Duration 9:32

How an Outboard Lower Unit Works | How an Outboard Gearbox Works |

236 654 watched

0

3.1 K

Published 22 Aug 2019

How does a boat transmission work? In this video from Boats.net, Garrett will use our lower unit cutaway to show you precisely how the gearbox works in your outboard. He’ll take you on a tour of the lower unit from the drive shaft, through the water pump, and into the gearbox where you’ll see how power is transferred from your motor to the water. See the lower unit diagram for a Yamaha F225 here: https://www.boats.net/catalog/yamaha/outboard-by-hp/225hp/f225tlr-0408/lower-casing-drive-1?utm_source=youtube&utm_medium=video&utm_campaign=description_btf_BDN Read more here: https://www.boats.net/blog/outboard/lower/unit/how/it/works?utm_source=youtube&utm_medium=video&utm_campaign=BDN-description-blog-link VIDEO HIGHLIGHTS Drive shaft - 0:30 Water pump - 1:00 Shift shaft - 2:40 Gearbox cutaway - 3:00 Lower unit seals - 7:30 Talk to us: Twitter: https://twitter.com/boatsnet Facebook: https://www.facebook.com/boats.net/ Instagram: https://www.instagram.com/boatsnet/ RELATED VIDEOS Yamaha 225 input shaft seal replacement: /watch/IOf_LB8RaYVR_ Yamaha 225 output shaft seal replacement: /watch/MJEG0XmH70NHG

Category

Show more

Tags

Boats.net

Outboard parts

Oem boat motor parts

Honda marine

Yamaha outboard parts

Tohatsu outboard parts

How an Outboard Lower Unit Works

Lower Unit Cutaway

How does a boat transmission work

How does an outboard work

How a lower unit works

How an outboard gearbox works

Outboard lower unit diagram

Outboard lower unit gearbox

Outboard gearbox cutaway

Comments - 199

@

@barrymullan63634 years ago As a novice boater, this was an amazingly useful video. Very well explained. 27
@

@cemyanikk11 months ago I am a marine engineer and I learns too much good knowledges from your channel. Thank you so much. 2
@

@globalfunseeker6733one week ago Terrific video. Very informative and simple to understand. Thanks.
@

@user-cl2ls7kz7o4 years ago Very nice. I finally found a video the actually teaches me something about something. Every other channel is about selling something with only pointing out the obvious. 11
@

@allanthomson46394 years ago thank you - any chance you could consider showing the basic steps+using the "setting plate concept" to setting/inserting the correct shims to take up the pinion+F+R gear for optimum tolerances, good clear explanation - watched from South Africa ... 5
@

@DAlilbigman4 years ago Very detailed n thorough! Thanks I love the way you have the areas cut out so I can easily see n understand all working parts. Awesome! 12
@

@joseascensao42003 years ago Brilliant. Very informative, precise and concise. Thank you.
@

@frederickshandley54084 years ago Great job clear voice and nice detail. The cut away view is fantastic 1
@

@KenH7374 years ago Great explanation of lower unit basics.
@

@jarredburns84214 years ago Awesome video. Very detailed and informative. Thanks. 1
@

@roytaylor38572 years ago Finally a video that actually makes perfect sense 👌
@

@josephomalley66503 years ago This guy did an amazing job on this video! Well done! 1
@

@Leblueskee2 months ago Thank you so much for this. I'm building an electric boat motor and this was so helpful.
@

@purplefurture69608 months ago such amazing video that let noob like me understand things i wouldnt ever think i will be able to know
@

@richardhealey9399last month Great video, lots of good information!
@

@user-qy8xq3gv1w7 months ago Thank you for your love of sharing. Questions: any video for install inlet valve and exhaust valve spring valve and rocket arms. Thanks
@

@pashkoskoda38623 years ago Very nice video. very clear and informative.
Thank you for sharing.
@

