed Head

[jmortensen]

Just found this link also. It doesn't give the 5020 number but John Coffey in Post #3 does describe different springs for the 240 vs. the 280. Looks like you have the stiff 280 springs on your 240. Might be the problem. http://www.classiczcars.com/forums/thread36261.html

Edit - Post #9 describes a 240Z with 5020's as like a gokart, very stiff but handled great, couldn't handle a pothole though. Kind of like what you're describing. It's the springs...

180 in/lbs is really not that stiff. I would guess that 95% of people with coilovers go stiffer than that. With lowering springs you're still lacking travel. If it's bottoming and there are no bumpstops, that's the first thing to fix. Run the struts on 1 or 2 and it should be pretty comfortable.

[John Coffey]

Read up here: http://forums.hybridz.org/index.php/topic/88025-installing-tokico-280z-hp-springs-in-a-240z/

[grannyknot]

Well I just read everything on suspension that is pinned over on Hybridz plus the links within the threads...I need a beer.

I also discovered that in addition having no bump stops in the shocks that the bump stops for the lower control arms have been removed, no wonder I'm feeling the road.