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Thread: Efficacy of Motion Motorsport Splitter?

  1. #1
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    Efficacy of Motion Motorsport Splitter?

    I did a quick search but didn't find any results that specifically discuss the efficacy of the Motion Motorsports GT/A front splitter. Anyone have experience with it, and have a feeling for how much additional grip it creates for the front wheels?

    I find that my E36 tends to understeer a fair amount on the track, especially in tight corners, and am considering picking one of these splitters and underpanels up to see if it helps.
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  2. #2
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    Although I haven’t had my car on track with the motion motorsports splitter, based on its construction, i dont think it would do anything to assist your understeer.
    Based on your problems with understeer being mostly in low speed corners, basic aero wouldnt do much to help you in my opinion. You would need to have a much lower more aggressive splitter to create a significant change, again in my opinion.

    If your car isn’t on a square set up for tires, that would be your best bet.
    If you are running a square set up, you may need to look into work on suspension (sway bars or spring rates)

  3. #3
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    yeah, I think your issue will be better solved with alignment/suspension.
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  4. #4
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    I do have a square setup (245 Dunlop Direzza ZII Star Spec's all around) with a TC Kline double adjustable suspension/camber plates set at -3.5deg front camber. The car has the stock sway bars front and rear, and I had heard that going to the largest possible front sway bar and remove the rear sway bar helps the E36 with understeer. Do you think this might be the best option?
    2003.5 BMW M3 Coupe (Daily Driver) | Titanium Silver | Black Nappa Leather | 6MT | Cold Weather Package | Premium Package | Navigation | Harmon Kardon | Matte Black Grills | Dice iPod Integration

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  5. #5
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    Its hard to speak for your particular situation, and i am no expert..for reference
    I run square 275 NT05s with TCKline D/A with very stiff rates (800f 900r) with stock sway bars.
    I had a little bit of understeer when i first took the car out with -3.0deg camber and 37psi hot, i assumed that the NT05s were not sticky enough to compress my stiff springs enough to utilize that much camber.
    I dialed back the camber to -2.4deg and played with tire pressures down to 30psi hot and the car feels completely different.

    If i were you i would play with what is free (tire pressures, unbolt each sway bar to see what it feels like, damping ajdustments) before you throw money at it.
    Ive read somewhere that TCKline has a very knowledgable staff that im sure would be willing to help you if you reach out.

  6. #6
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    Quote Originally Posted by propcar View Post
    yeah, I think your issue will be better solved with alignment/suspension.
    ^This.
    My E36 is fairly neutral. To the point that one position on the front sway bar, a few clicks of rebound, or a few psi tire pressure, makes a noticeable difference. Driving technique will also make a big difference, once you get close.
    Just for the record, here's my setup:
    ~ -3.7 front, -2.5 rear.
    TCK SA, 550f/650r. Can't recall where my rebound is set, but they are weird...like one end near full soft and the other end near full hard.
    UUC front sway currently at full soft.
    OEM rear sway.
    235/17 Toyo RRs, around 26-28psi cold.
    Only the easy stuff removed from the interior and most from the rear, so probably 51/49 f/r weight bias or so.

  7. #7
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    I'm not sure, but I would do more reading before I decided to stiffen up the front end and loosen up the rear.

    Generally if I stiffen up one end of the car, the other end settles faster and gives me more traction. Sounds like your complaint is about corner entry, and when I have that problem, I improve my E36 by stiffening up the rear a little at a time. For me, that means adding stiffness to the rebound setting in the rear, a little at a time.

    I don't have compression adjustments, so I have to get by with rebound changes. Have you been trying to fix the understeer by cranking the compression up to stiff? Maybe your compression setting on the front is too stiff to allow the front end to take a set on turn-in and let the tires do their magic.

    Also, your front springs are 100-200# lower than your rears, right? I can't seem to get my E36 to balance without that ratio. And your current sways are stock, so you know you don't have an excess of bar at either end knocking things out of balance?
    Last edited by JBasham; 02-20-2018 at 04:47 PM.
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  8. #8
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    I might be able to help a bit here. For reference I am running the following:

    E36 M3 coupe
    245/40-17 (RE71R or Hoosier R7) Square setup.
    TC Kline D/A
    -3.5deg front camber
    OEM LTW Front splitter and rear wing
    H&R 27mm front sway, no rear sway

    I have not used the splitter in question but I will speak to the notion that you need much more aggressive aero to feel a huge difference in understeer. I would highly recommend playing with lower tire pressures up front, dial back the alignment and practice a bit of tire management.

