Grime's Spec Koni Shock Dyno Plots - Q's and C's
03-31-2010, 12:16 PM
#41
Former Moderator
Originally Posted by TheNick,Mar 31 2010, 12:36 PM
He even gave me the line "Rebound increases grip" - ha, my ass it does...
I wonder what the thought process was? Even if it was that the car stays flatter you're still loosing grip on the outside tires from bumps and even though the course looks smooth there's still enough bumps to cause issues.
If you walk around the paddock of an afm race it's so easy to tell who's running too much rebound but I haven't seen the same thing with cars?
I think the easiest and quickest way to learn that too much rebound will slow you down is to stick them on a bike with too much rebound. They'll wonder why they can't go faster and why their tires are torn up.
03-31-2010, 12:25 PM
#42
With the talk of "too much rebound" what are some examples? Do any of the popular shock offering have "too much" of either? As I stated before, I ran the auto-x spec Konis, revalved them higher for Nationals, and now the TC Kline DAs (only 50% though). Would any of these have too much of onne or the other for auto-x? The custom revalved Yellows performed great for me at Nationals last year (maxed out) and improved upon the current auto-x valving, yet it seems they were valved wrong based on the comments here. While many of the views here make sense, the opposite proved fastest for me. What gives?
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
03-31-2010, 12:26 PM
#43
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Originally Posted by TheNick,Mar 31 2010, 11:36 AM
Has less to do with cavitation for autox and more to do with compression valving. Twin tube and non-remote reservoir monotube shocks MUST HAVE GAS PRESSURE to have compression damping. If you have no gas pressure - then you have really inconsistent compression damping.
So on a twin tube shock - the amount of gas pressure increases the compression damping. On a reservoir shock - it doesn't. It can increase the stiction and nose angle (initial movement of the shock). It also preloads the spring. It can add spring rate - but not in the same way as a coil spring.
So on a twin tube shock - the amount of gas pressure increases the compression damping. On a reservoir shock - it doesn't. It can increase the stiction and nose angle (initial movement of the shock). It also preloads the spring. It can add spring rate - but not in the same way as a coil spring.
03-31-2010, 12:58 PM
#44
Former Moderator
What is really considered low speed?
From looking at the dyno that Matt posted it looks like low speed is 0 to roughly 2.0 seconds and med starts at roughly 2. It varies with the adjuster -and of course this is just on his shock, others will vary depending on valving.-
Would it be right saying that the adjuster doesn't do much for low speed until after 4 on up to 6?
-edit-
From looking at the dyno that Matt posted it looks like low speed is 0 to roughly 2.0 seconds and med starts at roughly 2. It varies with the adjuster -and of course this is just on his shock, others will vary depending on valving.-
Would it be right saying that the adjuster doesn't do much for low speed until after 4 on up to 6?
-edit-
03-31-2010, 01:05 PM
#45
Originally Posted by sirbunz,Mar 31 2010, 03:25 PM
With the talk of "too much rebound" what are some examples? Do any of the popular shock offering have "too much" of either? As I stated before, I ran the auto-x spec Konis, revalved them higher for Nationals, and now the TC Kline DAs (only 50% though). Would any of these have too much of onne or the other for auto-x? The custom revalved Yellows performed great for me at Nationals last year (maxed out) and improved upon the current auto-x valving, yet it seems they were valved wrong based on the comments here. While many of the views here make sense, the opposite proved fastest for me. What gives?
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
I'm sure with spring rates as low as stock and with tires as grippy as the Hoosiers, too much rebound is probably better than the craziness of having tons of kinetic energy manifesting in the chassis (roll). Shoot, even with stiff springs and stiff shocks, my car was a mess on street tires at Dixie.
03-31-2010, 01:11 PM
#46
Former Moderator
Originally Posted by Forcednduckshn,Mar 31 2010, 01:26 PM
Understood on gas pressure creating a preload and having an "added spring rate effect." Regarding your other thoughts, you're saying that because these Koni's (designed originally to be twin tube low pressure gas) are running with zero gas pressure, that it is having a negative effect on compression? Be more specific- will it lower compression damping across the range or only in a certain shaft velocity? Or are you just saying that because there is no gas pressure, there is increased likelyhood to cavitate, creating inconsistency in compression damping over the course of a run?
Hope this makes sense.
03-31-2010, 01:14 PM
#48
Originally Posted by sirbunz,Mar 31 2010, 03:25 PM
With the talk of "too much rebound" what are some examples? Do any of the popular shock offering have "too much" of either? As I stated before, I ran the auto-x spec Konis, revalved them higher for Nationals, and now the TC Kline DAs (only 50% though). Would any of these have too much of onne or the other for auto-x? The custom revalved Yellows performed great for me at Nationals last year (maxed out) and improved upon the current auto-x valving, yet it seems they were valved wrong based on the comments here. While many of the views here make sense, the opposite proved fastest for me. What gives?
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
With the last custom rebuild I did with the Yellows, I have Performance shock go higher with both the compression and rebound (fronts only). All new internals were purchased, but no gas pressure was added from my understanding. Sounds like I need to call and ask them the specifics to the rebuild...
I do know with the TC Klines, I was packing the inside front tire at Dixie.
-Marc
What gives is that you are fast in spite of your setup, not because of it.
03-31-2010, 01:29 PM
#49
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Originally Posted by TheNick,Mar 31 2010, 01:12 PM
Yeah I'm saying that basically the 0 gas pressure Koni's essentially have 0 compression damping (if its less than 100lbs at 3"/sec - its basically worthless). And yes its really inconsistent because of cavitation and you only get some at the bottom of the piston stroke after the gas/fluid becomes incompressible
The dyno's are all zero'd out to eliminate the gas pressure offset/effect on the plot. This makes plot's comparable to each other at different pressures.
The dyno's are all zero'd out to eliminate the gas pressure offset/effect on the plot. This makes plot's comparable to each other at different pressures.
03-31-2010, 01:31 PM
#50
Yeah like I said - a twin tube relies on gas pressure to get any compression damping at all. The problem is - if you add gas pressure - it doesn't just change the low speed. I have no idea how much it effects low/high speed separately. But if you have an imbalance in gas pressures on your 4 shocks - then you now have 4 different compression valvings too. Hence the goodness of remote reservoir shocks.