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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > e92 335xi spring rates



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      01-02-2012, 11:59 PM   #1
gmazzu
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e92 335xi spring rates

I have read a lot of posts on here about suspension differences between XI and I models. Hopefully I'm correct that the springs are interchangeable but the shocks/struts are different. Does anyone know what the stock XI e92 spring rates are?
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      01-03-2012, 08:50 AM   #2
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145/460

Springs all around are interchangeable. Rear shocks are interchangeable, but front struts are not.
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      01-03-2012, 11:23 AM   #3
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Are the springs the same for the i and xi? I believe from your numbers they are. I'm surprised I would think the added weight would require a small changes in front rate
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      01-03-2012, 11:54 AM   #4
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There are only one set of springs for xi's: 145/460.

The extra weight is why they went with the "sport" spring rates, and not the regular spring rates. Also, due to the front geometry being reworked to accomodate the axle, the motion ratio is a little higher, thus increasing the wheel rate while not increasing the actual spring rate.
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      01-03-2012, 03:38 PM   #5
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Thanks a lot for the replies. I have been looking to replace the suspension on the car, it roles to much and the shocks/struts aren't very comfortable. I have a E46 M3 and I just replaced the shocks and struts with Koni's, the ride is great now. I don't feel the stock springs on the xi are up to the task do you have a recommendation that I could put with koni's for the E9X. I was looking to drop the car just a small amount to keep the travel correct. I havent looked much at coilovers as the cost and setup is a lot more.

Thanks for your suggestions and info
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      01-03-2012, 03:54 PM   #6
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Quote:
Originally Posted by gmazzu View Post
Thanks a lot for the replies. I have been looking to replace the suspension on the car, it roles to much and the shocks/struts aren't very comfortable. I have a E46 M3 and I just replaced the shocks and struts with Koni's, the ride is great now. I don't feel the stock springs on the xi are up to the task do you have a recommendation that I could put with koni's for the E9X. I was looking to drop the car just a small amount to keep the travel correct. I havent looked much at coilovers as the cost and setup is a lot more.

Thanks for your suggestions and info
The two options are the Eibach Pro Kit (same part numbers as the i) and the H&R Sports.

The H&Rs are generally reviewed as a bit lower and stiffer, and the Eibachs seem to have slightly less drop, and a bit more comfortable of a ride (though both are stiffer than stock).

For the record, I own neither, that's just my summation from reading this forum. I'll be going with the Bilstein struts and Eibach springs on my e92x shortly.
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      01-03-2012, 04:00 PM   #7
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My understanding is the Eibach Pro-kit is:
Front: 148 lb/in
Rear: 456 lb/in

which is lightly higher rate in the front but lower in the rear. I got that info from the suspension section sticky, it may be wrong. I haven't seen any info on the H&R spring rates.

Do you like Bilsteins better than Koni's? I haven't been in a car with Bilsteins in many years. The Konis drive really well and comfortable.
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      01-03-2012, 04:10 PM   #8
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I'd also look into the BMW Performance Springs (yellow ones). They are pretty close to the M3 rates, IIRC.

Right now, Bilsteins are the only shocks/struts available. Konis should be available soon.

There is a thread where a 328i driver used M3 front springs, linear rear springs, and custom valved Bilsteins to mimic the M3 setup. He seemed pretty pleased.
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      01-04-2012, 12:24 PM   #9
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Quote:
Originally Posted by Doyle View Post
145/460

Springs all around are interchangeable. Rear shocks are interchangeable, but front struts are not.
I'm a little confused by this post. From the numbers listed, I'm interpreting the spring rates to be:
145 lb/in (Front)
460 lb/in (Rear)
However, Doyle states that the springs are interchangeable all around (swappable amongst all 4 corners?), which goes against the front/rear notation.
Which part of the info above is correct, because they can't both be unless I'm misunderstanding something.

Lastly, if 145/460 does denote front/rear, why is there such a big difference between the rates? It seems as if the front rate is low, especially for the xi.

Last edited by Bakeneko; 01-04-2012 at 12:34 PM.
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      01-04-2012, 02:18 PM   #10
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The springs on all four corners of the x-drives are interchangeable with the spring from the respective corners of the RWD. Eg: Front left= front left, Front left =/= rear left.

The reason for the difference between the rates are the motion ratios. Motion ratio measures the relative leverage a spring can have on the wheel. Since the rear spring is much further in board, it has less effect on the wheel rate. The front motion ratio is close to 1:1, whereas the rear is close to .5:1.

The spring rates are fine for a comfortable grand tourer.
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      01-06-2012, 12:51 PM   #11
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While the spring rates are fine for a grand tourer the look of the stock suspension in the front especially is so high. I'm not looking to drop much, not slammed, and improve handling. Right now the car isn't eager to turn in and understeers a lot.

Doyle - What would you suggest for a daily street driven 335xi for a suspension setup? curious if you have a lower cost solution and if money was less of concern what would it be?

Thanks
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      01-06-2012, 01:04 PM   #12
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We should really sticky my "End-All..." thread. Anyone know how to do that?

