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Vorshlag: E46 BMW Bilstein PSS vs PSS10 review

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  • Vorshlag: E46 BMW Bilstein PSS vs PSS10 review

    This thread has more details and our review of various Bilstein PSS coilover kits for BMW E46 models.



    The info I'm sharing here is part of what we have posted in our E46 TTD build thread posted elsewhere on this forum, but this is just more focused on the BMW E46 Bilstein systems we have played with on this car and others.



    There are a few Bilstein PSS kits I want to talk about in this thread. Most of these are listed in our online store, where you can see how attractively priced these can be.
    • E46 PSS: 47-249134 (non-adj damping; see picture above)
    • E46 PSS10: 48-126380 (haven't used this one yet; below left)
    • E46 M3 PSS10: 48-126687 (have used this one; below right)




    The Bilstein PSS coilover sets are all very durable, high quality kits that are made to be street driven and are TUV approved. As such they all come with somewhat goofy spring packages which, due to TUV requirements, can never become "unseated" (more on that in a minute). The struts are all massive inverted units that are super strong. The prices are all low because Bilstein does not set any prices, so any dealer can sell at whatever price they want, driving the prices way down.



    After many many hundreds of shock sets sold for BMWs over the past 12 years, I feel that the PSS10 is one of the best bang-per-buck coilover systems made for the E46. The prices on say... a single adjustable MCS TT1 kit (monotube single adjustable without remotes) are only a few hundred bucks higher than the PSS10, but MCS kits (like virtually all other high end monotube adjustable kits) don't come with springs or ride height adjusters, which can add up. The PSS also uses a big beefy inverted monotube strut with German built Bilstein quality.



    The adjustable valving used in the PSS10 version is admittedly a little odd. The ONE knob controls BOTH rebound and compression (compression changes by about half as much as rebound). So for a dedicated race car these "one knob / two adjustments" type shocks are not really the solution you want, as tying rebound and compression together doesn't help you tune for conditions as well as separate rebound and compression adjustments. Even single adjustable "rebound only" adjustment is preferred by racers. Double adjustable monotubes cost considerably more, of course.

    The "10" in the PSS10 name comes from 10 settings on this knob, whereas the "9" in PSS9 has 9 settings. The PSS10 is actually a much newer, superior piston/valving adjustment design than the PSS9 has, and you can see this on a shock dyno. But for a pure street car... you won't care about those differences. Only legacy cars still have the PSS9 version offered, which was replaced by the PSS10.



    If you use the Bilstein PSS kit's included springs you can get a pretty large amount of lowering and still maintain good ride quality. The struts and shocks are shorter than the OEM length units, so dropping the car 1-1.5" won't eat up all of your "bump" travel - unlike many other popular shock kits sold (which end up in the "bump stops" if you use the wrong spring). These aren't just set length "lowering springs", either... they are truly ride height adjustable at all 4 corners, so you can choose how much you lower your car at both ends, and even have the car corner balanced. You can't do any of that with lowering springs.



    The ride height ranges will vary by E46 model... The E46 M3 PSS10 kit shows Front Lowering Range: 15-35mm and Rear Lowering Range: 20-35mm from stock. The non-M E46 models start out a tick higher, and both of the PSS kits for this car show Front Lowering Range of 35-50mm, Rear Lowering Range 25-40mm from stock. The rear ride height adjusters are made to work with a "divorced spring" in the OEM location. They are simple units (see above right) but they work well enough. The front ride height adjustment is part of the coilover style strut - with a threaded coilover lower spring perch.



    These kits are made to work with the OEM front rubber strut mount and upper spring perch, but for even light track or autocross use you will want to add a quality camber plate to the front struts. This removes a giant hunk of rubber and gives you camber and/or caster adjustment. Of course I have my brand preference, but do get some camber adjustment if you track your E46 - your front tires will thank you for it! The camber plate can be coupled with the OEM type upper spring perch to work with the tapered PSS springs, as shown above.



    For more serious track use, what we do is chuck the relatively soft, variable rate "tapered" front springs and "beehive" shaped rear springs. The fronts have a 60mm ID lower size - which fits the adjustable lower perches on the struts - and they "taper" to a larger diameter at the top to work with the OEM upper spring perch and top mount. With a new upper spring perch you can replace the front springs with a straight rate 60mm coilover springs. This removes the TUV's "spring has to stay seated" feature, but that only comes into play on the front when you have the car lifted up on a jack or 2-post lift.



    By going to a straight 60mm coilover spring up front you have a nearly infinite number of choices to increase the spring rate - which then reduces body roll, brake dive, and squat under acceleration. Spring rate becomes very important as you increase grip levels via tires and/or aero downforce. On a mildly track prepped dual purpose car, some folks opt to only change the front springs to 60mm coilover versions, too.



