Lift arm shock

[hunterracing]

What are affects goin from say 2.5c 7r to more compression and little more rebound

[RCJ]

I run my shock more forward on the bigger tracks then move it back on the short tracks.When you move it back it does change the motion ratio some ,so going stiffer on the shock makes sense.Just adding compression will make it hook a little harder but the sweet spot for staying hooked gets narrower.One thing I did on a modified and I know people that have had this problem on a l/m, is to get the lift arm hitting so hard and quick that it hits the chain on the l/r the starts lifting the r/r till it comes off the spring.Then gets erratic on corner entry when it comes down.

[junebug]

What did u do that caused it to do that???

[RCJ]

When I had the r/r lift off the spring it was on a modified with a pull bar.The mount above the rear end was in front of the axle centerline with a long pull bar.A friend of mine had his shock to far back and preloaded on a big track on a l/m with a lift arm.There are videos on you tube of a l/m coming off the spring.

[hunterracing]

What's that got to do with a little more stiffer compression and more rebound on lift arm shock

[RCJ]

I thought Junebug was asking how it lifts off the r/r.

[hunterracing]

Oh ok oh ok

[junebug]

U were saying how u had it hitting extremely hard...I mean on a lot of cars rr spring has 3/4 compressed height or so...with steep rr upper bar it's easy to make it lift off spring...but I was more asking what u were doing different that made it made more traction

[hunterracing]

Any. Body on some shock help?

[MasterSbilt_Racer]

More rebound, tighter entry. More compression? It depends...

[hunterracing]

Say compression is 2.5 now

[Stede Bonnet]

Say compression is 2.5 now

How much more?
If you go too stiff it won't hook up. Way back when I was a teenager, before I went to work at Carrera, the car I was working on tried using a dummy on the 5th arm. This created all sorts of weird reactions. When the driver would throttle up on exit at first it would hook, then suddenly let go, then suddenly hook again... It wouldn't finally bite till the flag stand. This resulted in my meeting D!ck Anderson from Carrera shocks for the first time. The car owner was perplexed by the cars behavior and we ran into D!ck later in the week and told him what was tried and how it responded. He had a look of shock and humor come across his face and explained it like this. Running the dummy shock on the 5th was like taking the spring and standing it up on the shop floor and hitting it with a sledge hammer. The spring compresses, but there is nothing to dampen the stored energy and it just violently fires back! I only mentioned this to demonstrate one extreme on dampening the 5th arm, the traction is actually in the spring, not the shock.

All things being equal(same length 5th arm, etc.), going softer makes the car hookup quicker, going stiffer delays the car hooking up. Think of a shock as a kind of a timer for the spring, but there is a narrow range for optimum performance, probably 2-4 on compression. Now if you get really short on the 5th arm length the useful range will need to be stiffer in order to control the torque.