Model A Shocks Compression - Rebound

[Phred]

After installing both rebuilt and new (Brattons) Model A shocks i have found the following to be true:

The adjustability of the shock seems to affect the rate of rebound resistance much more than the rate of compression resistance. In other words, the resistance to compression is always relatively light while the resistance to rebound can adjust from relatively light to quite stiff.

Since this is the case in both rebuilt and new shocks I will assume that "that's the way they were designed".

What is the reason they are designed this way?

Wouldn't a more equal compression/rebound resistance be better?

Thanks in advance for any reasoned input.

[H. L. Chauvin]

Works similarly to a hand operated tire pump ...... hard to press down because of pressuring air in an enclosed tube ...... easy to pull up.

After installing new Stipe shocks, and after testing with a tool similar to Ford's Service Manual's indicated K.R. Wilson testing device, one can notice that 1/16" of a turn on the adjustment bolt can make lots of difference in resistance.

[Tom Wesenberg]

When you hit a bump you want the tire to ride up and over the bump, rather than pushing the whole car up. The slower rebound should help control the bounce after the bump.

[H. L. Chauvin]

As far as rebound, when one hits a bump, the shock resisting force is greater because it is like resisting hitting a railroad nail with a railroad maul ........

[Smog Tech]

Tom is right on!!

[updraught]

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There are often complaints about tube shocks giving a harsh ride on this forum. With the buggy springs, little resistance on compression will be needed.

Found this quick explaination for adjusting Koni shocks:

"Bump damping controls the unsprung weight of the vehicle (wheels, axles, etc.). It controls the upward movement of the suspension as when hitting a bump in the track. It should not be used to control the downward movement of the vehicle when it encounters dips. Also, it should not be used to control roll or bottoming.

Depending on the vehicle, the ideal bump setting can occur at any point within the adjustment range. This setting will be reached when "side-hop" or "walking" in a bumpy turn is minimal and the ride is not uncomfortably harsh. At any point other than this ideal setting, the "side-hopping" condition will be more pronounced and the ride may be too harsh."

Adjusting the REBOUND Damping Control

"Once you have found what you feel to be the best bump setting on all four wheels, you are now ready to proceed with adjusting the rebound. The rebound damping controls the transitional roll (lean) as when entering a turn. It does *not* limit the total amount of roll; it *does* limit how *fast* this total roll angle is achieved. How much the vehicle actually leans is determined by other things such as spring rate, sway bars, roll center, ride heights, etc.

It should be noted that too much rebound on either end of the vehicle will cause an initial loss of lateral acceleration (cornering grip) at that end which will cause the vehicle to oversteer or understeer excessively when entering a turn. Too much rebound control in relation to spring rate will cause a condition known as "jacking down." This is a condition where, after hitting a bump and compressing the spring, the damper does not allow the spring to return to a neutral position before the next bump is encountered."

From
WWW.bimmerhaus.com/tech/shocktuningTN.html

[Phred]

Thanks for the help!