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2G 2G suspension analysis and testing rig

Posted by ec17pse, Mar 14, 2019

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  1. ec17pse

    ec17pse Freelancer

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    Post #1:

    Hey everyone,

    As many know I’m very into suspension design, kinematics, and dynamics. Some of you may have even bought some of my parts over the years!? Well today I’m here to show you the Suspension Test Rig I’ve been working on! It’s some very exciting stuff for me and to my knowledge has not been done for our cars before. Hopefully the data extracted from The Rig (Should we give this thing a nickname?) will be useful in some way to the DSM Community.

    54028981_10162141812506337_4786619426508111872_n.jpg 54268365_10162141812066337_2700405432605736960_n.jpg 54368179_10162141812556337_7327497889565900800_n.jpg 53602138_10162141812296337_9099860476912730112_n.jpg

    It sometimes can be difficult to visualize or imagine how a specific component is going to function when modifying and what it does altering another thing. So in an effort to clear the fog and gain a better understanding of our vehicles front suspension, I’ve created this test rig and will be using it to establish a baseline of camber, caster, and toe / bumpsteer with respect to changes in steering angle. Bumpsteer data maybe not in the first couple of tests as I’m still working out the jig itself, but it’s a start. I really don’t know how this came about exactly… I think we was talking one night and he just spurted it out, but this is definitely @mountain_man (Roger’s) fault. He made me do it, LOL! So here we are.

    Hey guys, Roger here… I made Bobby do this by threatening to get him banned from Disney. It was surprising effective, haha! But in all seriousness, the purpose of The Rig as bobby mentioned above is to establish a measurable baseline of the 2G DSM suspensions behaviour before we begin using any type of suspension modelling software. Basically, if we make a 0.5 deg. camber change in the computer and it states you pick up 1/16” of toe-out. How do we know that’s actually what’s occurring? How are we to know that we’re not picking up ½” toe-in in reality? The Rig will help us 1.) verify our computer model is providing good data, 2.) provide us a way to meaure the effectiveness of new parts, 3.) help us visualize the suspensions behaviour when making changes, and 4.) quantify what’s working and what isn’t. Back to Bobby…

    The Rig is not complete and it’s still being tweaked but the main components are there. I still have to:

    • add brackets for measuring the height of the arms in order measure ride height(s)
    • add a point for raising and lowering of the system

    The items I will be measuring and gathering data on are:
    • camber
    • caster
    • toe
    • bump steer

    I’ll be able to do this by having 2 lasers attached so I can plot the full range of motion (up and down movement) on a sheet of paper. Yes, paper. The first data pulled will all be from OEM suspension items (thankfully I’ve kept a lot of it) with OEM parts so I can see exactly what’s going on, this will be done at various ride heights.

    lasers.jpg 53599048_10162138167386337_9038342809928597504_n.jpg

    After the OEM setup is complete, I will then run the same battery of tests on my adjustable arms and get data for those too. Roger and I have a rough outline of a testing plan but we’ve got plenty of time for trial and error.

    I think this is it for now so hope you like our plans and I shall try keep this updated as we go.

    Thanks Bobby and Roger
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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  2. mountain_man

    mountain_man Supporting Member

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    @ec17pse Once we get this working, how long do you think it's going to take before people begin asking us to model their suspension set-up? You might have to make a couple more of these rigs, haha.
     

    Road Race Build 2K  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
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  3. Black95TSIawd

    Black95TSIawd Proven Member

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    Extremely exciting.
     

    4K  8

    1998 Eagle Talon TSi AWD
    184.4 whp · 251.0 lb/ft · 2G DSM
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  4. DogWhistle

    DogWhistle Proven Member

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    St. Paul, Minnesota
    Thank you for doing this.

    In a dynamic application, there are a lot of factors, but displaying the relationship between the adjustments will be extremely beneficial to our set-ups, particularly for the track.

    If there is any way to eventually test for the affects of wheel offset, that would be even more helpful.

    I’m looking forward to learning.
     

    2K  6

    1999 Mitsubishi Eclipse Spyder N/T
    fwd · automatic · 2G DSM

    2K  0

    1991 Mitsubishi Mighty Max
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    2K  6

    1996 Eagle Talon TSi AWD
    385 whp · 378 lb/ft · 2G DSM
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    mountain_man likes this.
  5. ec17pse

    ec17pse Freelancer

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    No doubt this will happen but only 1 is to be made because of its size, will just have to wait for the data
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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  6. ec17pse

    ec17pse Freelancer

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    I can do something like this by extending the lasers. It most likely will just exagerate the effects, things like feel and tires will allways play a role is it but a base RAW data will be a good start
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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  7. Dentor

    Dentor Probationary Member

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    Stuttgart, Europe
    Hey ec17pse, nice project. I hope you will get the results you're hoping for.
    As you can see in my build thread, I already measured all suspension points on my GSX and analyzed the complete system with the suspension analyzer from Lotus.
    I wanted to minimize the bump steer as well ;)
    I think the problem with the Rig is to transfer your results back to a vehicle. Because depending on the amount of lowering, static chamber, toe,… the starting point is different to each car.
     

