Reply
 
Thread Tools Search this Thread
 
Old 13 February 2020, 14:33   #1
Member
 
Country: UK - England
Town: Southern Uk
Length: 8m +
Join Date: Jul 2019
Posts: 11
Bravo 3 sterndrive

Bravo 3 X sterndrive wanted 1:81 ratio

Message me if you can help
__________________

__________________
Gareth231 is offline   Reply With Quote
Old 13 February 2020, 15:31   #2
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,352
Quote:
Originally Posted by Gareth231 View Post
Bravo 3 X sterndrive wanted 1:81 ratio

Message me if you can help
My pal has a 1.81 bravo 2 if your on a single engine its a straight swap and more reliable
__________________

__________________
beamishken is offline   Reply With Quote
Old 13 February 2020, 16:22   #3
Member
 
Country: UK - England
Town: Southern Uk
Length: 8m +
Join Date: Jul 2019
Posts: 11
Quote:
Originally Posted by beamishken View Post
My pal has a 1.81 bravo 2 if your on a single engine its a straight swap and more reliable
Thanks for the offer but it needs to be a bravo 3
__________________
Gareth231 is offline   Reply With Quote
Old 14 February 2020, 08:12   #4
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,352
Whats up with your old drive?
__________________
beamishken is offline   Reply With Quote
Old 14 February 2020, 13:58   #5
Member
 
Country: UK - England
Town: Southern Uk
Length: 8m +
Join Date: Jul 2019
Posts: 11
Quote:
Originally Posted by beamishken View Post
Whats up with your old drive?
Its the wrong ratio + lower unit is badly corroded
__________________
Gareth231 is offline   Reply With Quote
Old 14 February 2020, 16:35   #6
Member
 
Country: UK - England
Town: Waterlooville
Boat name: Tickler
Make: Halmatic P22
Length: 6m +
Engine: Inboard Diesel 140HP
MMSI: 235115642
Join Date: Sep 2015
Posts: 806
RIBase
That'll be those aluminium anodes
__________________
GuyC is offline   Reply With Quote
Old 14 February 2020, 19:20   #7
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,352
Quote:
Originally Posted by Gareth231 View Post
Its the wrong ratio + lower unit is badly corroded
Ah ok good reason to switch to a b2 they don't rot half as bad as a b3

Could you get away with just a lower unit? What ratio do you currently have?
__________________
beamishken is offline   Reply With Quote
Old Yesterday, 04:05   #8
Member
 
Country: UK - England
Town: Southern Uk
Length: 8m +
Join Date: Jul 2019
Posts: 11
Quote:
Originally Posted by beamishken View Post
Ah ok good reason to switch to a b2 they don't rot half as bad as a b3

Could you get away with just a lower unit? What ratio do you currently have?
The boat is being re powered petrol to a diesel, current ratio is 2:1.

Engine being fitted is a yanmar 6lp-dte 260hp from research 1:81 seems the ratio required.

Lower unit could possibly be replaced on its own but I have been told it needs to be a x drive due to the high torque of a diesel
__________________
Gareth231 is offline   Reply With Quote
Old Yesterday, 05:23   #9
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,352
your 2:1will work if propped correctly you could change the lower unit but you'd still be 2:1 as the ratio change is done in the top end from 2.0 to 1.81:2. you could also fit a 1.65:1 ratio lower to your 2:1 upper which would give you a 1.65 drive.
The x drive top end is supposed to be stronger but the yanmars will still smash them without careful application of the throttle. I once bought a petrol drive that had done 1600 hours behind a 315hp 6lp and it was fine. Depends how careful you are with it I guess.

To be honest the b3 is the least reliable of all the bravos. depending on the boat I wouldnt discount a bravo 1 or bravo 11 both are usually cheaper, there more reliable and rot considerably less
__________________
beamishken is offline   Reply With Quote
Old Yesterday, 06:10   #10
Member
 
Country: UK - England
Town: Waterlooville
Boat name: Tickler
Make: Halmatic P22
Length: 6m +
Engine: Inboard Diesel 140HP
MMSI: 235115642
Join Date: Sep 2015
Posts: 806
RIBase
Quote:
Originally Posted by beamishken View Post
you could also fit a 1.65:1 ratio lower to your 2:1 upper which would give you a 1.65 drive.
I don't understand this I'm afraid.

If the input shaft at the top of the stern drive is doing a 1000 RPM and the top bevel gear is 2:1, then the shaft between the upper and lower bevel gear would be travelling at 500 RPM. If the bottom bevel gear is 1.65:1, then isn't the output shaft at the bottom travelling at 303 RPM which is an overall ratio of 3.3.

Do you not just multiply the ratios?
__________________
GuyC is offline   Reply With Quote
Old Yesterday, 06:45   #11
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,352
Quote:
Originally Posted by GuyC View Post
I don't understand this I'm afraid.

If the input shaft at the top of the stern drive is doing a 1000 RPM and the top bevel gear is 2:1, then the shaft between the upper and lower bevel gear would be travelling at 500 RPM. If the bottom bevel gear is 1.65:1, then isn't the output shaft at the bottom travelling at 303 RPM which is an overall ratio of 3.3.

Do you not just multiply the ratios?
The overall ratio is a combination of upper & lower reductions. to achieve the ratio changes mercruiser use a selection of upper and lower gear sets to obtain the final overall ratio. IE a 1.65 ratio uses the same top gears as a 2.0 while a 1.81 uses the same lower as a 2.0 and changes the top gearset. Its just a case of knowing which top gears matched with which lowers give what overall ratio
__________________
beamishken is offline   Reply With Quote
Old Yesterday, 07:17   #12
Member
 
Country: UK - England
Town: Waterlooville
Boat name: Tickler
Make: Halmatic P22
Length: 6m +
Engine: Inboard Diesel 140HP
MMSI: 235115642
Join Date: Sep 2015
Posts: 806
RIBase
OK thanks
__________________

__________________
GuyC is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT -5. The time now is 23:45.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.