You want to replace that cheap repulsive stock trigger that Smart Parts supplied with your Impulse with a nice new blade trigger and wonder how to get the most out of it? We'll show you how to install it in this article and even give you a few more pointers to fine tune it to help enhance the maximum rate of fire you can attain from your Imp.
I still wonder why Smart Parts supplies such a cheap junk trigger with the Impulse and doesn't supply a tapeworm with them either but I suppose I'm not going to change their policy about that by dwelling on it. Our only alternative as Impulse owners is to dabble into the humongous Impulse aftermarket supply and fork our hard earned dollars for that blade or similar trigger of our choice.
NOTE: I would suggest reading this whole instructional before attempting to do any of this because you may need some materials and pre enlightenment before starting.
Choosing a trigger
I'm not going to go too far in the selection of any particular trigger but I will say that the two most popular aftermarket triggers for the Impulse have been the New Designz and Eclipse blade triggers. New Designz even makes a magnetic blade version and some rave upon it but others may prefer a spring response blade. Before just jumping on either, I would suggest trying both if you have the option before purchasing one or the other. My personal preference is the spring response blade because when it comes to all around tuning, it has many variable options.
Removal and Installation
To remove the stock trigger you must first separate some parts from your Impulse. You cannot just remove the trigger with everything intact. For some this will be more of a challenge than others. You'll need to first disconnect the macroline from one end of its connection point. Remove the solenoid tray and trigger frame assembly from the body by removing the 2 screws that attach them to the body. If you have a Vision Imp be careful when removing these screws because there are 2 connectors holding the motherboard in the noid tray to the Vision board that is connected to the body. If taken apart incorrectly you can crack the plastic connectors.
Once this has been completed you must remove the noid tray from the trigger frame. Before attempting this you'll need to remove the battery from the trigger frame by simply removing 2 screws from either side of the grips and disconnecting the battery. The older trigger frames as meaning the '02 and first released '03's had 1 screw holding the solenoid tray to the trigger frame. After that period Smart Parts used 2 screws. Removing 1 screw from the mid area of the noid tray is simple but if you have to remove 2 screws, the second is placed under the board which is inaccessible until you remove the whole motherboard. The motherboard is removed by removing the 2 plastic screws. Be careful to put the dwell buttons, button housings and on/off button in a safe place so you do not lose them. Once you get to the point where you're separating the solenoid tray from the trigger frame, you must snake the battery wires and connector from the trigger frame first then separate the two assemblies.
NOTE: Rather than having to go through the hassle of removing the motherboard each time you want to separate the noid tray from the trigger frame, there's a simple resolve. I would suggest this for those that have 1 screw to remove as well because most times it's trial and error of aligning these two together before attaching them to the body. Find a long screw of the same thread size as the screw that holds the tray to the trigger frame. Put a dab of blue Loctite on the screw and install it in the front threaded hole of the trigger frame. Cut the head from the screw so there's about 1/8 - 3/16" protruding from the top surface of the trigger frame. File the jagged end of this to smooth it out. What you have now is a locator stud for the front portion when you connect these two assemblies together. The back screw is enough to hold them together until you use the main 2 screws to attach the noid tray and trigger frame assembly to the body. For a more in depth account of this mod see the Impulse Trigger Frame Locator article in the SPPS tech section.
Now that you have the solenoid tray and trigger frame apart you can get to the task at hand. Remove the large set screw towards the back top portion of the trigger frame. This is the trigger spring tension adjuster. A spring will come out if you tip the trigger frame upside down. Now you'll need to remove the 2 trigger retaining pins. This is accomplished by removing the c-clips from the left side of the trigger frame. They can be a bit much to remove if you don't have the right tools. This can be simplified if you have a pair of needle nose pliers. Put both tips of the pliers on both ends of the c-clips and push it off of the trigger pin. If you do not put your finger over the top of the c-clips they will most likely go into orbit never to be found until one day accidentally stumbling across it when you don't need it. Once they are removed put them in a safe place so they don't get lost. Losing these is a very common problem for people that are changing or working on their trigger. If you have a piece of masking tape handy you may consider sticking them to a small piece and sticking the tape to a table or whatever you're working on for safe keeping. Push the trigger pins out and you can now manipulate the trigger from the trigger frame. Taking the trigger out and putting the new one in its place can be a bit trying as well. You may think there's something wrong but you'll just need to try different angles until it works.
Before putting your new trigger back in place, look to see if there is a set screw at the opposite/bottom end of the threaded trigger adjustment spring channel. Older Imps didn't have this second adjuster. If not, I highly suggest putting one in. It's the exact same size as the one that you removed from the top earlier in this instructional. The hex needs to be facing towards the bottom as it is accessed at the bottom of the hole from the outside of the trigger frame. You'll want to put a bit of blue Loctite on it once it's at the bottom of the hole so it won't rattle out of position once adjusted. Make sure you have it all the way to the bottom of the hole so you'll be able to get the trigger in. I will explain later in the adjustment portion exactly what it's for. Another thing you may need to do is put some blue Loctite on the 2 adjustment screws in the trigger especially if you have the Eclipse blade trigger. If you don't, they will come out of adjustment very often and you'll need to continually adjust the trigger. Make sure the top adjuster in the blade is flush or protruding no further than 1/16" from the top of the trigger before putting it in place.
Once you have the new trigger in position, reinstall the 2 trigger pins and c-clips that you removed earlier. Reinstall the spring or a lighter one if you choose to and the spring adjustment screw. You'll read more on this in the adjustment portion of this guide. Now that your new trigger is in place, you'll just need to put everything back in the reverse order that you removed it in.
Adjusting & Tuning the Trigger
Though you have 2 adjustment points on your blade trigger there are actually 4 points of adjustment.
1. Micro switch adjustment at the top of the blade trigger -
2. Post travel adjustment in the center of the blade trigger -
3. Pre travel adjustment at the bottom of the threaded spring adjustment channel -
4. Spring tension adjustment at the top of the trigger frame -
All but one of them, which is the spring tension adjuster, can be adjusted after everything is reassembled so I suppose we should start with that.
Spring Tension Adjustment: There are a few different options in which you can approach this adjustment with. First being, use the stock spring and adjusting it further in for a heavier pull or further out for a lighter pull. The set screw cannot be adjusted up any further than the top surface of the trigger frame or the noid tray will not fit flush with the trigger frame. Another option is to stretch and snip the stock spring for a lighter pull. If you choose this route I would suggest to snip at most 1/4 - 1/2 a loop at a time until you think that the pull feels sufficient for your liking. When putting a snipped spring back, put it with the snipped end up towards the set screw adjuster. Your third option is going to a hardware and finding various springs of different tensions at a 1/8" - 3/16" diameter. These may be longer than the stock spring but you can always cut them to the size that you need. These can be stretched as well for fine tuning them to your liking. You'll find that what may feel just right tinkering at home with may not feel the same way when using it on the field in action. It took me all of 2 months of trial and error to get mine perfect for my liking. I suppose it depends on how tenacious or easily satisfied you are about your trigger pull that will be the deciding factor as to how long it will take you to get it there.
Pre Travel Adjustment: This will indirectly affect the spring tension adjustment because it is actually pushing up on the trigger tab in the trigger frame from the bottom which could leave more tension on the spring the more you adjust it in. This as well as the other two adjustments will be performed after you've gotten everything back together. The pre travel adjuster will be accessed from the hole in the trigger frame just back of the center of the trigger. You can see it in the photograph above. Insert the allen wrench in the hole and turn it left for a forward adjustment and right for a backward adjustment. Set this before proceeding on to the last two adjustments.
Micro Switch Adjustment: This is the set screw in the top of the trigger. You will need to have everything back together and have your Imp gassed up and powered on to adjust this and the post travel adjuster. If you have the Eclipse blade, it uses a metric size allen wrench. If you use the New Designz blade, it uses an inch size allen wrench. Hopefully you found out what size you needed prior to this. Pull the trigger and see if it sets the micro switch off. If it doesn't adjust the allen screw in to the right(CW) a full turn or two and see if it does afterwards. I always put a finger in back of the trigger when doing this to be sure it doesn't fire while turning the allen screw. The more you turn it in, the less pull you'll need to set the micro switch off. If you turn it in too far, it will cause your Imp to cease firing because the button on the micro switch has to return to a certain point before it can fire again. If you reach this point just turn it out a couple of turns until it fires once more. You should actually adjust this a little at a time because if you adjust this too far in, there's a chance you can actually break the metal tab on the micro switch off and you'll need to have a new micro switch soldered in.
Post Travel Adjustment: This is the set screw in the middle portion of the trigger. This adjustment is to stop the triggers travel just after it sets the micro switch off so there is no excessive movement past the point of ignition. Pull the trigger slowly and see exactly where it is when it fires. Turn the adjuster to the right(CW) pulling the trigger in between adjustments until it doesn't fire. Once you hit this point adjust it to the left(CCW) until it fires again. Try shooting it fast or walking the trigger to be sure that it fires every time you make a pull. If not adjust it out slightly until the shots flow.
Now your new blade is installed and tuned perfectly, ready to mow faces and anything else that happens to make the mistake of crossing your string of paint. You might find that it could possibly take more than one tuning session to get the perfect pull because as I stated earlier, what feels fine tinkering at home may not suffice when in action on the field throwing paint. With a little patience and tenacity, you can tune your stock trigger frame with blade trigger to ripper status that can parallel any other $150 aftermarket frame available or you can give it a basic adjustment and be humbly satisfied with what you have. The choice is all yours.
Technical Information
