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shelby drop and suspension ?'s

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panteramatt

Member
I want to do a couple mods to my 69 mach to make it handle better. Right now, the front end seems to "float" goin down the road which make me think the shocks are shot. So I have a few questions:

1. Does the shelby drop actually lower the front end and if so how much? If I lower the arm 1", is anything else needed?

2. Need shock recomendations. Mainly a street car with some drag strip time in its future.

3. It has 15" mag 500's and Im goin with some 17's soon with 245/40 fronts and 275/40 rear tires. They are 17x8 with a 4.75" backspacing and a 17x9.5 with a 5.5" backspacing. How much can I lower the car without rubbing issues?

4. Does cutting the front springs make it handle better or should I buy a set of better lowering springs? Really dont want to drop the car much more than 1"

5. The rear shocks look to be aftermarket with airlines going to them. Are these good or should I upgrade?

6. Any rear suspension upgrade suggestions or tips?
 
1. Does the shelby drop actually lower the front end and if so how much? If I lower the arm 1", is anything else needed?
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You'll have varied responses to this question, but IMO, no, the Shelby drop does not lower the car 1". What it does do is change the operating angle of the UCA to create a more desirable angle for the UCA's ball joint. It may physically lower the front of the car 0.25" or so, but this is purely a side benefit of performing the modification. The Shelby drop goal is not to "drop" or lower the front of the car, but alter the front suspension geometry to gain negative camber when cornering. Nothing else is needed other than the template to drill the new/lower UCA mounting holes.


2. Need shock recomendations. Mainly a street car with some drag strip time in its future.
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Before I altered the existing ride height I'd wait until the new 17" wheels/tires were installed. It would suck to alter the ride height to fit the existing 15" wheels/tires and then have it not work for the 17" combo.

3. It has 15" mag 500's and Im goin with some 17's soon with 245/40 fronts and 275/40 rear tires. They are 17x8 with a 4.75" backspacing and a 17x9.5 with a 5.5" backspacing. How much can I lower the car without rubbing issues?
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The car's front suspension can be lowered incrementally by installing new springs with different spring rates. Another option, although not one that I use, is cutting your existing coil springs until the desired ride height is acheived.


4. Does cutting the front springs make it handle better or should I buy a set of better lowering springs? Really dont want to drop the car much more than 1"
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Cutting the front springs, which in turn alters the ride height, will effect the handling, but it's my opinion that the best way to achieve the desired ride height and handling is through the use of springs designed for that particular application. This is usually a trial and error process that results in you buying a set of springs, trying them on and then buying another set. It's difficult to nail down a "perfect" set of springs on the first attempt. The most you'll likely buy is three sets of springs.... as an example.... buy a set and they're too low.... buy a set designed to be a little bit higher.... and they're still too low.... buy one more set to get the front just a tad bit higher and they're perfect.


5. The rear shocks look to be aftermarket with airlines going to them. Are these good or should I upgrade?
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Those are air shocks designed primarily for adjusting the rearend ride height to accomodate additional loads/weights. They were first used on cars that served double duty as daily drivers and weekend trailering to pull your grandpa's boat/camper up to the lake. By adjusting the air pressure within the springs you could turn a "soft" suspension into a "stiff" suspension. During the 60's and 70's these shocks were popular with the muscle car crowd as you could cheaply increase the air pressure to "jack up" the rear of the car to "make it look mean" and install ill-fitting tires/wheels that did not fit within the fenderwells. Air shocks installed on a vehicle in todays day and age are "old school", but more often than not are masking a worn out set of rear leaf springs and hinder any possibility of rear suspension performance.

If I bought an old Mustang with air shocks installed and a dead rotting cat on the dashboard.... I'd remove and throw away the air shocks first.