@clmb511last year This was so helpful! Do it with a Verado someday?
@

@augustinepora4436last year Clearly explain the lower unit. Awesome
@

@apackwestbound59464 years ago incredible well explained and produced video. Thank you for another quality product. I have no idea how anybody could "dislike" this video. Thank you! 6
@

@1556990310 months ago This was a really great video. You guys rock!
@

@davestavers-pj6el11 months ago Thank you- very clear straightforward lesson, you are an excellent teacher,
@

@albertkofi93833 years ago I love your explanation sir. Thank you
@

@pawfan2 years ago Thanks for sharing how the lower unit works. I was curious on how it really works.
@

@TheSevillap4 months ago Such a great video bud. Well explained.
@

@JohnZamrok8 months ago New to outboards. Great instruction!! I "saved" it for future maintenance.
Thanks
@

@jamesjannell87062 years ago You guys are awesome. Thx for the education.
@

@carbide722 years ago Superb video, high quality content, thank you
@

@stevew61413 years ago Thank you for this informative video! The cut away leg is brilliant👍🏻 It explains visually how a gearbox works and operates
I recently bought a boat with very old unknown twin stern drives and twin 1.8 diesel Ford engines- so far I have found that engine 1. Crankshaft turns with prop In drive. engine 2. Crankshaft seized but prop in Neutral and turns! Both stern drive gear levers are stuck so do you think I’m looking at a loss or a project worth investing in? Are stern drives gears easy to unsieze? Thanks in advance for any advice ... 8
@

@tman21723 years ago This video was so awesome for us novice boat owners. Great job!!!! 1
@

@martinkoche43752 years ago Thank you sir very informative and helpful video
@

@brianl.30474 years ago I've always been automotive-oriented. My wife and I inherited a 1963 Starcraft a couple years ago with a 1994 Johnson 48 SPL. After a comprehensive online boating class, we became boaters. I'm trying to get up to speed on outboards, particularly in regards to routine maintenance. This video was VERY educational. Outstanding presentation. ... 4
@

@tenexchikumbalast year Keep teaching sir, it's great, class of mine
@

@johnakagi1088last year Great video that explains the seal points and the maintenance. I would be comfortable replacing the 6 seal point seals on the lower unit. Certainly replacing the water pump. Thanks.
@

@kenlow40282 years ago Top gun marine mechanic, full of knowledge
@

@geraldlacasse79863 years ago Great video! Since the reverse and forward gear are free on the prop shaft how can you hold them steady whille measuring the backlash? The clutch dog does not do that since the tooths are smaller than the ones they mesh on the gears. Thanks for your help..please help ! GL ...
@

@chrishampson13944 years ago Wow. Great video and explanation showing the different components and functions! Thank you
@

@dennisluce20563 years ago Such a great video for a novice like me! I hit a stump recently with my Merc 90 - and I have a little water leaking out just above where my Transom saver holds the motor - If there's no water in my gear lube I should be able to JB Weld that spot right? ...
@

@Whisbaby1Vr2 years ago Great video. TryIng to figure out why my Yamaha 4 stroke making a howling noise and bugs out once in gear in the water
@

@TheBluceRee3 years ago Before watching this, I barely knew the word lower unit meant. Now I feel like I could confidently tear a lower unit apart. Also am now able to diagnose many problems.
@

@georgeatallah19263 years ago Great job very clear video and Yamaha 115 four stroke 2002 model has a whining noise when travelling about 15-20 kmh noise goes away at higher speeds.otherwise motor runs perfect,can you suggest anything thanks! ...
@

@TheDuffman198610 months ago Brilliant information, my engine wasn’t going forward, just into neutral and reverse, took the gearbox apart n fixed what I thought was the problem but after assembling it back it now goes into neutral and forward but not reverse, I’m starting to think it may be something todo with the shift shaft? ...
@

@sgray19064 years ago Yall are Outstanding !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :)
@

