“Clacking” noise on SP 135

[angus99]

Gear rattle. You ought to hear my Cummins 450 at 550rpm. Lots of gear noise in N.

If something was wrong with that gear you would hear it when in gear with prop load. If it quiets down with added revs, that is good. If it gets louder with added revs, then time to worry.

My vote is to GO.

It just gets faster—not louder—with added revs in neutral. No sound at all in gear at any rev. Looks like we’re going!

I’m really grateful for the advice.

 

[kchace]

It just gets faster—not louder—with added revs in neutral. No sound at all in gear at any rev. Looks like we’re going!

I’m really grateful for the advice.

This is great news and IMHO you did the right thing. You had a concern, you dealt with it and lucked out that it turned out to be a non issue or at most something to watch.

Have a great trip!

Ken

 

[angus99]

This is great news and IMHO you did the right thing. You had a concern, you dealt with it and lucked out that it turned out to be a non issue or at most something to watch.

Have a great trip!

Ken

Thanks very much, Ken. The last place I want a break down on this trip is while running up the Jersey Coast. There might be an onshore breeze and I’d end up in Jersey (just kidding, Scott.)

We checked the screen/filter today for metal shavings and it was clean.

I’m hoping that if the noise does turn out to be the damper plate that it won’t seize the engine if it fails. It doesn’t have springs, but it does have a weird looking plate made of plastic or some composite. We pried and tested it for movement, but it felt rock solid.

I’m going to listen to it under load as part of my regular inspections under way.

 

[what_barnacles]

Thats a flex plate. they crack and then flex way too much and then rebound every time a piston inputs combustion pulses.



You need a new one or take it to a normal damper plate.

 

[angus99]

Thats a flex plate. they crack and then flex way too much and then rebound every time a piston inputs combustion pulses.

You need a new one or take it to a normal damper plate.

How would I know if it’s cracked?

If piston pulses are causing the noise, would that explain only hearing them in neutral?

 

[what_barnacles]

in most cases like my crossfire's drive shaft and the propshaft of my boat its easy to see the flex plate. in your case its covered mostly and you'll have to split the assembly to check it. cracks in the urethane material should be obvious when you can see it completely. just try and spread the ears/bolt tabs apart from each other. the cracks will be in between them.


also look in the bolt holes as the bushing can wear as well.

 

[angus99]

Thanks, the problem is the plate was reinstalled after the yard inspected it. I don’t think there’s any way to pry it open as you describe without destroying it.

In researching this, some of these plates are designed to fail safe—even if the polyurethane cracks and disintegrates, they are designed to continue operating. I don’t know if mine are designed that way, but it will be my first question to tranny specialists tomorrow.

 

[what_barnacles]

It should bolt together. The dark bolts hold the flex plate to the flywheel. The light colored ones hold the flex plate to the trannys spline plate.
You can unbolt it from the flywheel and simply flip it around to inspect the urethane.

 

[angus99]

It should bolt together. The dark bolts hold the flex plate to the flywheel. The light colored ones hold the flex plate to the trannys spline plate.
You can unbolt it from the flywheel and simply flip it around to inspect the urethane.

Mine doesn’t have bolts holding the smaller and larger plates together. The two plates look like they’re peened together. The whole assembly is bolted to the flywheel.

 

[Ski in NC]

That's the same style drive plate that Richard on Dauntless is using. He pulled his tranny to replace some seals and inspected the drive plate at the same time. We discussed it and being that it looked ok and had lots of hours on it, decided to continue using it as is.

Must be a pretty good design.

Did you get a mfr or model number off it while it was in your hands?

 

[angus99]

That's the same style drive plate that Richard on Dauntless is using. He pulled his tranny to replace some seals and inspected the drive plate at the same time. We discussed it and being that it looked ok and had lots of hours on it, decided to continue using it as is.

Must be a pretty good design.

Did you get a mfr or model number off it while it was in your hands?

Saw no manufacturer’s marks on it when it was out, but we’re pulling the tranny again. The yard thinks they’re looking at a crack in the smaller plate that was overlooked the first time out. It’s visible in the photo above. edit: actually, the resolution isn’t good enough to see the “crack” if it is a crack.

Two words for this and the first is “cluster . . .”

 

[latravcha]

It that a crack at 6:00 in the first picture?

 

[Tuttouomo]

Angus, just went through this on my port tranny. I pulled the tranny for a rebuild and found the same exact drive plate that your pic shows. Upon close inspection found small cracks in the poly material, and the poly was very hard.
The trans shop said that the tranny showed signs of gear rattle and chatter from that drive plate. Also that that design was for a much higher HP drive line.
The drive plate was not "dampening" the vibrations as it should have.

I replaced the drive plate with a new one recommended for the Lehman/Velvet Drive system, the difference in smoothness and quietness was very noticeable.

The new drive plate was 1/3 the cost of the poly insert one.

Talk to Mike Vogt at Harbor Marine in Everett ,WA. A world of knowledge on marine tranny's and propulsion systems. They do a lot of rebuilds on all makes, an impressive operation. He won't steer you wrong or sell you something that you don't need.


Bill

 

[angus99]

It that a crack at 6:00 in the first picture?

Turns out it was not a crack. The real problem was the “collar” beneath the clip ring on the flywheel side of the plate (pictured below). A groove had worn into it, allowing the splines to wobble. Also, the poly ring is not cracked, but it is slightly distorted.

Angus, just went through this on my port tranny. I pulled the tranny for a rebuild and found the same exact drive plate that your pic shows. Upon close inspection found small cracks in the poly material, and the poly was very hard.
The trans shop said that the tranny showed signs of gear rattle and chatter from that drive plate. Also that that design was for a much higher HP drive line.
The drive plate was not "dampening" the vibrations as it should have.