    I noticed that if I was giving the car too much steering input on turn in and often times found that I was sawing at the wheel at mid-corner. This added a ton of heat to the front tires. After a few laps, this extra heat caused a load of understeer and my lap times crept up until the end of the session.

    I dialed back pressures, focused on smoother and more thoughtful steering inputs and the understeer almost completely vanished.

    - Max

  9. #9
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    I wouldnt reccommend buying anything from motionmotorsport.net. Order the underpanel a month ago and they took my money and i havent got a tracking number and they wont reply to my 4 emails I’ve sent them.

  10. #10
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    They finally teplied back to me. I woukdnt say the communication was the best. I was worried they were never gonna repky it took so long.

  11. #11
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    They seem to be a pain to deal with as others have mentioned...

    E36 loves big sway bars. I would replace the stock one with something much stiffer. I'm using the big Hotchkis bar and I do not have a problem. I'm running similar spring rates (700fr, 900 rear) and the car is neutral. Also a bit less negative camber than you on a square setup.

  12. #12
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    I have a '96 328is...which stock, had huge body roll and massive understeer. I'm now running a much tamer setup than most here, but it solved the understeer issue and the car rotates quite easily under braking. Trail braking more aggressively on your current setup might help as well.

    Hotchkis bar in front, stock rear.
    Bilstein B8 + H&R Race springs (they are progressive, not sure the rate)
    -2.5 camber in front..can't remember rear...approx -2
    Don't remember the exact alignment settings, I think 0 front and a little toe-in in rear.


    just for laughs....here's the body roll with the stock setup

    3wheelmotion.jpg
    Last edited by RMF; 05-29-2018 at 11:05 AM.

  13. #13
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    Quote Originally Posted by denvercoutu View Post
    They finally teplied back to me. I woukdnt say the communication was the best. I was worried they were never gonna repky it took so long.
    Let me know when your undertray arrives. Any reason you went with the undertray instead of the splitter?

  14. #14
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    You won't find data like that unless you just but a digital manometer and do the testing yourself.

    I didn't have the motion motorsports uundertray, but my splitter, ~4" was making ~45# of downforce at ~75mph... I say roughly because this is garage engineering here. It was just a 1/4" birch splitter mounted flush to a stock E36M bumper.

  15. #15
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    Quote Originally Posted by Inflame View Post
    You won't find data like that unless you just but a digital manometer and do the testing yourself.

    I didn't have the motion motorsports uundertray, but my splitter, ~4" was making ~45# of downforce at ~75mph... I say roughly because this is garage engineering here. It was just a 1/4" birch splitter mounted flush to a stock E36M bumper.
    You instrumented your wood splitter with a strain gauge?

  16. #16
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    No he measured the air pressure and multiplied it by the surface area of the splitter to find the pressure exerted on it.
    COMSCC T70 E36 M3

  17. #17
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    Not that I'm going to get one of these, but if you're looking for a generic Kevlar splitter that can be cut to shape, this one is $210

    http://www.gt-racing.com/911-splitter-part-44c/
    Last edited by propcar; 06-07-2018 at 05:13 PM.
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  18. #18
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    Quote Originally Posted by Eddy@ApexRaceParts View Post
    I dialed back pressures, focused on smoother and more thoughtful steering inputs and the understeer almost completely vanished.

    - Max
    I agree with Max and a lot of the other advice in here regarding tire pressures and inputs. I see a lot of drivers add to much initial input and inducing too much slip angle initially. Pull the car into the corner with the least amount of input possible and add additional input slowly as needed. For pressures I would start at your normal pressure, daub the outer tire shoulder with shoe white and drive first session with softer initial inputs, and see where you are coming over on the shoulder. Not using the entire front tread block/shoulder, re-daub, drop 2 PSI up front, rinse, wash, repeat and see how the car feels and where you are on the outer edge of the tire.
    Other question I have is are you trail breaking into the corner to get the car rotated? Maybe you are not carrying it deep enough or applying enough/too much brake through the trail phase?
    There is a book available on Amazon called Triple XXX Main that is for RC racers, BUT the information is spot on for full sized car set up as well. The book is under $15 if I remeber right, and has some great breakdowns that address each suspension setting in a global term and then add in a break down chart of "if car is doing this, try this" through all phases of cornering.
    I have the Motion Motorsports front splitter and for high speed and medium speed corners I feel like the car is a bit better set...but it may be total placebo effect because I really like the way it looks and it was a great belly pan replacement for the front end.
    Hope this is not a "clear as mud" post?

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