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      12-25-2013, 02:04 PM   #1
seanblee
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Lower front spring rates with Ohlins

I'm thinking about upgrading from my current ZSP springs with Koni FSDs to the Ohlins R&T struts/dampers with Swift springs, but I'm struggling with the front rates. I've done a lot of reading and my current thinking is to go for 224 lb/in fronts and 672 lb/in rears, which gives roughly equal wheel rates with slightly higher rear natural frequency to maintain the factory flat ride, but front rates this low seem quite unusual...

The car is pretty much exclusively street driven and I already have uprated sways, Quaife and rear subframe bush inserts.

Does anyone have any thoughts or alternative recommendations, please? Many thanks!

Sean
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      12-25-2013, 02:28 PM   #2
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I went with 336F and 672R Swift springs when I installed my Íhlins last year. Very happy with this setup. 224 sounds soft I'd check with Harold for his recommendation. You will love your Íhlins!
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      12-25-2013, 05:58 PM   #3
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Definitely check with Harold. On our cars you generally want the rear spring rate to be double the front rate. Not sure how firm you want your springs overall, but I'd have to say that you'll end up with a great suspension.

Last edited by jjellyneck; 12-25-2013 at 10:05 PM.
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      12-26-2013, 03:06 AM   #4
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I'm considering some Ohlins myself and may stick with the springs they come with. With that said, what sway bars would be best to upgrade to? Has anyone tried the cobb front/rear bars? I do have quaife lsd and rear subframe bushings....... Should I just go wit m3 front sway or get the rear too
or does somebody have the Ohlins wit a better balanced swaybar set up to recommend?
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      12-26-2013, 08:31 AM   #5
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Stick with Íhlins front springs but consider substituting Swift 672 pound rear springs in place of the Íhlins rear springs. M3 front Sway only... no need to add M3 rear sway. Once again check with aHarold.
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      12-26-2013, 11:09 AM   #6
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Quote:
Originally Posted by Blaster400 View Post
I went with 336F and 672R Swift springs when I installed my Íhlins last year. Very happy with this setup. 224 sounds soft I'd check with Harold for his recommendation. You will love your Íhlins!
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Originally Posted by jjellyneck View Post
Definitely check with Harold. On our cars you generally want the rear spring rate to be double the front rate. Not sure how firm you want your springs overall, but I'd have to say that you'll end up with a great suspension.
Thanks for that. I was looking at those rates because I've read that the motion ratios are 0.96 front, 0.56 rear, so 224F/672R springs gives 206F/210R wheel rates, whereas 336F/672R gives 310F/210R at the wheels, which seems very stiff on the front and would surely lead to more understeer?
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      12-26-2013, 11:34 AM   #7
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I am running 396 lbs up front with the ohlins and 672 lbs. I was running 336 lbs upfront with koni/tckline. I could not see going softer than 336. I like the 396 better though.
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      12-26-2013, 12:45 PM   #8
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Quote:
Originally Posted by sutter2k View Post
I am running 396 lbs up front with the ohlins and 672 lbs. I was running 336 lbs upfront with koni/tckline. I could not see going softer than 336. I like the 396 better though.
Thanks. How do you find the ride quality on the street? As well as the obvious handling improvements from the dampers, I'm looking to get rid of the crashing and 'twitchiness' over bumps that comes with the stock suspension, so I'm planning on doing the M3 front control arms (and possibly the rear uppers) at the same time...
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      12-26-2013, 03:51 PM   #9
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I think, as does Harold, that those spring rates are too low. Your car will be too soft and will most likely bottom out if you lower the front from a stock ride height (as well as bind). As I have said a bunch of times, spring rates are all subjective. Some people mind xxx while others like xxx.

You can go with whatever spring rate you want, however I believe you won't be that excited about your new spring rate.

-Mike

P.S. I roll around on 560lbs in the front and I like em (on ASTs though).
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      12-26-2013, 03:59 PM   #10
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Quote:
Originally Posted by HP Autosport View Post
I think, as does Harold, that those spring rates are too low. Your car will be too soft and will most likely bottom out if you lower the front from a stock ride height (as well as bind). As I have said a bunch of times, spring rates are all subjective. Some people mind xxx while others like xxx.
Thanks Mike. Would I be right in thinking that you typically recommend 336F/672R for street use?
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      12-26-2013, 04:46 PM   #11
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I ran 336 front and 672 rear with my Ohlins and it was night and day compared to the standard M-sport set-up in regards to comfort and performance.

