Excellent post from
@FasterNU deserves immortalization here:
Quoted from A-A-Ron:
With these "rate plate" set ups... what I am mainly looking at is the distance from the first shim that is covering the piston holes to the flexible or inflexible plate. Basically, the largest diameter shim is what has to bend first to allow fluid to pass thru the piston. Just for the sake of it, I am going to call the largest diameter shim the main shim. I am also going to call the thick factory rate plate a "real rate plate" ... again, just for the sake of discussion.
If you make a short distance from the main shim to a real rate plate.... once you hit a certain amount of flow, the main shim will hit the thick rate plate washer... and will not flow anymore. Playing with this distance is going to change the max flow. Playing with the shims in between this distance is going to affect how it behaves before it gets to that max flow.
So, add up the distance from the main shim to the "rate plate". In DoDah's case... he has .032" of distance before his main shim will hit his 1.5 x.020 "flexible rate plate". So, once that main shim bends .032", it will hit that flexible rate plate. In his case, if it needs to flow more, it still will because it is thin enough to bend ... although it will become much stiffer at this point. If he would have left the 1.5 x.062(real rate plate) ... it basically would choke it off at .032".
With a top mounted reservoir shock like a coil over, once you hit that wall where there is no more flow ... it's going to push that column of oil into the reservoir, AKA cavitation. (And create a nice pressure spike, and create a shit ton of heat and start cooking that oil)
Now, you still have some options with the middle shims between the main shim and rate plate too. If you make the second shim a smaller diameter than the standard diameter second shim, it's going to let that first main shim bend easier at first. Play with the diameters and heights here to get the desired ride. Most of the initial feel seems to be in that first shim or two. Larger diameters on the small higher speed shims will stiffen things up. Thinner shims can also make it stiffer. That might seem backwards, but think of the column of metal disks and height you are creating and it will make sense.
FWIW, I had a real rate plate set up on 2Ghetto before I installed the front bypasses. I was at .028" distance. I could not flow any more than whatever amount of oil could squeeze past that .028" of distance. It actually worked real well. I've been wanting to play with a flexible rate though, because I feel like hitting a wall of flow can't be the most desirable thing. I will probably do this in my brothers truck, G3. Right now he has .030" of distance to a real rate plate on his front coil overs.
Now, let's look at what barge did below. As you can see, he still kept that real rate plate in there. However, he has what is mostly a traditional pyramid stack (small flutter on main shim) ... then there is a flexible rate plate which is 1.65 x.020..... which he has spaced .100" off of the real rate plate.
I had read before that the shims don't bend much more than like .050" ... but barge has called BS on that, and I believe him.
Compression:
1.65x0.012”
0.90x0.008 flutter fulcrum
1.5x0.012”
1.35x0.015”
1.2x0.015”
1.05x0.015”
0.90x0.015” (what is the point of this shim?) Spacer for this vvvvv
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 1.65x.015
0.90x0.100” washer
1.5x0.062” plate
So, total flow in this case(if you can get everything to bend that far) would be .080" until you hit the flexible rate plate ... and then .100" more distance until you hit that wall. So, the grand total there would be .180". That seems like quite a bit to me... but hey, it never hurts to try it!
Happy tuning! I am going to work on posting up some videos from this weekend. We went testing in Plaster City with the new bypasses on BroDaddy, my new settings on 2Ghetto, and G3's rear end with the free bleed plugged in the back. We were running 3 wide for a bit too. Big fun!
Oh, and LOL at the "astute reader" noticing the bolt slots on your last posts. HAHAHA.