Rear suspension too stiff

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68original

68original

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I just purchased a 68 Fastback, Formula S 383 4 speed car with what I assume are super stock leaf springs and QA1 shocks. Previous owner had homemade traction bars on it that were crap, so I put correct shock mounting plates back on.

QA1's are adjusted maximum soft, but still rides like the proverbial "lumber wagon". I don't mind a stiffer ride, but this is too much on the extreme side for my liking. I have no idea what the spring rate is on the leafs.

Here's the question - is removing one or two of the leafs from the leaf springs an option to soften the ride vs. purchasing different leaf springs? Leafs have 6 springs.

Looking for options before spending $100's on different springs.
 
The best long term solution to your problem (in my opinion) would be a spring and shock replacement.

I would get mopar XHD springs (in theory these are a stock replacement for Formula S springs) and KYB rear shocks.

You can recover 1/3rd to 1/2 of the money you spend be selling your old stuff here.
 
Did you torque the shock plate u bolt nuts correctly? They are only supposed to be tightened to 45 LB FT. Over tightening them can result in a harsh ride.
 
RustyRatRod said:
Did you torque the shock plate u bolt nuts correctly? They are only supposed to be tightened to 45 LB FT. Over tightening them can result in a harsh ride.
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RustyRatRod, is this for real? Maybe I'm naive, but I don't see how the torque of that shock plate would affect the ride. Or are you just yanking our chains? If it is so, could you please explain?
 
1967 'cuda said:
RustyRatRod, is this for real? Maybe I'm naive, but I don't see how the torque of that shock plate would affect the ride. Or are you just yanking our chains? If it is so, could you please explain?
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he told me this before and ive really been thinking about it... the leaves are already bolted together with that stud so i dont know what the u bolt tq would change. the leaves can not move fore and aft due to that...
 
1968FormulaS340 said:
It would only take 10 minutes to re-torque those bolts and it doesn't cost anything. May as well try it.
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The ride on my '67 Barracuda is awfully stiff (the same as 68original described). So I guess I'll try that torque technique RustyRatRod suggested. - But it still doesn't make sense to me. I need to finish up my rear brakes this weekend after parts arrive. I'll post back in a few days to let you know if the ride improved.
 
No, I was being dead serious.

It will also help if after you loosen the nuts, then bounce the car up and down in the rear and then retorque the nuts to 45 LB FT.
 
I never thought of it before, but to me it makes sense. Unless its a bushed mounting point, I guess, nothing in a suspension should be "fixed" or held in place without some type of movement. Those individual leaves still move, I think all the center bolt does is keep them moving together. It makes sense that if the u-bolts are too tight, you would be clamping the center of the springs together and not letting them do their full job of suspension peices. Hmmmm...pretty awesome idea.
 
1968FormulaS340 said:
If you turn your rear view mirror so it's facing forward then floor the car in reverse you will go backwards in time.
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Dammit. Is that all it takes? I need to go back and correct a LOT of screw ups.
 
Thanks for all the responses.

I'm sure the nuts are WAY over-torqued so I will try that first. I've been leaning towards the KYB shock option also as the QA1's are overkill for me. Fronts are Monroes so probably replacing all 4 as have no idea how old the fronts are.

Will post when shock swap is done if anyone interested in the QA1's. Single adjustable if you are wondering.

If all fails, I'll turn my mirror around, drive real fast until I reach the time when the previous owner did all of this suspension change and slap him silly. Ha!
 
Another question - are part numbers stamped on the leafs to determine exactly what I currently have? They are pretty clean so should be easy to spot, just wondering where to look to save time.
 
I got my '67 back on the road after re-assembling my rear brakes. I backed off the u-bolts a few turns and then torqued them to 45 ft lbs. Although it's really hard to quantify the difference in ride, I do believe the ride feels less stiff. I guess RustyRatRod may be right.
 
Guess i will be torquing mine too!!!


1967 'cuda said:
I got my '67 back on the road after re-assembling my rear brakes. I backed off the u-bolts a few turns and then torqued them to 45 ft lbs. Although it's really hard to quantify the difference in ride, I do believe the ride feels less stiff. I guess RustyRatRod may be right.
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Superstocks really don't ride well. Have them on one of my cars & ride is really stiff as well. Now the car does feel solid when I'm rowing the gears but otherwise I'd never recommend them for a 90% cruiser.
 
Make sure you have the correct length shocks. SS springs require longer shocks. If your shocks are to short, you will get alot of noise ,which could be mistaken for a harsh ride.
 
isolate the issue....

unhook the shocks and see how it bounces....if still too stiff...change/ check into different springs

if bounces easy....check into different shocks

usually the springs hold up the car and the shocks dampen the bounce....but as memory serves, the super stocks are fairly stiff
 
I know this is an older post, but since you just bought it last fall, have you checked to see if the previous owner installed frame connectors ? That will give you a stiffer ride.
 
70 DUSTER CRATE said:
I know this is an older post, but since you just bought it last fall, have you checked to see if the previous owner installed frame connectors ? That will give you a stiffer ride.
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really?....how so?

the too tight nuts thing was news to me....and now this? I need to go back to school.
 
HemiDenny has the right idea. Check to see if your Shakels are too tight, they do need to "Swivel" forward and backward. Could your Leaf springs be too long ? When you re-torqued the "U" bolts 68origional did it help ?! The suspence is killing US ! (or just me ) Let us know. Thanks, Tim
:thumleft:
 
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