Noobie Question - Suspension

[siu_loong_bao]

Ok....

I have a V35 sedan in which I replaced the "stock" suspension with 350z Track suspension to lower it 1". I have driven it for a few months now and my Mrs keeps complaining that it was a better ride b4....

Seeing as my original V35 suspension can't be refitted (one front shock is leaking) and they looked like NISMO shocks (dark red colour), I am in the market to buy some coilovers....

My question is:

1. Can a coil over setup be adjusted to match stock ride comfort and also be lowered by that 1" I want?

2. Someone explain to me what the damper setting is and what the spring rate is?

I really wanted a the TEIN EDFC setup, but seeing as it's $4K+ easy...I will opt for a cheapy manual setup, say under $1k being advertised on ebay...

Valuable advice would be hugely appreciated...

Once the 'issue' is fixed, my current 350z suspension will be up for sale..

[V35_Paul]

Easy fix..

get a new girlfriend

[n15m0]

^^^ +1

in all seriousness, there is almost always a compromise between comfort n handling. If ur gf wants the comfort of stock suspension back, fitting aftermarket coilovers will almost guarantee to be worse than ur current 350z setup. Lowering a car will also mean a firmer ride in most cases, improved handling at the cost of comfort. IMO the z suspension would be your closest bet to stock comfort.

[n15m0]

Oh I just remembered u swapped to 19s. That is part of your problem too. Swapping back to 18s with 45 profile or 17s with 55 profile tyres will give u back some ride comfort too.

[mosoto]

Bilstein PSS9 or PSS10 coilovers for 350z will apparently give you a better than stock ride comfort if you don't take the car to the track.

http://g35driver.com/forums/brakes-suspens...-w-updates.html

I've got the Ohlins DFV coilovers w/- 20" and I or the wife don't feel there is a massive differance to stock on the softer damping settings. There's a noticeable increase in feedback from the road, but no harshness.

I wouldn't want to go any harder on the street tho.

Edited January 7, 2010 by mosoto

[scathing]

I have a V35 sedan in which I replaced the "stock" suspension with 350z Track suspension to lower it 1". I have driven it for a few months now and my Mrs keeps complaining that it was a better ride b4....

How bad is it for her? Is it just a bit too harsh, or way too harsh?

If its only a little too harsh, if you're on a budget consider getting Koni Yellow dampers. I ran a set with stock 03 Z33 springs. When they're at the softest setting the setup is softer than stock. The car's a bit floatier as a result, but its not a major issue on the streets.

Firming them up when she's not around will involve jacking the rear of the car up, unfortunately, but unlike some brands its not a "strut out" job (assuming you can't get to the top of the struts in a V35 sedan, which is the case in a 350Z if you don't want to drill into the trim). If you can reach the rear strut tops easily, consider another brand of adjustable dampers. I think Bilstein sell dampers separately, but I don't know of anyone who's bought them before.

2. Someone explain to me what the damper setting is and what the spring rate is?

The spring rate is the amount of mass required to compress the spring by a unit distance. Australia and Japan uses kg/mm, so a "7kg" spring requires 7kg to be put on top of the spring to compress it by 1mm. 14kg compresses it 2mm, etc. The higher the number, the more load required to compress it. Which means the harder it will feel.

Springs can come in linear rate and progressive rate. The former spring is simple. Lets say a spring can compress a total of 30mm. The extra weight required to compress it from 29 to 30mm is the same as compressing it from 15-16mm, which is the same from 0-1mm. The feel of the suspension is linear as a result.

A progressive rate spring requires less mass at the beginning of its range than the end. As a hypothetical example, it might only take the addition of 5kg to move it from 0-1mm but it you might need to add an extra 7kg when its compressed to 10mm in order to get it to 11mm. This means it'll feel softer over small movements (like bumps) but as you load it up harder, it'll stop letting the body lean as easily. It also means the car will feel a bit less responsive initially, as small lateral G-forces get absorbed by the spring rather than being converted into a change in direction.

Dampers (aka shock absorbers) control the movement of the spring. Dampers can control the movement both during compression (or bound) and expansion (rebound). Increasing the bound damping increases the hardness of the ride as the entire setup is less willing to compress. Increasing the rebound damping means the spring is slower to decompress, and softens the ride.

For your aims (and, by yours, I mean your girlfriend's) I wouldn't bother with a Tein setup. I've never been in a car with Tein Comfort Sports but they do run the same spring rates as Super Streets the last time I checked. The SS' are noticably harsher than stock. Even with a softer damper, the higher spring rate will still not make it comfortable.

