volvo shaft coupling

[[448]]

I'm referring to the 4 'doughnuts' which connect the gearbox output flange to the propshaft flange. Engine is MD2B.
Does anybody know how these are constructed?
The nuts on mine have never been dead tight, and any attempt to tighten them results in the whole doughnut turning.
The engine has done many hours in this condition, with no apparent ill effect.
All advice welcome.


Cheers, Dave

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[colvic987]

replaced mine a couple of seasons ago , they have a stud imbedded in rubber, then the other end has a stud welded to washer which is bonded to rubber, this side normally shears from the rest of the unit, if it is turning and not tightening then suspect, one side is detached from rubber , to replace them it will cost around £30 each, so it is not an inexpensive once you have multiplyed by 4, there are other solutions, r and d couplings ,a replacement in polyurethane, which costs around £38, but i did not want to have to do any major repair, i just needed to get the flexi coupling back to working order, the job is easy to do, once the old doughnuts are off, try some penetrating fluid on the nuts first, but i suspect you have a sheared doughnut, why are you replacing, do you have symptoms of engine moving around on the mounts, when engine in gear, if so most probably 1 sheared doughnut...

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[[448]]

Bit the bullet this afternoon. took off the complete coupling including outer plates. Three doughnuts sheared, one still looks OK. Hate to think what would have happened if the last one had failed when in reverse!
I would be interested to know a bit more about your solutions. What's r and d?

Cheers, Dave

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[colvic987]

Hi dave, this is the web site for r and d couplings,
www.randmarine.com, i spoke to the technical director when i was down at the boat show a couple of years ago, i was quite impressed with the coupling itself, anyway all explained on website, and i am sure that they are approachable if you have any queries... there are other types of couplings available, asap supplies, might also have details, but i am sure that the r and d coupling would be the easiest to fit , the major difference would be to get the width of the gap between flexi coupling plates, measured , so that the coupling is the same width as the doughnuts you have replaced, which would eliminate any adjustment of shaft length, and prop, hitting rudder, ( if there is not much gap between prop and rudder) , hope everything goes well for you, graham...


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[seaesta]

My MD1 has 4 rubber elements between two plates. These sheared whilst on passage several years ago. The "originals" turned out to be identical to the exhaust hanger off an old mini. I wombled two sets from Kwik-fit and they worked OK for 2 seasons before shearing again. I then wombled some Renault exhaust hanger rubbers (flat steel plates with threaded studs either side and rubber donuts between) from the same source (god bless Tom Farmer). These are a bit beefier and have worked well for 10 years. I inspect them twice a season and so far so good.
I dont recommend anything other than a propriety item but these have worked well for me so far.
Martin

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[[448]]

Many thanks to Graham and Martin. I have spoken to R and D and ordered one of their couplings. I did think about the car exhaust mounting brackets, but the additional cost of the R and D item was very small.
Cheers, Dave

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