Vibration at low speeds

schoolsOut · **Posted:** Sun Oct 06, 2013 3:43 pm

Had the boat out today. Put the original aluminum prop on and snugged it down. It has a smaller radius than my ss. SS is 14.75 and aluminum is 14 or 14.5, don't remember for sure. Both are 19 pitch. The boat seemed very different. Sounded different. Less hole shot. For some reason, I could trim it much farther with this prop on. I seemed to get more prop slip in hard turns. Seemed like less high end. Vibration still there too. I will pull the drive int he next couple weeks and look at the u-joints and gimbal to see how they look. Starting to think my u-joints are shot.

Quote:

However, in the case of the maintenance free ones, the whole drive shaft needs to be replaced

So you are saying I can't knock out the u-joints and replace like on an automotive drive shaft? I really have to replace the whole drive shaft? I was assuming that no-maintenance just meant that the could not be greased.

Graham R · **Posted:** Sun Oct 06, 2013 4:21 pm

You can remove the circlips and press out the UJs like automotive ones.

You can refit the UJs like automotive ones.

The issue is whether you can find replacement UJs ! VP no longer supply or even list them even for the earlier SX/ DPS drives. I've not found any listed for the later drives anywhere ( even on the Rockwell site, I wonder why; not really !).

You might find old VP stock, but the early UJs do not fit the later shaft assembly. The later ones use internal circlips in the shaft assembly as retainers, the early ones use C clips that fit externally on the UJ bearing housings.

Please let me know if ou find replacement UJs !

schoolsOut · **Posted:** Sun Oct 06, 2013 4:44 pm

Graham R wrote:

Please let me know if ou find replacement UJs !

Is item #3 not it? Lists for $56.82.
http://www.volvopentastore.com/Bearing- ... wcart.long

schoolsOut · **Posted:** Sun Oct 06, 2013 4:53 pm

Appears to be several available on ebay also for less.

http://www.ebay.com/sch/i.html?_odkw=vo ... 2&_sacat=0

Graham R · **Posted:** Mon Oct 07, 2013 4:20 am

Those 3850812 ones, with the C clips are the early UJs for input shafts up to mid 2000 ( I fitted a set to the driveshaft on my previous 1999 drive), Some VP sites I've looked at list them as discontinued, some don't , sorry I gave the wrong information about the early UJs availability.

I've never seen a part number for the later UJs though and there is actually a VP bulletin where they state a whole shaft has to be fitted if the UJs on those are worn. Yours being a 2005 drive and mine being a 2004 means the whole shaft on our drives would need to be changed, unless the UJs can be sourced from somewhere other than VP. Rockwell, the shaft supplier could be a good place to start, but they may well have a deal in place with VP limiting the availability of the actual UJs used in those assemblies.

schoolsOut · **Posted:** Mon Oct 07, 2013 3:48 pm

Graham,
Thanks for all the info. I do appreciate your expertise. Looking around in VP's store, it sure appears that I can get the u-joint. I am not questioning your info, I am just trying to understand how this works. Based on the drive info stamped on my motor, my drive is an SX-M 1.60.

When I follow the parts list it takes me to the list I posted above. There is also an SX-M1 1.60 which does not list u-joints for purchase. What is the difference? Since my 2005 appears to have the SX-M 1.60 which lists u-joints, can I buy them and use them? I also considered just pulling them and taking them to a auto parts house and matching them up with an automotive u-joint. Can't imagine that there is a difference.

Graham R · **Posted:** Mon Oct 07, 2013 5:01 pm

There may be some anomalies I suppose regarding the input shaft and UJs , depending on the drive ratio, if they had some complete upper units on the shelf; the engine in my 2004 boat (late 2003 build) is a GXi-F, yet yours on your 2005 boat is a GXi-E; the previous model year ( with no difference as far as I can ascertain!)!

A sure way of recognising the differentr driveshafts/ UJs is the means of retaining the UJs. Early ones had external C clip retainers on the UJ outer casings ( machined inner surfaces on the shaft yokes and intermeduiate coupler). The later ones have grooves machined into the yokes to take an internal circlip, like they had on automotive propshafts int he 1960's, before they discovered staking as a means of selling a new propshaft, rather than the UJs !.

The UJs on mine are still fine, but taking a fatalistic approach, I know they will fail sometime. I've lookd to find alternative automotive UJs, I have yet to find any !

