I was reading an article in the new issue of Rod & Custom where they fix the geometry on a mustange II with cut coilsprings . They put in 2"dropped spindles but also used what they called "big block mustange II springs" and cut several coils to get the lower A-arm level. Wouldn't this make the car ride excessively Stiff or Hard ? Whats the correct way to figure what spring rate is correct for a particular vehicle ?
mustang 2s and Pintos never came with big blocks. The pinto had a 2.8 v6 option and Mustang 2s had a 302 v8 small block. Stiffer springs were probably used on v8 cars.
Yea I know , Aparently they are using stiff - strong springs and cutting them which I imagine would make them even a bit stiffer ! I know Eaton spring has several different rates for different aplications of Must II suspentions , how do ya know where to start with a spring rate ?
That is the main reason i choose air bags in the front. With running close to 750lb motor i didnt want to deal with a terribly stiff ride. the trouble you run into is pring rate in comparison to the space allowed.
There are a few calculators available for determining proper spring rates and spring heights for various IFS suspensions. If you want to know the specifics of what spring to choose, you need the loaded ride height and weight of the vehicle. AND you need to know the distances between the lower control arm pivot (known as K1) and the spring as well as the distance between the lower control arm pivot and the centerline of the tire (known as K2). To be ultra specific it would help to know the angle of the spring in relation to the lower control arm, the diameter of the spring, how much spring pre-load is desired and the quality of the ride, firm, soft or somewhere in between. And just so you know this also applies to "airbag" springs too. They are not a magic bullet spring that automatically works for everything. Most of the time we are shooting for a 150-225 lb/in effective spring wheel weight. If you would consider that the K1 is nearly 50% of K2, then a 300 lb/in spring would be effectively 150 lb/in. Likewise, if you are carrying 1800 pounds on the front axle, each spring would need to carry 1800 pounds at loaded spring rate each. So in this theoretical car with 1800 lbs on the front, we have a loaded spring height of 9 inches at our desired ride height and want a bit more of a sporty ride so we will shoot for an effective spring rate of 175 lb/in. To find the free length of the spring, you can multiply the ratio of K1:K2 to the effective wheel rate and come up with 350 lb/in. Now divide your front end weight by the spring rate, in this case we need 5.1" of preload. Add that to the 9" loaded spring height and we get 14.1" free length. I hope that helps your situation.
Mustang II springs are short and they don't have much travel. 5.1" of preload would be on the bump stops. You need stiffer springs than you'd use in a suspension with more travel.
Not sure about this...............so I am ready to get educated but. I think the 80's Bronco II springs were the same diameter but were taller and had more load rating. That may be possibly the spring in question. I know I bought a '53 Chevy truck with a MII and the thing looked like it was a 4X4. Turned out to have Bronco II springs under it that I promptly removed and made boat anchors out of.........
Actually the four cylinder Pinto springs are just about right for a M2 suspension under a hot rod with a SBC. In the typical hot rod the front suspension is forward of the engine with the weight biased toward the rear. In the Pinto the engine weight is centered over the front crossmember.
I myself learned the hard way on my first mustang II kit a few years back.Don't know about calculating for the correct spring.I pretty much asked the kit manufacture tech's and gave them the info of what car, engine and trans a will be installing to match the spring for the MII. The mistake I made was that I cut the springs to the ride height to were I wanted the car to sit. A few days have gone by after I did the install of the MII and started to notice the car was lowering and got to the point that the crossmember hit the ground.WTF!!! What I didn't know that you are suppose to put in the springs uncut and let them settle as i'm driving around.The Tech guy mentioned that it's normal to cut the coils and asked me how many coils did I cut,and I said 2.He said after they settle in you should only be cutting no more than a 3/4 turn,Your springs are no good.So I bought a new set and slapped them on.The ride was stiff at first but slowly started to soften up and the car finally got to a settling point.I cut only 1/2 a coil to the desired height I wanted and the car drove smooth.
Are you responding to my post? If so, I don't think you read my post correctly because your post doesn't make much sense as a response. According to my TRW spring book most all of the Mustang II's came with CS8556, CS8558 or CS8582 springs. The CS8556 springs are: 13.81" tall and have an effective spring rate of 364 lb/in. The CS8558 springs are: 13.44" tall and have an effective spring rate of 353 lb/in. The CS8582 springs are: 13.94" tall and have and effective spring rate of 317 lb/in. Interestingly enough the CS8582 springs are common to the non A/C 302 cars. Actually, it's not common to cut coils. That is a last resort when you can't find the spring you need or just don't know what you're doing.
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