I must have missed the comment on pointing the laser down. I would also think that having the laser attached to something that represents the radius of the wheel/tire would also be useful while pointing down. I'll think about that today and see if I can try it. The car is still apart in the garage.

 

you need two lasers to draw the line between those dots, or you need to do two plots, one with a laser mounted forward of the centerline, and one mounted rear of the centerline. OR!!!!! you could get one of those picture level things and mount it to the face of the hub! You know, the ones that spin and send a line around the room. mount it so that it draws the line that is parallel to the face of the hub, and draw that line on a peice of paper on the ground. All you care about is the change in angle.

hot damn, that could be the trick.

 

you need two lasers to draw the line between those dots, or you need to do two plots, one with a laser mounted forward of the centerline, and one mounted rear of the centerline. OR!!!!! you could get one of those picture level things and mount it to the face of the hub! You know, the ones that spin and send a line around the room. mount it so that it draws the line that is parallel to the face of the hub, and draw that line on a peice of paper on the ground. All you care about is the change in angle.

hot damn, that could be the trick.
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2 lasers is a good idea, but I think it'd be better to mount them perpendicular to the hub (I was thinking taping two laser pointers with the rear against the rotor and front at the hub pointing out) so the lasers point to the side of the car. Put one on the front and one on the rear. Then you could put a vertical surface (like a wall) 10 or 12 ft away so the displacement of the laser is magnified.

If you could find a way to mount one of those spinning lasers that'd be even better.

 

Funny, I was just at a friends house (MR-2 STR driver) telling about this and he pulled out a spinning laser that makes a straight line. He said point this at the ground and measure the change in angle, so I borrowed it. When I get home later I'll give it a try.

 

The spinning laser did not work well either. I tried it both pointing at the ground perpendicular to the hub and also pointing at the wall straight out from the hub with a vertical line. There was still lateral movement of the line with some angle change. I'll post these when I get a chance.

I then removed the second shock and took a bunch of measurements with toe plates at varying ride heights. Once I get the data sorted/plotted I will post. It definitely showed toeing out (still total toe in measured) while compressing up to roughly a 15" ride height then it started toeing inward. At 16.25" it was 0.5". It was almost down to 1/8" at 15". At 12.5" toe was 3/8". This clearly shows a toe out motion followed by a toe in motion. So, if you operate at less than a 15" ride height over the entire compression/rebound stroke then it will be toe in only on compression and toe out only on rebound. The next question is if that curve is linear or otherwise. I may have to take more data to figure that part out.

If you are going to characterize the rear toe curve I recommend doing a measurement every 0.5" of motion.

 

Rob, can you expand your explanation of the ride height measurements? Most of the STR guys have stated ride heights from center of the hub to the fender lip, and these are usually in the 12 - 13" range at rest.

You have measurements at 15" and I just wanted to see if these were applicable.

Also, thanks for looking into all of this!

 

Finally got around to this...

Method for Measuring Rear Toe Curve

1. Removed rear wheels
2. Removed both shocks
3. Disconnected sway bar
4. Loosened upper a-arm pivot bolts to allow more droop (over come rubber flex limitation)
5. Installed wheels
6. Placed folded plastic garbage bags under wheels
7. Used two low profile aluminum racing jacks, one on each side to control ride height
8. Started at highest ride height with tire tread touching and parallel to ground
9. Set and measured ride height at various ride heights from bottom of 949 wheel to metal fender edge and subtracted 9.25" (radius). Double check both sides because changing height on one side affects the other (iterative).
10. Measured toe using toe plates
11. Repeated measurements to confirm
12. Reassembled car
13. Plotted data using Excel

Observations

1. Toe out movement occurs under compression until about a 15" ride height, the remainder of the compression stroke experiences toe in
2. The minimum toe was at a ride height of about 15"
3. The suspension travel range used for most STR setups will only encounter toe-in during compression (no toe out)
4. The lowest ride height achieved during this exercise was 11.0 inches due to the minimum jack height
5. Repeated measurements varied from 1/16" to 1/8"
6. Recommend others repeat this to see if data collected is reasonably consistent
7. Recommend making toe measurements at ride height increments of 0.5" to better define the curve.

 

Would anyone be so kind as to share their compression and rebound settings for the newer Moton Clubsports that have 15 rebound / 11 compression?

I am new to DA shocks, and with 850/700 springs the car is bouncy with compression at 4/11 (11 being stiffest) and rebound at anything less than 6/15.

I understand rebound well, and expect that I will need a lot to control the high spring rates, but compression tuning is new to me and I am looking to know what people use since I cannot follow the only guidelines I found (by Koni for their DA's) until I get a chance to find a test and tune. And since compression is seemingly supposed to be set first, I am in the woods still with rebound, which is to be set subsequent to compression.


Thanks for assistance with te relatively novice question. (especially compared to the recent discussion)

 

So the 12.5" ride height has a nice linear compression and rebound toe change.

 

car being "bouncy" seems more like rebound to me then compression.