GrassStripFlyBoy Posted November 1, 2021 Report Share Posted November 1, 2021 Working on condition inspection, airbox door shaft needs repair, that's straightforward enough. The carb vent tube cross over needs attention too, O rings were chewed in half, and the fiberglass opening rubbed a ways through the PTFE tubing. Will replace the tube and O-rings, probably will last another 15 years as these ran for service. Wondering if anyone has suggestions for improvement beyond going with the O-rings? Seems like a fine idea to replace as originally built, but since I have some time ahead repairing the airbox thought I'd quiz the experts here on the situation. Second question, the "Ace Aviation" weather strip seals will be replaced. Same question, use the stuff I see in place, or anything better for seals? Those are not in MM, are they factory and just not shown as items? Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted November 1, 2021 Report Share Posted November 1, 2021 Just replace the grommets, I don't think you will find a better option. Also be aware there are scallops cut out of the tube as it passes through the box, so you may not be seeing a worn spot, but rather one of the scallops. I think it works better to use two pieces of tubing, with the ends stuck into the box. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 1, 2021 Author Report Share Posted November 1, 2021 Thanks Tom, and clear on the scallops, tube was still centered up, this is slit where the fiberglass chewed a straight looking saw cut into the tube. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 1, 2021 Author Report Share Posted November 1, 2021 So, I'm a bit further into this, and wondering with the flap door welded to shaft on the inside, and the short control arm welded on the outside, how are the new bushings / washers / whatever people are using installed onto the shaft? The control arm side appears the bushing is captured in place... I suppose the arm could be cut off and rewelded, but looks to be stainless and would need to TIG it? Is this one of those magic ring games and I don't know the trick to take it apart? Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 1, 2021 Author Report Share Posted November 1, 2021 Searched back further in the posts and see others are splitting the bushing, or slotting washers (found Rogers old post), so I'll work something this way. Quote Link to comment Share on other sites More sharing options...
procharger Posted November 2, 2021 Report Share Posted November 2, 2021 I split some plastic washers glued them around shaft worked fine should be a permanent repair. Washers were about 3/16 thick.. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 4, 2021 Author Report Share Posted November 4, 2021 Started down the path of repair and brainstormed a different twist to this, not against the split bushings / washer concepts, my thoughts are more wanting to make this a serviceable repair and not having to glue things as an assembly. The root issue in this component is the micro thin single layer of fiberglass, it's like a knife through the aluminum bushing, as well as the O-ring for the carb vent tube, that both chews into the mating parts but also has little integrity to hold up itself. The real brainstorming occurred once the door was removed and I was playing with new O-rings, realizing if the door arm had a radius it could slip through a grommet. Ultimately I placed 2 layers of glass on the outside, and one on the inside. This developed ~ 1/16" thickness which is more appropriate for mating up to the grommets and not chewing through them. Here's the Arm with some ground off sides and the rad placed on corner: And some pic's of the door installed back in place: In the end, I think there now is adequate structure and bearing surface for the grommets to hold up, and a pack of grommets is a dollar, can simply pop in new ones if the time comes they are worn. The door still swings easy enough too, and as everyone knows carb heat is not frequently used, so having something that is vibration resistant is more of the function here than the need to pivot. Quote Link to comment Share on other sites More sharing options...
sandpiper Posted November 5, 2021 Report Share Posted November 5, 2021 Good job Darrell! I'm about to do my annual and have the same problem. Will likely follow your lead. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 5, 2021 Author Report Share Posted November 5, 2021 I've been contemplating stringing safety wire through the foam gaskets under the door. They have a hallow cross section and drilling small holes would allow securing them in place. The adhesive seems decent now, but two were missing and either fell out the bottom opening or went through the engine. For as much as I love my SW, every now and then you see some cheesy design elements that just beg to be improved upon. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 6, 2021 Author Report Share Posted November 6, 2021 Status update on this concept, reinstalled this morning - the spring force is marginal on returning the door back down, and I can't say I'm impressed with that side of the design either... Sprayed a shot of INOX on both grommets and that is enough to allow it to return, probably will hunt for a slightly stiffer spring to add some extra force in system. So, if anyone decides to use this repair method be aware you'll be fiddling with the return spring as well. Quote Link to comment Share on other sites More sharing options...
Anticept Posted November 6, 2021 Report Share Posted November 6, 2021 Glue metallic spacers with rubber cement inside the grommits and lubricate them so that the door doesn't ride on a rubber surface. Use a soft metal like aluminum so that it wears and not the steel shaft. You'll have to roll them around the shaft when installing. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 6, 2021 Author Report Share Posted November 6, 2021 After a bit of examination I realized the control cable was too slack, having reinstalled as it came apart, there was ability to shorten the cable length which in turn creates more spring force. I think all is ok, it's not super strong in shut force, but this flimsy spring of the SW design is far from robust as a starting point. Here's pic of final set up, I suppose a stiffer spring with more axial straightness would help a lot. I also foresee the ram air of the front cowl vent will help force door closed too. Ultimately I'm happy with the the corrected vent tube, and this door and seal repair, both were pretty sad and good to have these dealt with. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted November 6, 2021 Author Report Share Posted November 6, 2021 2 hours ago, Anticept said: Glue metallic spacers with rubber cement inside the grommits and lubricate them so that the door doesn't ride on a rubber surface. Use a soft metal like aluminum so that it wears and not the steel shaft. You'll have to roll them around the shaft when installing. That would be a good approach, and the opposite side could simply slip a 6mm ID tube between the rod end and grommet. That would correct 50% of the drag which is probably enough. I'll kick that around. Thanks Quote Link to comment Share on other sites More sharing options...
procharger Posted November 6, 2021 Report Share Posted November 6, 2021 That's why I used split plastic washers make sure it works rubber will dry out in the hot cowling. 2 cents Quote Link to comment Share on other sites More sharing options...
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