What is actual diameter of .250" flex cable?

[ray schrauwen]

I am going to make a coupler for 6mm to 1/4" for a build.

Really need to know the exact diameter of the flex cable as I have noticed 3/16" and others are always smaller than the indicated size.

I just want a nice tight fit, after all the 6mm motor shaft is actually 5.98mm also....

Haven't got the cable yet, holding off on spending the $$ yet...

I was going to make my own cables with 3/16" flex, 1/4 stub turned down to 3/16" but, I thought making a coupler will be easier even if the cables are frikin $36 each, Whoa... everything costs more on big boats....

Thanks in advance!

[graill]

.250 is just that. 1/4 inch. it will fit snugly in a 9/32 tube but you really do not want to do that for a couple or three reasons. In the end its your choice.

If your speaking driveline you do not want a "nice tight fit".

Pros of a nice tight fit:

1. Little or no deflection of the driveline at high speed.
2. Little water entering the hull.

The cons of a nice tight fit:

1. Restricted run times due to friction, more load on your motor/hardware because of it.
2. Fast failure with little or no warning due to lube starvation because of close tolerances (again restricting run times)
3. limited top end rpm due to close tolerances and heat build up and galling (that loud screeching sound at high rpm) once the lube is evaporated due to heat
4. less lube capacity to protect the driveline due to those tight tolerances resulting in less run time and top end, and more heat.
5. Maintenance dissasembly and relube after each run is a must, skipping one time isnt a good idea.

I could go on but you get the picture, the cons outweighs the pros. If your doing 2 second SAW rig then you make your own choices. If your making a reliable race rig listen to the folks on this board on tolerances in regards to rpm limits, lots of excellent info and tested and true builds.

[ray schrauwen]

Just a nice tight fit for the coupler, not the stuffing tube.

I thank you for the good info.

With that, what size Brass stuffing tube is best for 1/4" cable?

Teflon or not because I have an auto lube cross bar coming... Thank you!!

[andym]

Most gas people use 5/16 and 9/32 for a stuff block through the hull, no teflon

[ray schrauwen]

Do you mean the 9/32 holds the flex & lube and the 5/16 tube is glued into the hull? I did that on my Whiplash 20.

That is I used those sizes but, I have .250" OD teflon inside the 9/32" holding 3/16" flex cable.

[andym]

Yeah, Sorry Ray I had it arse about face and wrong. In my gas whip I have a 5/16 stuffing tube and a 11/32 block through the hull. My mind is still at the pond after running my gas whip and sd3 seaducer FE

[ED66677]

Ray,
5.98 for 6mm is a good fit, not tight but 2 hundreds of a millimeter is just good!

[ray schrauwen]

Andy, no problem

Ed, I got that, thank you!