Cobra swerves when backing off the throttle!!

[FatBoy]

It may just be the angle of the photo, but that top bolt looks like it's half way out. If so, that may also account for the broken top bush if it is moving and flexing.
You can't possible start fine tuning your suspension until everything is sound and bolted up tight.

Paul

[RICK LAKE]

commercialcobb.What have you done to the car? Built it, brought it new assemblied, brought it used? I am trying to get get a base to work with. To start with are you runnning a complete iron 429-460 motor in the car?
Have you started at the front of the car and check and tighten every nut and bolt?
Do you have the correct tire pressures in all 4 tires?
Have you measured the ride height in all 4 corners and is it level with your weight in the drivers seat?, If not you need to adjust it.
What shocks and spring rate are on the front springs?
Are the motor mounts tight and not split where it goes to the frame?
Any chance you have an alignment sheet of specs for the car?
Any change of a short video of this happening? can you get it here on the forum? this would be a big help in seeing what happening.
If you have a dirt track friend in the area, see if he will let you weight the car in 4 corners to start. Make sure your body weight is in the drivers seat. After this, go and align the car, About +1/2 degree of camber each side, +3.0 degres of caster l/s. +3.3-3.4 on the r/s. toe in the car about 1/16" and road test it. See if the car is still all over the place. If not you are good to go.
If you still have a problem I would be looking at the front shocks and spring rates. Both are too soft of the car. If that motor is all iron, thats about 700 lbs. You could have the wrong setup in the front end or the shock valving could be broken. Springs being too soft will also cause this problem.
Let's start at the top of the list and get the basics done first. Check for arms for play when you check for the bolts and nuts to be tight. Check the wheel bearings, ball joints, and bushings for play. If you find some repair and recheck. Tierod end play for none and play in the steering rack or dead spot on center. You would feel a small knocking noise through the steering wheel. The picture you showed us, is the suspension under load? IMO there is not enought clearance between the spring coils for them to work correctly and cause the car handling to be all over the place with coil bind. You should have about 4" of travel from loaded to unloaded in each corner. I am getting ahead of myself. Let's look at the beginning and go from there. Rick L.

[commercialcobb]

Originally Posted by RICK LAKE

commercialcobb.What have you done to the car? Built it, brought it new assemblied, brought it used? I am trying to get get a base to work with. To start with are you runnning a complete iron 429-460 motor in the car?
Have you started at the front of the car and check and tighten every nut and bolt?
Do you have the correct tire pressures in all 4 tires?
Have you measured the ride height in all 4 corners and is it level with your weight in the drivers seat?, If not you need to adjust it.
What shocks and spring rate are on the front springs?
Are the motor mounts tight and not split where it goes to the frame?
Any chance you have an alignment sheet of specs for the car?
Any change of a short video of this happening? can you get it here on the forum? this would be a big help in seeing what happening.
If you have a dirt track friend in the area, see if he will let you weight the car in 4 corners to start. Make sure your body weight is in the drivers seat. After this, go and align the car, About +1/2 degree of camber each side, +3.0 degres of caster l/s. +3.3-3.4 on the r/s. toe in the car about 1/16" and road test it. See if the car is still all over the place. If not you are good to go.
If you still have a problem I would be looking at the front shocks and spring rates. Both are too soft of the car. If that motor is all iron, thats about 700 lbs. You could have the wrong setup in the front end or the shock valving could be broken. Springs being too soft will also cause this problem.
Let's start at the top of the list and get the basics done first. Check for arms for play when you check for the bolts and nuts to be tight. Check the wheel bearings, ball joints, and bushings for play. If you find some repair and recheck. Tierod end play for none and play in the steering rack or dead spot on center. You would feel a small knocking noise through the steering wheel. The picture you showed us, is the suspension under load? IMO there is not enought clearance between the spring coils for them to work correctly and cause the car handling to be all over the place with coil bind. You should have about 4" of travel from loaded to unloaded in each corner. I am getting ahead of myself. Let's look at the beginning and go from there. Rick L.

To start off: My step dad said this problem existed 4 years ago before it entered the shop. Yes the guys in the shop had it 3 years before I came into there shop to finish the job. They have lost their arse on this complete overhaul and wouldn't put anyone on it so I stepped up. Reason I posted this question is because he has expressed major concern about it but I have not seen it myself. It will be on the road this week and he swears it will still do it, and the pic I showed it is the shock under load and the bolt has since been tightened. Old pic.

1. Yes, Iron 429-460.. 2. Bolts will get an entire recheck.. 3. Tire Pressures will be exact.. 4. Ride Height has not been checked.. 5. Shock and spring rate unsknow.. 6. Motor Mounts are new and tight.. 7. No video yet.. 8. No alignment yet.. 9. Do know some dirt track guys, will have them weigh it.

[FWB]

the rear spring, as someone else had mentioned, has no travel, when it crushes the force is transferred to the frame, the frame then twists under torque and the car torque steers. let off the gas and torque is removed spring relaxes frame relaxes. springs are wrong at the least. the bushings are toast because they are first in line receiving all of the pressure.

[kitcarbp]

I agree with Rick and FWB having "pinned" it as rear coil spring bind and as FWB pointed out with no spring travel (if fully compressed at normal ride height) , the shock bushing is being hammered to a pulp. In any case it has to be in the rear suspension for such a drastic change in yaw under power.

[commercialcobb]

Originally Posted by kitcarbp

I agree with Rick and FWB having "pinned" it as rear coil spring bind and as FWB pointed out with no spring travel (if fully compressed at normal ride height) , the shock bushing is being hammered to a pulp. In any case it has to be in the rear suspension for such a drastic change in yaw under power.

I think your both right and this will be my first course of action that I take to fix this dangerous condition. Also "kitcarbp" I like your use of the term "yaw" as I am a pilot and that makes perfect sense to me. In aviation "yawing motions" can have dramatic affects on aircraft perfomace and handling so now you have given me my first clue as to the extent of what all this means. I'll let you guys know what the outcome is. By the way, how can I tell what the spring weight is? Is it stamped on the spring? Also by loosening the adjustable spring, is that only going to raise up the rear end?? The car already sits higher than I'd like. Are springs universal or do I need a spring to fit my coil? Let me know what to do first and I can take it from there I think.. Thanks fellas again for everything!!

[Bryan Wilson]

That shock looks coil bound where the coils are close together not allowing the shock to travel in a downward direction. Just my 2c worth.
Cheers,
Bryan