Suspension Options

[nmlss2006]

1) roll and dive are a good thing. See 'dynamics of weight transfer'. I prefer 'effective' to your definition of 'fun', which I personally don't even agree with, for the very simple reason that the stiffer you go, the faster the car's reactions get (again, see 'dynamics of weight transfer'). The faster the car's reactions get, the harder it is to control at the limit.
2) Bouncing off bump stops on US roads? With effective rates of 159lb/in front and 171 rear, over 50% over stock? If this occurs, perhaps when you see a bump you should slow down. Unless someone else is paying for the car (this, incidentally, is why eliminating fender gap may very well LOOK cool but the reduced suspension travel is, again, the very opposite of 'effective' - and why therefore I find it a pretty bad idea for anyone who calls themselves an enthusiast, but that of course is my opinion).

[rammstein]

How much of a drop on each? I'm not wanting any gap.

The E30M3 springs don't drop the car very much, if at all. The Intrax do. I don't know how much, as they weren't on my car when I bought it (but it came with them). However, here is a picture of my car when they were on it:



Drops it a decent amount from the looks of it.

$75 + shipping if you're interested.

[nando]

1) roll and dive are a good thing. See 'dynamics of weight transfer'. I prefer 'effective' to your definition of 'fun', which I personally don't even agree with, for the very simple reason that the stiffer you go, the faster the car's reactions get (again, see 'dynamics of weight transfer'). The faster the car's reactions get, the harder it is to control at the limit.
2) Bouncing off bump stops on US roads? With effective rates of 159lb/in front and 171 rear, over 50% over stock? If this occurs, perhaps when you see a bump you should slow down. Unless someone else is paying for the car (this, incidentally, is why eliminating fender gap may very well LOOK cool but the reduced suspension travel is, again, the very opposite of 'effective' - and why therefore I find it a pretty bad idea for anyone who calls themselves an enthusiast, but that of course is my opinion).

sounds good in theory, but the reality is far frome true.

as far as needing a perfectly smooth track for anything stiffer than sport springs - bollocks. maybe with blown boge's or KYBs, where the damping is completely ineffective. there's a point, to be sure, but sport springs are generally made to be an inexpensive OE+ mod, not necessarily because they handle (or even ride) the best. Otherwise you'd better let the guys who seriously track their E30s that they're doing it wrong, and have been since the days of DTM.

[Jean]

You have to decide if you just want "looks" or if you want "performance". I will also agree H&R Sports are too soft for their drop.

[balooshinakus]

1) roll and dive are a good thing. See 'dynamics of weight transfer'. I prefer 'effective' to your definition of 'fun', which I personally don't even agree with, for the very simple reason that the stiffer you go, the faster the car's reactions get (again, see 'dynamics of weight transfer'). The faster the car's reactions get, the harder it is to control at the limit.
2) Bouncing off bump stops on US roads? With effective rates of 159lb/in front and 171 rear, over 50% over stock? If this occurs, perhaps when you see a bump you should slow down. Unless someone else is paying for the car (this, incidentally, is why eliminating fender gap may very well LOOK cool but the reduced suspension travel is, again, the very opposite of 'effective' - and why therefore I find it a pretty bad idea for anyone who calls themselves an enthusiast, but that of course is my opinion).

There is a point where stiffer = worse, sport springs are nowhere near that line. Also, earlier you suggested using 22/19mm sway bars.. Sway bars actually reduce suspension independence, which is not a great thing to do, especially in the rear of our cars. I'm not saying that sway bars are a bad thing, I'm just saying its a bit stupid of you to suggest upgrading to much stiffer sway bars and at the same time suggest that HR Sport springs are as stiff as anyone but a hardcore racer needs.

Having suspension compliance is a good thing, but you don't need springs as soft as HR Sport to get suspension compliance. Having massive amounts of body roll and dive aren't good if you are trying to make fast transitions in your car. Stiffer springs with the right strut/shocks can still offer plenty of compliance while stiffening up the car so you can make rapid transitions.

