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Should new Bilstein sports feel this still.

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  • Grinder
    replied
    Thanks for the info. I am also running 16" wheels (type 5 from an e34 5 series). I'll wait th hear from Koenig on he's inquiry to GC.

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  • AlpineRunner
    replied
    Originally posted by RAD2LTR View Post
    I have Bilsteins on the front with H&R race springs and until I added roll center spacers, and spacers on top of the camber plates, I just blew through all the travel over the smallest bump, like pulling into the garage. The excessively low roll center just caused all kinds of issues.
    Will
    Roll center spacers have nothing to do with ride height or ground clearance... not sure if you were trying to say that or not. But to be clear, the roll center spacer goes below the hub and thus has nothing to do with the "stack height" of the spring, shock, and camber plate. It simply lowers the outboard mounting mount of the control arm and tie rod to compensate for the lower inboard mounting point you get with lower springs. Ideally you would want the thickness of the roll center spacer to match the drop in ride height. I wasn't able to do that because I have 16" wheels so I had to shave it down.

    Regarding the original issue of overly stiff ride, I have noticed that about Bilsteins in multiple cars. I had them in an e39 and that ride felt harsher than my M3 with the GC Koni setup. Bilstein uses a traditional German philosophy of high bump damping to make a car corner well. The problem is that 1, it creates a harsh ride, and 2, in quick transitions it jacks the car up.
    Another way to improve handling is to focus on rebound damping, this is what Koni does. It controls extraneous wheel movement just as well, but with the added benefit of a smoother ride and the car "settling down" in quick transitions instead of jacking up. This is the same suspension philosophy that Dinan uses to make their suspensions handle better than stock but also ride smoother.

    As far as travel, get Ground Control's shortened strut housing and you won't have any problems.

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  • hardtailer
    replied
    Steve beat me to it, didn't mean to repeat almost the same but his reply wasnt there yet when I posted

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  • hardtailer
    replied
    Originally posted by Grinder View Post
    The stock spring on the US model 31331130043 is $91.56 at my local dealer. The strut listed is 31322225397 ($139.52). On real OEM there are two additional springs listed for the Euro model: 31332226791 - M Sport E3 ($88.82) and 31331130046 - vehicles with AC ($91.56). Are both of these sport MTechnic options? Does anyone have this set-up? Does it drop the car a little but keep the original feel of the ride?
    US vehicles had AC standard and the weight of that is probably accounted for in the front spring (both ride height and stiffness). Euro cars had AC as an option hence the separately listed PN. Sport evo spring lowers ride height a little to make up for the larger fender gap the Sportevos would otherwise have had due to the bigger cut outs in the front wing.

    Don't know why US spring and euro AC spring have different PNs perhaps because the US vehicles were better specced from the factory (sun roof).

    The 130043 and 130046 were also used on other E30's (4cyl.) so probably available cheaply second hand

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  • stevesingo
    replied
    The Sport Evo spring is 10mm lower, to allow the tyre to arch gap to remain the same with the 10mm larger arch cut outs of the SE front fenders.

    There are also different springs for AC non AC cars.

    I believe the spring rate is broadly the same at 100lb/in.

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  • hardtailer
    replied
    ...The lack of damper travel between Konis and Bilsteins is also an issue. The fact that the Bilsteins are a little taller than the Konis makes all the difference in the world. I'd love to run my set of Konis up front again, but the lack of travel and lack of compression damping is just a bad combination. The bilsteins have the travel, and the compression damping, but the rebound damping is lacking even for the H&R race springs, any more spring rate they are totally useless.
    ...
    Will
    Not doubting your statement but merely pointing out some general info on mono and twin tube shock absorbers before someone thinks it's a general rule valid for any comparison between bisltein and koni shock absorbers.
    The body of a bilstein monotube houses the gas charge and the separator piston and must therefore be longer than a twin tube shock absorber (like Koni) for a given travel.
    The perceived greater compression damping is probably the internal bump stop being compressed.
    Koni offers shocks for the E30 that are limited in their travel to make them suitable for shorter lowering springs in order to maintain pretension in the spring at full droop. They achieve this by putting a spacer around the piston rod between the piston and seal/cap without needing to use a shorter housing and piston rod.
    As such one can't really tell which shock has a longer stroke by just looking at them.

