Replacing Damper Plate

[SoWhat]

hi all,
with all of you here that have changed the dampner plate in your boat did you notice that the engines idled smoother at all ? I am wondering if mine need replacing on my FL 80 hp engines. the vibration in the boat seems eccessive up to about 850 rpms. changed all otor mounts last year. not much better.

Did not notice any difference. Old plates had plenty of life left in them. Once I had everything apart it made sense to replace the dampers. 4 Cyl engines will rattle at low rpms. Mounts probably make a bigger difference than damper. (Assuming shaft is aligned properly and prop balanced.)

 

[Sailor of Fortune]

some gear boxes have low end gearbox chatter. The Twindisc 502 has it. A lot of these gearboxes were matched to DD8.2s ( Mainship) and other yachts. My mechanic assured me it wasn't damper plate...He was right, I changed on and still had chatter.

 

[Transaxial]

#25
05-08-2020, 03:03 AM
Duvie
Join Date: Nov 2011
Posts: 290
71c series transmission
Transaxial, the transmission I did this on was a 71c. The front seal can be tapped in place after everything else is put back together. I installed the sleeve and seal without dismantling the transmission at all. I would think that yours would be similar but it sounds like from your post your mechanic is saying the pump section on yours has to come apart to replace the seal.

The sleeve and seal was a quick, easy 10 minute job on the 71 series. I see no reason why it should not last a very long time.

Duvie thanks for the comments. I am in agreement with you that I think the Speedie sleeve should be a simple, quick, low cost fix. I think my transmission guy was concerned about damaging the seal when he was sliding the new seal over the sleeve. But the fact that you and others have done this successfully might downplay his concerns. I have used sleeves successfully in lots of other applications without any problems. Thinking back about the conversation with my transmission guy, he seemed to be intent on going deeper than just changing the seal to be sure the oil pump and input shaft were all in good condition. I did discuss with him that this transmission only has 100 hours since it was all rebuilt. So the question still remain, why is the front seal leaking? Is it pitting on the shaft? Which could be repaired with a sleeve. Why is my guy insisting on going in further after only 100 hrs???

 

[jleonard]

I have a 1982 Albin 40 with a 135 hp Ford Noreast diesel (similar to a Lehman) and a Borg Warner 1013 transmission. I have owned the boat since 2005. I have never replaced the damper plate and based on the skills of the previous owner, neither did he. My transmission is working fine but it doesn't get a lot of heavy use because I do most of my cruising here in Nova Scotia just in August and September because of time constraints. My question is, should I proactively pull the tranny and replace the DP even though there is no indication of a problem? Even though I am getting good performance now, is this thing about to turn to dust?

Thanks to all who reply (especially Jay Leonard because I'm sure you've already done this with your boat).

Jeff

LOL. I just saw this.
Yes I changed mine out. After the first season I owned the boat I pulled the tranny after fall haul out and rebuilt it. It was shifting fine, but I'm glad I did because it would have failed the next season. (that's a whole post in itself)
It did not make sense to re-use the old damper and since it was right there it was already done. $135 and 3 bolts. Old one seemed ok maybe a little loose.

Postage stamp version of tranny story:
Took oil sample. It showed 3500 ppm iron. Called Bob Smith he said they recommend rebuilding at 350 PPM so he said my tranny was totally shot and I needed a new one.
Talked to local Velvet drive distributor, he said BS it can be rebuilt. Once apart the clutch material (paper) was just about gone and there was rust on part of the reverse cylinder.
There was also a magnet epoxied to the case bottom and guess what, yes that's where I took my sample. No wonder iron was so high! DUH
Everything else looked great, bearings were in good shape, but I put all new ones in anyway, had it bench tested and it's still working.

 

[Sangraal]

Changing the dampers at the dock is a straight forward job as others have described. The only complications are if you have to push the prop back the cutters will likely disengage. We did both our engine damper plates over a couple of days and had a diver available to align the cutters and mesh them as we pulled back the shafts. Easy enough at the dock but not a job I would relish in a breakdown. It is a 3 to 4 hr job with the right tools. In a seaway I am not sure it would be as easy and probably very stressful too, not to mention too hot. There is a recommended engine hour to do this. On the ones we changed out one was fine and the other was failing. Got lucky!

 

[Mako]

How did you pull the shaft back from inside the boat - was that just clamps and come along?

 

[Sangraal]

How did you pull the shaft back from inside the boat - was that just clamps and come along?

Just rotated it by hand. It moves relatively easily. The diver was there to align the cutters on each shaft.

