Exposed shock shaft length at ride height ?

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johnh
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Exposed shock shaft length at ride height ?

#1 Post by johnh » Wed Aug 12, 2009 11:47 am

On a drag car with leaf springs and sliders, caltracs, rancho shocks.

How much (length) exposed shock shaft should be seen between upper shock mount and body of shock?

1, 2, 3 , 4 inches?

We are not worried about ride quality at this point, this car see's no street time now a days.

Thanks :thumb:
6.01 @ 116 on 9 Inch Slicks

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John_Heard
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Re: Exposed shock shaft length at ride height ?

#2 Post by John_Heard » Wed Aug 12, 2009 12:20 pm

Depends really on how much travel you have in the shock. Most leaf springs cars need to have the majority of their travel available for extension because the rear will separate from the body at launch. My car has about 1.5-2" of shock showing at rest.

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johnh
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Re: Exposed shock shaft length at ride height ?

#3 Post by johnh » Wed Aug 12, 2009 12:51 pm

Thanks John "My car has about 1.5-2" of shock showing at rest."

I had 3-3.5 inches, then I relocated the bottom shock mount hole position and it left me with 1-1.5 showing at rest. I was worried because with the rancho setting on 5, I can push down on the rear of the car a bang the shock.

should be ok then.....?

Just curious as I really never measured it, how much shaft or travel is typically in the shock.
Did I word that right?

Thanks
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Re: Exposed shock shaft length at ride height ?

#4 Post by John_Heard » Wed Aug 12, 2009 12:58 pm

The compression is a LOT tighter than that on my car. You can not push down on it and run out of travel, well I can't anyway... But I have some shocks that can be set very stiff if need be. On your rancho's you may have to find a happy medium, You don't want to run out of travel in either direction or it will beat the shock up.

The amount of travel depends on your shock. I don't know how much travel the Rancho's have. Take one end off and see how far it will extend.

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johnh
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Re: Exposed shock shaft length at ride height ?

#5 Post by johnh » Wed Aug 12, 2009 1:11 pm

Thanks
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Re: Exposed shock shaft length at ride height ?

#6 Post by John_Heard » Wed Aug 12, 2009 1:18 pm

I forgot to mention - how stiff the shock is will also effect travel a lot. A soft shock on a leaf car may extend easily 4" on a hard hit and run out of travel. That same amount of travel is no problem on a stiffer extension shock.

You might want to rig up some kind of witness marks to detect how much travel you're getting in both directions during a pass.

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Re: Exposed shock shaft length at ride height ?

#7 Post by johnh » Wed Aug 12, 2009 1:31 pm

A cable wire tie around the shaft of each shock, one up high and one down low on sep shocks should do the trick, huh?

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Re: Exposed shock shaft length at ride height ?

#8 Post by John_Heard » Wed Aug 12, 2009 2:44 pm

A wire tie will tell you how much it compresses, but not how much it extends. Also, be careful with those, sometimes a wire tie can get stuck inbetween the shock shaft and seal and bind a shock up.

There are probably a number of ways to make an indicator, but here's the general concept

Image

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