[moe30]

I don't know why everyone is talking about hr sports lol, they aren't an option if I get hr's they will be race springs. Sports are too soft and don't drop enough for me.

[balooshinakus]

Got sidetracked :P

Get koni's and GC's

[nmlss2006]

Nando, FFS, I wrote: 'If roads are awful, I'd stay with the Konis and put on H&R sports. that is already over 50% stiffer than stock: anything else will help if you are VERY smooth in a track setting with good paving and hamper otherwise'.
So you are entirely correct: people who track their cars exclusively have very different requirements. And by the by, while you are also entirely correct that poor damping will worsen performance (and indeed, most cars stock and otherwise are undershocked more than they are underspringed), if you INCREASE the damping rate of the shocks to where it's correct for the springs you will FURTHER LIMIT suspension travel - which is great in any situation... but it won't help if you need that suspension travel to copy the road or, God forbid, to help absorb the weight transfer of a mistake/correction/what have you.
And, I believe the OP was talking about 'poor US roads'. With the roads I've seen in the US, you WILL get poor tire contact with H&R races or IE3s, unless the 'poor roads' he's talking about are significantly better than here, especially if you couple them with shocks that can actually take an effective wheel rate of 570x0.45 = 256 lb/in. There is no way around it folks: if the surface is uneven you need compliance until physics changes. If you want controllable reactions you want the springs to absorb energy instead of transmitting them to the tires, doubly so on uneven surfaces. Yes, on DTM circuits it makes perfect sense to have 900 lb/in springs *if you're a professional*. The problem is, none of us are professionals, we're not racing in our DDs and even the circuits here (In the NE, I suspect the others aren't any better) have MUCH worse paving jobs. The roads are best left unmentioned (PA and NY take the cake around here, I'm sure there are areas in other states that are even worse).
Just to mention an example of what happens *even with a professional at the wheel*, go look on Youtube for a now-infamous video of a person driving a FXX at Rijeka. The paving there is significantly worse than at other european tracks, not as bad as, say, jefferson @ summit point and he is spending most of his time trying to keep the car on the road, not going fast, because his sidewalls and suspension are too stiff to go fast.
Jean, by the by, if the H&R sports are indeed too soft for their drop, which is something *I haven't personally experienced* but I admit my experience is limited to OE sports, which have about 0.3" less drop, increasing shock stiffness may help. I am surprised that noone (and I do mean noone, I asked TC Kline, Turner, etc) has stock vs. koni vs. Bilstein damping diagrams. With those and a somewhat serious investigation on effective travel of the suspension (again: noone knows how many MM of travel you have from stock BMW riding height to bump stop contact and/or to bottoming out without bump stops?) we can start talking quantitatively about damping Nm vs spring Nm. Let's also keep in mind that an E30 weighs 1300kg on a fat day so forces will be different than what they would be for a 1600kg E90 or 911.
On top of all this, noone has been talking about tires, which I believe I mentioned earlier: using 250 lb/in (44N/mm) spring rates on 126mm sidewalls is again not what I would call particularly well matched.
balooetc, apart from the above, I suggested 21/14.5 swaybars, not 22/19, in my comment but I allowed for 22/19 because I know that many, as yourself, cannot quite mentally decouple roll from actual effectiveness despite physics, unfortunately, working the way it does, so you will have more fun, tuis verbis, with a car that rolls less despite any actual loss of performance. Besides which, if it is true that increasing the effective spring rate is a benefit as you maintain, I would say that my comment is anything but stupid - not that I find the qualification entirely justified but I've given up a long time ago on civilised conversation in forums.
To sum my point of view up: I will, in the next few months, acquire more experience with H&R sports on a 6 cyl car and it may very well be that you are correct and H&R sports + bilsteins are not as good a match as I think though the numbers seem reasonable to me - I will be running Koni SAs however: Bilstieins, according to the people who make them, have a VERY steep compression curve to compensate for reduced travel. I would find it very, very surprising if this, however, meant that going to H&R Race's 315/570 rates vs 118/265 stock (that's over 200% stiffer!) with bars that are stiffer on top of that were the best approach for a car to be driven *on poor roads i.e. not on a track* as the OP asked.
OP, sorry for the threadjack.

