coupler questions..possible problem

[diesel1984]

i got an OSE coupler...its on and all, at low rpm's it seems to vibrate the hull...in a semi circular fashion, like it loops but as soon as i hit the throttle it straightens out immediately and is smooth. only reason i ask is earlier this week i had a gradnuper coupler twist in half..meaning the ends on both sides of the coupler ripped apart..leaving nothing but the 2 parts that connect to the flex wire. (wire ripped off) should i worry or just drive the thing?

[JimClark]

Are you sure your shaft is in line perfectly?

[rcBPman]

Is you motor mount loose at all? When was the last time that you oiled your shaft? Vibration is not good and you should make sure that there is not slack in the coupler and that the motor should be moved slightly back so that the coupler shaft is not at much of an agresive angle.

[diesel1984]

is it supposed to be at an angle or no?

[saleens7]

well, i think that if flex shafts have more of a curve in them (most preferable an S curve) they will run more efficiently and not vibrate as much....ive heard this before, but i need someone who knows this to back me up before i was to call this a fact....

[diesel1984]

how would slack be in the cable...meaning its not straight?

[saleens7]

well, most engines have a downward facing angle, this would get the flex shaft to get to as deep as it can get in the keel of the hull and it would then straighten out, so it will have a long curve to it...

[diesel1984]

so the way i have it set up is correct or should i angle it and then bench test it for a second or 2

[saleens7]

could you explain how your current setup is?

is the cable strait from where it connects to the motor to where it exits the hull or does it have a curve to it?

[diesel1984]

the coupler has a bit of a turn/angle in it, but what can i do about that

[saleens7]

so the motor isnt in line with the coupler.....that means that the coupler isnt snugly fit to the motor shaft....that tells me that the set screw it pushing one side of the coupler over against the motor shaft.....

i thought we were talking about a flex shaft this whole time....some pics would help....

[diesel1984]

ill get you some pics when i get back home from my intern...its possible that is the problem(sorry about my terminology, im still new to this rc boat stuff) since i had a really hard time getting it up as far on the motor shaft

[saleens7]

it should be a lot furthur up the motor shaft, that way it will have more shaft to keep it strait....

its basically the same if you hold a pen, if you only hold about 2-3" of the pen and the rest is sticking out of your hand, it will wiggle around easier, but it of you hold more of it, its harder to move it.....

[diesel1984]

i feel that the coupler is all the way up..but ill let you have a look for yourself everything runs smooth except for a little vibrating wooping at low rpms, and if this helps not sure it gets loud like the boat is jarring and moves around a bit on the table

[JimClark]

pardon my stupid question but why do you have what appears to be two couplers in the system. It also looks as the stuffing tube is not in line with the motor coupler as there is a slight bend in it.

Jim

[diesel1984]

thats a flex coupler something special(not really) that you have to do for aqua jets. how do i fix the stuffing tube?

[JimClark]

They must do that to cover up sloppy workmanship.
Is the stuffing tube epoxied in?

[diesel1984]

possibly lol it should be epoxied in i do have another stuffing tube just never messed with it..how do i put it in right?

[Mich. Maniac]

I see that as well, between the 2 couplings the flex shaft looks like it has slack. may be causing whip at low rpm and then vibrating as a whole at high rpm

[Doozie870]

Everything is wrong, first bend the motor mount way down until you get ONE smooth arc in the flex, then take out the motor mount screws and run the motor connected on say 1/8 throttle, while running, move the motor around slightly from side to side and forward to back, until you find the sweet spot,(motor rpm will increase and sound free running). drop some ca to hold it there and redrill the motor mount holes. Also check your tube bushings for play, most vibration including an out of balance prop, are absorbed by the coupler, IMO.

[diesel1984]

sorry if im coming off say RETARDED but what exactly is a tube bushing? so im starting from scratch getting new mount and putting in new stuff brass tube and the whole nine yards i guess. any suggestions on how to mount the stuffing tube back...im not supposed to bend it or am i? only asking since on the tips section they do..but my stock one was not bent so just stick it in at angle? here is a pic of the stuff tube, let me know if i should change it i havent set it in yet just sitting in place. thanks, michael...also should my stuffing tube be loose for when i bench test it?

[diesel1984]

i bought this boat used and seems to give me nothing but hassle..but i prolly mess with it too much...but im not giving up yet? does my hull look ok or do i need a new one of those 2?

[Doozie870]

Definatly dont run it with the stern tube not fixed!! so are you planning to slide the solid shaft into the brass tube? if so it will heat up and bind quickly,I think OE has a kit that has the tube, bushings,and shaft in one package, I would recommend one of those. clean out where the tube is going to fit real good, maybe with a little acetone, and epoxy the new tube in. the boat looks fine, once you get the kinks out it should be reliable and fun.