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Mercruiser Outdrive to Volvo TAMD31 Engine

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SamSXM

New member
Hi,

Is it possible to fit a Mercruiser Bravo 1X outdrive onto the Volvo engine? If so, what are the steps and the potential pitfalls?

Thanks!
 
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Far as I know Volvo uses regular old GM engine so yeh it'll go. Prolly need to put the mercruiser flywheel housing on there. Drive coupler on Volvo is some weird thing so count on that too. Otherwise all the bravo stuff should bolt right up. Transom hole should be same. You may have to drill for the two upper studs as I think Volvo doesn't have those.
I'm sure Rick the Marine wunderkind will report in shortly and overanswer this for you.
 
Anything can be fit to a Bravo drive. You will need the correct gear ratio for your diesel. Possibly the same ratio used with the Merc/Cummins B4 engine.

Are you replacing a Merc engine with a Volvo engine or is your boat originally Volvo and you want to install a Merc drive?
 
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Docksidemarineservices said:
Anything can be fit to a Bravo drive. You will need the correct gear ratio for your diesel. Possibly the same ratio used with the Merc/Cummins B4 engine.

Are you replacing a Merc engine with a Volvo engine or is your boat originally Volvo and you want to install a Merc drive?
Click to expand...

Thanks, the boat had a Volvo outdrive but it broke spectacularly and we've decided to put on a Mercruiser drive in its place... mainly for cost and availability of parts... the old outdrive ratio was 1.79 but I'm not sure what the Bravo is.
 
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SamSXM said:
Hi,

Is it possible to fit a Mercruiser Bravo 1X outdrive onto the Volvo engine? If so, what are the steps and the potential pitfalls?
You will need a Merc flywheel cover (bell housing in the auto world) that will mate to the TAMD 31 Diesel engine.
You will also need a rubber hubbed drive coupler that will mate to the diesel engine.
Click to expand...

o2batsea said:
Far as I know Volvo uses regular old GM engine so yeh it'll go. Prolly need to put the mercruiser flywheel housing on there. Drive coupler on Volvo is some weird thing so count on that too.
Volvo Penta uses an industry standard, all steel, Borg Warner drive coupler. The same drive coupler found on many inboard transmission installations.

Otherwise all the bravo stuff should bolt right up. Transom hole should be same.
The TAMD31 was used in both I/B and/or I/O scenarios......... if I/O, it would be one of the AQ series drives in either the s/p or DP version.
(OP says 1.79:1 reduction..... so its a Duo Prop drive)
Since the OP is wanting to change to a Merc B drive, he needs to know that the Merc transom unit will require the transom cut-out to be in-filled and re-cut to the smaller size!
Or.....use the adapter plate that you can find.


You may have to drill for the two upper studs as I think Volvo doesn't have those.
I'm sure Rick the Marine wunderkind will report in shortly and overanswer this for you.
Yes, I will "over-answer" in hopes that the OP has enough information in order to make an educated and informed decision.
Click to expand...

Docksidemarineservices said:
Anything can be fit to a Bravo drive. You will need the correct gear ratio for your diesel. Possibly the same ratio used with the Merc/Cummins B4 engine.
OP says that the ratio was 1.79:1 (of which is actually 1.78:1 and is a Duo Prop ratio)
If going from a Volvo Penta DP to a Merc B1, someone will need to do the math.


Are you replacing a Merc engine with a Volvo engine or is your boat originally Volvo and you want to install a Merc drive?
Chris, as I understand it, he now has the TAMD 31 with the AQ series Duo Prop drive and is asking about installing a Merc B1 behind it.
Click to expand...

SamSXM said:
Thanks, the boat had a Volvo outdrive but it broke spectacularly and we've decided to put on a Mercruiser drive in its place... mainly for cost and availability of parts... the old outdrive ratio was 1.79 but I'm not sure what the Bravo is.
The Merc B drive transom unit is considerably smaller than the AQ series transom shield.
In order to use the Merc B drive on a transom that is set-up for an AQ series Volvo Penta, you will need to have extensive structural transom work performed.
Or..... there is an adapter plate that can be used.

I would strongly suggest staying with the Volvo Penta AQ series drive that you now have, and do the necessary repairs.
With the AQ series:
No annual engine drive coupler alignment check/adjustment in lieu of fixed geometry.
All steel Borg Warner drive coupler in lieu of a rubber hubbed drive coupler.
No Gimbal suspension system in lieu of main suspension fork/pivot tube geometry.
No Gimbal bearing in lieu of fixed PDS and bearing arrangement.
No thru-prop exhaust outlet.
Very user friendly drive shaft bellows replacement.
The larger foot-print of the AQ series transom shield places FWD thrust torque over a greater area of the structural transom.


Perhaps the deciding factor will be availability of parts and service for you.
Click to expand...
 
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Thank you all for your input, much appreciated.

Yes we are hoping to have better price & availability of parts here in St Martin/Sint Maarten.

He's nearly there with the conversion we hope... He's not had to modify the transom so I think the unit he's installing had an adapter plate. But he's been struggling with fitting the leg into the engine itself... hence our doubts whether this was actually going to work!

There was only one prop being used so perhaps it wasn't the original outdrive on this engine, or it had been adapted previously...

Sam
 
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See? Right?

So the problem is finding a drive coupler that will bolt to the back of the flywheel. I'm guessing Volvo has one cz the Mercruiser ones are either Ford or GM. Let's go see if there's a part number on here somewhere. Back in a minute.
 
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SamSXM said:
Our original Volvo outdrive was an SX-M1.

I will take some pics n post them when its done... fingers crossed!
Click to expand...


I could not find anything showing that the TAMD 31 was fitted to the SX-M1 stern drive.
What I see is that this engine (as an I/O fitment) would have used the AQ series drive.

