Justin35

I have a 2006 350Z roadster that was handed down to me from my parents. Now, on their driveway was a bit of a frame twist test (not too bad though) and it drove across this for 7 years. The car seems to have a fair bit of chassis flex and its especially noticeable in the passenger door region where I can hear a sound (hard to explain) whenever I cross over an uneven area of pavement.

I see there are several types of chassis braces out there. I don't know which is the most effective, if any, and which don't work at all. The car is mostly stock and has no rust on the bottom.

Thanks for advice/feedback/suggestions.

dkmura

iTrader: (64)

Before you get too concerned about chassis flex, I'd suggest you jack up this ZR and check how bad it is. The FM platform is pretty stiff to start with, and I'd start by looking to see if the W-shaped underbody brace is undamaged. Unless there's been some serious damage to this chassis, jacking up the PS front should see the rear QP also rise without drooping.

As for the sound you hear, that can come from a variety of sources unrelated to chassis flex (ie. worn suspension parts or bushings). Rule those out first, before you start trying to weld in any reinforcements.

Justin35

Can do.

Unrelated question 1: While we're talking about jacking the car up, is it safe to use the diff as a jack point? I see people doing it but would like advice from those more accustomed to the car as to whether that's advisable or not. Asking because I need to remedy the axle click.

Unrelated question 2: Its the 5 speed auto. When I put into drive, there's a deep "thunk" that just began. I suspect bushings near the diff. Is this common?

MicVelo

Diff: Yes, preferred for back half jacking then SUPPORTED with stands. There are side jack points as well for single corner lift. Suggest you download the FSM to know exactly where.

Thunk: It "could be" the differential bushings. But it could also be a number of other things. Thunks from trans, u-joints, differential itself, etc.

As dkmura said, spend the time up front inspecting and testing versus "throwing parts at it" (unless your desire is refresh the entire chassis).

Justin35

Has anybody looked into chassis stiffening? I noticed the car bends and flexes over uneven pavement. I understand, there's no roof, but would like to try and tighten it up as much as possible. Didnt know if anyone here has tried this before.

PS- We dont have door bushings, do we? I know Miata's have them.

travlee

iTrader: (8)

didnt like the answers you got in your other thread about this?
https://my350z.com/forum/maintenance...ertible-z.html

Justin35

Haha, not that. I found this sub-forum where I can ask a more targeted/specialized audience just for the sake of being thorough. That being said, I did jack up one end and the rear tire eventually also raised. This is frustrating because its clearly flexing alot, but I cannot find any single review on chassis stiffening products. I'm beginning to think I'll just have to be the guinea pig. I appreciate all answers. The other thread can be deleted if deemed necessary.

travlee

iTrader: (8)

have someone video you raising the car

where were you jacking from, one side i am assuming

Justin35

Driver side front.

jhc

You are correct, the ZR will have more flex than a coupe. Keeping each corner properly planted is the end goal. Strut tower bracing, upgrading to Hotchkis anti-roll bars and stiffer dampers sound like a more logical approach than adding additional wieght with bracing but Hey, it's your car.

If the perceived body flex outweighs the pleasure of having an open car you should sell it and get something that better suits you. Not being snarky, just factual.

Justin35

Unpossible, its a family thing. I shall explain.

In 1980, my dad had to sell his beloved 280Z because I came along and it just wasn't practical. He was finally able to get another Z in 2006 when he got this one. They recently upgraded to a Tesla and I got the Z, for free. Its an 06 with 100k. I'd like to keep it in the family and not disrespect anyone by selling it. I would in fact prefer a coupe, but is what it is. May look into the Hotchkis bars.

MicVelo

Hotchkis anti-sway bars will NOT do anything about the chassis flex. They are strictly for controlling suspension roll (a good thing). The slight added lateral stiffness might make the car SEEM as though its flexing less but no actual chassis stiffening comes from such bars. You will need to upgrade the chassis braces for that or install a roll bar which will help a little.

iideadeyeii

iTrader: (6)

They sell fender and h-braces. I have no comment on these as I have never used them.

BORNGEARHEAD

Is the underside of the coupe and the convertible Identical? If I'm looking for any under bracing for my convert, will the coupe ones apply?

JunierPhillips

Did you change your sway bars , that make the car stiffer in lateral movement, just need to buy one bigger size, what kind of shocks do you have, stiffer spring will help you and a mid chassy brace will help too

JunierPhillips

just love those brace

jcandas

I still get some flex when cornering at speed, it is a very uncomfortable feeling LOL.

Then again, it might just be my bad lines.

jcandas

I like the idea of keeping the roadster, as it is an awesome feeling driving without the top.

I have the Hotchkis sway bars installed and still feel the body flexing going around corners at high speed. I will be looking into more ways to accomplish this later this year. i will let you know if I find anything that works well.

Justin35

Yeah, keeping it is not the worst burden to bear in the world. As I mentioned, it was a free gift to me from my parents since I always took good care of it for them. (washes, detailing, maintenance etc.) I have mentioned selling it once, and I was met with a look from them that indicated I might get taken out of the Will. So, that's not happening!

You guys might be happy to know I've bought about $2300 worth of parts for it and this weekend, I plan to begin installing stuff. BTW, aren't you guys coming to Tail of the Dragon? That's where I live, at the town at the base of the Dragon. (ZDAYZ 2023) I'd like to bring it to hang out and check out other Z's. I'm installing new Koni Sport adjustable shocks, new rear wheel bearings, new Stoptech rotors and pads, a new stereo with Car Play/Android Auto, new trunk struts, JWT pop charger, a new battery, and my favorite thing of all..... an old school Weldina Nismo S-tune full cat back in addition to all the waxing, polishing, steam cleaning and ceramic coating that I've already done. In the fall, a manual swap.

Back to the point; I think the noise I hear on uneven pavement might be suspension related. Maybe a bushing is dried out.

This is a current, or "before" pic.

State as it was given to me.

State as it was given to me.

Heel Til I Die

iTrader: (2)

Sorry to be the bearer of bad news my fellow NC brethren, but ZDAYZ is no longer held at Fontana as of a few years ago. The host city is now Blowing Rock. 2019 was the last year. Maybe your Z made an appearance in one of the pictures I took? https://my350z.com/forum/2003-2009-n...yz-2019-a.html

I wish it was still at Fontana as I loved the venue and driving the Tail with the top down was amazing. Cherohala Skyway was also too much fun for words.