JAE Mini Sprint up & running

[martin]

The aluminium tube at the rear is 2" long this is machined out inside to take the assembly but only machined to a depth of 1.25" so leaves a step inside the tube so the assembly only goes in as far as the step. The rest of the stuffing tube is 3/16" o/d brass tube, this rear alloy tube plugs onto the brass stuffing tube & is bonded to it then the whole lot is bonded into the rear of the ski.

[martin]

Using 3/16" for the main part of the stuffing i can use either the .130" flex with no teflon liner or i use the wire drive with .098 teflon in the tube.

[Gary Mullens]

Thanks, Do you leave a gap at the rear at the drive dog for drive shaft shrinkage on throttle? What do you use for the bonding?
In your setup are the two bearings at the rear or the front?
Ok, So the bearings are bonded inside the piece of alloy and the alloy is then bonded into the 2" piece of stuffing tube which then goes into the main stuffing tube 3/16". How do you get the bonding to release for servicing?

Thanks,
-Gary

[martin]

With the wire drive i leave a very small gap as theirs no wind up (shortening), with the flex i use a larger gap for wind up. I use 1 bearing at the front & 2 at the rear (you need 2 at the rear to take the torque & side loads as 1 at the rear wears to quick. I have also used 2 both ends as well, the bearings are not bonded into the tube only a slide in fit. Its the 2 tubes that are bonded together then bonded into the boat. I use Z-Poxy 30 min epoxy on all off the builds.

[Gary Mullens]

the bearings are not bonded into the tube only a slide in fit. So the bearings don't go into the alloy piece?

[martin]

Where getting a bit lost here, as an example say the 3/16" brass stuffing tube is 9" long it then has the aluminium tube which is 7/16" o/d x 2" long plugged onto the end of the 3/16" brass stuffing tube. The 2" long aluminum tube is the piece you see coming out the back of the hull which the bearing assembly slides into.

[Gary Mullens]

Gotcha. The alloy piece then plugs into the aluminum tube, correct? Now do the bearings go into the alloy piece or are they on the out side of the alloy piece? If they are on the outside of the alloy piece, then the alloy piece acts as a spacer?

[martin]

Yes that is a spacer in between the ball bearings, this whole assembly ie front bearing, spacer & 2 rear bearings simply slide into the tube coming out of the rear of the boat.

[pyroM!KE]

I like seeing this.Im to the point now of glueing in the tube and having second thoughts..But, Im not racing it..Im just tearing up the local pond...Ill be doing pretty much straight runs just messin around...I want to use the stock tube and flex but I will be running 3s 4400..Pretty much Im at a halt because of the stock flex issues...Hmm..

[martin]

I like seeing this.Im to the point now of glueing in the tube and having second thoughts..But, Im not racing it..Im just tearing up the local pond...Ill be doing pretty much straight runs just messin around...I want to use the stock tube and flex but I will be running 3s 4400..Pretty much Im at a halt because of the stock flex issues...Hmm..

I take it that your refering to some of the stock flexes coming unbonded from the stub joint, this didnt happen to me as i never used this flex but had heard of possible issues so cant comment first hand on this.

[longballlumber]

Martin,

I am curious how you can be sure the bearings aren't spinning on the ID of the brass stuffing tube?

Later,
Mike

[martin]

Martin,

I am curious how you can be sure the bearings aren't spinning on the ID of the brass stuffing tube?

Later,
Mike

Mike these bearings are a nice slide fit in the tube, this is a machined tube to suit the bearings, The stub & bearings spin so freely your never going to spin the o/d of the bearing in the tube unless a bearing siezed. Been using this method for years with no probs re bearings turning, you can soon tell if a bearing was spining as the clean grind marks on the outer ring of the bearing will show witness marks to which ive never had. I know a few that use ball bearings on this way with no probs either. Even the Little Joysway Warrior uses this system with no probs as well. Martin.

[Gary Mullens]

Mike these bearings are a nice slide fit in the tube, this is a machined tube to suit the bearings, The stub & bearings spin so freely your never going to spin the o/d of the bearing in the tube unless a bearing siezed. Been using this method for years with no probs re bearings turning, you can soon tell if a bearing was spining as the clean grind marks on the outer ring of the bearing will show witness marks to which ive never had. I know a few that use ball bearings on this way with no probs either. Even the Little Joysway Warrior uses this system with no probs as well. Martin.

Martin,
Would you be willing to make a few and sell them? I would be interested in one.

[martin]

Im afraid i dont have enough time to make my own things at the moment as i have so many things that i need to get done but time restricts.

[NativePaul]

Martin, my rudder is mounted at stock wooden bracket height and I cut my rudder off just below the water pick up and it still handles the oval and the square well in all conditions, so that was a success as far as I am concerned.

Gary, I lost the stock stub and a prop that had a lot of work in it when my flex came unbonded from the stub, so I believe it is a problem, if you are using plastic/carbon props I would save my cash and run the stock shaft as it lasted quite a while before it broke, but if your investing time/money in metal props I would chuck the stock one out and get a quality .130flex with 4mm-1/8" stub from OSE.