propuckstopper
New member
Hi everyone. I just wanted to let you know that I have finally purchased a shock dyno! After attending the Performance Racing Industry show in Orlando, Florida a few weeks ago I realized that this was exactly the tool I needed to check all my rebuilds on circle track, snowmobile, and MX shocks.
The dyno runs the shock through its compression and rebound cycles and generates a computerized force vs. velocity graph. After using this dyno for only one week I am amazed when I see the differences in readings between what should be identical shocks. A friend brought over his well-used Polaris XC500 Fox ski shocks last night and we ran them on the dyno. After generating a baseline graph (which indicated the shocks were very weak), we rebuilt the shocks using 5W Amsoil Shock Therapy oil and dynoed them once again. Following that, we dumped the oil and tried 10W oil. The differences in the three graphs are astounding. The dyno is very sensitive to changes, and now my friend has a "baseline" to go off of. We can run his shocks again in a couple of months and see if they have "fallen off" any. Obviously, this dyno could save many people the costs of unnecessary rebuilds.
Let me know if you have any questions. I am located in Manitoba, Canada.
Have a safe and happy holiday season!
The dyno runs the shock through its compression and rebound cycles and generates a computerized force vs. velocity graph. After using this dyno for only one week I am amazed when I see the differences in readings between what should be identical shocks. A friend brought over his well-used Polaris XC500 Fox ski shocks last night and we ran them on the dyno. After generating a baseline graph (which indicated the shocks were very weak), we rebuilt the shocks using 5W Amsoil Shock Therapy oil and dynoed them once again. Following that, we dumped the oil and tried 10W oil. The differences in the three graphs are astounding. The dyno is very sensitive to changes, and now my friend has a "baseline" to go off of. We can run his shocks again in a couple of months and see if they have "fallen off" any. Obviously, this dyno could save many people the costs of unnecessary rebuilds.
Let me know if you have any questions. I am located in Manitoba, Canada.
Have a safe and happy holiday season!
Yama49601
New member
Sounds awesome to me. I've been doing a ton of reading about this type of thing lately (suspension and shock stuff). I never knew there was a dyno though for shocks. 
propuckstopper
New member
Shocks are very important. In fact, many racers (circle track, snowmobile, MX) will tell you that shocks are more important than horsepower. If you can't hook up the horsepower you already have, there is not much point spending money trying to make more horsepower. This is where knowing your shocks and how good or bad they are becomes very important.
As a side note, I tested two mini-sprint car shocks this morning. Both were "7500" Pro Shocks. These shocks actually tested very close to each other, so the driver of the car was pretty happy about that!
As a side note, I tested two mini-sprint car shocks this morning. Both were "7500" Pro Shocks. These shocks actually tested very close to each other, so the driver of the car was pretty happy about that!
propuckstopper
New member
Results From Shock Dyno!
Hi folks. I finally figured out how to convert a shock dyno graph to JPEG so you all could take a look at a "before and after" shock. The shock in question is from a 1997 Polaris XCR, and is made by Fox. It is a ski shock.
The first graph is the "before rebuild" graph. The graph shows the relationship of a given shock absorber as "Force vs. Velocity". Force is measured in pounds, while the Velocity is measured in inches per second. The numbers on the chart to the left that are important are shown in red and blue. Red is the Force (in pounds), while blue is the velocity.
While viewing the "Force" chart, you'll notice that the top half of the chart shows positive numbers (93, 155, 217, 310). This is the shock's COMPRESSION phase. The bottom half of the chart shows negative numbers (-85, -142, -198, -283). This is the REBOUND phase for the shock.
Okay, let's go over to the positive numbers and the compression phase. Let's take 155 pounds, which caused the shock to travel at 10 inches per second, and 217 pounds, which caused the shock to travel at 15.38 inches per second.
Now, keep those velocities in mind while you look at the second graph, which is the "after rebuild" graph. Notice the changes in the shock's characteristics. Although we have the same force of 155 pounds, the shock travels at just 5.88 inches per second, down from 10 inches per second before the shock was rebuilt. Obviously, the shocks is travelling LESS distance with the same force applied, telling us that its true damping charactersitics have been restored through the rebuild. To further support this finding, take a look at the 217 pound column. Before rebuild the shock travelled at 15.38 inches per second. Now, it travels just 10 inches per second. We went from a very soft shock to a good one here.
The funny thing about life before the dyno was this: I could take a shock, compress it down, and let it return. You could clearly see the shocks that were "very dead", but some looked OK because they returned to full extension with some smoothness. I now see just how innacurate that type of testing really is. The shock dyno shows EXACTLY what's going on at each pressure. For serious riders and racers alike, it's a great thing. I truly love the learning curve here.
Have a great Christmas and a Happy New Year!!!
Hi folks. I finally figured out how to convert a shock dyno graph to JPEG so you all could take a look at a "before and after" shock. The shock in question is from a 1997 Polaris XCR, and is made by Fox. It is a ski shock.
The first graph is the "before rebuild" graph. The graph shows the relationship of a given shock absorber as "Force vs. Velocity". Force is measured in pounds, while the Velocity is measured in inches per second. The numbers on the chart to the left that are important are shown in red and blue. Red is the Force (in pounds), while blue is the velocity.
While viewing the "Force" chart, you'll notice that the top half of the chart shows positive numbers (93, 155, 217, 310). This is the shock's COMPRESSION phase. The bottom half of the chart shows negative numbers (-85, -142, -198, -283). This is the REBOUND phase for the shock.
Okay, let's go over to the positive numbers and the compression phase. Let's take 155 pounds, which caused the shock to travel at 10 inches per second, and 217 pounds, which caused the shock to travel at 15.38 inches per second.
Now, keep those velocities in mind while you look at the second graph, which is the "after rebuild" graph. Notice the changes in the shock's characteristics. Although we have the same force of 155 pounds, the shock travels at just 5.88 inches per second, down from 10 inches per second before the shock was rebuilt. Obviously, the shocks is travelling LESS distance with the same force applied, telling us that its true damping charactersitics have been restored through the rebuild. To further support this finding, take a look at the 217 pound column. Before rebuild the shock travelled at 15.38 inches per second. Now, it travels just 10 inches per second. We went from a very soft shock to a good one here.
The funny thing about life before the dyno was this: I could take a shock, compress it down, and let it return. You could clearly see the shocks that were "very dead", but some looked OK because they returned to full extension with some smoothness. I now see just how innacurate that type of testing really is. The shock dyno shows EXACTLY what's going on at each pressure. For serious riders and racers alike, it's a great thing. I truly love the learning curve here.
Have a great Christmas and a Happy New Year!!!
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