Bravo 3X drives

John G · 19-09-2006, 11:14 AM

I know this has been talked about many times before but I've searched Boatmad & 'the other site' & can't find the answers I'm looking for so am putting this one out there again;

I know these drives keep failing but...

Is it only with the Yanmar 315hp engine?

Does the 3X version suffer the same problems?

Exactly where/how do the drives fail?

What are the differences between 3 & 3X?

Does the 3X use a shower - if not will this help?

Thanks guys - hope you can respond to this 'old' question

verytricky · 19-09-2006, 11:55 AM

showers are innefectual imo.

John G · 20-09-2006, 12:02 PM

Any one else have any comments / ideas - especially with respect to the Bravo 3X - JF, NeilT ??

Is it the U joint / upper leg section that always goes? Also does it only/mostly happen to performance boats which are more likely to be leaving the water in waves?

Many thanks,

John

Jon Fuller · 24-09-2006, 06:58 PM

The weakness in the B3 drives only really seems to be apparant when coupled to the Yanmar. The B1's have also suffered, but not to the same extent.

There have been failures in both the normal Bravos, and the 'X's, though to complicate issues, the first batch of 'X's had a manufacturing fault which meant they were a time bomb anyway, so it may be that a later 'X' is perfectly safe & happyon a Yanmar.

Mark Wildey may know more about whether there's been any failures on late 'X's, as he fratenises with the enermy, and they use em a lot!

To the best of my knowledge, it's always the upper gearbox that fails, that is, the pinion/FWD/REV gears, and cone clutch assy, usually it seems, the whole upper gets knackered, though I'm not sure eactly where it starts.

The 'X' drives have a few differences, including larger UJ on the input shaft, larger input shaft/pinion bearing assy, and tougher gears. I think the gears are the same dimensions, but are shot piened and have supperior heat treatment etc, but would stand corrected.

My understanding (having never actually had a Bravo fail on me) is that it's not just boats that 'get air', that see failures using the Yanmar/Bravo, so not nessasarily anything to do with torque peaks being too high.

I was given an opinion by an engine importer, that the failures common to the Yanmar/Bravo setup, were due to a harmonic issue tween the 6 pot Yanmar and the 'B' drive. I feel this is a possibility, as my own 325hp deisels, produce their power at lower RPM's than the Yanmar, and peak torque is also at lower RPM's, but they're 8 cylinder, so produce a different pulse pattern in the output.
So I doubt it's just a strength issue.
Mine have now covered over 3500 miles, mainly in excess of 60mph, and they're not 'X's.

All I've ever had to do is change the oil.

Hope this helps.

JF

jw. · 24-09-2006, 07:27 PM

It's a few years since I spoke to the Barrus reps about the problem. They were open about there being problems with the early drives. I'm hurting my brain thinking back so far but I seem to recall it was and alignment problem in the upper case. At that time they said they were happy to recommend the new drives with the Yanmar with the lower power, 2 hundred and something, but they were very reluctant about the 310/315/320 (They seem to have had various powers quoted over the years.). It was the reason I didn't buy one. The story is somewhere on Ribnet. You're looking back about 4 years. There were two of us speaking with the reps, the other chap is now JIY on Ribnet but I think at that time he used a different name, anyway he had previously had a Volvo Kad, 44 I think, and he did go for the lower power Yanmar and 3x but he subsequently had problems. I seem to remember it was U/J problems. Hope this is of interest to you. Speak to JIY, he's a nice, genuine bloke.

Me brain's sore.

Johnny Rocket · 24-09-2006, 09:02 PM

Quote:

Originally posted by Jon Fuller
Mine have now covered over 3500 miles, mainly in excess of 60mph, and they're not 'X's.

You only go out when the sea's like a millpond though. Maybe that helps?

Jon Fuller · 24-09-2006, 09:40 PM

Nob!

grInch · 24-09-2006, 09:49 PM

Quote:

Originally posted by Jon Fuller
Mine have now covered over 3500 miles

As 2800 of those miles have been going down the river to get to the sea, the next part should read......

Quote:

Originally posted by Jon Fuller
mainly in excess of 6mph

grInch · 24-09-2006, 09:50 PM

Here. I'll save you the trouble.............

Quote:

Originally posted by Jon Fuller
Nob!

Jon Fuller · 24-09-2006, 09:57 PM

Quote:

Originally posted by grInch
Here. I'll save you the trouble.............

Thank you.

John G · 25-09-2006, 10:59 AM

JF & JW many thanks for the replies

Johnny Rocket · 25-09-2006, 12:07 PM

Quote:

Originally posted by Jon Fuller
Nob!

Obviously I was having a dig at you (I think that's still allowed, because this isn't the racing section!), but it may actually have some relevance.

I reckon that an offshore cruising boat that is used on longer trips, plugging through some crappy weather, must put a load more strain on the drives than your fair weather cafe racer.

What do you reckon?

Jon Fuller · 25-09-2006, 01:33 PM

Quote:

Originally posted by Johnny Rocket
What do you reckon?

Still think you're a nob!

Johnny Rocket · 25-09-2006, 08:16 PM

Quote:

Originally posted by Jon Fuller
Still think you're a nob!

Even though I'm right!

Admiral P. Brain · 27-09-2006, 08:50 PM

John G, we had an extreme 26 yanmar 315 bravo1, broke the upper gears after 60hours, then we had extreme 26 with bravo 1 X, no problems after 120 hours, its sold now but dont belive had any other issues since...
although with the second boat we took it a lot easier on nailing the throttle from idle...

John G · 27-09-2006, 08:59 PM

Quote:

Originally posted by Admiral P. Brain
John G, we had an extreme 26 yanmar 315 bravo1, broke the upper gears after 60hours, then we had extreme 26 with bravo 1 X, no problems after 120 hours, its sold now but dont belive had any other issues since...
although with the second boat we took it a lot easier on nailing the throttle from idle...

Thanks Admiral