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Stock spring + shorter/stiffer shock in rear?

Old 07-20-2017, 11:20 PM
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Stepica
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Default Stock spring + shorter/stiffer shock in rear?

Hi guys, I am a proud owner of '03 roadster and my rear shocks are shot. They were pretty soft even new, being '03. My questions is as follows : I am happy with my ride height (did the rear shock mount hack) but the rear is loose as ****. Will stiffer and a tiny bit shorter shock work? My logic is it would preload the spring a little bit and would help (and I am ok dropping another 0,5-1 inch no problemo). Any thoughts or ideally any specific shock tips? I am European but my car is US spec (I love those silly amber lights, we dont have that here ). Btw I replaced everything swaybar related except the swaybar itself, so I a really gunning for the suspension itself and I feel bad throwing away perfectly fine springs. Cheers!
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Old 07-21-2017, 06:19 AM
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Welcome and isn't Brno the site of a famous race circuit? I think DTM or another road race series has raced there in the past.

As to your question, preloading the rear spring with a shorter shock would not be a good solution to oversteer. It could be your dampers are simply shot and have little rebound or bounce control. Replace them with some high quality shocks and play with the rear swaybar to soften the rear end to get more bite. Good luck!
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Old 07-21-2017, 07:40 AM
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Originally Posted by dkmura View Post
Welcome and isn't Brno the site of a famous race circuit? I think DTM or another road race series has raced there in the past.

As to your question, preloading the rear spring with a shorter shock would not be a good solution to oversteer. It could be your dampers are simply shot and have little rebound or bounce control. Replace them with some high quality shocks and play with the rear swaybar to soften the rear end to get more bite. Good luck!
Totally this! ^^^

Adjustable bars are the way to go to tune the chassis to YOUR liking/needs.

AFTER replacing dead/dying shocks; which may fix the problem before needing to go with new bars.
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Old 07-21-2017, 09:24 AM
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Originally Posted by dkmura View Post
Welcome and isn't Brno the site of a famous race circuit? I think DTM or another road race series has raced there in the past.

As to your question, preloading the rear spring with a shorter shock would not be a good solution to oversteer. It could be your dampers are simply shot and have little rebound or bounce control. Replace them with some high quality shocks and play with the rear swaybar to soften the rear end to get more bite. Good luck!
Yeah, Brno is a home of Masaryk circuit and it hosts DTM, WTCC, Supermoto and MotoGP series for example.
I will replace the shocks with standard height and lets see what happenes. I have my Z for little over a year now and the rear is getting really sloppy, transitions are slow and its getting dangerous during spirited driving. I guess I was making the problem bigger than it is. New shocks will go in, I already have swaybar poly bushinhs and swaybar endlinks with poly as well, thats why I am sure the slop is because of the dampers.
Btw, gents, I have done some reading and 2005 and later Zs have higjer spring rate in the rear, but keeping the same in the front. Am I correct to assume that would make the rear quicker to transition and firmer overall? Might swap the springs for later model ones if that is a case, these is one front end wrecked Z nearby, 2007.
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Old 07-21-2017, 09:53 AM
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I just changed out my shocks, went with Bilstein B8s. Absolutely love! Firm and in control but your teeth don't click on potholes haha.
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Old 07-21-2017, 10:07 AM
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Originally Posted by Stepica View Post
Am I correct to assume that would make the rear quicker to transition and firmer overall? Might swap the springs for later model ones if that is a case, these is one front end wrecked Z nearby, 2007.[/left]
By adding poly bushings to the rear swaybar you are, in essence, stiffening the rear. This creates more oversteer, and you want less. Replace the shocks first, and then see how your Z handles.
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Old 07-21-2017, 10:17 AM
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Originally Posted by dkmura View Post
By adding poly bushings to the rear swaybar you are, in essence, stiffening the rear. This creates more oversteer, and you want less. Replace the shocks first, and then see how your Z handles.
I didnt say I want less oversteer. My Z is pretty standard, turn-in is great (contisport5 are helping there), mit turn its pushing out as a pig and car rotates very well under throttle on the corner exit. What I want is generally firmer rear, its tilting left and right like a boat, especially in quick left-right-left-right type of driving. I figured thats swaybar job, so put poly there and endlinks, but then I realized the rear is still too mushy.

Btw, any idea on going with new rear shocks (oem or billstein) + 2005 and later rear springs (they have higher ratings).

I have a roadster so I do understand there will be always a play in a chassis and disconnect between front and rear (I dont make nearly enough money in my country to do full bracing).

But thanks all for your comments and help, was sceptical joining the forum, but you guys rock!

