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Old 19-08-2016, 10:28   #1
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Terminology help: Damper plate, clutch disc, pressure plate, drive damper

All I know for sure is when I had my Velvet Drive serviced I was told I should replace something that was wearing out.

I believe it was mounted on the flywheel of my Isuzu 6BD1 engine. My transmission is a direct drive Velvet Drive 72C (10-18-012).

I recall the term damper plate, however, the notes I took from serviceman say to buy a new CD with 26 keys. This I take to be a clutch disk.

On the web I find a wide variety of devices all with 26 keys, some round, some triangular, some cheap, and some expensive.

My local Isuzu dealer sells pressure plates and clutch discs.

Could someone help me narrow down exactly what I need.

Thanks
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Old 19-08-2016, 10:55   #2
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

The drive plate looks just about like a clutch without friction plates, The center spline and spring damper plate assembly is bolted to the flywheel.
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Old 19-08-2016, 10:57   #3
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

I can almost guarantee you it's not a clutch disc or pressure plate you're looking for. Unless you've got some sort of cobbled together drive train.

the Damper plate is the doodad that bolts onto the flywheel and has a spline shaft socket in the middle to drive the transmission. It lives to absorb shock when the transmission is put into gear, as well as to remove the shock of each cylinder firing. I'd be you're mechanic wanted you to get one with 26 teeth on the spline.

Problem, what spline shaft diameter, what flywheel diameter.....etc...there are a lot of variables here.
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Old 19-08-2016, 11:12   #4
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

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Originally Posted by Sailmonkey View Post
I can almost guarantee you it's not a clutch disc or pressure plate you're looking for. Unless you've got some sort of cobbled together drive train.

the Damper plate is the doodad that bolts onto the flywheel and has a spline shaft socket in the middle to drive the transmission. It lives to absorb shock when the transmission is put into gear, as well as to remove the shock of each cylinder firing. I'd be you're mechanic wanted you to get one with 26 teeth on the spline.

Problem, what spline shaft diameter, what flywheel diameter.....etc...there are a lot of variables here.
The local Isuzu dealer website is geared for Isuzu engines used in road applications where shifting is involved so I agree it seems I should not be looking for a new clutch disc, or pressure plate.

I just don't like the fact my notes, now six years old, say to buy a new CD. I think I will try and call the serviceman in Singapore and hope he is still working. He was a former direct Borg Warner employee and repaired my Velvet Drive after reverse failed.

I found one website blogger describing a flexplate. This I take to be one in same as damper plate.

I sent off emails to both Velvet Drive and local Isuzu office.
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Old 19-08-2016, 12:31   #5
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

I guess you guy's have never seen a clutch plate? You will find that they are quite similar and made from many of the same parts. There is nothing cobbled together at all. It's how they are made.
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Old 19-08-2016, 13:21   #6
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

They have several names, drive plate, damper plate, vibration damper, engine coupling, drive coupling, whatever.

A pressure plate is a device that bolts onto a flywheel to clamp a clutch disc to the flywheel so that power can be transferred through the clutch disc, and when it is dis-engaged the transmission can be shifted.

What you want is probably most commonly called a transmission drive plate and is bolted directly to the flywheel, where the transmission is always engaged with the engine, and the clutching mechanism is contained in the gear itself.

Most likely what you want is this, or something very close to it



which is a 26 tooth drive plate for a Velvet drive transmission. This particular one is Item #:ALTDA107 and is 123.00 from these people. talk to them to see if it's correct, they have a wide selection.

ALTO DA107 Drive Plate 14" - Drive Plates - Dampers - Inboard Drive Systems - Drive Systems

or the local people shouldn't have any problem getting it either.
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Old 19-08-2016, 13:30   #7
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

On your transmission you have a triangular shaped damper or drive plate located between the engine and trans. It absorbs shock and couples the engine and trans.

Inside the trans you have a "clutch pack" consisting of several clutch steel discs and clutch friction discs (72 &73). The shift lever engages and disengages these discs (via hydraulic pressure) to control the power transmitted to the trans output shaft.

Both pictured in the attachments.

Doesn't help you know what you need but maybe helps explain what you have.
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Old 19-08-2016, 13:30   #8
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

Unless you have the existing damper plate in your hand, I think the likelihood of finding the correct one will extremely difficult. If you look at the order form for R & D damper plates at -- PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D --, you'll notice there are 9 questions they need answered before they can recommend a specific part number and that's besides the questions about engine and transmission models numbers.

I wish I had ordered a spare when I bought our new engine. When we were in Fiji, I was having some troubling noises coming from the transmission and when I contacted my dealer for Beta Marine, he was able to get me the exact replacement part. I installed the one I ordered but I still had the same noises. Still do.

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Old 19-08-2016, 14:20   #9
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

Here's another one from the same supplier. ALTO DA106 Drive Plate 14" - Drive Plates - Dampers - Inboard Drive Systems - Drive Systems



Note all the holes at the ends of the three triangles. I assume this is to fit a wide variety of engine flywheels. This one is 100.00 and is also for a Velvet Drive transmission, with a 26 tooth spline.

