V drive troubles

[Jack Clarke]

Hello everyone,
I am currently in Dominica and yesterday on our way to Les Saints the V drive started vibrating like crazy. I shut it down and sailed the 5 miles back to Portsmouth and then got towed to a mooring.  After changing the milky oil in the V drive, the problem was the same.
I have a few questions for the group with regards to this;
Does Walter still have any parts for the R – 20 ?
Can you change out the V drive with the boat in the water?
Is the replacement V drive a straight switch out?

I haven't contacted Walter as yet but they are my next e mail.

Any help will be greatly appreciated.

Thanks

Jack
Xanadu IV

[Ken Page]

I'd suggest checking all the bolts that hold it down and for alignment. I had a similar big vibration problem and saw that some mounting bolts had backed out. I realigned added new lock washers and all is fine. 

Ken 

Taking what comes as I get it, using it all as much as I can and trying hard to leave all the shit behind.

[jhowell6]

I had same type of problem on my new (to me) P 365 – which had been

VERY lightly used the last 3 years.  Turned out the bolts holding

the drive shaft from V-Drive to Engine had come loose.  

Tightened them up and we were good to go!

Otherwise LOTS of R20 options available (from Florida even) on EBay

Fair Winds!!!

Joe

Joe and Lorre Howell

S/V Perseverance

Pearson 365 Sloop

[RichCarter]

Jack,
V-drive parts are available from Walter but most parts are simple car parts used or adapted for their use. It sounds like you lost a bearing and depending on how lucky you are you may have done some serious damage to the gears but perhaps you can just tear it down and rebuild what you have. Your cooling jacket is leaking so you if you repair the RV-20 you need to either fix the leak or run it without cooling.

You can pull the V-drive without pulling the boat. This is a five-hammer job so if you don’t consider yourself very handy don’t attempt to rebuild this thing. You should be able to remove the unit yourself with patience and a few tools. Rebuilding requires special tools and aligning the unit when its reinstalled is very tricky. If you chose to repair the leak, you need to thoroughly clean the cooling jacket. It took me hours to clean mine. Rebuilding would best be done by someone who has the right tools. The hardest part is finding a wrench that fits the special nuts they use. I made a couple of them years ago and gave them to another member.

Walter no longer has cases for the RV-20. I don’t know if they would be willing to touch it if the cooling jacket leaks.

I pasted my notes from when I rebuilt mine years ago below.

Read this too if you haven’t already.
http://www.richardcarter.net/repower/Vdrive.html

Rich

—–Original Message—–

[Tor]

Jack,

Looks like my earlier email about this never arrived. I’ll paste it below, but will also mention that long before I had my V-drive rebuilt I found some of the coupling bolts – the special, case-hardened (or whatever the term is) bolts that secure the shaft coupling to its mate on the V-drive – had come loose. Over time their wobbling had worn the holes in the couplings to ovals, so just re-tightening them wasn’t a viable remedy. The action had also damaged the loose bolts. As I recall, I had to buy a new coupling and a set of bolts.

As for the rebuild, here is what I sent earlier (that didn’t arrive):

A few years ago I pulled (and later re-installed) Silverheels’ V-drive while in the water, no problem. Just leave the coupling on the prop shaft so it can’t slip out (although that’s unlikely in any case if you have shaft zincs in place forward of the cutless bearing strut). I shipped the unit to Walter in New Jersey and had them refurbish/rebuild it. It was pricey – in the $500 range, if memory serves – but a lot cheaper than a replacement. No problems since then.

Good luck,

Tor

[RichCarter]

I replaced the coupling bolts on my RV-20 with socket screws. They are easier to access with an Allen-wrench.

I suggest reading the RV-20 manual and following the troubleshooting section. Peter has one posted online.

Good luck
Rich

—– Original Message —–

[Tor]

Rich,

How long ago did you replace the coupling bolts on your RV-20 with socket screws? A pretty savvy mechanic who helped me with mine said those bolts have to be (I think it was) case-hardened to stand up to the sheering forces. Was he mistaken?

Tor
———————-
Silverheels, P-424 #17
http://www.silverheels.us
——————

[theller85]

I would think it would depend on what type of socket screw you use… Grade 8 has one hell of a shear strength. 

Here's a little quick engineering math.

Quick calculation… assume 55 hp at 2000 RPM, resulting torque is 195 ft*lb. Convert to In*lb  2340 in*lb

Total area of the bolt under load, say its a 1/4″ bolt is pi*.25^2 = .196 in^2

We assume that the load is transferred as a shear force rather than a torque (it is resisting a torque, but it is applying point loads to resist the torque)

So, now the actual value of the point load. Say the bolts are 2″ from the center line of the torque. Torque = Force * distance

2340/2 = 1170 Lbs. 

So now we know what the load is required to hold the torque load with a single bolt. Divide by the number of bolts to get the actual force, but for sake of the discussion, lets just use 1. 

Stress, in this case shear stress, = Force / Area = 1170/.196 = 5696 PSI (pounds per square inch)

minimum yield strength of a grade 8 bolt is 130,000 psi… 

The next lesson here would be the calculation of the fatigue strength of the bolt in said condition. If anyone cares for it, I can run that down too…. but generally it starts by dividing your ultimate tensile strength in half (in this case ultimate is 150,000 PSI) and then applying a bunch of factors to determine the yield strength for infinite durability. You divide that number by the stress applied and that is your safety factor.. Just a quick guess is that you probably have a safety factor somewhere around 2 or 3 with a single bolt holding the load. 

My real concern in this situation would be corrosion, which could drastically reduce the strength of the bolts over time. If you have the same material on both sides of the bolt, i would keep them well greased to avoid rust.

[Tor]

Exactly what I was thinking. 😉

[RichCarter]

Tor
I replaced them many years ago, probably around 1995. Alignment of the V-drive and service of the thing in general is easier when you can get a wrench on the bolt, and the walter bolts don’t fit that bill. The RV-20 was designed to handle much larger engines than the anemic 50 HP W60 so I don’t think there was ever an issue with bolt strength. I went to my local hardware store and bought steel socket screws, not stainless. They were black in color. I don’t recall if the box said “case hardened”. As I recall, the lock washers even had to be smaller than normal so I reused my original lock washers. Don’t lose them. They might be hard to match.

The RV-26 is a different design and takes a larger bolt. There is room there to get a wrench on the bolt.

Rich

—– Original Message —–

[Author]

Posts