Leaf spring and alignment
Thread Starter
Racer
Joined: Jul 2009
Posts: 337
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From: South Bend IN
NCM Sinkhole Donor
Leaf spring and alignment
I just finished the suspension on my '79 and I have realized the rear of the car is higher than the front and I would like to lower it some. I have some room on the bolts to lower but I just had it aligned and I don't want to screw up the alignment. How much will lowering the rear affect my alignment?
Melting Slicks
Joined: Feb 2006
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From: Japan
Lowering the rear will ADD caster to the front, which will give you a little more self-centering as well as adding some effort to the steering. I'm not very good at trigonometry right now but there are reasonably simple formulae (yes, that's how you spell it!) for converting inches over a given span (the wheelbase) into degrees. Whatever degrees you remove from the car's 'rake' will be added to the caster, so dropping the rear an inch would add roughly a degree to whatever caster number you're at now.
Thread Starter
Racer
Joined: Jul 2009
Posts: 337
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From: South Bend IN
NCM Sinkhole Donor
Actually that picture was taken before I put the new spring in the rear. It actually sits a little higher than that now.
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Racer
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From: South Bend IN
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Drifting
Joined: Jan 2008
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From: Schererville IN
Did you also replace the front suspension???? Is the front also sitting higher than before? If not, lowering your rear back down would only put your specs back to what they where. (assuming the front suspension is still the same)
Either way, changing the rear ride height a little bit won't affect handling that much. If you changed front and rear suspension, your in need of an alignment anyway.
Either way, changing the rear ride height a little bit won't affect handling that much. If you changed front and rear suspension, your in need of an alignment anyway.
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Thread Starter
Racer
Joined: Jul 2009
Posts: 337
Likes: 7
From: South Bend IN
NCM Sinkhole Donor
Did you also replace the front suspension???? Is the front also sitting higher than before? If not, lowering your rear back down would only put your specs back to what they where. (assuming the front suspension is still the same)
Either way, changing the rear ride height a little bit won't affect handling that much. If you changed front and rear suspension, your in need of an alignment anyway.
Either way, changing the rear ride height a little bit won't affect handling that much. If you changed front and rear suspension, your in need of an alignment anyway.
Drifting
Joined: Jan 2008
Posts: 1,962
Likes: 5
From: Schererville IN
Yes, I did change the front suspension as well. The front sits lower now with the new springs and I'd like to get the rear a little lower. I had a shop do most of the front and then had it aligned so I didn't notice the difference until it was aligned. I just don't want to spend another $70 for an alignment just because I made a change for looks.
Setting the rear ride hight to the same hight as the old spring will put your specs back to the aligned setting then. No issue unless you moved shims on your trailing arms. If you leave the rear high, your alignment specs are now off.
Or was the car aligned after the rear spring install?
Thread Starter
Racer
Joined: Jul 2009
Posts: 337
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From: South Bend IN
NCM Sinkhole Donor
So the car was aligned after the front was rebuilt? Correct?
Setting the rear ride hight to the same hight as the old spring will put your specs back to the aligned setting then. No issue unless you moved shims on your trailing arms. If you leave the rear high, your alignment specs are now off.
Or was the car aligned after the rear spring install?
Setting the rear ride hight to the same hight as the old spring will put your specs back to the aligned setting then. No issue unless you moved shims on your trailing arms. If you leave the rear high, your alignment specs are now off.
Or was the car aligned after the rear spring install?
Drifting
Joined: Jan 2008
Posts: 1,962
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From: Schererville IN
Thread Starter
Racer
Joined: Jul 2009
Posts: 337
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From: South Bend IN
NCM Sinkhole Donor
Le Mans Master
Joined: Apr 2007
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From: Graceland in a Not Correctly Restored Stingray
FWIW, and just to make sure nobody mistook that parallel half-shafts (with the road) is a goal, due to C2/C3 rear toe-steer characteristics such an arrangement doesn't make for the best geomtry when the rear suspension travels into bump or squat.
Race Director
Joined: May 2006
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TheSkunkWorks:
Looking at this dated publication http://www.corvettefaq.com/c3/ChevyPower.pdf on page 6-6 and 6-7 they have a diagram where they show the height difference between the inner and outer strut rod mounting points of 1 1/4". I have found this results in the half shafts being parallel to the ground. How does this publication tie in with your comment about rear toe-steer and parallel not being a goal, thanks.
Looking at this dated publication http://www.corvettefaq.com/c3/ChevyPower.pdf on page 6-6 and 6-7 they have a diagram where they show the height difference between the inner and outer strut rod mounting points of 1 1/4". I have found this results in the half shafts being parallel to the ground. How does this publication tie in with your comment about rear toe-steer and parallel not being a goal, thanks.
Last edited by MelWff; Aug 11, 2011 at 05:15 PM.
