Life of cutlass bearings?

jimg

jimg

Well-Known Member
Joined
30 May 2001
Messages
1,901
Location
Dartmouth
Visit site
How many engine hours do people think that cutlass bearings should last? Or is that the wrong way to measure a reasonable life span. Also how much play is tolerable before thinking about replacing them?
I thought they should last a good few seasons, but I replaced them in April and there is quite a bit of movement on them again. The boat is a Nimbus 370 with KAD43P's on V drives.
I would be interested to hear how long yours last!!

<hr width=100% size=1>
 
I would expect 10 years plus, and I do a fair few hours each year. Are you running in very sandy or silty conditions? That will have some affect.

<hr width=100% size=1>
 
The boat is on the River Dart and cruised on the Devon coast and France. I agree they should last a lot longer than a year, but the dealer is claiming that it is not a problem.

<hr width=100% size=1>
 
Well the Dart is neither sandy or particularly silty so it's some other problem. In my books undue wear after only one year is a big concern, something must be causing it and I'd want to know what!

<hr width=100% size=1>
 
I have just replaced one of a pair, both of which were new nearly five years ago. This is on a TS37, with TAMD61A's driving 1.75 inch shafts. The reason I replaced only one (port side), was that the stbd one had no play at all, and the port one some 2 mm but offset to 2 O'clock. I've estimated the've done some 500 hrs.
Now I had suspected that the port one had gone, due to excessive vibration. When I looked at my port side one, it was obvious that the wear was assymetric, due possibly to the shaft being missaligned to the "A" bracket. I do remember my boat's previous owner had replaced the engine mounts. This should mean realigning the prop shaft to the "A" bracket. I suspect this was not done.
Furtunately, instead of removing the shaft from the coupling which I could not budge, I decided to remove the "A" bracket instead, which actually was a much easier job. On replacing the "A" bracket, with the new bearing in, I allowed the shaft to sit in it's natural mid position, and chocked it up. The "A" bracket was now slid back on. And guess what? The holes didn't line up; in fact about 6mm out. So I re-drilled the holes, re-sealed and bolted it up. The vibration is now substantially reduced, infact on a par with the stbd.
The moral of this story is about checking shaft alignment. In my case the "A" bracket was forcing the shaft downward, and a little to the side, hence the assymetric wear.
So I would suggest, as in fact LJS has suggested that something is wrong. If at all possible, check the type of wear. If uniform, then that means severe prop inbalance. If as mine, it is offset, then the prop shaft is missaligned.


<hr width=100% size=1>
 
Depends if your engines are out of alignment or not.

Many are and therefore would not last for ten years. I would have thought 5 years was more realistic.

If you are going to fit new ones, worth getting an engineer to check the alignment properly at the same time and they will last.

<hr width=100% size=1>
 
I also think they are out of alignment, I just need to convince the dealer now. If I had got 5 years/500 hours then I would have said that was OK.

<hr width=100% size=1>
 
The potential dispute is with the dealer, the boat was new in June 2002 and when it was lifted at Easter this year the shafts had a lot of movement and so the bearings were replaced by the local engineers. The dealer paid for the work but asked for the bearings to be sent to them, on seeing them they claimed that they were hardly worn. The boat has just been lifted ( i.e 6 months in the water ) after another 90 hours run. Again the shafts have a fair bit of movement. I am expecting a visit next week from the dealer to look for himself. I am personally sure that there must be an alignment problem.

<hr width=100% size=1>
 
OK I see your problem. Did you yourself, see the bearings? If there is shaft misalignment, then as I stated before, there will be asymmetric wear. If it is uniform wear, then that suggests, either bent shafts, or severely out of balance props. I am not sure if you mentioned if you have had acute vibration.

Presumably there is some sort of warranty with NIMBUS.

Another thing. Who initially, is deciding that the bearings have abnormal play. Is it you, the local engineer or the dealer?
If, as you state, that on the first occasion, the dealer said there was no play that he could see, then why were they changed? - strange!
If I were you, and this is likely to drag on, I would get an independent engineer to assess the situation. At some stage Nimbus themselves ought to be involved, if not already.


<hr width=100% size=1>
 
Hi Stuart,
I did see the bearings and there was asymmetric wear, thats what started me off on the alignment route. However I posted the bearings to the dealer and when he saw them he did not agree.
The "new" bearings are still in place and after he comes on Tuesday I will let you know what his explantion is for the excessive wear. Hopefully he will agree this time or indeed I am going to have to escalate it.

<hr width=100% size=1>
 
You must log in or register to reply here.

Share this page

Top