PRM 80 Gearbox Repair.

basic

basic

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My PRM 80 is starting to slip in forward gear. !0 years old 2900 hrs.on Beta 28. These are not expensive but I thought I would like to strip and repair this winter. Give me something to do. Probably the clutch unit as everything else working ok. My question is has anyone on the forum done this and was it straightforward job or are there any pitfalls to watch out for? Also cheapest place for spares. Thanks.
 
Spares for PRM can be purchased from ASAP. The cone set is about ,£170 ish plus gaskets oil seals and bearings. Not worked on these boxes so cannot advise.
 
Give jez a bell at pilkinton marine, very knowledgeable. Can't find his number but a quick Google search will bring it up. Just a thought, when was the oil last changed? I know this can affect the clutch.
 
Thanks you guys. Gear oil changed regularly so I don't think that's the problem, but I just found on another forum that the manufacturers have updated the advice on the correct oil. They say to use ATF not engine oil and that the oil level should be checked with the dipstick SCREWED DOWN! I will remove some oil tomorrow morning and see if that helps. I normally check oil without screwing the dipstick down which is what was recommended on my old Hurth box.
 
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basic said:
Thanks you guys. Gear oil changed regularly so I don't think that's the problem, but I just found on another forum that the manufacturers have updated the advice on the correct oil. They say to use ATF not engine oil and that the oil level should be checked with the dipstick SCREWED DOWN! I will remove some oil tomorrow morning and see if that helps. I normally check oil without screwing the dipstick down which is what was recommended on my old Hurth box.
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Yes defo ATF...I would check the dipstick method again, too much oil can cause problems with overheating which might be the cause of your problem. Like I said give the guys at pilkinton marine a bell, the really were helpful last year when I was having trouble with my zf.
 
I had similar problems with a PRM 80 about six years ago. This was about the time PRM revised the oil spec from engine oil to ATF which, as said, should definitely be used. They also modified the faces of the cone clutch at about the same time. (I discovered all this when visiting the Coventry factory to pick up a new cone, etc.)

Stripping the box is straightforward if you're used to spannering, so much so that I can't remember a thing about it. This vid should help: https://www.youtube.com/watch?v=p_cp0UADP5I

There's a workshop manual, here: http://www.prm-newage.com/media/uploads/5073d799123d1.pdf

Regarding gearbox oil levels in general, there are appears to be no industry norm for whether a disptick should be screwed down or not. So for all boxes: RFM.
 
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