Flywheels and flywheel housings are to a certain extent standardized, for various reasons, and sometimes one will find that certain interconnecting parts will work within different manufacturers.

On the other hand, you will also find manufacturers that specify and manufacture items to be proprietary to them and them alone, in order to, among other things, ensure their parts customer base.

If one can find a trusted and knowledgeable parts supplier, the parts savings on an overhaul, for instance, can quite literally be thousands...
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Old 19-08-2016, 14:48   #10
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

Hey Jim, to clarify, earlier I was posting as you were posting the round plate.

I noted the triangular shape just to make it easier to spot in the attached image. And not to suggest the round plate is incorrect.

Agree with your last post. Round or triangular isn't an issue. Overall diameter, bolt patern, and splines are the key.

The round plate has those edge slots to prevent harmonics in the plane of the plate. The triangular plate choses to eliminate the surface area where harmonics occur.

In some installations the round plate is attached at three of the six mounting locations. Sometimes the aftermarket is smart enough to eliminate the number of items needed to be manufactured and stocked. And can offer the savings as a price advantage to the customer.
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Old 19-08-2016, 16:04   #11
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

A very frustrating aspect of what should be a simple exercise is I have the complete "Workshop Manual" for my Isuzu Engine and

Zero mention of a damper plate is made and zero dimensions of the flywheel are shown.

The best thing the manual told me is my engine is 5.785 liters.

The manual shows me a drawing of the flywheel and I see 12 bolt holes. Many images I see of damper plates only show 8 bolt holes.

Obviously the triangular version doesn't use all bolt holes available.

One interestingly tidbit I gained was from the website I was directed towards

" Today's marine diesels are designed with lightweight flywheels which do not create the inertia of an older heavy flywheel. The lighter flywheels result in gear chatter or rattle at low RPM's. This rattle translates into gear wear and damage to the drivetrain. Our damper plates eliminate this problem."

In other words the damper plate according to above us nothing more than weight hung onto the flywheel to help reduce chatter at low revs.

Well golly gee! I already have a damper plate on my engine so the weight is currently present and obviously not doing its job well. Pulling its weight. Ha, ha.

This website shows a round one with 12 holes.

-- PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D --

It introduced two new terms too.

"A "Hammer Head" damper plate is designed for general use where motoring at low Rpm's is common."

It is common for me to be at low revs to conserve fuel.

" A "High Deflection" damper plate is designed for use in vessels where low RPM engine use is the norm as in work boats or where gear noise is being experienced."

Well that is me too. Groan.

This brings me back to the central problem. I am obviously here because of noise at low revs and a worry the transmission guy told me I should replace the disc soon.

A "high deflection" damper plate sounds like the thing for me. I bet it is expensive.

I filled in their form and was given 403Error reply. The form indeed asked for wide range of information that I don't have despite having manuals for both engine and transmission.

# of holes is a guess of 12 based on drawing
Max revs... hmm low
Flywheel diameter unkown
Pitch of holes...don't even know what that is
Hole diameters... unkown
Shaft diameter...unkown

All these questions and people keep telling I have one of most popular engines and transmissions.

This is frustrating fast. Well actually slow I have been carefully reading manuals cover to cover for information not present.
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Old 19-08-2016, 18:34   #12
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

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Originally Posted by Guy View Post
I guess you guy's have never seen a clutch plate? You will find that they are quite similar and made from many of the same parts. There is nothing cobbled together at all. It's how they are made.

What I was saying was if his engine has a clutch plate, then it is likely some sort of cobbled together drive system........not that clutch plates are cobbled together.


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Old 19-08-2016, 18:38   #13
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

Pbmaise,
The damper plate is not just mass added to the flywheel. It is in fact very little mass. But it is a spring loaded torisional damper that attempts to smooth out the low speed variations in engine speed.


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Old 19-08-2016, 19:31   #14
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

A 5.7 litre engine, that's more than five times larger than my little 3gm yanmar. And the same size as the V8 in my last truck. Damn.


Anyway, I'm reading the manual for your transmission. And it mentions that there is an adjustment/alignment process for the damper plate. That seems unusual to me. Further, it says the instructions for this are in the Installation Manual, not the service manual.

Do your noises go away above 1000 rpm?

Do the noises occur in forward and reverse?


I think the twenty questions thing you are seeing is because you're looking at aftermarket sources.

If you check with your engine maker it may be more clear what is the defining plate needed.
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Old 19-08-2016, 21:07   #15
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Re: Terminology help: Damper plate, clutch disc, pressure plate, drive damper

OK, my last post here, bear with me.

Starting to understand why this is such a puzzle. Apparently Isuzu doesn't really care what happens past the crank flange on back and takes no responsibility.

Seems the 72c trans is bolted to everything from 4 cylinders to V8 Lincolns.

The installation manual has a damper selection chart by Warner Gear. No dimensions are given. It's based on gas or diesel, number of cylinders, HP, torque, etc.

Mentions how power pulses and firing order affect spring choices in the plate. And the wrong springs will lead to trans damage on splines or gear teeth.

Mentions how "body fit" bolts must be used, regular bolts won't hold up to the dampening oscillations.

What a freaking puzzle.

Hope you get it sorted soon.
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