    Street Build 266  1

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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    tametalon92 likes this.
  8. ec17pse

    ec17pse Freelancer

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    Thats why i will have different starting ride heights which will then give me what happens during compression and rebound, this rig is only to confirm what my software is telling me is correct as what roger told me is along the lines of is that software is good but how accurate is it vs real useage. So we are taking mechanical data and checking it against software data and see whats what.

    I have a huge range of different starting points to go from and we are going to check everything possible.

    I have not listed all the arms or mounting solutions yet so in time you will see i am covering all angles for the best data to be extracted
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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  9. Dentor

    Dentor Probationary Member

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    Joined Oct 10, 2017
    Stuttgart, Europe
    Oh, okay. I think there will always be a difference between CAD and reality. Just because of measurement errors and the fact that you can't replace all the rubber bushings. Specialy on the front suspension compression arm you have some deformation in the bushings because of the multi link type suspension.
     

    Street Build 266  1

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  10. mountain_man

    mountain_man Supporting Member

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    Thank you posting. Your thought has got me thinking about the decision of using wheel spacers vs. elongated suspension arms... I'll be keeping this in mind as we begin testing and analyzing data.

    Roger
     

    Road Race Build 2K  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
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  11. ec17pse

    ec17pse Freelancer

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    From what i read it will exagerate the effects being further apart or away from the center point.
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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  12. ec17pse

    ec17pse Freelancer

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    It might be close or spot on we dont know and thats what this is for to see how close it is to digital input, its also a bit of fun and different.
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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    tametalon92 likes this.
  13. ec17pse

    ec17pse Freelancer

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    POST #2

    When we left off we spoke about what our goals were and the main rig. Now here i shall run down on the process to how i got that jig/rig and what my thoughts were before i got into all of this,

    When starting out I looked at a few ways to get the initial input locations and how to extract it with minimal to zero movement for accuracy, A few things crossed my mind, initial thoughts were to clamp it but straight away that was a bad idea, I then thought welding all the oem suspension items together and bracing the lot in hopes it will transfer over ok, This lead to a few things in my head and the main one was the stock rubber mountings!!

    As you take them off they tend to twist back into a NON tensioned state so this for me would possibly give me inaccurate data not only for the extraction but the build of the external jig, so to over come this I decided the best way was to machine a few parts and make it a solid mount to the chassis on the car, This way its exactly the same locations and never going to give me altered readings when taking it off. This is how it looked all tack welded in/on the chassis before removal. getting the steering toe rod in place was fun as i had to whip up a cup to data the back from so I knew where full lock was.
    56960682_10162223914776337_2494909041541644288_n.jpg 56990292_10162223915311337_1893416738800795648_n.jpg 56870083_10162223913406337_6496533773486653440_n.jpg

    After the inner jig was set I then proceeded to make the external jig, this again required some machined parts to make everything mount nicely, and this is how we have come to the rig I have to date!

    Current rig has had no work done to it recently as works been quite busy and some house work has taken my weekends away and i do not always feel like staying super late in the week.
    But the next steps for the rig are to finish the base and this includes adding a data point for the lower arm so i can start the process at different ride heights, I shall then use or glue a rule to this so i can raise it every 5mm and take a reading, This shall also be the same on rebound also to make sure i get data from both directions,

    raising system is yet to be chosen, my thoughts were to pull it from the top but then the data might be off seeing as the force from the road is always pushed from below so for that reason i shall get something that pushes the lower arm up to get the most accurate readings, it may be a simple thing as a small bottle jack or small floor jack,

    These will be the lasers uses, just tiny little DOT laser and thinking of wiring them into a battery pack which is rechargeable and easy to switch on and off. ada fruit.jpg adafruit,.jpg

    As I said in the original post I will eventually get around to the adjustable arms part for getting various data over a wide range of setups so for now I made some parts ready because I had a few things laying around spare,
    57029160_10162223882596337_4356011494379356160_n.jpg 57364753_10162223882951337_5601818701918633984_n.jpg
     

    Road Race Build 7K  34

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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    mountain_man, Atuca and DogWhistle like this.

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