TRS MERC

[allanlval]

I have a 1976 18 classic with a TRS. please give me info. on this drive.

[Forrest]

It's big and heavy and tough as nails. If you ever need to remove it, don't try to lift it by yourself - get a helper! Most likely you have the MercTrans rather than a Borg-Warner transmission between the engine and the drive. This is a great transmission as Big Grizzly has proven by pushing nearly 750 HP (or more) through his MercTrans to take the high honors at the recent Eufaula IV Donzi event with a top speed of 89 MPH in his 22' Donzi Criterian with no more than a stock TRS drive and his favorite propeller.

[Rodger]

Most likely you have the 330 TRS. If you do, then you have the Merc Trans. I also have that unit on my 1978 F22. I'm running similar power and speeds as Big Grizzly and it's holding up pretty well. I did have to replace the clutches with some H.D. ones but with the 330 you may never have to worry about that.

[Formula Jr]

There's TRs and there are TRSs - have no idea of the differences. The real designations are the II-TR and the II-TRS. Introduced in 1970 and ran up to 1987. There is also something called a 215E and 215H (1970-1973) that had external transmissions and as with the TR/S can be set up right hand or left hand. The 330 tr and trs didn't start till 1977 model year. In '76 ya had the 255, 270,280 and the 370. I believe Randy put a wing of his own design on the skeg of his TRS. :D

[Gearhead99]

Had a TRS on my cigarette with a Borg-Warner Transmission. Never had a problem.

Bullet Proof combo.

[Rodger]

The TR's have bigger lower gear cases and use elephant ear props. Used often on house boats and other low speed slugs.

[Bad-Tat]

Hey Rodger,
Don't be calling Randy's 22 a slow speed slug!!! That boat really moves with a TRS!

[BigGrizzly]

Wait, Thanks for the build up, but lets get this right. I don't have over 700 HP and that boat goes on its best day high 86 mph. But I do agree the trans is tough and it is really smothe when put into gear. There has been a discussion about the power robbing trans, this is bull. Yes the TRS and Merc trans does use more hp than a bravo I by about 7->14 HP. I heard stories ot 20 to 40 Hp so I asked Tom Huber of Huber marine who is an expert and modifies the Borg trans forand he gabe me the numbers. This is the guy that the other guys copy

[Rodger]

Hey Bill. I assume your teasing me. If your not though; what I am talking about is the TR unit being for low speed slugs, not the TRS. I have a TRS on my 22. Under the water, they are more hydrodynamic than the Alphas or Bravos because of the longer gear case. The diameter of the gear case is about the same.

[Forrest]

Actually, if it's a small-block TRS setup in that '76 18 Donzi, it's most likely a 255hp or 280hp TRS. The Merc TR (not TRS) swings a 20" diameter prop and is designed for moving heavy loads.

OK Grizz, if figured the BG shirt was worth at least 50 more hp and 3 mph! :D

[olredalert]

Allan,

-----TRS drives with small blocks went on a number of 18s.How many I dont know,but not a particularly large number.John Chisholm told me back in 79 when I bought an X-18 with TRS and big block(new left-over)that there were only 6 of those built.The factory was concerned about liability issues.And I can add that the boat was a handful.There may have been a few small-block/TRS combos converted to big-block as well.Although heavy,the packages were(as stated above)very hearty,shifted nicely,and as a bonus looked bitchin!Carburetor clearance was always an issue though.......just......ol red!......Bill S

[Rodger]

I personally know of 3 people who bought original Big Block TRS 18's. As I remember they had to put bumps in the engine cover for the flame arrestor and both exhaust risers.

[allanlval]

Thanks for the info! My 18 is a 350 chevy TRS and hatch cover does have the bumps for the risers and a scoop for the flame arrester. Does any one know the gear ratio,or how I could figure it out? The owners manual that came with the boat gives two options;2:1 model 255-TR, or 1.5:1 model 280-TRS.

[MR MAGOO]

You most likely have the 280TRS package. The TR drive was for heavy work /house/cruiser boats.

The TR drive lower was deeper and would accept a 20" dia prop

[DS88]

I also own a 1976 18' 280-TRS. The 280 was a 1.5 to 1 ratio where as the 255 TRS was a 1.33 to 1. I have the two scoops for the risers on the hatch but none for the flame arrestor although it was pretty much scraping the hatch cover. The 350 is no more, a 383 is on the way but for reference, the 280 TRS was basically an L-82. The heads were nothing special, 1.94/1.5 with the cast iron quadrajet intake and carb. The bottom end of the engine was pretty decent - four bolt block with nodular iron caps, 6-quart baffled oil pan and windage tray, forged crank, forged aluminum pistons and "pink" rods. The best performance I could get was 62mph at about 5000 RPM. This was on a pitot tube stock Teleflex speedo not GPS - hard to say what the real speed was. I was using a 14 3/4 " X 21 pitch cleaver prop. It may have done a little better if I had a better ignition - stock single point Prestolite distributor. The cam that came out of the engine was an L-82 cam. Hydraulic lifters, 222 @.050 on both intake and exhaust, .450/.460 lift in/ex on a 114 degree centerline - GM p/n 3896962. I matched up the casting # off the cam to the Chevy parts book to derive these numbers.

The boat shifted great although I did burn up 1 shift motor which wasn't cheap then and isn't cheap now. I spoke with BAM marine recently and they told me that with two comparable boats, one with a TRS and one with a Bravo, The Bravo is about 2-3 mph faster. I considered switching to the Bravo but have decided to keep the TRS for now.

The 383 I'm putting together(due 2008), according to the desk-top dyno, will make 430HP. I will never blow the TRS with that.

Question - I'd like to have the bellhousing separated so I can prime and paint it properly with awl-grip and then have it re-assembled. It's hard to tell if the bushings/bearings actually need to be replaced but since the boat is totally disassembled and it's a quarter century old, I can't see putting it back together without going through it first. It has about 420 hours on it. The question - is it really worth it or am I just inviting problems with parts being frozen, then cracking and then not being able to get replacement parts.

Also, if I go this route, I need a recomendation of some one who can do it. Any/all suggestions will be appreciated.

Thanks,

Dave

[CDMA]

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

[Cuda]

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

[DS88]

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.

[KMLFAMILY]

On BAM MARINES web site www.go-fast.com (http://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..

[Rodger]

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.

[DS88]

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

[Rodger]

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.

[KMLFAMILY]

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.

[DS88]

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

[Sagbay32]

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

Mike

[smoothie]

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.

[DS88]

Thanks for the info!

Dave