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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14305
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 1996 Yamaha 90HP TLRU 2 stroke. The lower unit case

Customer Question

Hi
I have a 1996 Yamaha 90HP TLRU 2 stroke.
The lower unit case is cracked. I would like to buy a used case and swap
internals.
There are three case (shell) part numbers (not lower unit part numbers):
84-93 6H1-45301-02-EK
94-96 6H1-45301-02-4D
97-2006 6H1-45301-03-4DAll the guts (gears, bearings, seals, bearing carrier, drive shaft etc)
are used on 1984-2006. The propeller shaft is the only difference I could
find. The same prop shaft is used in 84-93 and again in 97-2006. 94-96 list a different
part number for prop shaft.Part number investigation came from Boats.net site.I have a choice of used cases available 1992 and 2002.My question is: Will a 1992 or 2002 case be compatable with 1996 guts?
Will have more questions about shims.Thanks
Dan
Submitted: 12 days ago.
Category: Boat
Expert:  Jason replied 12 days ago.

Hi Dan, my name is***** received your question an I am reviewing it now.

Expert:  Jason replied 12 days ago.

1994 through 1996 60 HP, 70, 75 an 90 are all the same gear case. Other years and models will not be compatible.

Did you have any other questions on the issue or was that your primary concern?

Expert:  Jason replied 12 days ago.

If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you
Jason

Expert:  Jason replied 12 days ago.

Was there anything else?

Expert:  Jason replied 12 days ago.

It looks like you read my answer without replying back or putting through a rating for me. Please keep in mind the website did charge you to speak with me, but they will hold your money and not credit me for helping you out if no rating is put through. If you have a further question on the issue by all means please feel free to ask. If not, kindly select a rating for my service. If you have a problem with the ratings box or can not see it please let me know.

Thanks

Jason

Customer: replied 12 days ago.
Hi Jason,Can you tell me the difference between a 1992 90hp lower unit and a 2005 90HP lower unit.?
Thanks
Dan
Expert:  Jason replied 12 days ago.

They are dimensionally different. Different castings. For example, the water pickups are completely different.

Customer: replied 12 days ago.
Hi Jason,
Do you have any Yamaha gurus you could contact to ask. ? Is there a way to put this question out to the yamaha expert community?
Reason is all gears, bearings, seals, drive shafts, shift shafts, bearing carrier , shims etc are used in 1988 to 2006 lower units.
I researched part numbers and noticed that a 1988 lower unit was the same (99.9%) as a 2006 lower unit. Only a yamaha
guru would be able to explainThanks
Dan
Expert:  Jason replied 12 days ago.

Hi Dan. No, there is no one else to ask but me. I have a degree in marine technology and am Yamaha certified (as well as being certified in different brands as well) The issue is you are asking a non-standard type of question. The way Yamaha is structured is if you need a certain gear case you look up that case part number by model number. For the 3 cylinder engines, there is one gear case that was used from 87 through 93. Another that was used from 94 through 96, and yet another that was used from 97 on up. I know that they might all look the same on paper, but there is going to be some differences between them. It costs Yamaha a lot of money to make molds for different gear cases, Yamaha felt that they could use an 87 gear case on a 2006 motor they would just do that, and they wouldn't go through the trouble of design a different one. The only thing I can tell you is that there is going to be something different between the 3 gear cases. One thing I saw immediately was the water pickup design was different. The mounting bolts are also different, so i'm guessing the mounting bolts (and the related bolt holes) are going to be different sizes as well. Let me ask you this. The gear case on a 96 and a 2005 are the same price, why don't you just order the correct gear case? It's no difference in price and it would make your life a lot easier.

Customer: replied 12 days ago.
Hi Jason,
Thanks for reply. I am looking at used gearcases. =/- 150.00. vs 700 new.
Now one more question. If I have two compatable cases they should be stamped with shim info for pinion,reverse and fwd.
If I'm moving guts from one unit to the other. Is there any baseline shim info I can start at using stamped info.Thanks
Dan
Expert:  Jason replied 12 days ago.

The service manual says to start with a 0.50 mm shim and go from there.

Expert:  Jason replied 12 days ago.

You are very welcome. The ratings box is located at the top of your screen, if you do not see it you might have to scroll up. If you still can not see it, or have a hard time when trying to select a rating for my help, please let me know and I will alert the moderators.

Thanks again and good luck!

Jason

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