Weaponx83

Hi

I'm building a Falcon 41 right now, does the stuffing tube have to be inserted into the strut or just butt up against it , if so what's the best way to reduce the O.D. of the stuffing tube, short of puting it in a lathe and turing it down?




Thanks

Ron Olson

My Feedback: (1)

Depends on the strut. On most you can slide it part way in. Make sure that you're using the right size tube as you don't want the cable to be too loose in there. If you're using a Teflon liner that will also add to the problem.

dicko

If you are using a teflon liner you can slide the liner into the strut & but the brass tube up against it. It is preferable to have the brass stuffing tube without a teflon liner and slide it into the strut a short way. Then use 3 inserts in the strut to keep the prop shaft in line.

danielplace

Just simply run a standard 5/16" brass tube from within 1" of the engine to flush with the rear of the strut assembly( all the way trhrough it) and reduce the I.D. in the back with a standard 5/16" - 1/4" sleeve bushing and slide the welded flex shaft(with new drive dog installed so you can figure your length to cut it) through up into the standard round flex collet engine coupler. Not a bad idea to glass a 11/32" tub through bottom in case you ever need to pull out the 5/16" stuffing tube to repalce it. Teflon sleeved stuffing tubes are absolutely not necassary, grease is all you need. Brass is one of the best surfaces to run steel with and it lasts forever and is very low friction. Be sure to leave a full 1/4" between the drive dog and the strut when you cut the shaft. There is no kind of thrust washer needed with this setup and all the forward force directly transferred to the engine. The shaft shortens under load because of it's windings and the fact it is torqued up agianst several sides of the looser fitting tube it is in. If there isn't a full 1/4" gap you will destroy your strut, drivedog and likely break the flexshaft.

Weaponx83

Hi,

I'm using the hardware kit that Promise Hobby recomends for their Falcon 41 , and the stuffing tube has a liner.
weather this is a bad setup or not I didn't trust the teflon liner that does slide in, not to shear off.
But if that's how it's suspossed to be assembled and no one else has had any issues then I guess I will follow suit.


Thanks for the imput guys, very apreciated

danielplace

I would still dump the teflon they do cause problems They like to spin and slide out or get thin and bind the flex shft up breaking it and making it locked up in there with the teflon bound up around it so tight you can not get it out. Seen it many times. They are useless. There are ones that have never had a problem but sooner or later it could happen, i would eliminate the possibility altogether by simply sleaving the tube with a piece of 5/16" inside before you bend it. Not familiar with that hardware kit really but the tube is better if it can be run into the strut without affecting the design by hitting or binding anything.
Is there enough meat at thenose of the strut to drill it out to fit the stuffing tube and then file it back perfect on the nose because the bit will booger it up a little. Also becareful if you do drill it. Better to do it in a drill press if possible. The twist drill bits love to pull themselves deeper into the aluminum than intended.

Ron Olson

My Feedback: (1)

I'm waiting to see if the tube that he's using does have a Teflon liner or not, that's why I asked the question. Some struts have the bushings in them set so far back that it won't allow the tube to go in, like some made more for mono hulls.

danielplace

It does and uses a one piece shaft also. I believe their struts have teflon or oilite bearings pressed into place though which wipes all the grease off the shaft when reinstalling it unless you pump it into the strut and push the shaft in through it. I know what I would be doing if it were me and that would be knocking out those bearings and running a 5/16" tube to the back of vthe strut and useing a conventional
sleeve shaft bushing that is easily removable. But this is what he bought and likely will use as designed. I just went on the Pomise Hobbies site and saw how they do there setups. If the front strut bushing isn't in the way or can be knocked in a little I would find a way to support the stuffing tube to keep it aligned to the strut. Maybe rather than drill it and risk boogering the nose of it up solder a smaller diameter brass tube in the stuffing tube to go in the strut. Of coarse that would mean that the teflon would have to be replaced from the engine end but not a big deal.
The teflon liner should be cut long on the inside by the engine a slit into four and folded back over the stuffing tube and tywrapped to keep it from working forward and being chewed up by the collet and/or
spinning with the shaft causing real problems.

Weaponx83

I think I might just bite the bullet and go buy a skeged strut, stuffing tube and brass bushing from TSB. I'll still use the mounting brackets from the first strut I bought though.