Hmm...and that's despite the fact that the LCAs are connected to relocation brackets.
If you want the lowered look while retaining the proper suspension geometry, you may have to go to 19" rims.
Running no rear sway bar on track?
- Thread starter mitch
- Start date
Hmm...and that's despite the fact that the LCAs are connected to relocation brackets.
If you want the lowered look while retaining the proper suspension geometry, you may have to go to 19" rims.
Fabman
Children Of The Corn
There's a couple holes there, I switched to the upper hole.
Thats where i want to be to reduce roll steer and still have some anti squat....no?
This makes no sense. 25.5" diam tire + 2" gap = 27.5" Yet you measured 27". ( front)
25.5" diam + 3" gap = 28.5" Yet u measured 27.5" (rear)
Something is amiss. Measure from center of hub to top of wheel well arch. That dimension will not change..if tire diameters are changed.... but everything else stays the same.
What is the aprx max width rear tire, you think could fit, using your new rear coil overs ? I would think a 11" rim + 305/315 tire would still fit?
The max I have seen..(with a conventional oem rear separate spring /shock) is a 335mm tire... on a 11 7/16" wide rim. To pull that stunt off, the protective cover on the top of each shock had to be removed, the bump stop brackets relocated...and one other item I have forgotten.
Fabman
Children Of The Corn
I wasn't being literal...I did wonder to myself at the time if anyone would catch the math error. You win Pent.
Last edited:
Fabman
Children Of The Corn
My street wheels are 11" wide 335mm tire and clear with the boot intact. I haven't tried yet, but I believe they will still fit.
The problem area would be in droop where the rim may contact the adjusting nut on the coil over sleeve. Stay tuned on that one.
Roll steer is dependent upon the angle of the arms relative to parallel at ride height, though, not just the location of the hole.
Which is to say, you tune the LCA location in response to ride height adjustment, not really the other way around. If you lower the rear of the car, that changes the angle of the LCAs, and you have to relocate one end of them in order to bring their geometry back into acceptability. You then fine tune the height of the rear to fine tune the geometry.
Cortex is going for more than that, though. It appears they specify a rake angle of the car, after specifying the front ride height (assuming stock front ball joints) in order to control the relative roll centers. The front ride height is specified not just to control the roll centers, but also to control what the camber curve in roll looks like, along with other things like bump steer.
If you lower the rear of the car more than what Cortex is recommending for that end, then the rear roll center will be different, and the handling balance will change (if I remember right, the roll center drops half as quickly as the CG, so you'll end up with less roll in the rear than you had before, and if I'm not mistaken, that will result in more understeer).
Because of all these factors, I'd discuss all this in great detail with Cortex. The guy who owns it is a mechanical engineer, so he'll have a really good idea of what to expect as changes are made.
Last edited:
Norm Peterson
corner barstool sitter
Assuming no changes in axle roll steer, shock balance, tire grip, or other effects . . .
What you get when you lower the car is a little less load transfer through the suspension geometry, with relatively more of that happening at the rear. When you re-balance the car to the same steady-state ratio of front to rear load transfer as you had at stock height, you'll be using (relatively) more front roll stiffness.
IOW, if you started out with 2" front and 12" rear RC heights with suspension stiffnesses distributed 65/35, when you lower the car an inch and the RC's go to 1" and 11.5", the suspension roll stiffness distribution might end up looking more like 66/34 or 67/33. Numbers for illustration only and do not represent any particular car.
So the car should initially be a little bit looser early, with a bigger change toward 'tight' happening as roll develops.
Norm
Last edited:
Fabman
Children Of The Corn
Couple things:
1) I know how roll steer works and about relocating holes and all that. This hole happens to be in the right spot for this particular ride height. (Used to be in the lower hole when the car was lower)
The car sat with the "Pre adjusted spring perches" even lower than it is now. I had to raise the rear to get it this high, and I'm almost out of height adjustment on the coil overs. That hole just happened to work here.
This is what prompted me to stop and task myself....
