FNR Standard Driveshaft Tube

[fleetingcontact]

I dont expect to find one with perfect chrome, but the possibility of having it re-chromed would be nice, so anything badly corroded would probably be unsuitable...

Thanks all.

[Charles uk]

Need the complete engine number to identify exactly which drive shaft tube your looking for.

[seagull101]

I have one, the chrome is peeling off and it has lots of surface rust, but no deep pitting!

PM me if interested.
I will assume your motor is a EFNRL as i sent you longshaft EFNR gear linkage a while back.

Jacob

[Oyster 49]

New ones are available at pretty reasonable prices:

http://www.sheridanmarine.com/product/b ... sing-tubes

[fleetingcontact]

Didnt expect such rapid response! Nice.

Oyster 49:

I didnt know Sheridan had new ones, gosh! At first look £50 ish quids seems a lot but if you factor in the cost of re-chroming it starts to seem better - nice one.

Jacob: I said standard 'cause thats what I want...

Charles

At the risk of excommunication I confess I'm toying with the idea of a bitsa, some parts I have, some I dont. The finished item (should it ever be so) might best be described as a 102 ENFR...and I have a question or two I imagine you know the answer to...

1. Is there any engineering reason I cant or shouldn't use a 102 tube with a FNR box?
2. Having never actually seen one, I assume or maybe more accuratly hope, that a FNR tube would connect without difficulty to a 102 block. No?

So exactly which FNR model driveshaft tube to go for is a bit irrelevant at this point.

Any pearls of wisdom gratefully received.

Regards all! Martin.

[Charles uk]

The model 90 is fitted with a 3.1 : 1 FNR gearbox, the model 90 designator means that the motor imparts 90 lbs push on the back of the boat, the problem you will have is that the best 102 powerhead will give circa 70 lbs push with a propeller & gearbox that will allow the engine to rev at about 4000 revs.
The model 90 prop which is the smallest prop that will fit on a 3.1 : 1 gearbox, I don't think a 102 powerhead will have quite enough oomph to spin it fast enough to get much above 3000 revs, unless you cut the prop down a bit.

The EFNR drive shaft tube was thicker walled than the 102 to prevent bending, I doubt that will be a problem with a 102 powerhead so any drive shaft tube should do.

Try it out & let us know what revs you achieve before you mod the prop.

[fleetingcontact]

Charles, as far as the potential issues regarding prop speed go, if it doesn't work I'll use a 3hp box instead. But maximum effeciency isn't a particular concern - this is more about something called fun than anything else.

How would you attempt to measure RPM? Mechanically or electronically?

Anyhow, to return to an earlier question, would an FNR tube connect without issue to a 102 block?

And lets not forget the original question: Do you have anything that might suit?

Regards - Martin.

[Charles uk]

Martin before you spend any money, put it together with whatever you have to hand to see if your 102 is man enough to do the job.

Look for any digital tachometer on ebay i.e. tiny tach.

[Hugz]

I've seen a EFNR leg fitted to a 102. A chap in Sydney did it. The transom bracket will have to be changed to so you can lock the tilt in reverse. A faint bell is ringing in my mind that the exhaust and torque tube are slighly different centres and if this the case the two tubes may not be parralel but it wont be out by much. The thicker drive tube will be needed to use the rubber flange that the EFNR transom locks onto. I can see no difficulty in physically attaching. The prop has a different sheer spring arrangement as the std one will unwind in reverse. Whether you can adapt another prop to the EFNR box l can not tell you but hey just change the leg over. Only should take you an hour. Go for it. Drive shaft flange the same. Exhaust diameter the same. Water pipe connection the same.

[fleetingcontact]

Thanks Hugz! Some usefull and encouraging info...you have to love the Ozzies.

I have a rusty 102 tube that could be used for testing purposes. I say this because in order to fully test the arrangement, either the hole for the gear selector arm pivot bolt needs to be bored and tapped to allow for the larger diameter bolt used on the FNR models OR some kind of bush found to take up the slack. And I don't yet know what size the bolt is (Imperial threadforms - jeez, no wonder everything went metric) or the size of drill required to create the bore prior to tapping it...mmm, who among us would know the answer to such a technical question I wonder? I'm actually quite tempted to substitute a metric bolt in this case.

Also I have a rubber bush which I salvaged made for the 'standard' diameter driveshaft tube so if it worked then the mounting bracket would not require any mods. By the way, if the 'standard' tube wasn't up to the job, why did Seagull make a bush designed to allow the part to fit the FNR bracket?

As for the differing centers thing, I have to confess such a thought hadn't occurred, I'll just have to try it and I'll post the result.

I'd still ike to acquire a FNR driveshaft tube!!! Anyone?

[Hugz]

I would just bush the lever to get it up to desired internal diameter. Should be easy enough. Some of that taped copper foil used in stained glass lampshades etc would be a home handyman temporary fix.

I have an EFNR in the lower dungeon but unfortunately there is a reptilian poltergeist down there and as such I'm not game to go down there until Mars is in retrograde which wont be for another 9 months

Is the FNR driveshaft different to silver Century? Don't know much about the newer motors.

Are these the same?

Edit:
I just had a thought that there must be two rubber driveshaft flanges as the short (std) diveshaft is narrower against the thicker longshaft. Or is the std EFNR driveshaft a thicker one as well?

[Charles uk]

Didn't Nudge post a list of the thread sizes?

[Nudge]

I Did! here is the thread
viewtopic.php?f=2&t=6040

[fleetingcontact]

Hugz,

Some later models fitted with FNR boxes have a substantially thicker outer diameter for the driveshaft tube, this was done to overcome an issue with flexing in the tube. The difference is obvious.

The difference between a 102 tube and (for example) a Silver Century tube is in the casting at the top. A 102 tube can be made to work with a later bracket but just not so neatly as the one it was designed for, so if this bugs me I could just as easily use a Silver Century tube as a 102 tube. But the fatter FNR (Curlew?) tube would a) accept the clutch lever bolt, b) obviously have no issues with the FNR mounting bracket and c) there would be no possibility of tube flex.

The flange/bush I have came from a rusty Silver Century bitsa pile of horribleness and fits well enough on either a 102 or Silver Century tube so I assume there is no difference in outer diameter, especially as either tube fits any water-pump housing I've offered it to. Never bothered attempting to measure it though.

And finally...you are right that the tube centers of an FNR are different to those of earlier models...curses! However, as you also rightly say, the difference isn't great - a crude measurement shows a difference of 6mm between the top and bottom of the exhaust and driveshaft tubes. Also as you say, its probably not enough to make a serious problem, although it is enough to see with the naked eye and this pisses me off since it detracts from what at least I percieve as the aesthetic value. Also the driveshaft will be running at an angle other than 90 degrees inside the driveshaft tube. But there's no getting around it so I either abandon the idea or accept it. Think I'll go with the second option, but the acid test is wether or not the driveshaft moves freely. Still, its been done before!

Nudge,

Your list of thread sizes is very helpfull but the one I want isn't in it. When I discover the correct size I'll post it. But as mentioned, the other key bit of data is the size of the drill required to create the new bore prior to tapping.

If I could just find a decent FNR tube though...

[Charles uk]

It is on there 3/8 BSF, tapping drill 8.25mm.