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Old 05-11-2010, 03:46 PM
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How low can I go?

I have installed a set of rear parallel leaf springs with a 6" arch and I want to de-arch the springs by 4". There are 5 leafs in the springs. If I remove one or two leafs to lower the set point, will I be compromising the spring's resistance to spring wrap under accelleration/deceleration loads? If I remove one or two leafs, which are the most preferred to be removed? I have checked out the KNOWLEDGE BASE and did not find any discussion that discussed this question in any great detail. Your advice and ideas are welcomed.
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Old 05-11-2010, 08:07 PM
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you can take out the bottom one or two leaves (sometimes)
how heavy is the car? how much horsepower?what kind of use?
does the springs second leaf go full length?
i have cut bottom leaves in half leaving the front half to work like a traction bar helping with the wrap
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Old 05-12-2010, 08:12 AM
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Matt,
The rear axel total weight is 1,730 lbs. After deducting the wieght of the axle, sway bar, wheels, tires, brakes, springs and brakes the total weight is 1,390 lbs. Dividing that in two results in 695 lbs per wheel. That weight consists of the body, bumper, interior, spare tire, jack, 16 gallons of fuel, fuel tank and exhaust system.
The motor is an L84, 5.7L GM 350 linked to a 700r4 and the rear gear is a 3.42 posi-12 bolt GM axel. Horse power is estimated at 300. Intended use is as a street rod/cruiser. The second leaf covers about 75% of the longest leaf.
Have you been satisfied with removing the back half of the second leaf? Did you go any further by removing the back half of the third leaf? Did you get the lowering you were expecting? Did the modification adversely affect handling or spring carrying capacity?
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Old 05-12-2010, 08:42 PM
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of course the best is to leave as much and as many as you can
do you have any other choices such as fliping or a longer shackle
or blocks
a smaller version of the lowering block, is you can put a couple of the smallest bottom leafs onto the top of the spring
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Old 05-13-2010, 07:47 AM
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Matt,
I might consider blocks as a last resort. I do not like them because of the eccentric loading that occurs when they are used. Changing shackle length is not possible. They are already as short as possible. Flipping leafs around does not seem right either because it will result in gaps between the leafs. That would be weird.
I'm going to try removing the shortest leaf and the third shortest leaf and see what that does.
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Old 05-13-2010, 01:04 PM
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I removed 2 of the 4 leaves in my S-10's spring pack. It did soften the ride a bit, but there was no change in ride height. I did this to allow my Cal-trac's to work better.

Russ
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Old 05-13-2010, 06:33 PM
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does the spring shackle go from the mount on the frame down to the spring or up to the spring
does the spring mount under the frame or outside of theframe?
we've taken spring shackle mounts that are on the outside of the frame off
and turned them over so the shackle goes up to the spring

if you take the bottom couple of leaves out you can replace them with small plates on top
to take up the space on the bolt that hold them together and it also works like a small lowering block
with out the major crazyness that blocks create
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Old 05-22-2010, 08:10 PM
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UPDATE!

OK. So I removed the number 3 leaf leaving 4 leaves. I then had the springs de-arched 2.5". All was going well. I reattached the springs to the car. Had everything set up. Mounted the first wheel and was in the process of lowering the car onto the wheel when .........WHAM! The spring snapped! At the rear knuckle! It looks like when the springs were de-arched, the mechanic decided he didn't like the center bolt bushing fit. So he replaced it with a tighter fitting one. I think what happened is when I bolted the shackle together, the bushing did not rotate in the spring eye as the load of the car was applied, stressing the spring into failure. Good thing the springs are new and the manufacturer's warranty will cover the replacement. What a downer! I was ready to take the car out for its maiden run until that happened. So now I have to wait to see if the ride height is right once I get the replacement spring on.
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