PRM 160 / Beta 43 Drive plate question

[Bobbybass]

I have a strange rattle that comes from my PRM 160 gearbox...especially at low revs.

I have kept the box well maintained...with regular oil changes ...and it works without fault in forward and reverse...ie..it doesn't appear to slip.

 

If I increase the revs..from tickover 800 to 1000 it goes and sounds fine through the whole range.

It doesn't rattle...until you engage gear.

 

It produces the rattle at low revs...when you engage gear...and is worse in forward than reverse.

Somebody suggested that the drive plate may be on its way out (its done just over 8000 hours)

 

A couple of questions:

 

I am on the Thames at present..and then heading back to the midlands.

Could the plate just fail and leave me stuck ?

 

Is the plate actually inside the gearbox..or can I remove the box and 'expose' the plate...like a car clutch ?

 

Thanks..in anticipation.

Edited August 21, 2012 by Bobbybass

[Offcumden]

Presumably the plate could fail, its located in the Bell housing exactly like a car.

 

If you are going to expose it I assume you are going to replace it at the same time ?

[bizzard]

I have a strange rattle that comes from my PRM 160 gearbox...especially at low revs.

I have kept the box well maintained...with regular oil changes ...and it works without fault in forward and reverse...ie..it doesn't appear to slip.

 

If I increase the revs..from tickover 800 to 1000 it goes and sounds fine through the whole range.

It doesn't rattle...until you engage gear.

 

It produces the rattle at low revs...when you engage gear...and is worse in forward than reverse.

Somebody suggested that the drive plate may be on its way out (its done just over 8000 hours)

 

A couple of questions:

 

I am on the Thames at present..and then heading back to the midlands.

Could the plate just fail and leave me stuck ?

 

Is the plate actually inside the gearbox..or can I remove the box and 'expose' the plate...like a car clutch ?

 

Thanks..in anticipation.

This is almost certainly drive plate noise and yes they can fail suddenly, it can be drive spline wear noise and or like a clutch plate the drive plates shock absorbing springs and buffers worn. The drive splines in the plate can shear right off stopping drive immediately, and yet some have been known to rattle on forever.

It is quite an easy job to do, yes similar to renewing a cars clutch, disconnect prop shaft and slide back a few inches, disconnect any other rigid fixtures which prevent the gearbox from being withdrawn backwards a few inches,unbolt gearbox from engine, once clear drive plate is bolted to engines flywheel like a cars clutch pressure plate. a couple of hours work.

Edited August 21, 2012 by bizzard

[Bobbybass]

Presumably the plate could fail, its located in the Bell housing exactly like a car.

 

If you are going to expose it I assume you are going to replace it at the same time ?

Hi..

 

I haven't made plans to expose it or replace it yet.

I wondered what is involved to do that..?

Do I unbolt the gearbox from the engine...simply swing it out the way...bolt in a new plate..and bolt the gearbox back on..?..(blimey..if life was so easy..)

or is it a job that will have me cursing and swearing and in need of specialist alignment tools etc?

 

Tah

Edited August 21, 2012 by Bobbybass

[David Schweizer]

It sounds very much like the sound the plate on our PRM 160 made when it was beginning to fail. It went on for quite a long time without failing, but the centre fell out when the gearbox was eventually taken off.

 

Replacing it appeared to be a comparatively easy job, althouigh I left it to a marine engineer who completed the task in under and hour. From memory he detached the prop shaft and pushed it backwards, disconnected the linkage and oil cooling pipes, and then removed the screws holding the housing onto the engine block and slid the box off the shaft. The plate was unbolted from the Flywheel and then slid (or in our case, fell) off. Replacement was a reverse repeat of the dismantling process.

 

If you intend to do the job yourself, you have to be prepared for how heavy the box is, and have supports ready to support it's weight when you take it off.

Edited August 21, 2012 by David Schweizer

[Offcumden]

Probably the latter, on my boat the plate went just after we bought it at 4000 hours which we were informed was about the norm.

 

I replaced it myself (ex Car Mechanic) with a lot of blood, sweat and swearing, after a further 6000 hours the tinkling started rang RCR plate replaced for £50 excess.

 

In a quarter of the time it took me. No Sweat. Result

[bizzard]

Yes withdraw box backwards enough to clear,they are not too heavy just an awkward shape, resting it on a block and then you probably have the converter plate, bell housing to remove another few bolts and probably the starter motor, depends on your exact set up, its all quite obvious really especially if you've renewed car clutches in the past.

 

Ps If the drive plates drive splines should sheer stopping all drive i doubt whether the gearboxes input shaft splines will sheer,''the ones that enter the drive plates splined hole'' as the metal of the drive plates centre splined boss is of a weaker strength cast variety designed to strip splines leaving the gearboxes drive splines unharmed, well i've not known one to anyway.

Edited August 21, 2012 by bizzard

[RLWP]

Be aware that some installations mean you are removing the rear engine supports when you take the drive plate housing off to get to the driveplate. Ours is like this, so the engine has to be supported while you do the job

 

Do check the splines on the gearbox input shaft for wear when you are in there

 

Richard

[Trev]

I have the same Beta 43 and 160 PRM. I replaced ours about 18 months ago. I contacted Beta and gave them the serial number of the engine and the driveplate was there the following day. My engine has a soundproof housing so I had to juggle with ropes etc and lift the gearbox out completely. If you dont have to do this its a bonus!

Once the gearbox is out of the way just undo the driveplate bolts and it will pull off. Just reverse the procedure and job done.

 

You can rest assured that if the driveplate was to fail it would be when you go to put the engine in reverse to stop in an emergency!!

My old driveplate was literally falling apart and wouldnt have lasted much longer.

No special tools just a good socket set and a sense of humour!!