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  #31  
Old 01-23-2018, 08:48 AM
croustibat croustibat is offline
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I did some real world testing with an s13 subframe and adjustable length arms. That was trial and error, and i had access to a lift for a whole day so it helped

The idea was to measure ride height, lift the car, remove wheels, coilovers & arbs, then use a workshop hydraulic gearbox lifter to move the suspension up and down 1/4inch by 1/4inch.
I fitted a magnetic laser level on top of the wheel studs (5stud conversion) with a heavy nut hanging from the opposite 5th, so i would not get annoyed by the rotating knuckle effect. The laser pointed to a paper sheet that was glued in the wheel arch. For every up / down position, i checked the level and corrected when necessary, fire up the laser, then mark on the paper where it did hit. I then played with the traction and RUCA rod length until i got nearly no toe change for most of the travel, no binding, and enough camber. I got it to toe in slightly on full compression, which helps the car on fast corners and acceleration.

The car is lowered maybe 2 or 3", it is not slammed as i want suspension travel.

Something interesting was that whatever i did, i could not have more camber than -1.5 (i.e: i wanted -1 as it was enough but it was not possible). if i did that AND wanted the toe curve to be set correctly/neutral, either or both bushings in the RUCA and traction rod (on the knuckle) bind. When that happens it kinds of toe out before locking the suspension, meaning the car goes all over the place.

The problem is amplified with ball/rose joints in the knuckle, as it limits even more their usable angle. Fortunately using the S14 subframe allows more adjustment.

On your simulation, can you limit these ball joint angles ? This should avoid some troubles with impossible positions.
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  #32  
Old 01-23-2018, 09:50 AM
Stingy49 Stingy49 is offline
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gills: I wonder if we could attach a rotating object like I had done but add a mass to the bottom of it to keep it aligned correctly. Just like croustibat did with his real world version. I'll take some time and look into how the dynamic simulator deals with mass.

Ya I also got really frustrated trying to align that piece relative to the subframe throughout the suspension travel. I had many kind words for the inventors of inventor.

croustibat:
Sounds like a fun way to spend the day :P

Yeah we have the ability to limited the ball joint angles. I was just more concerned with getting a usable simulation before I spent the time to do that.

If you don't mind, what values did you end up at? I found Jason M's final s13 subframe values and I'm trying to find other people's to compare.
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  #33  
Old 01-23-2018, 11:39 AM
Def Def is online now
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Quote:
Originally Posted by croustibat View Post
I did some real world testing with an s13 subframe and adjustable length arms. That was trial and error, and i had access to a lift for a whole day so it helped

The idea was to measure ride height, lift the car, remove wheels, coilovers & arbs, then use a workshop hydraulic gearbox lifter to move the suspension up and down 1/4inch by 1/4inch.
I fitted a magnetic laser level on top of the wheel studs (5stud conversion) with a heavy nut hanging from the opposite 5th, so i would not get annoyed by the rotating knuckle effect. The laser pointed to a paper sheet that was glued in the wheel arch. For every up / down position, i checked the level and corrected when necessary, fire up the laser, then mark on the paper where it did hit. I then played with the traction and RUCA rod length until i got nearly no toe change for most of the travel, no binding, and enough camber. I got it to toe in slightly on full compression, which helps the car on fast corners and acceleration.

The car is lowered maybe 2 or 3", it is not slammed as i want suspension travel.

Something interesting was that whatever i did, i could not have more camber than -1.5 (i.e: i wanted -1 as it was enough but it was not possible). if i did that AND wanted the toe curve to be set correctly/neutral, either or both bushings in the RUCA and traction rod (on the knuckle) bind. When that happens it kinds of toe out before locking the suspension, meaning the car goes all over the place.

The problem is amplified with ball/rose joints in the knuckle, as it limits even more their usable angle. Fortunately using the S14 subframe allows more adjustment.

On your simulation, can you limit these ball joint angles ? This should avoid some troubles with impossible positions.
Spherical bearings in an upright have less rotational angle than rubber bushings that have a thin layer of rubber? I find that hard to believe.

It's been a while, but I seem to recall about 6-7 degrees of articulation on my spherical bearings I designed (bare bearing could do 8-9 deg). You're not getting a stock rubber bushing to ~6-7 degrees often without destroying it.
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  #34  
Old 02-18-2018, 02:29 PM
Stingy49 Stingy49 is offline
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Quote:
Originally Posted by gills View Post
I set my rear ride height during my last corner balance with the toe rods at 6 degrees above parallel. They are straight toe rods. That's with my subframe tucked to chassis.
When you say "above parallel" are your toe arms sloping away from the diff or towards the diff?
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  #35  
Old 02-20-2018, 06:53 AM
gills gills is online now
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Quote:
Originally Posted by Stingy49 View Post
When you say "above parallel" are your toe arms sloping away from the diff or towards the diff?
I mean the angle with respect to horizontal. They are above horizontal and sloping toward the diff I suppose. The outboard/upright toe link pivot is typically always further forward (toward front) than the subframe pivot.

I stick the magnetic side of the digital angle finder on the toe link and make sure it's hanging as close to vertical as possible.
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