"Why is it so much lower than the directions and I'm almost out of adjustment but I'm still too low? The car looks like a truck".
2) Manipulating the rear roll center is easy, making an adjustable height panhard bar is next on my to do list. So far every builder I've looked at drops the rear roll center in their kit. So Does Cortex. Also, when you raise the rear roll center relative to the CG you get over steer, not understeer. As the roll center gets lower (longer moment between CG and RC) weight transfer is expressed more through body roll requiring the wheel rate to be stiffer to balance. As the roll center rises (closer to CG) weight transfers less through body roll and more through the CG essentially making the car stiffer (in roll) and looser and requiring softer Wheel Rate to balance the car.
What I needed was a reality check that I had the correct size tires on (as that would change everything) and that I wasn't the only guy with a 4x4 mustang.
Like I said, the directions state 5" ride height but it also said the coil overs were pre adjusted....so why wasn't it even close?
Gave me cause for pause.
To answer some previous questions now that I am at my shop where the car is:
Center of hub to fender lip is:
15.5 Rear and 15 front
Wheel gap is 2.5 rear and 2" front.
I'd love to here how this compares to others with the same body style.
1) I know how roll steer works and about relocating holes and all that. This hole happens to be in the right spot for this particular ride height. (Used to be in the lower hole when the car was lower)
The car sat with the "Pre adjusted spring perches" even lower than it is now. I had to raise the rear to get it this high, and I'm almost out of height adjustment on the coil overs. That hole just happened to work here.
This is what prompted me to stop and task myself....
"Why is it so much lower than the directions and I'm almost out of adjustment but I'm still too low? The car looks like a truck".
2) Manipulating the rear roll center is easy, making an adjustable height panhard bar is next on my to do list. So far every builder I've looked at drops the rear roll center in their kit. So Does Cortex. Also, when you raise the rear roll center relative to the CG you get over steer, not understeer. As the roll center gets lower (longer moment between CG and RC) weight transfer is expressed more through body roll requiring the wheel rate to be stiffer to balance. As the roll center rises (closer to CG) weight transfers less through body roll and more through the CG essentially making the car stiffer (in roll) and looser and requiring softer Wheel Rate to balance the car.
What I needed was a reality check that I had the correct size tires on (as that would change everything) and that I wasn't the only guy with a 4x4 mustang.
Like I said, the directions state 5" ride height but it also said the coil overs were pre adjusted....so why wasn't it even close?
Gave me cause for pause.
To answer some previous questions now that I am at my shop where the car is:
Center of hub to fender lip is:
15.5 Rear and 15 front
Wheel gap is 2.5 rear and 2" front.
I'd love to here how this compares to others with the same body style.
Mark Aubele
forum member
- Joined
- Feb 11, 2015
- Posts
- 247
- Reaction score
- 0
I guarantee the stated ride height is with stock height tires. Might be the whole issue here.
Fabman
Children Of The Corn
That is issue #1 for sure:
is it so? Or is it not so....that is the question.
I am afraid I'm going to have to make that call....
Fabman
Children Of The Corn
Stock tires for my ride are 27" so the delta between stock and current is 1.5 or a radius of .75 delta so that is how I arrived at the current height....but, I could be out to lunch on this.
Fabman
Children Of The Corn
Now if I can just get this shifter to work in the car...
Fabman
Children Of The Corn
And here it is...
From Cortex:
The OEM tires are about 27" tall so you'll be much lower with 25.5" tires.
My guess about 4.0". The geometry of the car does not like to be too low. 3.75" is the practical limit however you should be much higher unless you have the drop ball joints.
From Cortex:
The OEM tires are about 27" tall so you'll be much lower with 25.5" tires.
My guess about 4.0". The geometry of the car does not like to be too low. 3.75" is the practical limit however you should be much higher unless you have the drop ball joints.
Fabman
Children Of The Corn
Correct.
Similar threads
Support us!
Support Us - Become A Supporting Member Today!
Click Here For Details
Sponsor Links