I replaced the drive plate with a new one recommended for the Lehman/Velvet Drive system, the difference in smoothness and quietness was very noticeable.

The new drive plate was 1/3 the cost of the poly insert one.

Talk to Mike Vogt at Harbor Marine in Everett ,WA. A world of knowledge on marine tranny's and propulsion systems. They do a lot of rebuilds on all makes, an impressive operation. He won't steer you wrong or sell you something that you don't need.

Bill

So, a new plate is on the way from American Diesel. I did decide to go with the OEM-type plate with metal springs. This puts off our departure ‘til Friday, but the peace of mind is worth it. Big relief just confirming that it’s apparently nothing worse.

Thanks to all once again for the advice and support.

 

[Tuttouomo]

Good decision, have a safe trip.

 

[kchace]

I had the same plates on my boat. At 4800 hours I replaced them when I had the trans rebuilt. They were still good but wasn't going to find out how much longer they would last. Went with traditional spring type from AD.

Ken

 

[Jeff F]

That's the same style drive plate that Richard on Dauntless is using. He pulled his tranny to replace some seals and inspected the drive plate at the same time. We discussed it and being that it looked ok and had lots of hours on it, decided to continue using it as is.

Must be a pretty good design.

Did you get a mfr or model number off it while it was in your hands?

It looks identical to my new damper plate from R&D Marine.

 

[angus99]

It looks identical to my new damper plate from R&D Marine.

View attachment 78850

The very same. They’re very well made.

 

[angus99]

Clacking noise is gone!

But the saga continues.

The new damper plate went in easily and the starboard side is as noise-free as a 30-year-old drivetrain can be.

However, the tech noticed some play between the tranny and the aluminum adapter plate that bolts between the Twin Disc and the bell housing. You can see a slight movement in the lower seam when the gears shift (we really had it idling too high). (Ignore me saying “I’m not seeing it” near the end. Once pointed out, it’s obvious.)

Showed the video to Brian at American Diesel and he says the bolts appear to have loosened. So . . . the tranny is coming off tomorrow for the third time.

Next guy that says to me “hey, it’s a boat!” better duck.

https://youtu.be/EvR38Z6N2-g

 

[Jeff F]

The very same. They’re very well made.

I read a lot of good things about them and got one to proactively replace my old spring loaded one when I had things apart. It seems well designed and constructed.

It occurs to me in following this thread that the failure symtoms may be quite different between the spring vs elastic units, which likely made the diagnosis more difficult. I suspect that most field experience is with the spring ones that are pretty much ubiquitous.

 

[Jeff F]

However, the tech noticed some play between the tranny and the aluminum adapter plate that bolts between the Twin Disc and the bell housing. You can see a slight movement in the lower seam when the gears shift (we really had it idling too high). (Ignore me saying “I’m not seeing it” near the end. Once pointed out, it’s obvious.)

I was wondering about the damper plate failure, thinking about alignment. I'm no expert, but this seems like the root cause. Good catch.

 

[Wxx3]

So, it wasn't the damper plate?

I like that style of DP, nothing to break like springs.

Also, as Ski pointed out, from day 1, I noticed my Sp135 has a terrible rattle at idle, 600 rpms. I always increase idle to 800 after start and it runs are smooth as a baby's bottom.

5,000 hours later, no change.

 

[angus99]

So, it wasn't the damper plate?

I like that style of DP, nothing to break like springs.

Also, as Ski pointed out, from day 1, I noticed my Sp135 has a terrible rattle at idle, 600 rpms. I always increase idle to 800 after start and it runs are smooth as a baby's bottom.

5,000 hours later, no change.

The noise that started this thread was likely the damper plate—not so much a rattle as a rhythmic clacking sound. Replacing the damper plate stopped it. In my case, increasing rpms just made it faster. I tried to describe the problem in post 74, but the simple story is the splined hub had some play in it.

The question is why did it wear that way? The yard is speculating that loose bolts on the aluminum adapter plate—between the block and tranny—may have allowed enough play between engine and transmission to distort the ring/collar around the splined hub.

Here’s a photo American Diesel sent me of the adapter plate. The loose bolts appear to be the smaller ones on the inner circle that hold the tranny to the adapter plate.

 

[angus99]

Solved!

For those following this interminable mystery, here’s the Alfred Hitchcock ending.

We took the tranny off this morning (for the third time) because the tech noticed some vibration and a tiny gap between the transmission and adapter plate that holds it to the engine.

There are seven bolts holding the plate and transmission together—two can be accessed from the outside; five must be accessed from inside the bell housing.

The five bolts supposed to be on the inside simply weren’t there! It appears they were never installed. No trace of them in the bottom of the bell housing.

So the transmission basically was held to the engine by two bolts and the splined shaft. No wonder the damper plate was worn! I just hope nothing else in the tranny was damaged.

 

[greysailor]

Ian,
Glad you have solved the mystery, and that a major overhaul isn't in your near future!
You got off lucky on this one......I had a similar issue on a Case dozer I bought several years ago. The PO had installed a rebuilt transmission and misaligned the flex plate by one bolt hole, which resulted in the flywheel guide pin not seating in a hole. This put forward thrust on the crankshaft, which soon wore out the engine thrust bearings. Soooo, I got to pull the engine and do a complete overhaul that summer!

 

[bayview]

Very often the root cause of some problem turns out to be somebody doing a poor job when doing it right would not have been a big deal

 

[what_barnacles]

Wow. Glad you found the root cause.

 

[High Wire]

Twilight Zone theme song please!
Safe travels.

 

[Ski in NC]

Good catch on the bolts. Probably did cause that weird wear on the drive plate hub. I would not worry too much about any effects on the gear.

 

[Comodave]

Glad you found the problem.