 

[Alisske]

I consider myself an able bodied person. I have been caring for my Lehman 120 and never miss a service interval. When I got the boat, I redid the head gasket, injectors, injector lines, alternator upgrade, starter, raw water pump upgrade, Fresh water pump, antifreeze overflow system, all hoses, belts etc... All of it was “easy peasy”

The one thing I bought, but never did was the damper plate. It sat in a shelf for a few years, and I put 2000 hours in her. (Took my Groverbuilt 26 from Cape May to The Cape in Mass.)

I decided to do it this weekend. What a bitch. I now know why folks don’t change them. On the surface, easy job. Unbolt prop shaft, push back, unbolt tranny housing, support engine, pull tranny back a few inches, then “just swap out the plate”

Well, my damper was frozen to the splines on the transmission. That meant nothing was coming apart. I’m a big guy and manhandling a BW 72 series tranny was like taking the dog for a walk.

Until this. We must have tugged and sworn at the transmission for 3-4 hours. Finally, the damper plate splits in two (see pick) and the spring part stuck with the tranny, and the other half was still bolted to the fly wheel. All said and done, took me about 5-6 hours and Motrin.

Is there something I could have done to avoid this?

 

[Comodave]

I did my port damper this last winter when I had the engine out. Of course that makes it easier but it only took about an hour. I had the engine and transmission sitting stacked above the starboard engine on a supported deck. I took a floor jack and put a piece of plywood on it to spread out the weight of the transmission on the pan. Unbolted it and rolled it back about 6”. Unbolted the damper and put the new one on and bolted it on. Slid the transmission forward and bolted it onto the engine. Done, very easy, but mine wasn’t stuck to the shaft. I did lube the shaft before we put the damper back on though.

 

[SteveK]

I did both of mine after one failed. This discussion brings a question.
What do you guys think of drilling a hole in the bellhousing to accomodate a borescope for inspection purposes? There is no lube flying around, a small 1/2 inch hole, what could it hurt?

 

[Comodave]

I would not bother, the life of dampers is supposed to be several thousand hours I believe so I would just plan on changing them again in 1000 hours to be safe. You may never get another 1000 hours on your boat before selling it.

 

[FF]

Damper plates are like everything else in a boat , there are different quality levels .

I have no idea what the difference is , but it might be worth while to find out.

 

[psneeld]

Drilling an inspection hole is what a couple marine engineers recommended to me when I thought mine was failing.

As to lube, if you have a small rear seal leak like I do, there is a tiny bit flying around..but the good news is the oil made taking things easier to take apart.

 

[jleonard]

Drilling an inspection hole is what a couple marine engineers recommended to me when I thought mine was failing.

As to lube, if you have a small rear seal leak like I do, there is a tiny bit flying around..but the good news is the oil made taking things easier to take apart.

You could tap the hole for either a pipe plug or a bolt and seal it.

 

[catalinajack]

I rather doubt YOU could have done anything to prevent this. If it were I putting it back together I would have put never seize on the splines in the hope that the next time it would come off easily. Just yesterday I helped my son replace the wheel bearing assemblies on his four wheel drive truck. They are bolted to the A-arm from the back and pinned to the splined shaft with a 36mm gland nut. The nut came off easily enough but that bearing chuck would not slide of the shaft without a prodigious amount of beating with a five-pound sledge. I have done the same job on my truck three times without any difficulty but I always goober everything with anti-seize. Is there a lesson there as to splined shafts? I don't know.

Since we are talking about a Lehman 120, if you ever need to change your exhaust elbow, and you will, you may find the bottom two bolts seized. Consider backing them out now and putting anti-seize on the bolts. I do this once a year. I just changed both my exhaust elbows. Easy job that way.

 

[DCDC]

I have JD 6068’s with Twin Disc 507 gears. It looks like they have a “drive spider” with rubber blocks instead of a damper plate. It looks fairly stout. The service manual recommends replacement when the engines are rebuilt.

Any experience with this type of drive?

 

[Ted]

I had two boats with Twin Disc MG506 gears, same drive system.
Worked well. 10k hours on first one when I sold it

Ted

 

[Alisske]

Thanks for the replies.

I got the remainder of the damper plate off and cleaned up the splines. Damper plate slides on and off real nice. Gonna lube that with antisieze like I’m gonna make love to it, lmao.

Was gonna tip the tranny on its end and fill the bell housing with ice water, then burn it off, but then decided to try to cut some slots in it and then pry it with a pry bar. Long story short, it worked. First in half. Second half was still stuck, so on the third cut it popped loose. No hammering involved.

Have new motor mounts on the way, so reinstall next weekend. Been progressively going over the boat. I like offshore fishing in the northeast in September, but also wanted the boat in top shape for the covid season. Was driving my boat to and from work each day during the last outbreak in NYC.