[moe30]

You are fine, I don't have a problem with people explaining previous post

[nando]

Nando, FFS, I wrote: 'If roads are awful, I'd stay with the Konis and put on H&R sports. that is already over 50% stiffer than stock: anything else will help if you are VERY smooth in a track setting with good paving and hamper otherwise'.
So you are entirely correct: people who track their cars exclusively have very different requirements. And by the by, while you are also entirely correct that poor damping will worsen performance (and indeed, most cars stock and otherwise are undershocked more than they are underspringed), if you INCREASE the damping rate of the shocks to where it's correct for the springs you will FURTHER LIMIT suspension travel - which is great in any situation... but it won't help if you need that suspension travel to copy the road or, God forbid, to help absorb the weight transfer of a mistake/correction/what have you.
And, I believe the OP was talking about 'poor US roads'. With the roads I've seen in the US, you WILL get poor tire contact with H&R races or IE3s, unless the 'poor roads' he's talking about are significantly better than here, especially if you couple them with shocks that can actually take an effective wheel rate of 570x0.45 = 256 lb/in. There is no way around it folks: if the surface is uneven you need compliance until physics changes. If you want controllable reactions you want the springs to absorb energy instead of transmitting them to the tires, doubly so on uneven surfaces. Yes, on DTM circuits it makes perfect sense to have 900 lb/in springs *if you're a professional*. The problem is, none of us are professionals, we're not racing in our DDs and even the circuits here (In the NE, I suspect the others aren't any better) have MUCH worse paving jobs. The roads are best left unmentioned (PA and NY take the cake around here, I'm sure there are areas in other states that are even worse).
Just to mention an example of what happens *even with a professional at the wheel*, go look on Youtube for a now-infamous video of a person driving a FXX at Rijeka. The paving there is significantly worse than at other european tracks, not as bad as, say, jefferson @ summit point and he is spending most of his time trying to keep the car on the road, not going fast, because his sidewalls and suspension are too stiff to go fast.
Jean, by the by, if the H&R sports are indeed too soft for their drop, which is something *I haven't personally experienced* but I admit my experience is limited to OE sports, which have about 0.3" less drop, increasing shock stiffness may help. I am surprised that noone (and I do mean noone, I asked TC Kline, Turner, etc) has stock vs. koni vs. Bilstein damping diagrams. With those and a somewhat serious investigation on effective travel of the suspension (again: noone knows how many MM of travel you have from stock BMW riding height to bump stop contact and/or to bottoming out without bump stops?) we can start talking quantitatively about damping Nm vs spring Nm. Let's also keep in mind that an E30 weighs 1300kg on a fat day so forces will be different than what they would be for a 1600kg E90 or 911.
On top of all this, noone has been talking about tires, which I believe I mentioned earlier: using 250 lb/in (44N/mm) spring rates on 126mm sidewalls is again not what I would call particularly well matched.
balooetc, apart from the above, I suggested 21/14.5 swaybars, not 22/19, in my comment but I allowed for 22/19 because I know that many, as yourself, cannot quite mentally decouple roll from actual effectiveness despite physics, unfortunately, working the way it does, so you will have more fun, tuis verbis, with a car that rolls less despite any actual loss of performance. Besides which, if it is true that increasing the effective spring rate is a benefit as you maintain, I would say that my comment is anything but stupid - not that I find the qualification entirely justified but I've given up a long time ago on civilised conversation in forums.
To sum my point of view up: I will, in the next few months, acquire more experience with H&R sports on a 6 cyl car and it may very well be that you are correct and H&R sports + bilsteins are not as good a match as I think though the numbers seem reasonable to me - I will be running Koni SAs however: Bilstieins, according to the people who make them, have a VERY steep compression curve to compensate for reduced travel. I would find it very, very surprising if this, however, meant that going to H&R Race's 315/570 rates vs 118/265 stock (that's over 200% stiffer!) with bars that are stiffer on top of that were the best approach for a car to be driven *on poor roads i.e. not on a track* as the OP asked.
OP, sorry for the threadjack.

wow, while I'd like to read that and post a reply, I just can't. paragraphs?

