Trying to get rid of choppy ride

punchdrunk monkey

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I have a new to me Alumicraft prerunner. I have only driven it a few times and the front end is pretty choppy on the smaller stuff. It has 35" tires, 2.0 coilover/air shock, 2.5 three tube bypass (short compression is a gold valve, long compression and 1 rebound). Valving is (I think) 3.2/30. I'm running 200 psi in bypass and 150 in air shock. I put a gopro on the front last week and I noticed the secondary spring does not come into play until the last few inches of travel.

I went testing last weekend and here is what I have. First, I have never tuned a shock with a gold valve. I understand the concept that it controls everything. I also have not messed with the airshock pressure.

First run- Rebound was way loose. After a bigger hit, you could feel the front tire slam down hard. It felt like if you had a belt in your hand and pulled it tight quickly, the snapping. I kept tightening the rebound until it was all the way in. Now the rebound felt the best. I backed it out a 1/2 turn just so it wasn't closed off.

Now I wanted to see what the gold valve did, so I went all the way in with it and did a run and then all the way out and did a run. All the way in, everything was rough, all the way out felt better but the bigger hits were too soft. Also rebound issues again. So I ended up at 3 turns in. This seemed to be the best.

Now with the gold at 3 turns in, I was planning on tighting up the long compression and see where that would put me. Unfortunately, I ran into a few other technical difficulties that ended the session.

Here is where I ended up-
**I know I need to add more rebound as it was maxed out. I was going to go to a 40 shim stack, because I have it. Although I think I should go to at least 50, maybe more??
**The car was still rough in the small stuff but better overall. I would still like it softer for the first half of suspension and a little stiffer on the big hits.

Any ideas out there? Maybe lower pressure in airshock and then lower collar to get the heavy spring more involved? Remove the gold valve and replace with a compression?
 

punchdrunk monkey

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Drop the air shock pressure to 50 psi.
Thanks. Do you know what the working pressure is for an air shock (min-max PSI)? Bill told me that a 10 psi drop makes a big difference. I ran into other issues before I could play with the air shocks.
 

tinman

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Ditch the air shock shaft and replace it with a std Fox 2.0" X .875" 8.5" or 10" travel (depending on which model of alumicraft) shaft assembly. And if you leave that air shock assembly in there do not run more than 10psi!!!
 

*TRD*

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In addition to converting the air shocks I'd ditch the gold valve.
 

punchdrunk monkey

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I did another day of testing yesterday. First thing was lower the air in the "air shock" to 50PSI. This made a huge difference, all the harsh chop was gone! But is also did what I expected and the rest of the travel was too soft. A few turns on the gold valve and the final compression and the big bumps felt better.

I did notice the secondary spring almost never comes into play, maybe the last 1"-2" of travel. I wanted to slide the collier down a bit to get the secondary spring working a little more but I couldn't get it to spin. The springs are 250 top and 275 bottom. I'm not sure if it will make too much of a difference but it can't hurt to try it. I'm going to pull the shocks off and free up the collier. It will be much easier with the springs off.

Another question- When writing number of turns on the bypass tubes, is the number the amount of turns out (from fully closed) or number of turns in (from fully open). What is the industry standard?
 
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"Turns out" in my experience.
 

Goatpoker

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Moving the crossover point should be a step in the right direction. You'll move from 130lbs/in to 275lbs/in. That's a lot more spring rate to work with.


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cosmo

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What valving(if any) is in the air shock? Oil volume correct?
 

punchdrunk monkey

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What valving(if any) is in the air shock? Oil volume correct?
No valving. I don't remember the exact amount of oil but it's not very much, like a couple of cups? When I took them apart, I measured the oil and replace the same amount.
 
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