6. Any rear suspension upgrade suggestions or tips?


Performance handling relies greatly on weight transfer. The front and rear suspension should work together to effectively transfer weight. A front suspension that's too stiff coupled with a rear suspension that's too soft will never be as effective as a front/rear suspension that compliment each other. There is no "one solution" as there are too many variables between each car. When dealing with the rear suspension to alter ride height/handling there's only one thing to avoid and that's the use of "lowering blocks". To find the "perfect" rear springs I pick one and give them a shot, similar to the front coil springs, until I find the set that works best for the front suspension, the car and my particular driving style/how I want the car to feel/handle.

Front coil and rear leaf springs are cheap and although they can be time consuming are easy to install. The springs that didnt' work out can be unloaded on the next guy who's trying to find his "perfect" suspension.
 
Thanx for the great info Dave. I guess Ill wait till I get my new rims before I do spring upgrades but I will do the shelby drop now. I do need some shocks as my front end seems to float. Ive read that konis, bilsteins, and kyb gr2's are all great. Do you guys prefer one and are there any other really good ones?
 
That front end "float" feeling doesn't necessarily mean it is a shock issue. Some of that is just the nature of the 60's suspension you have up front. You mention your car will spend some time at the strip. With that in mind you may want to look into adjustable shocks that you can tune to let the front end come up faster for better weight transfer at the track and dial back down when you're heading home.

Same goes for spring choice. You are better off keeping that front up higher if you are serious about dragging the car.
 
I have done the Shelby drop and cut the springs. I have all new "Grab-A-Track" UCA's, LCA's, gas shocks, tie rods, etc. and ORP roller perches with a 1" anti-sway bar and poly bushings on everything. The front sits pretty low and doesn't wander or float even at speeds beyond what the speedo can count. I have 16x7" wheels with low profile tires, 205/40/16's in the front IIRC. I think the suspension design is dated but with good parts and a good alignment it can work pretty well. I have Grab-A-Track 5 leaf mid-eye rear springs and 17's on the back. I did a couple laps at an open track event and the car handled better than I thought it would. On the curvy roads here in KY it is pretty fun to drive. Although what works on the twisty's doesn't alway work on the 1320' I have not tried drag racing (legally) yet. I have a smoking problem (the rear tires ignite when I stomp on it).
 
A floating front end can be due to something as simple as needing an alignment and increasing caster.
 
Hey Mid, I saw on VMF the other day where someone had dug up a strut rod bushing thread from 2001 you had started. Before I noticed the date was a "WTH" moment!!! kip
 
"Horseplay" said:
That front end "float" feeling doesn't necessarily mean it is a shock issue. Some of that is just the nature of the 60's suspension you have up front. You mention your car will spend some time at the strip. With that in mind you may want to look into adjustable shocks that you can tune to let the front end come up faster for better weight transfer at the track and dial back down when you're heading home.

Same goes for spring choice. You are better off keeping that front up higher if you are serious about dragging the car.
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Any input on these shocks: Summit G7603 front and G7704 rear
 
"panteramatt" said:
Can you give me more info?
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The Spring Perches are bolted to the factory Upper Control Arm (UCA) and are the mount for the bottom of the coil spring. Within the factory spring perch is a rubber bushing that allows the UCA to travel through it's range of motion (up and down) while still providing the proper angle to mount the coil spring. If you're looking at an old used set of spring perches this bushing usually looks pretty worn out/rough.

The problem with the factory designed spring perch is that the rubber bushing does not allow freedom of movement for the UCA through it's range of motion. Factory spring perches with the rubber bushing induce "bind".

On a daily driver car the factory spring perches will work "okay".

For owners trying to get their car's to be more responsive and handle better, an improvement has been made that replaces the spring perches binding rubber bushing with rollerized bearings. Thus "roller perches". This is a very popular modification. A couple of the performance orientated members here.... Shaun of Street or Track and John of OpenTracker Racing Products offer these improved spring perches. Some members have even made their own. Either way, it's a great modification that only improves the handling characteristics. There is no "down side" to having roller perches, it's all benefit.

I can't help you with shocks, sorry.
 
Thanx for the info. Just looks like more $ Im gonna spend. So it looks like Im gonna do th eperches, kyb gr-2 shocks, and the shelby drop for now.
 
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