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Old 05-09-2013, 01:37 PM   #1
E30Jack
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Adjustable Coilovers - spring rate question?

Hey so I'm looking into getting adjustable coilovers for my 1991 bmw 325i. These coilovers are "made" for my specific car, I'm just wondering if the spring rate is appropriate (maybe a little more info on what spring rate is too?). BTW I'm currently on stock springs and shocks.

This is the coilovers specs (as noted on the website)
"Spring rate are 8kg for front & 10kg for back. (8kg/mm = 448lbs/in and 10kg/mm = 560lbs/in). It can be lowered from 0-2.5"! Comfortable for daily driving and Racing Cross"

Would these be good for my e30?
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Old 05-09-2013, 02:17 PM   #2
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Check out the spring rate master list

http://www.e30tech.com/forum/showthread.php?t=40472

That should give you an idea. Also you should have whatever struts you choose valved for the spring rates you choose.
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Old 05-09-2013, 02:28 PM   #3
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Okay I see that stock spring rate is front 106 lb/in and back 245 lb/in...but I really don't get what that means...should the spring rate on coilovers be closer to that spring rate? Or would front 448 and back 560 work? They also sell coilovers that are 336 in the front and 448 in the back...which would be more ideal?
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Old 05-09-2013, 02:41 PM   #4
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The diff between front and rear stock is 141lbs
The other 2 options the diff between front and rear is 112lbs

Pretty much the less lbs between front and rear the less weight transfer you will have with braking and cornering.

Its kinda hard to say what would be best for your car and if your car is also a dd.

I have 375lbs front and 475lbs rear. I should have gone with at least 300lbs in the front. I find my front a little too bouncy around some corners and thats with my koni yellows set to full soft. Keep in mind im running a m42 its a little lighter than your m20.

I do find my current spring rates comfortable as a dd.

Im sure others will have some sound advice for you as well
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Old 05-09-2013, 03:10 PM   #5
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Quote:
Originally Posted by E30Jack View Post
I see that stock spring rate is front 106 lb/in and back 245 lb/in...but I really don't get what that means...
The spring rate is how stiff the spring is. 245 lb/in means that every 245 pounds placed on top of the spring it will squish 1 inch. The higher the number the stiffer and rougher your ride will be.

Quote:
Originally Posted by E30Jack View Post
Should the spring rate on coilovers be closer to that spring rate? Or would front 448 and back 560 work?
Generally people want stiffer sprigs for a sportier ride. 448 and 560 would work but I think would be very stiff for street duty.

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They also sell coilovers that are 336 in the front and 448 in the back...which would be more ideal?
Depends on what you want. 336 and 448 are still fairly stiff. Comparable to the H&R race springs according to the spring master list.

One of the biggest advantages of a coilover kits is the springs are usually 2 1/4 or 2 1/2 inch ID standardized springs. So if you don't like the spring rates you can buy softer or stiffer springs.
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Old 05-09-2013, 04:20 PM   #6
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Thanks "food". I am leaning more towards the 336 lb/in and 448 lb/in now...I'm looking at them cause I can get them for a killer deal just a few hundred bucks..I just don't want a ride that's too stiff cause this is for a street driving car.
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Old 05-09-2013, 05:01 PM   #7
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Just also wondering what would be a good spring rate for daily driving? Thanks guys
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Old 05-09-2013, 05:23 PM   #8
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Why do you want coilovers? if it's just for having a low car then you could get stock rates if you wanted to. Of course depending on how low you go you may run into other issues.

As a starting point I would suggest rates in the H&R Sport area.
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Old 05-09-2013, 05:41 PM   #9
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Why do you want coilovers? if it's just for having a low car then you could get stock rates if you wanted to. Of course depending on how low you go you may run into other issues.

As a starting point I would suggest rates in the H&R Sport area.
Yes it's for lowering my car as I just got bbs wheels but I'm on stock suspension so wheel gap is bothering me. I need to be able to adjust the height so the wheels don't rub...preferably not paying a lot of money
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Old 05-09-2013, 06:33 PM   #10
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Based on the numbers you gave, the components you are looking at are for racing. If it's cheapness you're after you might want to just pick up a set of lowering springs. Unless you have really low offset wheels you shouldn't rub. Alternatively ask the company company you are looking at if they can source street springs for you. Or just buy softer springs yourself.
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Old 05-09-2013, 06:47 PM   #11
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Alright ill have to either save some money for some high quality street coilovers or look into some lowering springs...as long as I can get low enough to not rub and still look good it's fine with me...but I have a parts car that might have a full set of koni shocks, I know for sure they're on the back but haven't checked the front ill have to look at that.
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Old 05-09-2013, 08:29 PM   #12
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Some good springs may be better for your budget -- IE3 or H&Rs are popular, pretty cheap and shouldn't rub. What wheels are you running? Have you taken a look at some pix of people running these setups?
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Old 05-09-2013, 08:47 PM   #13
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I just bought 15x8 bbs rm's which is why I'm trying to make the suspension cheaper cause I spent my car budget for the month on those wheels. I've been looking into H&R but they give an approximate drop not an exact, sometimes you lose like 1/4 or 1/2 an inch which could make the difference between rubbing and not rubbing. I'm just trying to figure out what lowering method to use after I wrap the wheels in 205/50s in the next week
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Old 05-10-2013, 09:41 AM   #14
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What is the offset of those wheels?
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Old 05-10-2013, 11:15 AM   #15
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