OK, I finally got around to replacing the stock rear springs with Mach 1 rear springs. With the CHE adjustable arms adjusted all the way down, the rear sat about 28.25" from ground to bottom of fender lip. With the front lowered & sitting just over 26" ground to fender lip, the rake was too much and looked a bit silly. Using some quick calcs I did in my head, I installed the Mach 1 rear springs and raised the CHE pedestals 1 1/4".
(http://s43.photobucket.com/albums/e360/Domeskull/th_DSCF1246.jpg)
The springs are quite a bit different in height - the Mach1 are about 3" shorter!
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1244.jpg)
So here is the new spring installed:
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1245.jpg)
When I finished, I lowered the car and found a level parking lot so I could take pictures - not an easy task finding a level spot anywhere in NH! :hick: The rear is now 27" from ground to fender well lip. There was no change at all in the front.
Passengers side:
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1248.jpg)
Drivers side (still 3/8" shorter on drivers side front - battery?):
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1249.jpg)
The car rides great and the rear is much firmer without feeling the slightest bit harsh - I really like the overall drivability improvement with the Mach 1 springs on all 4 corners.
Here is a bit of backward calculation that I did to try to estimate the spring rate of the stock springs. I'm sure if I screwed up, some of the smart suspension folks will point it out to me in a heartbeat - lol :D
(http://i43.photobucket.com/albums/e360/Domeskull/Springcalcs.jpg)
The second row is the estimated rate for the stock springs - looks like they may indeed be 200 lb/in as was used in previous years?
looks good man like the stance been reading bout doin this to mine getting real interested
holy that angle on the spring perch looks brutal. other the that, looks good.
Oh, that's fully unwound with shock detached!
Here - I just took one from below the car fully loaded.
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1250.jpg)
Are you still using stock struts/shocks?
I believe the stock rears are ~250 lbs/in. edit: Moog replacements are 249 lbs/in, but they have several more active coils indicating the OEM rate is lower)
Can you measure "d" and "D" from the old springs? A more accurate calculation can be performed using those (+/- 5%)
F/R weight split is probably more like 56%
Yep - well, stock replacement Gabriel.
Jeremy:
They could be 250 lb/in, but they are not constant then - well, the height may be deceptive anyway. The spring is 0.570" diameter wire but the top coil is 0.500" (about 1 full turn).
The outer diameter of the top coil is 5.07", but the average diameter may be slightly larger due to the smaller diameter of the wire at the top coil where I measured. I assume Ford uses the same grade/temper for their spring wire?
The F/R was there as an error check for those who know this. I "guesstimated" on the average distance from pivot to perch to mount point on rear end (well, I used a tape measure so the estimate would be somewhat close anyway.)
Plug'n'chug into the spring calculator at Efunda. [link (http://"http://www.efunda.com/DesignStandards/springs/calc_comp_designer.cfm#calc")]
d=.567 (30 mils for paint/rust)
D=5.15 (Average is probably bigger)
active coils = 7
k=214 lbs/in
That's just a ballpark figure due to uncertainties in "d" and "D".
-----------
Both springs are linear.
The coil at the top doesn't matter because it isn't an active coil. When installed on the car, that portion of the spring never moves.
Ford probably doesn't use the same grade/temper for their spring wire, but those properties don't factor into the spring rate, the modulus of elasticity does. The modulus of elasticity is pretty standard for steel, be it 58ksi 1018 or 160ksi heat treated 4130.
That's hotness. Now I definitely know I'm going with Mach 1 springs. How much did you have to bring the CHE adjusters up?
Read the post lazy :shakeass:
(http://i43.photobucket.com/albums/e360/Domeskull/DSCF1246.jpg)
Stupid tape measure moved when I was trying to get the camera held right, but it was 1 1/4"
Where do you get the Mach 1 springs? Can you buy them new?
TED
Ted,
Check out Carm (Thunder Chicken)'s thread in this section about springs. There's a link on there that has the set of 4 Mach 1 springs for $209 brand new.
I guesstimated 2.5-2.75" shorter then a TC/Sport spring, so at 3" I did pretty good :hick:
Yeah, actually the OD is about 5.2" which yields about 207 lb/in. Ford also used a 210lb/in rate on some springs so that's possible no?
You can tell I have never designed coil springs before. I have designed flat springs using 300 series stainless and they were marginally on the elastic/plastic line depending on the work hardening done (cold rolled I think). I was trying to skirt the line between tool life (they were stamped) and getting the needed force from the spring.
Your link wants to make me register - I was just about to check the Mach 1 springs as a check.
I nabbed mine from someone on Stangnet for $100 shipped. Good deal I think :D
You can delete the efunda cookie to regain access the content. ;)
Could we use front springs in the back? dont know if there is any differance in the springs but what is the height differance?
no you can't,for a few reasons the size and weight rate,also the shape of the ends.
Which way did you put the pigtails? I can't remember what way they go.
The ends point toward the drivers side.
