Mercruiser TR-2
 

How much power (HP/Torque) can the Mercruiser TR-2 handle?

Maybe Mbam will get in here, but the II-TR uses a different gearcase (lower unit) than a II-TRS. The overall ratio is 2:1 and has no provision for thru the prop exhaust. They were used mostly behind small block Ford and Chevies, and most likely for large, slow, heavy boats. There is also a "Type II" drive that was discontinued a number of years ago, but some are still around.

Thanks for the reply,

But it has provision for thru the prop exhaust, and the ratio is aprox. 1,6:1.

I cant say how much Torque or HP they will handle but I know that they stand up to pushing single screw 40' and up steel fishing boats in alaska and they are using big block or diesel power. I was told they are nearly unbreakable!

Rob

Do you have a transmission? If not, does the drive unbolt from the bell housing, or is it attached directly to the gimbal ring with horizontal pins?

I have done a little more research. The Type II doesn't have a provision for exhaust, nor does it have a transmission. Type II-TR was supplied in 2 versions. TR standard=2:1 ratio. TR commercial =1.5:1 ratio. Both can use up to a 20" dia prop.

David,

Yes it has got a transmission, and provision for thru the prop exhaust and aprox. 1,6:1 ratio.(The outdrive is mounted on a 21" Clipper sport boat from '85 with a Chevy SB 400") I've been told that it is a Trans 2 outdrive, which I thought was the same as TR-II. But perhaps it's a TRS-II outdrive?! If so how much power can it handle?

Sorry for any confusion and my lousy english:)

Measuring from the propshaft to the bottom of the "cavitation" plate, if you have about 10 1/4", then it probably is a type II-TR. I would venture it should be good for 500 or less hp, but also dependant upon actual condition of the drive.

TR or TRS
 

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

FAMILY AND PERFORMANCE BOATING MAGAZINE

TooOld another way to tell is if the bellhouseing can come off the tranny then you have a BW drive. If the bellhouseing is part of the tranny (ie. One piece) then you have the Merc Trans. :D:D Just some infor for your next boat search :P:P

Jon: