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Plotting suspension points


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#1 Nathan

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Posted 26 April 2018 - 16:34

Hello all,

 

I'm seeking wisdom/suggestions for how I can accurately measure the suspension pickup points to create a schematic to plug into geometry software.  The back end seems simple enough...the front end though :cry: ...

 

The car is a 2001 Acura/Honda Integra - front wheel drive.



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#2 Bloggsworth

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Posted 26 April 2018 - 16:53

Carefully... What type of suspension is it? McPherson Strut? If you measure the mounting and attachment bolt centres of all the moving parts correctly, the geometery follows, as long as you can measure the inboard lower bolt centres to the top strut mounting "Centre," that's the really difficult one - In theory. Alternatively, you might try a crash repairer who specialises in Hondas, they should have most of the figures, otherwise, how do they know when the body/chassis unit is straight when they have taken it off their hydraulic straightener?


Edited by Bloggsworth, 26 April 2018 - 18:55.


#3 Joe Bosworth

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Posted 26 April 2018 - 20:38

It is amazing what someone can do with a string line, plumb bob and a tape measure  Cheap easy and faster than investigating all kinds of science that only becomes sensible if one is going to do a whole lot of such measurements.

 

Regards



#4 Greg Locock

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Posted 26 April 2018 - 21:57

The posh way is with a Romer laser system. It is slightly more accurate than a tape measure on a full vehicle.

 

If you can dismantle the suspension it is a lot easier.  In the olden days for accurate stuff we used to use surface tables, measuring blocks, and big verniers, and a lot of 3D maths.

 

In practice when we are looking at competitor cars for vehicle dynamics that doesn't matter too much as the next stop is likely to be the K&C rig, from which readings you can reverse engineer the hardpoints sufficiently well. Alternatively you can skip the whole hardpoint thing and plug the K&C curves directly in programs like lapsim or carsim, which run faster than ADAMS and so are more suited to a lot of the work we do these days. 



#5 Nathan

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Posted 26 April 2018 - 23:31

Thanks everyone!

 

The best idea I had was along the lines of measuring the length of all control arms & shock when removed, measure their inclination angles when the car is back on the ground, and trying to piece it together off the lower ball joint which I can accurately measure.

 

The front suspension is a double wishbone.  A picture if anyone is inclined https://i.ytimg.com/...xresdefault.jpg



#6 Greg Locock

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Posted 27 April 2018 - 03:54

If you are dismantling it then with  he exception of the spindle you should get sufficiently good accuracy. The spindle is tricky as it is a bit more 3d. Using the installed angles is a very good idea. We tried to get that into production to measure the actual ride height accurately, but the program manager didn't want to pay for the machining, so we continue to measure the eyebrow height, with its +/- 5mm tolerance.


Edited by Greg Locock, 27 April 2018 - 03:58.