I've done a few trips since installing the rears and they definitely feel stiffer than stock. Adjusted up with the CHE adjustable arms, there is
no way they are going to coil bind or bottom out.
Are you running stock cat or stang shocks?
How is it since it been a while?
I totally love the ride of the car now. It's a bit firmer all around - maybe a little "tuner" jiggly since I am still using stock shocks/struts. I have had no issues at all in the rear - no binding or excess travel or anything - very tight and predictable. The fronts are great too - only on bridge construction where the road suddenly rises a few inches do the tires touch in the front. In corners the car feel tighter than it did with the 1.3" front roll bar installed. I am steering the car very precisely through corners - it may be a little twitchy based on the tow-in adjustment I did, but I like the added feel in curves compared to the oversteer I had with the car up high and the tight CHE upper and lower arms. Lowering the car with the firmer springs really brought back the handing characteristics and then some. The car is quite sporty now - I have to be careful as the S/C adds so much torque that I am forgetting that I can loose the rear in a heatbeat as the tires will spin at up to 70 MPH when I gun it - lol :hick:
Mach 1 stock or lowering springs?
Edit: nm, the springs called "Mach 1 lowering springs" on the net seem to be stock so I'm guessing there isn't a spring to go any lower on the Mach 1....?
These are stock take-offs that I bought used from a Mach1 owner.
Just curious I seen your measurements that you took off were roughly 15",I seen our specs for new stock springs for free height at 13.33".I'm about to do my rear and I'm gettin more confused.Also anyone know the difference between bullit and mach 1?.I'm ready to call PPI but need to know more what to ask them.
I put stock '95 GT rear springs in my car, with overload airbags, it lowered the car pretty well and I can put air in the bags anytime I'm hauling extra people or extra junk so the car doesn't drag. Pretty handy.
Thats interesting,Do you have to go under the car to do that?
That doesn't change height just load ?
Well, they have hoses running to them and a schrader valve I put at the back of the car.
Starting from no air in the bags, you can actually raise the car 1/2"-1" or so without seriously affecting ride quality.
Another nice bonus is that if you run about 7-10 psi in the bags, it actually improves handling a bit as it reduces roll in the rear.
This might be a new thread?,I can see this!.
But to my original ??,Can someone give me an idea?
Man, I'd like to put on some CHE adjustable lowers, except that it doesn't look like they'll be compatible with my airbags (since the bags sit inside the springs)
doh
Why does everyone on here seem to favor CHE arms of MM arms? Is there something I'm missing (besides the price)? And why don't I see arms with adjustable spring perches on there website? Oh yeah, and do the CHE arms do anything for quad shock removal like MM claims theirs do?
Theres a pic on this page.
http://www.cheperformance.com/cartgenie/prodList.asp?scat=30
I bought them for price "coolcat discount"and were recommended by others.
- Half the price
- not forced to use a harsh rod-end on one end
- MM says "The Heavy-Duty arms are suitable for cars with moderate horsepower levels that are not drag raced."
They don't make an "extreme duty" (drag race capable) for the Fox Bird/Cougar
Oh, and I removed my quad-shocks with the CHE arms and saw no wheel-hop at all using M/T drag radials that were dead-hooking.
Sweet! So, i was looking at this link. It shows the height adjustable ones but doesnt say what car there work on. Then, above to the left is the NON height adjustable version for the tbird/cougar. Just curious what the difference is...
Ok, so if I buy them, what quanity do I enter? I would assume they sell it in pairs, but then again why would it even ask quanity?!? My luck, I'd either end up with 1 or 4!!
The use of a spherical bearing results in less bind than poly in both ends, which is good for cornering.
From what I've read, the spherical bearings aren't much worse than poly.
I agree that the spherical will bind less (essentially none) in cornering. For me it was especially noticeable when I had the car jacked up in the back and stock height in the front. I had quite a bit of "push" (understeer) in the corners that was unpleasant. The fact that I removed the front sway-bar for drag-racing was a part of this as well. Pushing it hard could lead to "snap" oversteer (hard bind) which was even more unpleasant. Now, with the stiffer Mach1 springs all around and the car being lowered, the steering is like being on rails - the feel is outstanding and very neutral. I can now do refined steering adjustments even in hard turns. I assume that the higher spring rate in the rear matches up better with the stiffer bushings keeping the rate more linear through the typical travel range of the suspension. What do you think?
I am looking into a set.
Of what, the CHE's?
Do yourself a favour and don't get the adjustables. I bought 'em thinking that more expensive = better, but now I regret it because I've got a severe case of "sky butt". The adjustables add at least an inch of height (with stock TC springs), and combined with my lowered front (stock TC springs in a V8 car) my car looks ridiculous. The only good thing about 'em is that they allow you to use the Mach 1 springs as this thread shows...
Oh, and in case you're wondering, this is what I mean by "sky butt" (this pic was taken before the front spring broke):
LOL... Well, I plan on running Mach 1 springs. And since I have full adjustability in the front with the coil-overs I want some adjustability in the rear.