M_Body_Coupe
Well-Known Member
Folks!
Alright...so my Coupe is no drag racing machine, however proper setup should never be lost on anyone, so I've started to look at the leaf-spring geometry seeing that last time out at the track I was showing dismal 60' times and the video of car launching showed barely any chassis movement with a good amount of wheel spin (275-65R15 Nitto NT555Rs, so there is plenty of tire there).
NOTE: I suppose I shouldn't be surprised by this seeing as the car is much more focused (setup wise) on street handling: big sway bars, tight shocks, etc.
...but the angle the spring rear shackle makes has always bothered me. I don't have a picture handy at the moment, but the lower part of the shackle is ever so slightly leaning forward (at the spring eye), which is telling me that when launching the spring doesn't really have the "room" to flex and cause the body to rise - which normally is what you want to do b/c that body rise is actually what plants the tires against the pavement.
So off I went measuring my sping front and rear segments: 24.5" on the front and 34" on the rear, which is per spec (allow for +/- 0.5" here seeing as this isn't precisely off of the center bolt to the center of the front/ rear spring eye).
I am using a 5 leaf pack, and the rear of the car has always been somewhat high. I feel like it would be better for it to be about 1" lower.
All of this begs the question: so when our F/M/J-body cars needs such geomtery adjustments, what are you guys doing here?
Our rear suspension is different from the earlier Mopars where you could shim the shackle mounting bracket and that would in turn move the shackle pivot forward thus allowing the lower part of the shackle to lean/point back.
It would seem that the only way on our rides to accomplish the same thing is to re-locate the shackle mounting bracket forward on the frame rail and well, given that this is all boxed in I honestly can't quite fathom doing this w/o cutting things up, etc.
I did consider making a plate that would itself mount into the current as-is shackle bracket mounting points, but which would effectively relocate the NEW mounting point forward...that seems doable, at worst it requires some clearancing holes to be drilled in the framerail and of course the plate itself needs the nuts welded on so that the shackle mounting bracket can attach to it.
....but even that approach seems like it's very R&D (LOL)...so is there an easier way that I'm simply overlooking here?
Maybe a spring slider like these Calvert pieces (SPRING SLIDERS for Calvert Springs (SL-300CR ) – Calvert Racing, Inc. ...but even these would still require some creative way to mount them onto the rear frame rails!
As always, thanks for ideas and suggestions!!!
Alright...so my Coupe is no drag racing machine, however proper setup should never be lost on anyone, so I've started to look at the leaf-spring geometry seeing that last time out at the track I was showing dismal 60' times and the video of car launching showed barely any chassis movement with a good amount of wheel spin (275-65R15 Nitto NT555Rs, so there is plenty of tire there).
NOTE: I suppose I shouldn't be surprised by this seeing as the car is much more focused (setup wise) on street handling: big sway bars, tight shocks, etc.
...but the angle the spring rear shackle makes has always bothered me. I don't have a picture handy at the moment, but the lower part of the shackle is ever so slightly leaning forward (at the spring eye), which is telling me that when launching the spring doesn't really have the "room" to flex and cause the body to rise - which normally is what you want to do b/c that body rise is actually what plants the tires against the pavement.
So off I went measuring my sping front and rear segments: 24.5" on the front and 34" on the rear, which is per spec (allow for +/- 0.5" here seeing as this isn't precisely off of the center bolt to the center of the front/ rear spring eye).
I am using a 5 leaf pack, and the rear of the car has always been somewhat high. I feel like it would be better for it to be about 1" lower.
All of this begs the question: so when our F/M/J-body cars needs such geomtery adjustments, what are you guys doing here?
Our rear suspension is different from the earlier Mopars where you could shim the shackle mounting bracket and that would in turn move the shackle pivot forward thus allowing the lower part of the shackle to lean/point back.
It would seem that the only way on our rides to accomplish the same thing is to re-locate the shackle mounting bracket forward on the frame rail and well, given that this is all boxed in I honestly can't quite fathom doing this w/o cutting things up, etc.
I did consider making a plate that would itself mount into the current as-is shackle bracket mounting points, but which would effectively relocate the NEW mounting point forward...that seems doable, at worst it requires some clearancing holes to be drilled in the framerail and of course the plate itself needs the nuts welded on so that the shackle mounting bracket can attach to it.
....but even that approach seems like it's very R&D (LOL)...so is there an easier way that I'm simply overlooking here?
Maybe a spring slider like these Calvert pieces (SPRING SLIDERS for Calvert Springs (SL-300CR ) – Calvert Racing, Inc. ...but even these would still require some creative way to mount them onto the rear frame rails!
As always, thanks for ideas and suggestions!!!
