cheapracer wrote:
a.moore wrote:
How sensitive was the location of the holes to binding? If you moved a hole lets say 1/16" would it be enough to cause or eliminate binding?
By holes do you mean the heim joint/bushing bolt holes? By 1/16 do you mean the distance an average home workshop might be off by? If the builder was that bad and say 4 to 6 of the 8 holes were out then yes, there would be a noticable difference either way but if the workmanship was that bad then I would be concerned about the entire car!
a.moore wrote:
Its probably worth noting that having the links non-parallel will also create some amount of anti-squat.
(From the standard mounting position) I doubt you would notice it. Anyway, you are refering to just dropping the rear upper hole whereas you could also split the difference or raise the lower hole.
. . . .
I'm shagging down (U.S. meaning) the effects of trailing arm inclination of 4-links with respect to other issues, but knowing about binding in those cases is critical too, so I was reviewing this thread. I'm looking at what kind of angles are significant enough to make a difference with respect to other factors such as torque roll, rear roll steer and anti/pro squat.
Doing the math on your example here, there are two differing cases to consider: 1) all changes in height done on one upper link (one wonders if the result would be the same using one lower too - I think it would); and 2) splitting the changes between upper and lower links.
In the first case you get sine Ɵ = (140-132)/292 = 8/292 = 0.0274 ==> Ɵ = 1.5701° = ~1.6°
For case 2), if you split the difference symmetrically, each angle has sine Ɵ = 4/292 = 0.0137 ==> Ɵ = 0.7849°, which is slightly less than half the 1.5701° figure.
These are very small angles. It's amazing that they have such an effect on binding. If you pick the convergence point of the links (in your case both behind the vehicle some distance) I can't see that you'll have any
noticeable effect on anti/pro squat or lift. If you had compliant rubber bushings at one end of the links, I doubt you could measure the effects in terms of chassis behavior at all, although there would be very slight kinematic changes.
I'm trying to reconcile the degrees of inclination from Mallock and other sources (sometimes 5° or more) with respect to your binding solution at these small changes in inclination angles. Your angles are so small that I think this could be looked at as a "neutral" modification with a good benefit, namely greatly decreased or no binding with effectively zero changes to other steering effects of the 4-link as otherwise designed.
That sounds like "something for nothing", which we all know is never true, but I think the unknown "nothing" in this case is negligible compared to decreased binding and better range of motion. Implied in your experiment is that a change greater than 20mm for the standard 292mm link gets you back into trouble again. The angle in that instance (Case 1) is ~4° (3.9274 for fussy people) of inclination.
I'm going to keep working on this and see why more is recommended by some and why it appears to have been successful in other contexts. The Devil is in the details of these suspension configurations.
Cheers,
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