upper control arms
06-03-2009, 06:07 PM
#11
6th Gear Member
Join Date: May 2009
Location: PA
Posts: 5,232
I'll concede your shock broke, but I cannot accept that a properly-installed saddle can twist a 620 pound coil spring so far that it broke your shock. You probably couldn't deflect that spring 1/4" using a crowbar and the entire weight of your body, while the shock insulators could easily deflect 1/4" to account for the movement. Your gonna have to do a lot better than "it broke my shock". I have 400,000 miles on the original saddles and upper arms, and I had Koni shocks for over 100,000 miles, and another 100,000 with KYB Gas-A-Just, replaced the original GT springs in 1991 with Shelby-spec coils, and still no problems. I have also owned over a dozen Mustangs, and worked in the auto business, and I have never seen a broken Mustang front shock, not even a cheap one. Either your shock was defective, or the saddle was, or something was installed improperly.
Hmmm… Just a thought- You weren't using urethane bushings, were you? They are a menace. Here's a Mustang strut with urethane bushings:
Hmmm… Just a thought- You weren't using urethane bushings, were you? They are a menace. Here's a Mustang strut with urethane bushings:
06-03-2009, 08:54 PM
#12
6th Gear Member
Join Date: Aug 2007
Location: Elk Grove, CA
Posts: 5,896
Nope, rubber bushings. I've never seen or even heard of it either. After looking at the end of the broken rod (which tells a lot about the type of fracture) and thinking about when it broke, the logical conclusion is that the spring perch bound and side loaded the shock. It broke as I came over hill too fast into a depression, so the suspension (with stock springs) went from fully extended to fully compressed in a fraction of a second. That's a lot of force and enough of a change in the angle of the spring perch relative to the UCA that it could've caused the shock to fail. I don't think that's likely to happen to most people, but it's apparently possible, at least with the stock springs.
Even if it wasn't the cause, roller perches did make a noticeable improvement in ride quality and suspension response. The suspension is simply smoother. Any reduction in bind is going to improve the suspension, especially one with so much unsprung mass.
Even if it wasn't the cause, roller perches did make a noticeable improvement in ride quality and suspension response. The suspension is simply smoother. Any reduction in bind is going to improve the suspension, especially one with so much unsprung mass.
06-04-2009, 09:25 AM
#13
3rd Gear Member
Join Date: Jul 2005
Location: El Paso, TX
Posts: 630
The price for the Open Tracker upper street arms is pretty damn good considering a new Grab-a-Trak arm from M+ is about $75 each. If you want to do a 1 3/4" drop you can always get the negative wedge kit from Pro-Motorsports but it runs about $270.
Tad, any chance your shock may have been misaligned with the travel path of the upper control arm/spring perch? I was mocking up my front suspension the other day and noticed with the slots on the top mount and play in the lower mount before tightening, that the shock could be misaligned very easily. The perch should be perpendicular to the shock body.
From C-C.com
Tad, any chance your shock may have been misaligned with the travel path of the upper control arm/spring perch? I was mocking up my front suspension the other day and noticed with the slots on the top mount and play in the lower mount before tightening, that the shock could be misaligned very easily. The perch should be perpendicular to the shock body.
From C-C.com
In side view, there should be no bind, as long as the UCA has the same inclination as the shock mount (which it does in the stock configuration). Some racers relocate the UCA to reduce anti-dive in which case the lower (and upper) shock mount need sperical pivots.
In front view, the perch should be perpendicular to the shock body to be bind-free. The perch is contoured to match the lower coil of the spring, but it is possible that stiffer springs with less coils don't match the contours too well and try to pivot the perch + lower shock body relative to the shock rod, which also happens when the suspension travels up and down.
One easy thing to check is to unbolt the upper shock bolts and see if the holes align with the bracket at rest. If you need to force it inward or outward in order to mount it, it indicates that the spring tries to force the pivot to rotate. You could even push the bumper and let the body move up and down to see how much the shock rod moves forth and back. This should be rather easy with the shocks unbolted.
I don't know how much all this would affect the shock though. Some people contribute the improved ride of roller spring perches to reduced shock binding. Since the resistance in the stock rubber perch bushing works in the same way as uneven loading of the perch by the spring, there may be some bind left due to the issues I mentioned above.
In front view, the perch should be perpendicular to the shock body to be bind-free. The perch is contoured to match the lower coil of the spring, but it is possible that stiffer springs with less coils don't match the contours too well and try to pivot the perch + lower shock body relative to the shock rod, which also happens when the suspension travels up and down.
One easy thing to check is to unbolt the upper shock bolts and see if the holes align with the bracket at rest. If you need to force it inward or outward in order to mount it, it indicates that the spring tries to force the pivot to rotate. You could even push the bumper and let the body move up and down to see how much the shock rod moves forth and back. This should be rather easy with the shocks unbolted.
I don't know how much all this would affect the shock though. Some people contribute the improved ride of roller spring perches to reduced shock binding. Since the resistance in the stock rubber perch bushing works in the same way as uneven loading of the perch by the spring, there may be some bind left due to the issues I mentioned above.
06-04-2009, 09:51 AM
#14
Thread Starter
Join Date: May 2007
Location:
Posts: 17
with the 620 1" and shelby drop, Will I need to cut the springs any or will that look ok. I saw some pic of a 65 fastback that had same setup but cut 1/2 coil. Looks badass but not sure if it would rub. I have 225/45/17 on the front. Also what set up would be best on the back. mid or rev leaf springs and what kind. any input would be helpful. thanks alot
06-04-2009, 10:00 AM
#15
3rd Gear Member
Join Date: Jul 2005
Location: El Paso, TX
Posts: 630
As far as cutting the spring, I would say you will have to install it, drive it around a bit, then go from there on whether you need to cut or not to suit your stance preferences.
For the rear I went with 5.5 mid eyes but I would NOT recommend using these for your application. However, I think a 4.5 mid eye spring would be good for your car. Should give you a nice lower than stock ride height. If you want to go lower then you could go with a reverse eye.
This is what my car looks like with mide eye springs. Ignore the front as there is no motor in the car in this picture.
For the rear I went with 5.5 mid eyes but I would NOT recommend using these for your application. However, I think a 4.5 mid eye spring would be good for your car. Should give you a nice lower than stock ride height. If you want to go lower then you could go with a reverse eye.
This is what my car looks like with mide eye springs. Ignore the front as there is no motor in the car in this picture.
06-04-2009, 12:33 PM
#16
6th Gear Member
Join Date: Aug 2007
Location: Elk Grove, CA
Posts: 5,896
Tad, any chance your shock may have been misaligned with the travel path of the upper control arm/spring perch? I was mocking up my front suspension the other day and noticed with the slots on the top mount and play in the lower mount before tightening, that the shock could be misaligned very easily. The perch should be perpendicular to the shock body.
06-04-2009, 01:04 PM
#17
5th Gear Member
Join Date: Jun 2005
Location: So. California
Posts: 2,258
My ride has shelby drop, 1'' drop 620's that I cut 1/2 coil. Had to notch the frame about 1/2 inch so that the sway bar would not rub and squeek. Wish I had gone with 540 springs because it is too stiff.
06-05-2009, 08:39 AM
#18
4th Gear Member
Join Date: Jun 2009
Location: Orange County, CA
Posts: 1,162
If it makes you feel any better, Opentracker told me 620s are the same as 560s. Apparently 560 is their TRUE rating.