    To the OP: you never replied to what rate your front springs have. You mentioned Motorsport springs, do you mean stock M3 springs by that or the genuine race item?
    My guess too is that you are riding on the bump stops caused by the shorter lowering springs.
    Do a Google on shortening bump stops inside bilstein dampers to see what's involved.

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  • Grinder
    replied
    The stock spring on the US model 31331130043 is $91.56 at my local dealer. The strut listed is 31322225397 ($139.52). On real OEM there are two additional springs listed for the Euro model: 31332226791 - M Sport E3 ($88.82) and 31331130046 - vehicles with AC ($91.56). Are both of these sport MTechnic options? Does anyone have this set-up? Does it drop the car a little but keep the original feel of the ride?

    Leave a comment:


  • stevesingo
    replied
    The main reason I retained stock ride height was exactly as RAD2LTR states, not screwing with the roll centre and being able to drive over speed humps. These cares handle great as stock, probably the best trait the car possesses, why do we think we can screw with that. We can improve grip by lowering the CoG and increasing the roll stiffness and, but three comes a point where the gains from lowering of the CoG are cancelled out by the change in roll centre. Increasing roll stiffness is achieved by anti sway bars and stiffer springs, but we need to be careful that the increase in spring rates from to rear remain proportional.

    I had Bilsteins with H&R Sport springs Pt No 29664-1. It was dreadful! Under steer and lifting inside front wheel in track, excessive squat under acceleration, and even lifting inside front wheel on track. To top it all, it was really harsh on the road!

    I had the springs tested. The fronts are progressive 110lb/in-205 lb/in rising rate, hitting 205 at 5in compression. The installed length was 5.3in compression, so 205lb/in when installed. The rears are 259lb/in linear.

    If we compare those rates to the stock rates of 100lb/in front and 300lb/in rear. So an a set of springs that are supposed to improve our cars behaviour are in fact 2x the stiffness at the front and softer on the rear. It would seem that if we are increasing spring rates they need to be 3x as stiff at the rear that the front in order to maintain the similar proportion of roll stiffness front to rear.


    Went for a 150lb/in front and 430lb/in rear, which may seem excessively stiff at the rear for such a soft front spring. The car rides great, staying flat over high speed compressions, and the under steer and wheel lifting has been eradicated.

    As it turns out, the H&R 29664-1 springs are also the same spring as H&R sells for the 325i, which has a much heavier engine in the front. Go figure!

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  • Ironhead
    replied
    RAD2LTR speaks the truth.

    We all want our cars to look like DTM cars, but the strongest advice I could give would be to refrain from significant lowering. I would not go lower than about 1" from stock ride height. If you do I think you will find that you have a car that is worthless for pretty much everything besides "posing".

    When I first got the GC suspension I figured my car was mostly a track car, so I might as well go really low. So I lowered everything, which with the tires I was running at that time gave me roughly 2.5" lower than stock. I know that doesn't sound like a ton, but it made the car into a horror show. Not only did the car bottom/scrape on EVERYTHING (including a nearly invisible road heave that did a lot of damage to my exhaust system), it also transformed into an ill handling bump steering POS that ruined the confidence inspiring handling the car was built with.

    Keep in mind these were fairly low cars with marginal ground clearance as they came from the factory, if you go much further you will wind up with nothing more than a trailer queen good only for car shows.