PS : sry if my english is broken here and there, its my 3rd language
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Old 07-21-2017, 10:28 AM
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I would say start with shocks first. Then go from there.
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Old 07-21-2017, 10:29 AM
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Originally Posted by Desert Z View Post
I would say start with shocks first. Then go from there.
thats my new plan, thanks guys
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Old 07-22-2017, 05:56 AM
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Ordered KYB shocks, since they are cheaped and in stock in Czech Republic, should be veeery similar to OEM, maybe a tad stiffer. Will let you know how different they will feel compared to leaking, 72k miles oem ones from factory
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Old 07-22-2017, 12:42 PM
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You know the only way to actually preload the spring is to install an uncut oscillator. As you preload the spring, you add ride height
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Old 08-16-2017, 09:26 PM
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Sry for alte update guys. With vacation successfully behind me, I am happy to report my findings.

I ended up isntalling new KYB shocks on all four corners and I am very happy with my car again. I didnt even realized my front shocks must have been shot too, since the front feels much sharper as well. Plus I isntalled new outer steering links and front ball joints (again, sry for my english, not my first language) and the turn in is great again.

The balance is still the same (more grip and firmer up front), just more stable overall. So my next step will be stiffer rear sway bar, as I still feel the rear is lacking behind the front in stability in hifh speed corners. I daily my car, plus its a 2003 roadster, so I am not trying to get what you call in US autocross beast, but just nice, positive feedback and spirited drive inspiring car. I am happy with the front, tighten the rear sway and I am done.

3.5 liters is a huge motor here in Europe, so its plenty of power for me and I dont want stance nation or super stiff coilovers, that would be aweful to daily.

Oh btw, got 25 mm (one inch) spacers all around as well. Front fitment is perfect, rear could take 30 mm instead, but IDC, still looks way better than stock. Didnt notice any difference in ride quality or stability TBH.

Cheers!

Last edited by Stepica; 08-16-2017 at 09:28 PM.
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Old 08-17-2017, 05:51 AM
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Just a quick note of thanks for this update. It's surprising how many people never provide any feedback on suggestions, and it's great to hear that the shocks (dampers) did the trick for you. BTW- adding a stiffer rear swaybar will make your ZR oversteer more. You might want to add a set of matched front and rear swaybars if you like the balanced handling you have now.
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Old 08-17-2017, 06:45 AM
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Originally Posted by dkmura View Post
Just a quick note of thanks for this update. It's surprising how many people never provide any feedback on suggestions, and it's great to hear that the shocks (dampers) did the trick for you. BTW- adding a stiffer rear swaybar will make your ZR oversteer more. You might want to add a set of matched front and rear swaybars if you like the balanced handling you have now.
^^^ Yes, it's a breath of fresh air to hear RESULTS from suggestions.

I'm with dkmura on this suggestion. There is no single "better results tweak" than a matched (or adjustable) set of sway bars for the Z's handling.

Other than #drivingschool of course. Laff.... said I wasn't gonna say that any more but who could resist the straight line?
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Old 10-06-2017, 11:40 AM
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ok guys, I am back with more progress. Again, salaries in my country are very much lower (food, housing etc is cheaper too, but car parts are not :/ ). I scored second hand stillen sway bars, pair of them as suggested (again, thx so much for your help guys!). Set both of them to the medium and OMG, completely new car. I remember steering getting tighter and harder when I got my 25 mm (one inch) spacers and I felt about the same difference again with swaybars. More importantly, my car doesnt lean left to right like a drunk sailor anymore. I tried to go to the stiffest settings in the rear, but my TC would kick in all the freaking time. I tried setting the front one to the stiffest as well just for the heck of it and I actually liked it the best. I was worried at first, went back to medium medium, but no, I really like stiff stiff the best.

RECAP
- 2003 USDM Roadster daily driven on Czech roads (potholes galore, snow 4 months per year)
- fresh KYB "OEM like" shocks
- 25 mm (one inch) spacer on each corner
- stillen sway bars set to stiff + stiff
- originar R17 wheels with 225/50 + 235/50 rubber
- summer tires - Continental Contisport 5 (love them)
- winter tires - Continental Winter Contact T850 (LOVE LOVE LOVE them)
- last but not least, hacked half off of the rear top spring rubber seat
- fresh break disks and Yellow stuff pads
- other than that, she is stock

I have this car since I believe April or May 2016 and she is maturing like a good wine. Tires, pads, shocks and sways made a HUGE difference, without breaking the bank and ruining daily aspect of my car.

I believe I wont be doing anything else to this car as far as performance goes. Maybe better speakers and headunit, but you know, nothing really important.

One more big THANK you to all of you who helped me, you saved me a lot of time and money
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Old 10-06-2017, 02:34 PM
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Glad you had success with all the suggestions and remember that the swaybar adjustment may -change throughout the year. For example, stiffer settings in the front bar may make the car understeer in some conditions. Solution? Soften the front settings a bit and feel a bit until it becomes neutral again. Snowing or raining a lot? Swaybars might transfer too much weight in these conditions and just unhooking one end of the end links to disconnect the entire bar.
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Old 10-06-2017, 11:30 PM
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Got it. So winter settings medium medium and summer settings stiff stiff. Thanks
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