@russellfisher5710last year Great video, so I have replaced the impeller and now when I put it back together I cannot select the forward/reverse neutral properly from the control. I have selected neutral and put the lower unit back together but when I then try and select the gears via the controller it will go from neutral the reverse and back to
neutral but not into forward. I did not touch the gear selector when I replaced the impeller and it was all good before the impeller change. It s a good engine in tip top condition and been well
maintained and also not thrashed as it was a sailing club engine that a won in a sealed bid auction. ...
@

@williamlillie93094 years ago How do you keep your shims in place while installing the bearing carrier? Could I use a thin coating of grease or oil? I own a 1970 mercury 40hp 400 and I am in winnipeg Manitoba Canada watching this video. Great explanation and video. ...
@

@leonmaritz25983 years ago I enjoy your video's....I would like to know if the gearbox drive shaft must be shimmed? Must the drive shaft have a play up and down ?
@

@dkurth534 years ago My Yamaha 2011 175hp, I bent my prop shaft.With the bearing housing out can I pull the prop shaft out and preplace with a new one ? 2
@

@user-hq3fm2rt6e7 months ago Could you please show the replacement of the lock plate in the side control for a 2010, 60hp 4 stroke Yamaha. Hoping you can assist ... Bob
@

@willysoriano41966 months ago good evening Do you have a video explaining how to reinstall trim sender on a Suzuki DT85?
@

@Pre-Unit_Triumph4 years ago @Boat Parts Thanks, got it great video. Does the older (1974 Mercury) gearbox shifter work the same? i.e. To select reverse shift splines "clockwise & forward counter clockwise"?? The older Mercs have a sloped cam that goes over the splines. In which position must the spline selector be (forward, neutral or reverse) and at what rotation must the sloped edge of the cam be when fitting the cam? Not sure if this makes any sense. Your help will be greatly appreciated, thanks. Forgot to ask if the cables should be disconnected & if the power dead throttle cable position should be in the same position at the spline selector i.e. forward, neutral or reverse?? NB. This is a replacement motor. Thanks. ...
@

@wofaideal53122 years ago Very good and well explained wish to work with u
@

@bentramell7293 years ago Great video but I need help with gear alignment. Just replaced water pump and cant get the drive shaft back up into the power head. Ive put the gear shifter in forward and turned the gear selector on the lower unit to what I think is forward but im not sure ...
@

@Guerrero11873 years ago I don’t understand how people dislike these informational videos?? Some people just hate their life. I think it’s a great video,keep up the great work and content 👍🏼🙏 1
@

@michealmentoor-yw4cylast year Hi there can you guy's make a video or explain how the gearcase system of clockwise and anti clockwise works,does the gears differ between clockwise and anti clockwise will much appreciate it
@

@xelintuttle75814 years ago i would like to see a video on replacing the shift cam
@

@jordanking9054 years ago Is there a hose or something that hooks up to the tube. I’m new just trying to figure out how it works
@

@mrsmd46163 years ago Any tips on removing middle drive shaft housing thingy on a 9.9. Lower unit came off/apart easy. Seriously siezed together.
@

@DT-ob6ce2 years ago I would love to see a breakdown of an '82 Mercury Outboard
@

@jimmycoumanis70082 years ago Two questions. When greasing the drive shaft splines, why is it important to not grease the ends of the shaft. Also, is it necessary to go back into the lower unit to connect the speedometer tube if I forgot to reconnect it? ...
@

@markmarks96914 years ago Where on the site can I locate a clear assembly diagram and parts list for the lower casing assembly on a 2003-2006 Mercury 25hp 2-stroke outboard motor? Please provide a specific link for this diagram. Thanks.
@

@sonus33063 years ago I would like to know how the thrust from the prop is transferred through the drive shaft to the body of the boat? Is there a thrust plate somewhere in the system as there is in ships?
@

@garyevora83693 years ago Not really grinding noise but more of a clunking noise when engaged in either forward or reverse. Any diagnosis is appreciated
@

@rbtuby48602 years ago You failed to mention the sealing washers on the vent and fill plugs can allow water entry.
@

@billyphantha4 years ago Very good video, Garrett is a very good teacher.