    Like I said, we always use these Bilstein PSS kits with a quality camber plate setup in the front. If you want to go to 60mm springs, it is often cheaper to order the camber plates to work with 60mm upper spring perches. Some companies include a new upper spring perch with their camber plates, and the coilover version is often significantly less expensive than the OEM perch version. The image above clearly shows why our camber plate option for use with OEM springs costs more.



    We ran the non adjustable PSS kit on our TTD prepped E46 330 earlier this year. We did the car's very first track event with the included PSS springs and some camber plates, which is shown above. As you can see, it had a LOT of body roll and brake dive, but it rode really well on the street. Of course we had 245mm Hoosier R7s on 17x10" wheels - so a LOT more mechanical grip than even aggressive street tires would give you.



    Before our next track event we changed out the PSS kit's springs over to 60mm coilover springs front and rear. After evaluating the damping capabilities of the Bilstein PSS kit, we doubled the rates by using 350 #/in front and 450 #/in rear coilover springs. We had to machine the rear ride height adjusters down to fit the 60mm ID springs (they were a hair too large). The black part of the Bilstein rear spring height adjuster was chucked up in the lathe and turned down a hair. An easier fix is to use an aftermarket ride height adjuster made for 60mm springs (see below left). The front struts worked without modification - we just changed the upper perches on the camber plates to the 60mm option (below right) and used the correct length spring. For some folks this coilover spring change might seem out of reach initially - just know that all of the PSS kits can take a good bit more spring rate than the set of springs they come with, so you do have a path to improvement if your car gets more serious.



    On our shop's TTD prepped 2001 330Ci I chose the non-adjustable PSS vs the more expensive PSS10 and maybe regretted it - not having any damping adjustment limited us to about 2x the spring rates that Bilstein includes in their kit. We needed more spring rate, as we still noted too much roll in cornering (see below) with double the spring rate. The street ride and on-track damping felt right about at the limit of what these non-adjustable PSS shocks could deal with. Note - this car was still on stock swaybars (which cost "points" in NASA TT) at this point.



    We recently used Bilstein PSS10s in a customers E46 M3 with custom coilover springs but this time used even more spring rate than in our TTD 330 - and the M3 rode better! Adding that one damping adjustment on the PSS10 made it possible to get the dampers tuned closer to the springs we used. The less costly PSS "is what it is", but with the included kit springs it rode great. You can't always triple the spring rates and still have good ride on non-adjustable monotubes. But the PSS10 can take more spring rate...



    Last but not least, I made a video doing a street test drive with the PSS coilovers installed with the optional 350#/in front and 450 #/in rear coilover springs (double the Bilstein PSS kit's spring rates). It rode well enough for me and likely would be OK for most folks, and was semi-competitive in NASA TT (won 3 of 4 events like this).



    After a number of track events on the Bilsteins we have recently moved on to MCS TT2 doubles on our E46, and went up considerably in spring rates again. This was planned from the beginning - a progressive build that lets us test numerous versions of the same parts. You can read more about that in our TTD build thread located here on the Vorshlag forum in a future update.



    Anyway, that's my two cents on the Bilstein PSS kits for the BMW E46 chassis. Just wanted to show another option for budget conscience E46 users, something more than what OEM style struts and lowering springs can give you. If you don't keep "numbers on the side" of your car full time, the Bilstein PSS options are probably ideal for your BMW.

    Cheers,
    Last edited by Fair!; 09-30-2016, 03:22 PM.
    Terry Fair - www.vorshlag.com
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

  • #2
    Re: Vorshlag: E46 BMW Bilstein PSS vs PSS10 review

    We had a customer contact us and ask why our rates that were "double" the provided rates didn't match what other Bilstein dealers publish as the rates of the provided springs.

    Many retailers and manufacturers use "industry standard" spring rating methods that don't give us useful information for motorsport purposes. The standard method for rating progressive springs is to compress them until spring bind, back off a hair, and then measure the distance they were compressed and the force at that distance. Divide distance into force and you have the "standard" rate. The flaw with this is that in use we almost never get to spring bind with these springs. Instead we end up compressing them about half way.

    To give us useful data we rate the spring at every 0.5" and measure what length it is when at rest in the car. That tells us what the actual, neutral spring rate of the progressive spring is. We will look above and below this distance a little to see if we are near a knee point, where the spring rate dramatically changes, and take that into consideration when using this data.

    This re-rating of springs and collecting our own data rather than relying on rates provided by manufacturers takes some time, and often a lot of logistical hurdles to get the parts here and back, or off and on a car. We do the same thing with published data for other parts, like wheel weights, which we have often found to be inaccurate and frankly, wildly optimistic.

    That said, the rates we switched to aren't exactly double, but they are significantly higher.



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