brass tube keeps sliding out of the rear strut

[brad65]

Looks like a small flute LOL. I've tryed to glue it in but no luck. Now I have a small piece of fuel line holding it from coming out and hitting the drive dog. Any thoughts guys, my sv27 piece doesn't come out?

[Capt. Crash]

I would try cleaning the strut tube and bushing that keeps sliding out with alcohol to remove the grease, rough sand the outside of the bushing with course sandpaper and see if that will keep it from sliding/spinning in the strut bracket. You need for it to be able to come out when it needs replacement.

[detox]

If you ever misplace it here is the replacement part. This is the same piece that also fits the SV27.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMWA5&P=ML

[Grimracer]

Brad,

The bushing is made to slide. DONT GLUE IT!

Grimracer

[longballlumber]

In addition to what Grim said... Fluid just posted this earlier in the week. Listen to what these guys have to say they know a thing or two about boating!!!!

Brad,

The bushing is made to slide. DONT GLUE IT!

Grimracer

I have recently heard about a gross misunderstanding of the function of the sleeve bushings used in R/C boats. Some seem to believe that they are bearings that must be attached to the strut or stinger to hold oil and grease. Some even suggest putting solder on the bushings to keep them from rotating. This is simply wrong and gives away some of the advantages of the sleeve bushing.

These were developed years ago by nitro racers to reduce drag and play in their struts. The then-common lead/teflon bearings worked but their size was not very uniform and they quickly developed excess radial play due to their softness. Lead/teflon really works for 'slow' boats - full scale and models - but is pretty poor for high rpm/high load bearing use.

The solution was to use two nesting sizes of brass tubing. These are dimensionally uniform with just the right amount of play to avoid galling. The stuffing tube is commonly 0.25" brass tube, which allows the sleeve bushing for a 3/16" shaft to slide in perfectly. The holes in the bushing allow oil or grease to travel to both sides of the bushing. Why is that important? Because when the prop shaft is rotating the bushing rotates too and both sides need lubrication. This reduces friction by reducing the relative rpm of the surfaces - more power to the prop. Wear is also reduced - I have never replaced a sleeve bushing due to wear, and I've been running them for over seven years in most of my models.

In my UL-1 the original bushing was stuck in the stuffing tube and didn't rotate. I pulled it out and gently sanded it with 600 grit paper until it slid in easily, then polished it with 1500 grit paper (from the auto parts paint store). Now it works great, as designed.

Bottom line - use the sleeve bushings the way they were designed. They work, and very well too - I've set quite a few FE SAW records with them, as have many of the nitro guys. Whatever you do, don't glue or solder them into the stuffing tube!



Ths photo shows one 3/16" bushing I have used in three heats each month for a year. I can't find a dimensional change with a micrometer, it still works just fine. The 1/4" stuffing tube slides into the strut, and the bushing slides into the stuffing tube. I prefer gear oil, but others use grease with good results.



.

[brad65]

I guess I could put some silicone tubing in back just the right size in between this and the drive dog.

[Jeff Wohlt]

But what you do not see in that pic is the stuffing tube coming thru the strut and what you DO see is running inside of the stuffing tube so make sure that is how yours is set up. If you do not have the stuffing tube in the strut then a spinning bushing will do nothing but wear your strut ID even larger.

[longballlumber]

I guess I could put some silicone tubing in back just the right size in between this and the drive dog.

"If it's not broke, don't fix it"

In all the years I have been around boating I have never seen anyone put anything but a gap between the strut and the drive dog.... Just my $.02

Mike

[Jeff Wohlt]

Agreed, Mike. Me either.

Maybe a pic would be a better idea so we can see what yo are saying. Sounds like your shaft may be too long for the strut or you need to shorten the flexshaft. Anything between the DD and strut (besides a gap or bearing) can cause problems.

[brad65]

Agreed, Mike. Me either.

Maybe a pic would be a better idea so we can see what yo are saying. Sounds like your shaft may be too long for the strut or you need to shorten the flexshaft. Anything between the DD and strut (besides a gap or bearing) can cause problems.

I agree guys, I like to leave a gap for the flex shaft to shorten and pull back under torque. I understand totally, I'm just saying it comes out, hell I leave it like that if its no big deal. IMO some tolance isn't correct, It should press in tightly so it doesn't come out?

[Capt. Crash]

The information in the above referenced post is long and confusing talking about nitro and every other kind of boat. What about the UL-1? The manual does not mention removing anything other than the drive cable for lube. I assumed the brass insert sleeve/bushing/bearing/whatever was supposed to be stationary because I had to remove mine with pliers!


So is it supposed to slide out and hit the drive dog?

[Camman]

Yes
After installing drive leave a gap between that bushing & drive dog
That bushing is to be free and sliding spinning.

[Jeff Wohlt]

Read Jay or Mike post about this style of set up. You must have one with a flaw as they should rortate so you will need to sand it down so it rotates freely in the stuffing tube.

[Capt. Crash]

ok....thanks for the clarification....this newbie learns another lesson!