RE: Need some advice from the experts please!!!----1/5 scale ROBART Retracts
The air bleed adjusters on the Robart valve do not have big enough passages to allow for fine tuning the retract speed to any great extent. You can get more adjustment with a Sierra valve but in all honesty the guys I fly with would rather have gear that goes up and down all the time than mess with scale retract speed. One modification I can recommend is to buy the solid aluminum replacement parts for the Robart gear from Sierra. Makes the gear much stronger. I replaced the parts on my set of Robarts and have been much happier. Also if you take the gear apart you will see that Robart uses a soft steel cylinder that rides up and down to lock the gear up and down. Hard to describe exactly what it is but it is the part that engages in the locking slots at the end of the gear travel. This cylinder rides up and down on a steel pin. Every set of gear I have seen eventually starts sticking because the very end of the steel cylinder gets out of round from the stress of landing. It's easy enough to just drill out the hole to get it freeded up again but it will get out of round again with a hard landing. My solution was to ream the end of the cylinder out a little with a tapered reamer to give it more clearance. Just a little taper is enough. Has worked fine since, without getting out of round.
Larry