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SRT-4 Dynamic Suspension Geometry Changes


Vipercar93
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Tony got me thinking in another thread. What would I need to work out dynamic loading and geometry changes when in different conditions. What all do I need to work this out mathematically. I realize that with bushing deflection the numbers would be a bit skewed, but still.

 

The list

 

Springrate

Shock rate (Slow/fast bound/rebound?) (Range? They are adjustable)

Sway bar rate

pre-load

ride height

corner weights

caster

camber

toe

 

Guessing at...

 

Control arm length

Distance between strut top mount to chassis mount for control arm w/ degree of offset from vertical to each other?

Distance from strut top mount to the contol arm

Wheel size/ offset

Unsprung weight

 

 

 

I am curious, I have been to the track a little, and have always wanted to get into racing. I don't have the pennies to do it now, but maybe one day! In the meantime though gotta feed the brain in other ways.

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Most of your list is for build concideration rather than an actual geometric math. Your guess is correct and something we would apply during a calibration but most times it's what we find dynamically during the geometry that matters, like we can map dynamic camber gain during bump/ droop, we can measure body roll lock on lock and watch toe migration and calculate how much tyre is in the scrub radius.

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No not together, we pull the car down to map camber/ toe migration, then raise for loss, the we could measure the position of the sprung chassis to measure roll, don't forget this is done static so there's no inertia involved.

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My head is spinning Tony! Been reading a little bit on the front of the main site page. I must say you can be very 'eloquent'. I'm not used to such big words :withstupid: Getting my head around some of the terms. Some of them I know under different names, others they are completely new. Baby steps.

 

Anyways been reading over the alignment specs you guys did for my car. Getting down the whole degree/minute/second notation. Like most things in the USA it's dumbed down. I think a lot of times they must break it down to % of a degree which is probably why my specs sounded so far out! Which I think you mentioned when I had it done.

 

What I am curious about is my castor angles. The front left is 3.57 and the front right is 4.49. There a way to bring them closer to each other? Also I noticed that on my camber plates one was reading over a degree of negative camber, while the other is reading just on the positive side of 0. I know that with camber plates they are never exactly what they 'should' be. But that seems a bit extreme. I'm confident you guys did the right job. I'm more curious as to what is actually happening. Could my whole K member be shifted enough to cause these measurements or is there something more terminal?

 

 

Curious as well about the SAI measurements. The left side is 14o58' while the left is 13o44'. What can cause the difference? Should it be something to look into?

 

 

I guess as well it would be worth looking at this through two lenses. One is that I daily drive. The other is I do plan on hitting the track with it, be it hillclimbs or trackdays, depending on the costs.

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We measure degrees and minutes 60'/degree rather then decimal degrees and minutes 100'/degree. The castor is not adjustable on your car, so the lower value could allow the car to drift left, because of this the guys would stagger the cambers in order to belay any pull. The SAI is not directly adjustable plus there's no recognized global disparity limit between the values, i personally flag concern if there's more than two degrees between them.

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Sounds good Tony!

 

I think when I do eventually get to the point I am going to hit the track it will be worth loosening off the cross-memeber and straitening this out when I come to do the corner weighing and resulting re-alignment. I know it's not a huge deal, but long as it's in the air...

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