I don't "exclusively" track my car, either. and I *know* my ride quality improved with stiffer springs over the ultra-soft H&Rs, so you don't have to argue about it. I have a good idea how much travel I had with H&Rs - about an inch and a half with stock bump stops. that isn't very much. Handling isn't any better with soft springs that bottom out, in fact bottoming out is far worse.

[Jean]

nmlss2006 - I've had about 5 suspensions on the e30 alone, and I can honestly say h&r sports with bilstein sports were one of the worts combos I've had. I put a lot of miles on the car, smooth roads, bumpy roads etc. All of these changes were done leaving the tire aspect ratio the same, so I didn't change 10 things at once ;)

[Aciid]

Kyb/vogtland springs ftw. I just put this combo in my car, dropped it 1.6" front and rear and I am loving it! The ride is good and it looks awesome. I'll be posting pics of my car up soon when I get my new wheels on, so until then I'm rocking bottlecaps.

[nmlss2006]

Bringing this back up - Nando, the text IS divided in paragraphs :). In any case, if you are correct and there's 1.5ins - that is, less than 40mm - of travel left in the suspension then lowering the car 35mm with the H&R is lunacy: per what I was saying above and if we pretend to ignore a few things, we'd have to go to 2x stiffness, give or take, since we eliminated ~50% of the travel. In that case you and Jean would be 100% correct, the springs are way too soft. That surprises me because it would imply that a stock E30 from the factory has <3" of travel on the suspension. That's not very much at all - think 'a 911 has more'.
Jean, I hear you, but then the question becomes, what does one put in? Going to 250 lb/in front and 500 rear on a car that weighs less than 1300kg seems... excessive to say the least.

[nando]

maybe you're not accounting for wheel rate - that 500# spring in the back is actually only about 250# when you consider wheel rate. the front isn't as big of a factor but it's still there. also consider how tall and soft the typical suspension from the 1980's was. remember they had just come from an era of giant floaty sedans - just think of any 1970's chase movie where the cars barely make a corner with about 20 degrees of roll.

I think you would be challenged to find anyone running a linear spring with a rate of 250 lb/in. the H&R sport front springs for my ix were 220#, and that was far too soft for the height. most kits like GC start at 450# which is even considered fairly soft.

[nmlss2006]

Oh yes: from the old e30m3 page, the wheel rates are x0.88 F and x0.45 R.
We therefore have:
106 / 245 stock 325i -> 93.3/110.25, 84.6% F/R ratio
180/380 H&R sport -> 158.4/171, 92.6% F/R (so front is stiffer, in proportion -> more understeer, all else being equal), ~55% stiffer than stock
315/570 H&R race -> 277.2/256.5, 108% F/R (even stiffer in the front -> more understeer still), 132% stiffer than stock
I suspect the relative stiffening in the front goes with the fact that swaybars tend to become a lot stiffer in the rear and not quite as much in the front, one goes from 20/12mm to 22 (+10%)/ 19 (+58%!) or even 25/22. That probably balances out the F/R ratios.
With all this being said, if we assume that the 30-35mm drop of H&Rs more or less halves useful suspension travel, the spring rate has to double: therefore, 106/245 -> 212 F 490R. That would come out to 186.6 / 220.5 effective wheel rates, which is.. well. Not soft :). That would require a LOT of damping from the shocks and nice and stiff sidewalls.