For a daily driver:

Low cost-BMW Performance Springs, Bilsteins/Konis, RRT Custom Front Sway Bar, M3 rear sway bar, and Vorshlag camber plates if it is ever tracked (save you $400+ in front tires)

Higher cost-TC Kline SA front/DA rear, 500/800 Hyperco or Swift springs, RRT Front Bar, H&R rear bar, Vorshlag camber plates, M3 rear subframe bushings, Rogue rear toe arms, figure something out with the front arm bushings/ball joints

Money is no object- I require an up-front deposit before any advice is given
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      01-06-2012, 01:59 PM   #13
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I just read over the "End-All.." thread really great information, thanks for working on it and now my head hurts. The TC Kline stuff looks great but not sure I want to spend that much cash. I'm leaning towards the BMW Performance Springs with Konis/Bilsteins, most likely Konis because they have rebound adjustment and are fantastic on my e46 M3. I dont think a custom front sway bar is an option so would you leave the front bar and just add a M3 bar? The car will never be tracked so I'll skip the camber plates.

Thanks
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      01-06-2012, 02:11 PM   #14
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Glad you found it and it was useful.

Everyone has different needs and budgets. No reason to spend the money if you aren't going to use it to it's full potential.

When I say "custom", they take a stock bar, saw off the stock blades and weld on longer, multi-hole/adjustable blades. They aren't one-off bending/fitting a new bar.

If you leave the stock front bar, I'd get something a little softer than the M3 bar. Maybe the Hotchkis bar.
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      01-06-2012, 05:51 PM   #15
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I would spend the money if I knew what was on the other side was so incredible. My other thought is to buy the TC Kline and skip the rear bar and camber plates because that might just be a killer setup for the street. I have purchased some expensive suspension components for my motorcycle in the past and it was a case of you get what you pay for.

Have you seen or have any information on the Dinan springs? They have only a slight drop, I'm not sure how the handle or what the spring rates are, I could possible put them with a set of konis
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      01-06-2012, 06:35 PM   #16
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I have the dinan stage 1 suspension with a m3 rear sway bar and the car handles a million times better than it did. It feels much more like a rwd car with less body roll and a lot less understeer. As a bonus I found it to be much MORE comfortable than stock. Looks wise it looks like a regular 335i with sport suspension, definitely not slammed but noticeably lower than a stock xi. Only thing I want to do now is add the Koni front struts since they got released. Harold at hp autowerks stocks a few sets of the koni struts and shocks (unfortunately they are special order for the us so they aren't available everywhere) so you might want to contact him. He is very knowledgeable and helpful.
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      01-06-2012, 07:00 PM   #17
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Are the rear shocks the standard Koni or a modified version? If you can tell without comparing them to a stock rear?
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      01-06-2012, 08:11 PM   #18
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Dinan says that the rear koni shocks are re-valved to their specifications. I'm not sure how different they would feel compared to the regular koni rear shocks. I contacted them about the front struts and they told me I could run the koni they just hadn't done any research on adding them since they're not being released in the US. Luckily I have VAC motorsports near me and they build BMW race cars so some suspension tinkering shouldn't be too hard for them. The dinan is great but it is expensive for what you get (springs, re-valved koni shocks, smaller bumpstops and rear upper shock mount kit). I got it when they had a 15% off sale so it wasn't too bad and I liked the fact that it was more than springs and shocks and had bumpstops and the rear upper shock mount. I don't know how the car would feel just springs and shocks but the dinan matched suspension has been everything I wanted and more.
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      01-06-2012, 08:36 PM   #19
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Really the xi fronts aren't going to be released in the US?
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      01-06-2012, 08:51 PM   #20
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Yes according to dinan and to Harold at hp autowerks the Koni front struts aren't going to be released in the US. This could change down the road, but for now you have to special order them. Or you can get a set from hp autowerks as they're keeping a limited number in stock. I haven't seen any other vendor on the boards or the Internet in general offering them.
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      01-07-2012, 12:00 PM   #21
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Quote:
Originally Posted by gmazzu View Post
I would spend the money if I knew what was on the other side was so incredible. My other thought is to buy the TC Kline and skip the rear bar and camber plates because that might just be a killer setup for the street. I have purchased some expensive suspension components for my motorcycle in the past and it was a case of you get what you pay for.

Have you seen or have any information on the Dinan springs? They have only a slight drop, I'm not sure how the handle or what the spring rates are, I could possible put them with a set of konis
Suspension, more so than anything else, has to work as a system. If you don't plan on tracking the car, I would say that the results of the spring, shock, sways combo would be better for you.

I called Dinan looking for spring rates and sway bar rates, but they told me it was proprietary. I know Steve Dinan knows his stuff, but that is like going to a high end restaurant and the menu is off limits. And regarding special valving, if you know some basic info, any suspension tuner worth their salt can revalve them for your car.
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      03-03-2014, 02:18 PM   #22
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could i order 4 rear bmw springs if i wanted a little more drop on my 335xi? the stock ride height is so high i feel like the 1.3 isnt going to be enough
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