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Thread: TRS MERC

  1. #16
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    Why doesn't merc take a Bravo one case and make it non shifting. Then add a new Merc trans inside the new ITS. Heck almost all the tooling is done already!!

    Chris

  2. #17
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    This is from another board posted by Dennis Moore, the guy that wrote the two books about hi perf marine engines (BBC&SBC).

    Quote:
    There is the Mercruiser II drive otherwise known as the Mercruiser TR (Transmission) drive. The Mercruiser II TR swings a very large prop for houseboats, work boats etc.

    The Mercruiser II TRS drive (Transmision Sport) drive is the same as the TR but has a shorter lower gearcase that swings a standard size prop. Almost all Mercruiser II drives are of the TRS design.

    The Mercruiser II TRS is a very nice drive but was expensive to produce because it required a separate transmission between the engine and the drive. The transmission also moved the engine ahead another 15 inches taking up more space in the boat. Some came with a Borg Warner Velvet drive transmission that is hydraulicly shifted like a modern automotive trans. The trans is capable of withstanding high horsepower engines (it is also used in racing Super Speed Master drives) and shifts very smooth.

    To reduce costs Mercruiser built there own transmission and installed them in lower horsepower Mercruiser II TRS drives. This low cost trans was made from the internal parts of a Ford C-6 automotive transmission, had very small input and output shafts and was very weak.

    The TRS outdrive (upper driveshaft housing and lower gearcase housing) is very strong (much stronger than any Bravo drive) because it is a straight gear drive (no trans in driveshaft housing) with helical cut gears in the upper and lower.

    The weakness of the Bravo drive is that the transmission is incorporated in the drive shaft housing and the lower gearcase housing has straight cut teeth gears so a reverse rotation drive can be obtained by running the drive backwards (simple changing the shift lever linkage). The Bravo is a compromised drive for engine compartment space and manufacturing costs compared to the more expensive and higher quality Mercruiser II TRS drive.

    The Mercruiser II TRS drive with the BW Velvet Drive transmission will easliy accept 500 horsepower. The Super Speed Master II is the Mercruiser II TR with a high performance lower gearcase. The advantage to the SSM II gear case is that it is smaller in diameter, longer and pointed without through the prop exhaust. The SSM II lower gearcase was faster through the water and wouldn't "blow out" at high speeds. These lower gearcases are no longer being manufactured by Mercruiser Racing. They are not any stronger than the TRS lower gearcase (strength was compromised for a smaller diameter bullit).

    I really like the Mercruiser II TRS drive with the Borg Warner Velvet Drive trans and most of the parts are still being manufactured by Mercruiser.
    Because of the extra cost they were usually installed in more expensive boats and are not very common. If you have one hang on to it!

    Sincerely
    Dennis Moore
    Mercruiser Master Tech

  3. #18
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    That was a very informative post. Makes you wonder sometimes.

    Think about how much money changes hands fixing/replacing blown drives. If they sold drives that never broke, they'd have no earnings from parts/repairs. I know the technology is there for a bullet proof drive that's cost effective.

  4. #19
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    On BAM MARINES web site www.go-fast.com click on title knowledge base.In the columns there is TRS gear failure info.Apparently they sell an updated gear set for high h.p..
    1987 22 Classic Limited Edition #18 of 25
    Ken Lessard

  5. #20
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    Hey DS88, I had to replace the clutches in my Merctrans about 3 years ago. All bearings, bushings, ect. were in good shape. I did replace seals, although the trans was not leaking. I had about 900 hours on it at the time. It's likely that if you don't notice anything wrong with it now that it may not be a bad thing to just leave it alone. If you do want to have work done on it, you can save money by taking it to a place that works on automatic transmissions intended for drag racing. They will have no problem being able to work on it being that it is simpler than a car trans. Automotive racing clutches can be used in it. That will be better than the clutches you order from Mercury.
    "1978" F-22; Turbo'd & Intercooled.

  6. #21
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    Thanks KMLFAMILY and Rodger,

    I checked out the BAMS site, I never looked under the knowledege base before. I love reading that there are fixes in place for known problems. I wish I had a 550 HP problem!!

    I never thought about going to an automotive transmission place before. That's a great idea. I know more people in the car area then in the boat area - thanks.

    What do you guys think about separating the gimbal assembly? I know the bellows are shot but I'd like to change whatever else (bearings/bushings etc.) I can while it's apart. I can also prime and paint it with awl-grp as well at that time. Can any marina handle it? Do those parts normaly fuse together and break when attempting to separate? For the same reasons, do you think it's worth it? I plan on using either a single or dual piston external hydraulic steering system for safety and for the reason sited by BigGrizzly and his TRS, to save the wear and tear on the gimbal. I'd like to do everything right, once if I can.

    Thanks,

    Dave

  7. #22
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    I have separated those assembles your talking about successfully, on fresh-water boats. It shouldn't be a problem. The boats I have done that work to, were not boats that were continuously stored in the water.
    "1978" F-22; Turbo'd & Intercooled.

  8. #23
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    0n E-BAY right now there is an MERC.serv. manual on these drives for auction. Item #1864254744 ends Oct.4.It also has a buy it now option.This might prove to be a valuable resource to you sometime down the road.
    1987 22 Classic Limited Edition #18 of 25
    Ken Lessard

  9. #24
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    Talking

    Thanks KMLFAMILY, I bought the TRS manual off ebay, should definitely come in handy.

    Rodger - This winter I'm going to go for it and sepaprate the gimbal. If it breaks, I'll get what ever I need to fix it.

    Thanks for the help/advice.

    Dave

  10. #25
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    Thank you for the tip. I won the High Performance Mercury service manual.

    Mike

  11. #26
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    For Merc service manuals you can call Mercury at 1-920-929-5110,the merctrans II will be in the engine service manual,For obsolete parts you can call 1-800-558-6300.
    cubic inches = power
    power = speed
    speed = FUN

  12. #27
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    Thumbs up

    Thanks for the info!

    Dave

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