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View Full Version : TRS Drive -Is it worth the Effort??



JimG205
06-14-2012, 04:37 PM
The GT-21 I just acquired has the factory installed TRS outdrive circa '75-all components are there and it is a heavy duty outdrive from it's appearance.I am not an outdrive person-is it worth having it gone through by a knowledgeable TRS tech?,or should I just plan on installing an Alpha for the 280 HP engine.My concern is internal parts availability and why did Merc opt out of this drive.:confused:

silverghost
06-14-2012, 05:43 PM
The old TRS is a very robust "Bullet proof" drive. You cannot blow-up a TRS drive very easily.
It is built like a tank .
It was originally designed for the original 330HP, & up Big Blocks & higher horsepower engines, & for racing applications.

The Alpha outdrive is Merc' weakest drive.
It is not very strong.
It can not handle higher horsepower, & higher speeds very well on a performance boat .
It's crude internal clutch ,& pump, are a weak point.
As are it's smaller gears.
Alphas are easily "Blown-Up" and destroyed.

You will replace the Alpha many times before a single TRS outdrive ever fails.

TRS parts are out three~
They are not very hard to find.
I love the TRS outdrives.
Better & much more robust than a newer Bravo drive in my opinion.
No internal clutches to break.
No internal water pump.
No hot exhaust, & water, flow through it's housings.

I ran a TRS with a Borg Warner Velvet Drive Hydraulic transmission for 15+ years with very hard abusive use on my old Formula 27 without a single drive related failure.
If it were me~~~ I would surely keep & rebuild if necessary that old TRS outdrive on your GT 21 .

Pismo
06-14-2012, 07:18 PM
TRS is great on a GT. Bravo would work well too but wait until the TRS blows up, which may be a long time. Alpha is not enough.

A TRS will be no effort at all, turn the key and go for many more years, esp with a 280.

pipnit
06-14-2012, 10:44 PM
I like my TRS (76 2+3). I have had it gone through from tip to tail.
The failures you hear about with TRS drives have to do with slamming them in to reverse and gunning it; those planetary gears start SPINNING! Because they have the remote electronic gear selector, they were simple to use for long runs on house boats and bigger boats.
One of the weak links is the electronic gear selector. Even when they're "good" they often oscillate when in gear and this causes the journals to not match up all the time, restricting the flow of oil.
I installed an old morse and went with a mechanical selector to get rid of the oscillation. KC Marine out of Washington state took care of that, rebuilding the clutch and adding their "gattlin gun" cooler. http://www.kcmarinetr.com/MercTrans-Oil-Cooler.aspx I really like the "velvet drive" aspect and it keeps some of my boat original albeit somewhat of a restomod. If I had a higher X Dimension and a shorty Bravo, I'd be flying a lot faster but 75 is good enough for me in an 18' and, as stated, they are BULLET PROOF! :kingme:

71865

Sidney073
06-15-2012, 08:58 AM
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I rebuilt my TRS Drive myself, replaced all bearings and seals, I had no trouble finding bearings, seals, shims, etc. I opted for OEM Timken bearings, and OEM seals which did take a little searching, but nothing too in depth. The TRS has no shifting in the outdrive, and the internal components are massive when compared to other drives I've seen apart, which isn't many to be honest, which is why they're "bullet proof".
My guess as to why Mercury opted out of this drive would be two fold --- 1st = Simple math/economical, the TRS is just an outdrive so it requires a transmission = more parts to build, warrantee, and buy. 2nd = Physical size/room in application, the TRS setup is space eating in any application, and weight would also come in to play I would imagine.
After being innside of the TRS drive I like what I saw, the large gears, bearings, and shafts give me a secure feeling on the reliability, and like others have said, I'm OK with 70 - 75 mph out of my boat.
L8R,
Sid

olredalert
06-15-2012, 09:00 AM
----I have always disliked the transmission in my boat being underwater "outside" of the boat. Way to much chance for water intrusion. The TRS with its internal trans just seems like a much more intelligent solution. That,,,and its strong, strong, strong. I have had a bunch of them and never hurt one.

----I happen to have two Merc transmissions that I would let go of cheap, as I stepped up to B/W 72s with my Spitfire. Both are in excellent shape.......Bill S

silverghost
06-15-2012, 12:12 PM
As others have stated the TRS is slightly slower than a Bravo drive because of it's size & weight.
But if you find and install an old streamlined Mercury Racing #2 "Speedmaster" lower unit you will gain quite a bit of performance & speed over a standard stock TRS outdrive.
I ran one for a decade + on my old TRS outdrive.
These old "Speedmaster " lower units are out there for sale used all the time.
They are every bit as robust as the standard TRS lower~~~but have much less drag & thus will give you more top-end speed.

Long live the old TRS Racing drive !

JimG205
06-15-2012, 07:38 PM
To the guys that responded,you have convinced me to keep the original drive-I also learn something new on this site whenever I pose a question-didn't know a speedmaster lower would match up to the TRS housing.:yes:

pipnit
06-15-2012, 10:12 PM
Obviously I think you're making the right choice Jim.
I would be very curious to try a speedmaster 2 on my TRS to see what the difference would be if I could find one.

73donzibob
05-24-2013, 08:32 PM
I have a Super Speed Master lower if you're interested.

Sidney073
05-26-2013, 06:39 AM
What would you want for the Super Speedmaster, do you have any props for it, and if so what pitches?
Thanks,
Sid

joseph m. hahnl
05-26-2013, 07:55 AM
The GT-21 I just acquired has the factory installed TRS outdrive circa '75-all components are there and it is a heavy duty outdrive from it's appearance.I am not an outdrive person-is it worth having it gone through by a knowledgeable TRS tech?,or should I just plan on installing an Alpha for the 280 HP engine.My concern is internal parts availability and why did Merc opt out of this drive.:confused:
TRS / TR Drives
Lots of TRS drives are still operating out there!
They are very large and very tough. The main draw-back of the TRS drive was that it needed a transmission as no shifting occurred in the drive itself.
Newer and faster boats needed less weight and more room so the TRS has been discontinued by Mercury Marine and it's market replacement is the Bravo series.
The TRS initially was mated to Mercury Marines TRS transmission . This was Mercury's own design which used some Ford inner parts. The tranny had an internal oil cooler and an aluminum housing.
Mercury then changed to the Borg Warner Transmission which required that the TRS Drive input shaft be a splined male shaft instead of the older, hollow female splined shaft.
When ordering TRS stuff, make sure you specify what tranny set-up you have.
The TR drive used the same upper driveshaft housing as the TRS but it's lower housing and prop shaft were much larger for larger props.Many other drives such as the 215E and the 215 as well as the "A" and "C" drives still pop-up for service now and then but parts are hard to find and perhaps they are best displayed in a museum!

roadtrip se
05-26-2013, 10:40 AM
For when the the TRS needs to go would be a Konrad. Sweet drive system. I certainly wouldn't throw the TRS out until you had to.