Replacing Damper Plate

[boatpoker]

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.

His problem (like the photos I posted) is that unlike your engine, the rear mounts are on the transmission, not the engine.

 

[rgano]

His problem (like the photos I posted) is that unlike your engine, the rear mounts are on the transmission, not the engine.

Exactly, and the hint was the FL 120 will accept mounts there.

 

[Alisske]

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.

Mine has a similar set up to yours (rear mounts on tranny). I supported the engine off the cooler bolts (see pics). I spoke to Brian at American diesel and he recommended switching to rear mounts on the engine block. I am going to keep it the way it is. I am redoing the four engine mounts this week, so between the damper plate, tranny service and new engine mounts, I don’t plan to take that tranny off for a while, so not worth the extra bucks and hassle to switch.

 

[Alisske]

Just as a follow up. Everything except getting that tranny off was simple. Lmao.

Did the motor mounts while the tranny was out.

 

[catalinajack]

When replacing motor mounts, is an engine realignment advisable. Since the recommended transmission to propeller shaft flange tolerance is no more than about 4/1000 of an inch it seems to me new mounts are likely to change that tolerance such that an alignment is indeed advisable.

 

[Alisske]

When replacing motor mounts, is an engine realignment advisable. Since the recommended transmission to propeller shaft flange tolerance is no more than about 4/1000 of an inch it seems to me new mounts are likely to change that tolerance such that an alignment is indeed advisable.

Yes. Absolutely. I have read that you should check every season. (I’ll check mine every 2-3 years in all honesty.). I have 120hp pushing a 26 foot boat, so with the relatively low torque and RPM, I’m not so worried.

I use the tolerance of 3,000th of an inch. I installed the new mounts 1at a time, and paid close attention to the or existing height of each mount. I replicated that exactly so the mount would be in “mid play” meaning that I had equal amount of adjustment up and down post installment.

Amazingly enough, it was very close to spot on. (I had one very minor rear engine bump to port side to get the final 3/1000)

Very happy about that.

 

[Mako]

What size engine generally do you have to reach where damper plates are no longer employed?

 

[kapnd]

I’d use some kind of flex coupling no matter how small the motor.

 

[Alisske]

What size engine generally do you have to reach where damper plates are no longer employed?

I know I have changed a damper on a universal 25hp diesel. So thats a reference point.

 

[Alisske]

I’d use some kind of flex coupling no matter how small the motor.

I would love to do that, but i am cheap and don’t want to try to figure out how to do it.

I know it seems simple, just cut a few inches off the shaft and put the coupler on, lmfao. But those are “famous last words”

 

[Mako]

I was thinking about the opposite direction. How large? There coMes a size where the flywheel is large and heavy enough withOUT needing a vibration damper.


EDIT: My fat fingers on a little phone - haha

 

[Alisske]

I was thinking about the opposite direction. How large? There cones a size where the flywheel is large and heavy enough with needing a vibration damper.

Lol. My max HP experience was 120hp.

Ill defer to some of the guys that have the “big dog” diesels

 

[AusCan]

My old Volvo 36 hp MD17 didn't have one. It may be due to having such a heavy flywheel which tends to stop the chatter between gears. So engine size alone may not be the deciding factor.

 

[Choices]

The dampner reduces engine pulses and shock loading.

On bigger engines the mass takes that out of the system.

The drivetrain on a 36 trawler is much lighter than a 36 workboat. Although you could argue the abuse would be about the same...

 

[Knot Lost]

Hey folks. Just curious. I’m in the midst of replacing my transmission (the BW Velvet Drive AS3-71CR for my GB32. The new damper plate I got (Alto DA-107) has purple springs. But in photos here, all the ones y’all are putting in have red springs. Alto’s “red” spring ones (da-106) are totally different from mine. Am I missing something? Red vs. purple? Difference? It’s bolting up to the Lehman 2714E, btw.
And I’m still confused about torque spec? The 35 ft-lbs seems a lot! Any pointers or help for a GB newbie?
TIA Scott

 

[Alisske]

Hey folks. Just curious. I’m in the midst of replacing my transmission (the BW Velvet Drive AS3-71CR for my GB32. The new damper plate I got (Alto DA-107) has purple springs. But in photos here, all the ones y’all are putting in have red springs. Alto’s “red” spring ones (da-106) are totally different from mine. Am I missing something? Red vs. purple? Difference? It’s bolting up to the Lehman 2714E, btw.
And I’m still confused about torque spec? The 35 ft-lbs seems a lot! Any pointers or help for a GB newbie?
TIA Scott

I actually looked around the interewebs and see the difference in color, but I think its just that they are different manufacturers.

Good luck with it.

A

 

[SteveK]

Hey folks. Just curious. I’m in the midst of replacing my transmission (the BW Velvet Drive AS3-71CR for my GB32. The new damper plate I got (Alto DA-107) has purple springs. But in photos here, all the ones y’all are putting in have red springs. Alto’s “red” spring ones (da-106) are totally different from mine. Am I missing something? Red vs. purple? Difference? It’s bolting up to the Lehman 2714E, btw.
And I’m still confused about torque spec? The 35 ft-lbs seems a lot! Any pointers or help for a GB newbie?
TIA Scott

The spring color represents a compression measurement. If both the 106 & 107 are spec to your setup then note 106 has 6 springs and 107 has 8

 

[Alisske]

The spring color represents a compression measurement. If both the 106 & 107 are spec to your setup then note 106 has 6 springs and 107 has 8

Damn! Good to know!