mp competition rear leaf springs

[fj5gtx]

I have a set of the shorter front leaf MP competition leaf springs. I got them a really long time ago (like 15+ years ago), mailorder. Definitely not correct, the right side is way more arched than the left - causing the car to sit many inches higher on right side. I knew it when they showed up, but at the time the vendor told me they'd settle out once installed. They didn't settle. Are these MP competition springs all garbage, or is this just an anomaly of the reseller dumping a bad one on me (or somehow shipping damage). Wondering which one is the wrong arch.

1970 GTX 440/727 with a 3.91 8-3/4

 

[RemCharger]

That's the way they are . For the reason of traction.

 

[wagonman]

I just installed the Competition / Super Stock springs on My A-Body. They are a one size fits all A and B-Body. On the B you need to use a longer front hanger. They don't come with the rear shackle bushings. They did settle about an inch. They are also side specific, go on Summits site and you can do some research.

 

[Dave6T4]

They should be stamped with a part number. This will help you figure what weight they were rated for.

 

[fj5gtx]

That's the way they are . For the reason of traction.

Many inches difference in rear car height, side to side? This would be unstable on the road.

 

[Fran Blacker]

Pictures and part numbers would help.

 

[Demonic]

the right side is way more arched than the left - causing the car to sit many inches higher on right side.

That's how they're supposed to be. The old series of MP springs had a bunch of different weight ratings. Getting them matched to what your car actually weighs is important. As Fran and others said, pics and part #'s would help.

 

[RemCharger]

Many inches difference in rear car height, side to side? This would be unstable on the road.

You are correct, you'd have to try it and see if it's for you. That's what's meant by "competition " is built for on track drag racing.

 

[33 IMP]

"Many inches"? I doubt it. My matched pair of SS springs have the right side higher than the left, by less than an inch. I would have said it was level, till I measured it. (Xxx456, and 457 springs)

 

[RemCharger]

"Many inches"? I doubt it. My matched pair of SS springs have the right side higher than the left, by less than an inch. I would have said it was level, till I measured it. (Xxx456, and 457 springs)

Agreed, maybe there isn't enough preload on the LF to begin with

 

[33 IMP]

The part number is stamped into the bottom leaf on mine. If you find yours, you can find if they are a matched pair. (Like xxx002, xxx003, or xxx456, xxx457)
I think there are at least four different weight car spring sets.

 

[fj5gtx]

The part number is stamped into the bottom leaf on mine. If you find yours, you can find if they are a matched pair. (Like xxx002, xxx003, or xxx456, xxx457)
I think there are at least four different weight car spring sets.

These springs are:
P3690454/P3690455

Front hanger kit is P4120105

 

[33 IMP]

Those are a matched pair for a 3800 lb car. They should be right for your car.

 

[Dave6T4]

Mopar Performance sold those springs as 3800 lb. B-body springs. I have them in my cars. The problem that I have had with them is the passenger side spring ( 0455 ) always sags. If you look at the 0454 driver's side spring, you will notice that the second leaf extends almost back to the main leaf shackle eye, for good support. The second leaf on the 0455 spring stops well short of the main leaf shackle eye. Over time, the increased weight of the B-body ( these springs were designed for A-bodies ) causes this unsupported section of the spring to bend down, resulting in this side of the car to sag. For this reason, I use 0454 springs on both sides of my B-bodies.

 

[fj5gtx]

Mopar Performance sold those springs as 3800 lb. B-body springs. I have them in my cars. The problem that I have had with them is the passenger side spring ( 0455 ) always sags. If you look at the 0454 driver's side spring, you will notice that the second leaf extends almost back to the main leaf shackle eye, for good support. The second leaf on the 0455 spring stops well short of the main leaf shackle eye. Over time, the increased weight of the B-body ( these springs were designed for A-bodies ) causes this unsupported section of the spring to bend down, resulting in this side of the car to sag. For this reason, I use 0454 springs on both sides of my B-bodies.

They must have been seriously overcompensating for that potential sag with extra arch. Do you drag race your car with those springs? If so, do they work well?

When I bought those leaf springs, I was expecting to run the Dana 60 (3.54) and didn't have any plans to lighten the car. Since then I've sold the D60 and replaced it with a 8-3/4 (3.91s), replaced the iron water pump and housing with aluminum, as well as dropping the 6pack iron intake setup for a 4bbl aluminum. I have not yet pulled the trigger on swapping my iron heads for aluminum (trickflow 240). If I go aluminum, I'll replace the iron HP manifolds with dougs or tti headers. Now I'm sorta regretting selling the extremely lightweight centerline wheels I had....

My goal is street/strip while keeping the 20ft appearance as original, minus wheel/tires and exhaust. I'm assuming the shorter stiffer front portion of the spring is effective with reducing axle wrap when launching. I haven't widened the inner wheel housings or modified the leaf mounts to put them on the frame rail. I'd rather not do it, if I can buy a tire/wheel combo that fits and has great traction.

 

[VANDAN]

If you do not want the height difference, and are not tracking the car, why not install 2 left side springs ? You'll gain some height for tire clearance, if that's what your needs are, but should even out, side to side...

 

[Dave6T4]

No, I don't actively race my car, although I have run it down my local track a few times. I mainly just wanted to pick the back end of my R/T a little bit. I think the 0455 spring has more arch to counteract torque squat on that side of the car. However, that higher arch will go away as the rear of the spring sags. It really needs to have a longer second leaf installed like the 0454 spring. This may defeat the engineered action of the spring for racing purposes.

 

[70rcode]

The original (1960's) Chrysler SS leaf springs were right side & left side Specific & mostly made in Canada & Designed & Engineered for Serious drag race Function (launching straight & Anti-squat) over Form Appearance (stock appearing Equal height) & deff had Unequal Arch ride height ....The later date MP branded "SS" springs seem mostly "made in Mexico" & might not be Exact original quality & durability....I never saw Arch height difference over 1" from a matching pair.....If using for Tire Clearance or Appearance purpose only, of course use the Same of either on both sides.....

 

[lewtot184]

No, I don't actively race my car, although I have run it down my local track a few times. I mainly just wanted to pick the back end of my R/T a little bit. I think the 0455 spring has more arch to counteract torque squat on that side of the car. However, that higher arch will go away as the rear of the spring sags. It really needs to have a longer second leaf installed like the 0454 spring. This may defeat the engineered action of the spring for racing purposes.

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i like the looks if nothing else. i like stock ride height, the yellow, and torque thrust. you might find some AR Engineering front brackets with the dual holes to help with left to right ride height.

as i think about it, what's wrong with the street hemi springs those cars came with? they'll give good ride height and will handle more power than people think. also, they can be bought from Springs and Things in 1" or 2" more arch.

 

[70rcode]

If you're Replacing factory stock Mopar OEM street Leaf springs for high performance Street use, Might as well select from the "Factory Super Stock" series which by their Anti--Squat leaf Bias design generate axle Separation body Rise to significantly Improve tire Traction without additional hardware.....Most All factory Mopar street Oem leaf springs (without Slapper Bars) Squat during Acceleration regardless of Arch height.....