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  • RAD2LTR
    replied
    I have Bilsteins on the front with H&R race springs and until I added roll center spacers, and spacers on top of the camber plates, I just blew through all the travel over the smallest bump, like pulling into the garage. The excessively low roll center just caused all kinds of issues. I ran some awesome revalved Koni sports but they didn't have enough compression damping to offset the loss of spring rate due to the bad roll center. It was horrible because the car bottomed over everything. I mean everything, undulations in the road? Yep. Train tracks? Good god. All kinds of bad. If you are going for looks, you will be compromising a few things. Ride quality will be the first thing that goes away, you will have to jack the spring rate higher the lower you go to keep it off the bump stops. Going this route, you will need higher rebound damping rates, if you don't have custom valved dampers matched to the spring rate you are running, you will end up with a bouncy ride. (I had this issue with the Bilstein sport rears. It was making me feel sea sick.I re-installed the re-valved Koni Sports and backed the damping off till it matched the lack of rebound damping on the Bilstein fronts) With the high spring rate, I've found that the car skips around and feels nervous. That said, the H&R race rears could use with more spring rate as they squat under acceleration. The lack of damper travel between Konis and Bilsteins is also an issue. The fact that the Bilsteins are a little taller than the Konis makes all the difference in the world. I'd love to run my set of Konis up front again, but the lack of travel and lack of compression damping is just a bad combination. The bilsteins have the travel, and the compression damping, but the rebound damping is lacking even for the H&R race springs, any more spring rate they are totally useless.
    Yes, the DTM cars were crazy low, but their suspension geometries and attachment points were different. It would be amazing if someone would make a set of front springs (that work on stock struts) that are about 450 lb, and rears that are in the 575 range. (Yes I know the rears could be converted to running the adjustable springs, I might go that route.) Bottom line, by design, lowering the car from stock really messes up the suspension geometry, but it needs more spring rate that what the stock rates are. Its never going to be american car/land yacht soft, but its easy to make it feel too hard, yet too soft to stay off the bump stops. Pretty much the front end is a disaster. Why didn't they run A arms rather than the disaster of Mac struts? At least that way they wouldn't lose camber as the suspension compresses. Coilovers can make the car lower, but you can't raise it higher than the dampers extend. It sounds like you want to go low, but just remember that the lower you go, the less travel you will have, the more likely it will bottom out, and the more stiff you will have to make the springs to offset all the above issues, topped off by needing custom dampers to control the high spring rate.

    Will

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  • Ironhead
    replied
    The bump spacers go between the bottom of the strut and the control arm...very simple to install.

    Basically all they do is allow the wheels to sit further "up" (thus lowering the car) while retaining the stock suspension geometry.

    As far as the strut brace bar....yes you can still run it....because the camber plates mount inside the strut tower....if that makes sense.

    Konig- you are right....mounting the full GC coilover kit does require modifications to the strut housing that would be pretty much permanent.
    Last edited by Ironhead; 05-30-2015, 02:15 PM.

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  • Grinder
    replied
    Two quick questions, where do the bump spaces actually go within the stack? If I put plates at the top of the stack for camber adjustment, can I still run a strut brace bar? I currently have a racing dynamics custom-built bar but would like to change to a Mason (I think that's the name)

    Leave a comment:


  • Konig
    replied
    Good discussion here guys. Grinder, I actually just emailed GC about their offerings for my sporty-street-slight-drop application, I'll let you know what they say. I bought a set of Bilstein sports and was planning to go with H&R Sports but this thread and some friendly advice have given me pause.

    GC coilovers would be the easy choice except that it requires the stock strut housings to be modified... I like to keep all of my modifications reversible.

    I'm looking at this now: http://www.ground-control-store.com/...ion.php/II=912

    Leave a comment:


  • Ironhead
    replied
    Originally posted by Grinder View Post
    On the website they have three offerings: Coilovers, coilovers kit, and Coilovers street touring kit. Do I need the plates in the kit to get it to factory spec when it drops? I don't plan on tracking the car yet so I don't need excessive camber adjustment. Coilovers or street touring?
    I have the complete coilover kit.

    I am concerned about offering too much advice because I bought mine over 10 years ago and I know their offerings and kits have changed since then.

    If I were you I would just call GC to get specifics. Just make sure you talk to Jay Morris, the owner. GC got some bad reviews several years back because a lot of the "order filling guys" who worked there had a bit of an attitude and weren't too knowledgeable. I have never heard anyone say anything negative about the owner. He is a died in the wool BMW guy and I think he even owns a modified E30....or did at one time. He definitely knows what he is talking about and will steer you in the right direction.

    If you are going to significantly lower the car, you will definitely want some spacers like these (you can get them elsewhere) in roughly the same thickness of the amount you are lowering:

    http://www.akgmotorsport.com/catalog...ion%2FBushings

    Without them, bump steer will make the car very squirrely and you won't like the result.

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  • stevesingo
    replied
    Something I remembered is that the Bilstien Sports have internal bump stops. These are quite long and therefore if you lower the car significantly, you will be sat on the bump stops, which will increase the effective spring rate significantly.

    I use Bilstien Sports with 150lb/in Fronts and 430lb/in rears at the stock ride height and it rides perfectly well, even on the UK's crappy roads.

    In the UK, Bilstein offer a rebuild service and you can have them re-valved and the bump stops shortened.

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