If you do indeed have the SX drive, that will be a gimbal suspension system drive, in which case I would suggest going with the Merc B drive!
If it was the SX drive, the Bravo transom assembly will fit the existing transom cut-out without requiring any structural work to the transom.


Please do post a few pictures.


.
 
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Re:...There was only one prop being used so perhaps it wasn't the original outdrive on this engine, or it had been adapted previously..."

Perhaps this was a contributing factor in the "spectacular failure" of the Volvo... Spectacular Volvo failures usually relate to the drive not being maintained properly ( incorrect or no lube) or hitting something hard at speed. Neither one of which are inherent Volvo issues.
 
Your Flywheel housing needs to be swapped but the coupling can be used on the Mercruiser as the input shaft is the same diameter and spline
 
o2batsea said:
Your Flywheel housing needs to be swapped but the coupling can be used on the Mercruiser as the input shaft is the same diameter and spline
Click to expand...

So it worked for several hours (one fishing trip) but today there's been a problem with the Mercruiser yoke (replacement 866133A01) and the vibration damper (a Mercruiser version), both of which were used parts and not in great condition.

We're trying to find replacement parts and the yoke is affordable but the damper replacement is a Volvo part (3858749) and upwards of $1,400! Do you know if there's a Mercruiser alternative which will work or will we have to fork out for the Volvo part?

Thanks again for any info.
 
We're trying to find replacement parts and the yoke is affordable but the damper replacement is a Volvo part (3858749) and upwards of $1,400! Do you know if there's a Mercruiser alternative which will work or will we have to fork out for the Volvo part?
Click to expand...

Ayuh,...... Are you callin' the coupler, a vibration dampener,..??

If so, it depends on how it mounts to the motor,.....
If it bolts to the crankshaft, ya gotta match that bolt pattern,.....
Late model Merc couplers mount to the flywheel, in the standard pressure plate bolt holes found on standard Chevy flywheels,.....

'n just how did what you've got fail,..??
If it ripped out the splines, it's probably not engagin' enough(depth) of the splines,....
It should engage a full 2" of splines,.....
 
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Mercruiser damper.jpgMercruiser coupling & shield.jpgoil-stain-crank-shaft-compressor.jpg
bondo said:
Ayuh,...... Are you callin' the coupler, a vibration dampener,..??

If so, it depends on how it mounts to the motor,.....
If it bolts to the crankshaft, ya gotta match that bolt pattern,.....
Late model Merc couplers mount to the flywheel, in the standard pressure plate bolt holes found on standard Chevy flywheels,.....

'n just how did what you've got fail,..??
If it ripped out the splines, it's probably not engagin' enough(depth) of the splines,....
It should engage a full 2" of splines,.....
Click to expand...


It's possible I'm using the wrong/different terminology but its based on the parts I'm looking up!

The Volvo crankshaft attaches to the flywheel with 8 holes as per the attached oilstain pic, and because the volvo "damper" (part no. 3858749) was old and very worn, he attached the Mercruiser damper (attached pic) to the flywheel which bolted on fine with its 6 holes using a wider set of attachment points. But he had to use the Volvo inner transom mount plate in order to accommodate the Volvo engine.

This resulted in the Mercruiser damper being too far from the transom for the Mercruiser yoke (which was also quite worn) to engage the splines for more than about an inch.... obviously this arrangement didn't last long!

So he put the Volvo damper back on - this engaged the Mercruiser yoke along the length it was supposed to, but it's failed again today after only a few hours - yes the splines on the Mercruiser and the Volvo damper are old and worn... but could there be something else wrong??? Wrong number of splines???

Bottom line is we need to find a damper/coupler for the Volvo flywheel that will mate correctly with a new Mercruiser yoke (we need to replace the worn one, that's for sure!)

Thanks again for any help/advice
 
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sandkicker said:
Re:...There was only one prop being used so perhaps it wasn't the original outdrive on this engine, or it had been adapted previously..."

Perhaps this was a contributing factor in the "spectacular failure" of the Volvo... Spectacular Volvo failures usually relate to the drive not being maintained properly ( incorrect or no lube) or hitting something hard at speed. Neither one of which are inherent Volvo issues.
Click to expand...


It had only done bout 50 hours since being rebuilt by the local Volvo rep - suspect no lube...:confused:
 
RicardoMarine said:
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Click to expand...


Hi Ricardo,

Is it possible to fit a Mercruiser Bravo 1X outdrive onto the Volvo engine? If so, what are the steps and the potential pitfalls?
You will need a Merc flywheel cover (bell housing in the auto world) that will mate to the TAMD 31 Diesel engine.
You will also need a rubber hubbed drive coupler that will mate to the diesel engine.

I think this is where we might be going wrong - I'm not sure the splines on the Mercruiser Bravo yoke mate with the Volvo coupler/damper.... can you confirm?

Thanks a mill
 
SamSXM said:
Hi Ricardo,

Is it possible to fit a Mercruiser Bravo 1X outdrive onto the Volvo engine? If so, what are the steps and the potential pitfalls?
You will need a Merc flywheel cover (bell housing in the auto world) that will mate to the TAMD 31 Diesel engine.
You will also need a rubber hubbed drive coupler that will mate to the diesel engine.

I think this is where we might be going wrong - I'm not sure the splines on the Mercruiser Bravo yoke mate with the Volvo coupler/damper.... can you confirm?

Thanks a mill
Click to expand...


AQ series Volvo Penta I/O gas engines used the Borg Warner drive coupler.... also sometimes referred to as a vibration dampener.

Borg Warner drive coupler splines .jpg

B/W splines are not the same as the I/O propeller shaft (aka input shaft) splines.

As for the Volvo Penta diesel engine's coupler, I cannot confirm.
 
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