I now run 400 front and 800 rear with all M3 arms, bushes and H&R roll bars front and rear. It's just superb, and so much nicer to drive and still far more compliant than standard. It rides with a real quality feel, with no crashing over potholes or that twitchy feeling as if the rear end is moving about.
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      12-26-2013, 06:37 PM   #12
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Quote:
Originally Posted by seanblee View Post
Thanks Mike. Would I be right in thinking that you typically recommend 336F/672R for street use?
As Techevo describes above, if you have M3 suspension bits I would recommend 400/800 but if you have yet to upgrade those components I would suggest 336/672.

-Mike
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      12-26-2013, 09:44 PM   #13
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Quote:
Originally Posted by Techevo View Post
I ran 336 front and 672 rear with my Ohlins and it was night and day compared to the standard M-sport set-up in regards to comfort and performance.

I now run 400 front and 800 rear with all M3 arms, bushes and H&R roll bars front and rear. It's just superb, and so much nicer to drive and still far more compliant than standard. It rides with a real quality feel, with no crashing over potholes or that twitchy feeling as if the rear end is moving about.
Did you have the rear shocks revalved for double the spring rate?
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      12-27-2013, 08:20 PM   #14
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Quote:
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Did you have the rear shocks revalved for double the spring rate?
No, no need, I'm running 9 clicks from full hard, and the shock is controlling the rebound no problem at all.
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      01-02-2014, 06:44 PM   #15
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Quote:
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Did you have the rear shocks revalved for double the spring rate?
Although recommended it's not absolutely necessary. The Ohlins can handle 800# rears just fine.

Harold
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      01-02-2014, 07:53 PM   #16
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Quote:
Originally Posted by HP Autosport View Post
Although recommended it's not absolutely necessary. The Ohlins can handle 800# rears just fine.

Harold
If you get higher rate swift springs for the rear like say 672#, is the swift spring actually 1" shorter than the Ohlins kit spring? If so, does that give you 1" less shock travel in the rear? Can you get the same length Swift spring but just stiffer? Or how do you recommend doing it?

Last edited by nikitino25; 01-02-2014 at 08:01 PM.
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      01-03-2014, 08:23 AM   #17
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I took Mike and Harold's advice and am running with 560lb fronts and 800lbs rear with my Moton Clubsport shocks. I don't find it too hard at all. In fact even with full M3 suspension arms and solid subframe bushings it's more comfortable than stock when on the minimum compression setting on the shocks.
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      01-05-2014, 09:03 AM   #18
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Quote:
Originally Posted by nikitino25 View Post
If you get higher rate swift springs for the rear like say 672#, is the swift spring actually 1" shorter than the Ohlins kit spring? If so, does that give you 1" less shock travel in the rear? Can you get the same length Swift spring but just stiffer? Or how do you recommend doing it?
I believe the rear springs that come with the Íhlins kit are 10 inches. Per Harold's recommendation, the 672# rear Swift springs that I installed were 9 inches in length which allowed proper ride height adjustment.

10 inch 672# rear Swift springs will leave ride height way too high.
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      01-05-2014, 12:45 PM   #19
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Yeah, 9" 672 or 800 rear swifts are perfect. They allow stock ride height if required with plenty of suspension travel, or extremely low (too low!) if adjusted to extremes.
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      01-22-2014, 10:17 PM   #20
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Quote:
Originally Posted by sutter2k View Post
I am running 396 lbs up front with the ohlins and 672 lbs rear (still tckline shocks in back). I was running 336 lbs upfront with koni/tckline. I could not see going softer than 336. I like the 396 better though.
Quote:
Thanks. How do you find the ride quality on the street? As well as the obvious handling improvements from the dampers, I'm looking to get rid of the crashing and 'twitchiness' over bumps that comes with the stock suspension, so I'm planning on doing the M3 front control arms (and possibly the rear uppers) at the same time...
The ride quality is now great !!
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      01-22-2014, 11:21 PM   #21
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Street driven car? Then don't bother - the shocks aren't damped for those spring rates, it will never be optimal.
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