volvo 120 saildrive

[biasi]

Hi all,

I have a volvo 120S C saildrive on a 12m sailing boat. Recently bought a more recent but used 120S E with the intent to replace the 120S C because I suspect a crack in the gear housing due to corrosion of the sea water inlet resulting in finding oil from the drive on the rubber seal. While rebuilding the unit I noticed that while the 120S C unit's cone clutch is all brass even at the contact point with the gear drive surface where it is also grooved for oil drainage, the 120 S E clutch seems to be coated with what i am thinking is a friction coating at the contact point of the clutch with the driven gear on both the forward and reverse sides of the clutch. This would explain why volvo changed to synthetic GL5 gear oil for this model instead of the 10/40 engine oil of the SC

However part numbers on both clutches are the same.

The unit seems to operate fine though I cannot simulate the same working loads it would have installed on the boat while testing on the bench.

Can anyone confirm whether this is how the clutch is supposed to be?

Appreciate any information you can provide.

 

[scottie]

Are you saying that the number stamped on the cone is the same or the number in the parts book?

I would say that if the part physically changes then then Volvo,changes the part number and usually will show a supercession in the parts book if the new part can or should be used and the old pattern is no longer supplied.
This can cause a lot of problems if a unit had been repaired rebuilt with the later pattern especially if like cones there can be several changes and they show original part number replaced by a later number and you have something in the middle!

 

[biasi]

Hi Scottie, Thanks for the reply.

The parts manuals for all saildrives and the smaller gearboxes using a sliding sleeve cone clutch quote part number 851626 later superceeded by 873098. While I cannot be certain of the part number in the 120SC since it is currently installed on the boat, I had removed it 2 years ago and am quite sure it is the same part number (873098) as what is on the clutch from the 120SE.

Meanwhile I have also tested the SE by mounting a FIAT car clutch plate on the lathe, the splines of which match the input shaft of the drive perfectly. Load from the prop was simulated by holding the output shaft by hand (a bit dangerous unless very careful). Lathe speed was kept up to 200rpm for safety reasons, but otherwise the drive worked fine dis/engaging forward and reverse without problem and without any slipping of the clutch.

However before installing on the boat as it is I would like to be more certain that the SE clutch is not just damaged. I would be able to change the clutch in place however it is impossible to drain all the oil with the boat in the water and when I had accidentally used GL5 oil with the 120SC clutch, the clutch had worn considerably with the oil becoming speckled with brass dust when drained.

 

[duncan99210]

If the parts are identical, as seems to be likely, then perhaps the brass cone from the SC has worn away it's friction coating whilst the SE cone hasn't worn so retains its coating? You mention brass debris in the oil after you used the wrong grade in the SC: that could be an indication of what happened?

 

[biasi]

Hi Duncan,

No I am sure that the SC clutch is good since it still works fine and the clutch surface is vertically and horizontally grooved for oil drainage. It is the SE clutch which is smooth with only vertical grooves for oil drainage and with the frictions surface coated with a black substance. What I need to find out is whether this black substance is normal or damage.

 

[scottie]

Ask your local VP dealer for a look at the service bulletin regarding the cones.