How an Outboard Lower Unit Works | How an Outboard Gearbox Works | Boats.net

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: www.boats.net/catalog/yamaha/...
Read more here: www.boats.net/blog/outboard/l...
VIDEO HIGHLIGHTS
Drive shaft - 0:30
Water pump - 1:00
Shift shaft - 2:40
Gearbox cutaway - 3:00
Lower unit seals - 7:30
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[@barrymullan6363]

As a novice boater, this was an amazingly useful video. Very well explained.

[@user-cl2ls7kz7o]

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.

[@yam9635]

KZbins the place to go

[@cemyanikk]

I am a marine engineer and I learns too much good knowledges from your channel. Thank you so much.

[@DAlilbigman]

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!

[@apackwestbound5946]

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

[@jenniferday1481]

Q0

[@joseascensao4200]

Brilliant. Very informative, precise and concise. Thank you.

[@frederickshandley5408]

Great job clear voice and nice detail. The cut away view is fantastic

[@jarredburns8421]

Awesome video. Very detailed and informative. Thanks.

[@KenH737]

Great explanation of lower unit basics.

[@roytaylor3857]

Finally a video that actually makes perfect sense 👌

[@josephomalley6650]

This guy did an amazing job on this video! Well done!

[@nikkibiondo7399]

Thank you for explaining this so well

[@JohnZamrok]

New to outboards. Great instruction!! I "saved" it for future maintenance. Thanks

[@davestavers-pj6el]

Thank you- very clear straightforward lesson, you are an excellent teacher,

[@allanthomson4639]

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

[@pashkoskoda3862]

Very nice video. very clear and informative. Thank you for sharing.

[@richardhealey9399]

Great video, lots of good information!

[@grcooley]

Very helpful, thanks!

[@acetech9237]

You're a fantastic instructor

[@albertkofi9383]

I love your explanation sir. Thank you

[@augustinepora4436]

Clearly explain the lower unit. Awesome

[@globalfunseeker6733]

Terrific video. Very informative and simple to understand. Thanks.

[@octane_6327]

Thanks for the vid! Learnt heaps

[@joetart9905]

Awesome video. Very informative!

[@tman2172]

This video was so awesome for us novice boat owners. Great job!!!!

[@BoatParts]

Great! It was awesome for us to cut it apart.

[@carbide72]

Superb video, high quality content, thank you

[@hamnchee]

Solid video thank you!

[@MrCharleswr]

Excellent explanation, nice job!

[@rossnolan5659]

Super helpful, thanks!

[@jamesjannell8706]

You guys are awesome. Thx for the education.

[@cooperstownnyrealestate]

Great explanation thank you!!

[@WalwRafii]

Great video, thanks!

[@15569903]

This was a really great video. You guys rock!

[@bears198542021]

Great vid. Thank you!

[@phillipesch7556]

Amazing video thanks!

[@martinkoche4375]

Thank you sir very informative and helpful video

[@ImFishHead]

Well done!

[@ipuketshirts]

Extremely clear. Well done video. Would be good to know variances from freshwater to salt for seals etc given environmental factors for maintenance schedules.

[@markmurphy137]

Man excellent video thank you sir

[@dylanlangston6668]

simple and straight forward

[@brianl.3047]

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.

[@jimmyadams9257]

Installing new lower unit on a Yamaha 70etlh 1986 having trouble with shifter going in reverse on in forward very quickly. The shifter is in natural and the lower unit is also in natural what am I missing with the reverse problem

[@wxmyjnsn]

This was fantastic.

[@TheSevillap]

Such a great video bud. Well explained.

[@pawfan]

Thanks for sharing how the lower unit works. I was curious on how it really works.

[@grndhg86d]

Excellent video thank you

[@richardatyeo9903]

Very good presentation.

[@robertmalvarez4582]

AWESOME INFORMATION

[@Leblueskee]

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

[@purplefurture6960]

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

[@stevenstreet9754]

Very good information.

[@jameshalstead237]

NICE JOB WELL SPOKEN

[@hobiehollister951]

Very informative

[@trevortaliana5944]

great video!

[@alstonshipp9240]

Good explanation!

[@leesmith5419]

Excellent tutorial

[@danielboltz3635]

Great video!

[@stevew6141]

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

[@Patriottoo2]

Well done, mate!

[@tenexchikumba]

Keep teaching sir, it's great, class of mine

[@chrishampson1394]

Wow. Great video and explanation showing the different components and functions! Thank you

[@clmb511]

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

[@johnakagi1088]

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.

[@pino_7428]

Great video.

[@kenlow4028]

Top gun marine mechanic, full of knowledge

[@edy7951]

Tq bro....🤝

[@JoseHernandez-kl2wg]

Great video 👍

[@nicholasm2239]

great video.

[@sgray1906]

Yall are Outstanding !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :)

[@matthewbudlong9813]

Nice job

[@AutoDiag_]

Thank you

[@user-qy8xq3gv1w]

Thank you for your love of sharing. Questions: any video for install inlet valve and exhaust valve spring valve and rocket arms. Thanks

[@bouldernelsonbigfoot]

great vid

[@abrahamu5544]

thank you.

[@ash.133]

Very very nice 👍👍👍👍👍👍

[@wofaideal5312]

Very good and well explained wish to work with u

[@SaltyMechanicsJunior]

GREAT STUFF, MAN. JUST SUBBED 👍

[@OUTBOARD_USK]

👍🏻👍🏻👍🏻

[@larryklein7398]

Very nice informative video..Thanks

[@TheFrank1423]

Very good video 😂

[@TheBluceRee]

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.

[@geraldlacasse7986]

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

[@leonmaritz2598]

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 ?

[@dennisluce2056]

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?

[@xelintuttle7581]

i would like to see a video on replacing the shift cam

[@williamlillie9309]

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.

[@clarencesail]

Really great explanation of the system. Thank you.

[@georgeatallah1926]

Great job very clear video and voice.my 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!

[@billyphantha]

Very good video, Garrett is a very good teacher.

[@Guerrero1187]

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 👍🏼🙏

[@Pre-Unit_Triumph]

@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.

[@dkurth53]

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 ?

[@TheDuffman1986]

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?

[@willysoriano4196]

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

[@ihahahuhu3159]

good video bro.., what is the gear ratio ?

[@Whisbaby1Vr]

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

[@DT-ob6ce]

I would love to see a breakdown of an '82 Mercury Outboard

[@niaddaize7357]

Do a cutaway video on a lower case unit gearbox for a counter rotate(Left handed propeller) outboard engine please

[@PureLivingForOutdoors]

I need you all to rebuild a Mercury Pro XS 250 Torquemaster lower on video! LOL

[@russellfisher5710]

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.

[@jordanking905]

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

[@sonus3306]

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?