Go Power Dyno Support We NOW have Better Pressure Diaphrams: (Oct 2008) Working with Norm Schenck of Competition Fuel Systems (DEPAC Site #99) we now have custom made diaphrams that can take higher pressures and last. We have them in stock as a kit with instructions and dry lubricant. These should be the last ones you will ever need. 2 Diaphrams for $120 (includes shipping). Call (315) 339-1265 or BUY Now through GUNPAL. Stuska® Dyno Modification to improve LOAD response (especially useful with the ADL Control): The Stuska® Dyno is a good Power absorber but the water inlet is only into one side of the rotor and it must then flow arround the rotor to fill the other side. The result is a sluggish response to a quick increase in water flow. This slower response is now much more noticeable when using the ADL Control System and causes an overshoot response. There is one simple modification that will double the speed of response by drilling 3/8" (or 7/16") holes as shown below. We have been doing this for many years and its even more important now with the new fast ADL system. Also if you have the brake apart replace the original old style Stuska® water seals with a Much better replacement seal, using ceramic on carbon. Discard all the old Stuska® parts. PAC-SEAL #237 from Grainger 5NC16. Make sure you braze the ends of the new spring just like the original (to prevent fly-out of at the ends at hi-RPM). The original spring retaining cup to capture the spring is not really needed (if you braze the ends). Make sure these are properly installed and pressure tested. If it does not hold air then it will leak water into the greased bearings. Water in bearings results in FAILURE of the bearings in a short time. If you see water dripping out the ends of the shaft then your dyno is going to fail very soon. NOTE: Do not attempt to remove the rotors from the shaft....The outer holes are scribed from the outer edge and hand pilot drilled (1/8") as shown. Final hand drill to size and deep champher. As long as the holes are centered between the fins and the same distance from the outer edge the rotors will still be balanced. On a Stuska 800 dual rotor, Only the water-in side needs a deep champher. Use a 1/4" hand drill for Air Bleed holes, 4 to 6 as shown. When changing the ball bearings put in a better quality part (ABEC 3 or 5). No point in saving a few bucks using a POS part when a better fitting bearing will last much longer. (cheap stuff COSTS MORE!). We show a Stuska® 400 but it applies to the 800 dual rotor as well.