I do my elbow, batteries, and coolers every three years. I am doing my fourth elbow now with the tranny out. It’s not so bad. I rotate the bolts from bottom to top (throw the old top ones out and buy new bottom ones). Chase the threads with a tap, clean the threads and apply antisieze. Haven’t had a problem yet.

A

 

[Zoar]

What kind of noise would it make if it was going? A winding / whirling noise?

 

[Alisske]

What kind of noise would it make if it was going? A winding / whirling noise?

Mine wasn’t going. Was just about 2500 hours since the last time it was changed. I have heard that there is no warning. I heard that sometimes it gets a little more noisy.

Thing that worried me was that when it goes, the boat will stop in its tracks.

Just glad it will be finished this weekend.

 

[rgano]

Mine wasn’t going. Was just about 2500 hours since the last time it was changed. I have heard that there is no warning. I heard that sometimes it gets a little more noisy.

Thing that worried me was that when it goes, the boat will stop in its tracks.

Just glad it will be finished this weekend.

I had one go on my port engine as I was getting ready to leave a hurricane anchorage after storm passage. I was getting no action from the port engine and closer investigation revealed a scraping metal on metal sound. Limped home on stbd.

 

[Alisske]

I had one go on my port engine as I was getting ready to leave a hurricane anchorage after storm passage. I was getting no action from the port engine and closer investigation revealed a scraping metal on metal sound. Limped home on stbd.

Jesus. That sucks, but nice to have twins in that scenario

 

[rgano]

It was a very short run home. When the mechanic came ro repair it, after sliding the shaft back several inches, he replaced two side bolts holding the tranny to the engine with extra long bolts with their heads cut off and slots cut for a screwdriver to help drive it into the engine. Sliding the tranny aft on those two "rails and back on was a snap. the photo shows them lifting the tranny back onto the two extended bolts. You can see the red springs on the new plate in the bell housing.

 

[Comodave]

That is the easy way to do it if you have room to slide the transmission back. However in my boat there isn't room to slide it back so I am changing the damper plate when I have each engine out. One done last winter, one to do this winter.

 

[mahal]

On my boat, a Grand Banks with twin Lehmans 120, the rear motor mount brackets are attached to the gearbox. To those with the same set up, how did you brace the engine, while replacing the damper plate? I was thinking of having engine mount brackets fabricated and mounted to the rear of the engine with old engine mounts to rest on the stringer as my bracing tool. I figured that the old engine mounts will allow me to lower or raise the rear of the engine when reinstalling the engine mount and bracket that are attached to the gearbox. Thanks for your input.

 

[Cigatoo]

On my boat, a Grand Banks with twin Lehmans 120, the rear motor mount brackets are attached to the gearbox. To those with the same set up, how did you brace the engine, while replacing the damper plate? I was thinking of having engine mount brackets fabricated and mounted to the rear of the engine with old engine mounts to rest on the stringer as my bracing tool. I figured that the old engine mounts will allow me to lower or raise the rear of the engine when reinstalling the engine mount and bracket that are attached to the gearbox. Thanks for you input.

Also interested in others approach’s.

 

[boatpoker]

On my boat, a Grand Banks with twin Lehmans 120, the rear motor mount brackets are attached to the gearbox. To those with the same set up, how did you brace the engine, while replacing the damper plate? I was thinking of having engine mount brackets fabricated and mounted to the rear of the engine with old engine mounts to rest on the stringer as my bracing tool. I figured that the old engine mounts will allow me to lower or raise the rear of the engine when reinstalling the engine mount and bracket that are attached to the gearbox. Thanks for your input.

I have the same situation. Jacked it up with a cheap scissors jack and wedged in 2X4's under the engine.

 

[mahal]

I have the same situation. Jacked it up with a cheap scissors jack and wedged in 2X4's under the engine.

Thanks. But I have a fixed drip pan under the engine. Wonder if I can jam wood (cut to the right height) under the pan and place the jack on the pan.

 

[boatpoker]

Thanks. But I have a fixed drip pan under the engine. Wonder if I can jam wood (cut to the right height) under the pan and place the jack on the pan.

I wouldn't do that. We placed the blocks on the edge of the engine where the bell housing attached.

 

[rgano]

On my boat, a Grand Banks with twin Lehmans 120, the rear motor mount brackets are attached to the gearbox. To those with the same set up, how did you brace the engine, while replacing the damper plate? I was thinking of having engine mount brackets fabricated and mounted to the rear of the engine with old engine mounts to rest on the stringer as my bracing tool. I figured that the old engine mounts will allow me to lower or raise the rear of the engine when reinstalling the engine mount and bracket that are attached to the gearbox. Thanks for your input.

This is one of my twin FL 120s in my Grand Banks 42 with tranny and then bell housing removed. No special bracing here. I don't see your problem here.