FYI Teins (and most Japanese dampers) only adjust the rebound damping. Initial compression of the spring is unaffected, which means at low speed (i.e. over speed humps) playing with the dampers doesn't have a particularly noticable affect on ride comfort. Adjusting the Koni Yellows affects bound and rebound (not independently) so the change in ride/comfort can be felt at mundane speeds. In terms of adjustability, I much prefer my old Konis to my current Teins.

A mate of mine who used to own a Z33, who was after ride rather than handling, didn't like the Tein SS' because they were too harsh. He ended up running Tokico D-Spec adjustable dampers with Tanabe NF210 springs (which he felt was a spot on setup for his aims, even with his 19" Volk Racing wheels). The problem is that it'll lower your car even more, and there's no height adjustability in that setup.

Personally if the further ride height drop is acceptable I'd consider Eibach Pro Kit springs instead. They're progressive rate, and from what I can see the Tanabes are linear rate. I never rode in his car so I'm not sure how the Tokicos felt, but I can highly recommend the Koni Yellows from personal experience.

The 19s might also be killing the ride. Both in terms of the lack of sidewall, and the weight. The heavier the wheel the less control the suspension has over its movement, which will make the car feel crashier. Getting a smaller, or at least lighter, wheel might dial out some roughness.

[gtrtech]

Once the 'issue' is fixed, my current 350z suspension will be up for sale..

Hi,

I'd be interested in the 350 susp once your're sorted with new gear.

cheers

[not_a_zed]

Great explanation Alan.

[Touge Kyousou]

What Alan said is very good info.

One option i can think of is still getting coilovers, but custom order them and specify a low spring rate so it will be comfortable, then when you want to carve some corners, stiffen the coilover unit via it's adjustability to compensate for the spring. Also, you can adjust your stillen sway bars for this (from memory, you got stillen sways and exhaust?).

Also, another contributing factor of ride harshness is your stillen swaybars as the bars reduce independent lateral movement of each side of the suspension. So if yours are set to medium, you can try to set them to soft and see if your missus accepts that.

You can also try to hunt down some later model 350z sussy. 03 z suspension is the 2nd hardest z factory suspenion released. I know the 06s had softer dampers and possibly springs. Goodluck.

[scathing]

One option i can think of is still getting coilovers, but custom order them and specify a low spring rate so it will be comfortable, then when you want to carve some corners, stiffen the coilover unit via it's adjustability to compensate for the spring.

Fulcrum is the official importers of Tein, and they get their products revalved for Australia. I think they also use a softer spring. It'd be worth investigating, but ride comfort is so subjective I'd want to try it out first.

Also, you can adjust your stillen sway bars for this (from memory, you got stillen sways and exhaust?).

I'd try and find someone with coilovers first, and ride in the car. I know of one or two people on 350Z-Tech who've got PSS9s, but one of them has been custom sprung/valved for track use.

Also, another contributing factor of ride harshness is your stillen swaybars as the bars reduce independent lateral movement of each side of the suspension.

I found swaybars only had a subtle effect on ride comfort. In a straight line there's no change, and only if I hit a bump while cornering hard did I notice that the car wanted to skip.

You can also try to hunt down some later model 350z sussy. 03 z suspension is the 2nd hardest z factory suspenion released. I know the 06s had softer dampers and possibly springs

Yeah, I think it was the 06 that copped the Euro-spec suspension. Softer spring/damper setup, and stiffer swaybars. The 03 is nasty. It's not just that its stiff, but the dampers don't seem matched to the springs and so its crashy.

I believe that the Track also ran a harder setup than the Touring. I ran the OEM 18" wheels (with OEM tyres) for a while on my car. When a mate with an 03 Track and I swapped cars for a bit we both noticed that the Track was less comfortable over the bumps. However, I've never seen any documentation (official or Internet-sourced "spec sheets") confirming this.

Also, what tyre pressure are you running? Higher pressures will give you less sidewall flex, and I have found that it can make a noticable difference to ride. Same with the inherent stiffness of the sidewall on your tyre. With the same air pressure, my RT615s are firmer than my old FK452s and there's only a quarter of a mm difference in sidewall height.

You could try dropping the pressures first and seeing if it meets with the girlfriend's approval. If you've gone for a very aggressive sports tyre, try something with a softer sidewall. Toyo T1Rs have a reputation for soft sidewalls, but still provide a reasonable amount of grip.

Edited January 11, 2010 by scathing

[scathing]

Found out the V35s need to have the rear damper out if they want to be adjusted, unless you intend on cutting up the boot.

Koni dampers, or something with an electronic controller, would be the way to go unless you don't intend on ever adjusting it.