LouC · **Posted:** Mon Oct 07, 2013 5:18 pm

Thinking back I think that Technologic 80 may have posted something about this a few years ago, in that he had to have the ujoints replaced. The mechanic tried to replace them, but it may have been that they were the non replace-able variety, or the mechanic just did it wrong, and he wound up having a major issue in that they failed and took out the gimble housing and let water in the boat. So I'd be careful with this.
This is such a crappy lousy poilcy that many auto makers and others have used to make more money. My 07 Jeep has the same stupid thing and when those u-joints go, I'll get a new custom shaft made up by a 4x4 shop with greaseable joints. The OE ones on my 98 (not greasable but replace-able) are still working fine at 15 years and 147,000 miles. I hope the newer one does as well.

The ones on my Cobra are replace-able and greaseable and are original. That tells you something. When you grease them you can see if water got in and rusted things by how the grease looks coming out, same with a gimble bearing.

might want to take a look at this and maybe PM him and ask what happened....

viewtopic.php?f=11&t=1812

schoolsOut · **Posted:** Sun Oct 27, 2013 7:54 pm

Just to give an update:
Pulled the drive today. First time doing that. It was a breeze. I used an engine hoist with a screw eye screwed into the dipstick hole. U-joints were silky smooth and free. No binding or roughness. No "play" in their movement. Reached in and rotated the gimbal bearing and that was the same. It does not appear that the vibration that I am getting is coming from either one of those places. Gonna give the high five prop a go in the spring. Maybe the 5-blade will eliminate the vibration over the 3-blade. For now, I guess I will just have to wait and see.

LouC · **Posted:** Sun Oct 27, 2013 8:11 pm

That's good to hear, can you check your alignment with an alignment bar?

schoolsOut · **Posted:** Sun Oct 27, 2013 8:17 pm

LouC wrote:

That's good to hear, can you check your alignment with an alignment bar?

I did not. I did not have the tool, but the drive was very easy to reinstall so I assume that means that the all is properly aligned. There would really be no reason for it to be out of alignment from simply removing and re-installing the drive, correct?

LouC · **Posted:** Mon Oct 28, 2013 12:49 am

No taking it off will not change it, I just wondered if it might be off a bit and that might cause a binding that may cause a vibration. If it went back on easily, its probably fine. Still its a good idea to get the alignment bar if you are going to do your own work. You sure the prop shaft was never tweaked? Might be a good idea to check it with a dial indicator. Prop is OK right?

schoolsOut · **Posted:** Mon Oct 28, 2013 6:15 pm

LouC wrote:

No taking it off will not change it, I just wondered if it might be off a bit and that might cause a binding that may cause a vibration. If it went back on easily, its probably fine. Still its a good idea to get the alignment bar if you are going to do your own work. You sure the prop shaft was never tweaked? Might be a good idea to check it with a dial indicator. Prop is OK right?

I will get an alignment tool for next season just to have on hand. One prop blade has a slight ding in it. I have pics posted above on this thread. I can't imagine it would cause a problem. In fact, I switched back to the original 3-blade aluminum prop that was like new and I thought the vibration was actually worse. I will take a look at the prop shaft. I am pretty sure that I have not hit anything in my two seasons with the boat, but maybe it was tweaked before I purchased the boat. Thanks for all the ideas, Lou. By the way, I printed the winterization process that you posted on another thread and brought along to use as a guide while I winterized last weekend. You are a great help.

LouC · **Posted:** Mon Oct 28, 2013 6:51 pm

Thanks for the kind words....I did mine today as a matter of fact...nice 60 degree day. I had to pull the boat out at this morning's high tide and it was about 38 degrees....COLD....ole reliable carbed motor started up well and idled over to the dock...
Back to the vibration issue....
One thing you might try is to get both of those props trued up for next year. I'd also see about checking the run out on the prop shaft. They are not that easy to bend, but it can happen. If your u-joints were good and tight and the gimble was nice and smooth...the only other things I can think of is alignment (but that would probably cause a constant vib come to think of it), prop shaft run out and prop imbalance.

We're thinking drive line issues but could it be rough engine running at certain rpms?

I think that just about all I/0s will exhibit a vibration at a certain trim angle or when you have the wheel cranked over and you're making a sharp turn at low speeds. U-Joints are not as smooth as CV joints as anyone who has driven an old school 4x4 can tell you. You can feel it in the steering in my older Jeep even when its in full time 4x4 because the front axle half shafts use u-joints instead of CV joints.

https://www.dropbox.com/s/lat6n4fyprj4k ... 3.....jpg#

john55c · **Posted:** Mon Oct 28, 2013 7:14 pm

schoolsOut wrote:

Thanks for all the ideas, Lou. By the way, I printed the winterization process that you posted on another thread and brought along to use as a guide while I winterized last weekend. You are a great help.

I agree completely, and have it printed as well for this weekend. I have the OMC manual too, but yours is easier to follow and read. It's in plain English versus manual English...thanks again for your help!

www.iFourWinns.com

Vibration at low speeds

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