Ok, how much HP can a TRS drive handle
 

I am finishing up a winter project, a 32 baja with a set of new 8.1 S HO (496 HO), runing velvet drive trannys and TRS drives, how much HP can these saftly handle?

i have heard they are good to right around 500HP. a bit more if you watch the throttles. a friend of mine had 750's on trs's in a 38 scarab and went through a bunch of drives every season. should be fine with the 496's :cool:

thanks glass, do you know what the weak link is with these drives, do they self destruct or just twist shafts ect.

TRS Drives are known to blow the lower gears,especially the right hand rotation.JP Clear on here has had success with cryogenic treatment of gears and shafts.I think that he is pushing some serious hp in single engine V bottom.

Rob

If the drives are put together with the machined shim in the lowers , they are good to about 600 hp. If there put together with the regular crush ring I would say 500hp . The weak link in the drives are the right hand drive . The lower gear in the right hand drive that is located aft of the vertical drive shaft is the most common problem .This gear is not as well supported as the left hand drive . The left hand drive gear is located fore of the vertical shaft and is much better supported. The key to these drives is to machine the shim for the lowers and a make sure that the preloads on the bearings are proper. You should be more than fine with the 496's. Tom

Baby it out of the hole, and don't air it out all of the time, and you'll be fine! I love TRS drives!

I've had several TRS boats and they have worked very well for me. I had a lower gear failure last spring and then I replaced both left and right lower gears with the Cryo treated gears and have not had a problem since. Not sure what my hp is but I think I'm around 700

I would have to agree that the nose of the TRS gear-case provides better support for the prop-shaft gear than the carrier assmb. behind the pinion as used with the right hand drive, but I don't understand why the crushable ring won't work as well as a machined shim. The load pushing on the gear is directly against the carrier thrust ring and not the load ring. Can someone please explain? And yes; I highly recommend cryo-treating. Just be sure you have an EXPERIENCED professional do the assembly work. Shimming for bearing preload and gear lash is CRITICAL and the upper and lower must set up as a unit...not independently. I feel that most TRS drives that have been apart fail because they were not reassembled quite properly. I'm inputting about 600 H.P. to a RH drive with no problems, but I'm not a cowboy. --- Jer

Thank-you everyone, I am very impressed with the vast knowledge in this web site. I am going for a first time brake in run this weekend, ill let ya know how it all turns out

jp, you hit it right on the head, I cannot see a benefit in the solid shim.

Is it possible for the load ring to 'relax' over time? If so would the bearing preload go away?

Kurt

NO! The load ring only tells you when to stop torquing. --- Jer

I suppose it cold relax, but it would actually increase the preload. This also means that when you went to take it apart the retainer nut would be kind of loose. I have never seen a loose one.

Thanks Marc! --- Jer

Two seasons ago I was having problems with my lowers and started blowing pinion gears and by the end of the summer I had a box full of broken gears.

First the right hand drive went so I rebuilt it. I just thought it broke because it was the weak drive. Then a few months later I broke the left hand drive which also made the trans oil pump break. I got Mark (MBAM) to send me a new trans and I rebuilt the lower as well. Then a month later the right hand drive broke AGAIN! I rebuilt the lower again.

It was all pretty frustrating because I had already had the boat for a while and never had any problems. It made me think a little because I had installed nose cones that year and started hearing that other people were having similiar problems with thier drives that had nose cones. So that winter I removed the nose cones and never had any problems since.

BTW, I am running about 525 to 550hp.

I can't imagine why the presence of a nose cone would cause lower gear failure....but I've always felt that the extra length of the stock TRS gear-case made nosecones unecessary unless you were running in the upper 80's and at extreme "X" dimensions. --- Jer

I say again...Cryo-treated gears?? -- and who rebuilt it?? --- Jer

Jpclear... I hear you run big hp and single drive...What kind of boat/ setup are you running???
Eric

As much as it sounds wrong, that was my experience. The boat was rigged in 1995 and never broke a drive until 2001 when I put nose cones on and broke 3 in the same season. Then I got rid of the cones and haven't had any problems for the past two years.

I lost 1-2 mph with the nose cones and lost about 200-300 rpms. I think the drive may have been getting loaded from the loss of RPM's. I think if I went to a smaller prop the drives would have stayed together. The props felt really sticky with the cones, even if you barked the drive slightly if felt harsh. Once I put the nose cones on you had to be right on the money with the sticks.

Again, I only speak from my experiences, whether you believe it or not that is fine by me..

Where can I get the Cryo-treated gears?

I thougt it was hard to find stronger parts for these old drives.

I don't have any problems yet but I'm going for 8-71's and stellings next year,and I think that's over the limit for my stock drives.

sutphen30,

Did the change over to bravos effect the balance of the boat? Was it better or worse? E.g. engines are further back, and less weight etc.

I have contemplated a changeover, but then again I will be getting something bigger next year.

panther

OK DID A FIRST TIME RUN , FIRST TIME IN MY BIG TWIN BOAT!, AND THE DRIVES DID GREAT BUT AFTER 4 STRAIT HRS OF ENGINE BREAK IN I ENDED UP SMOKING 1 OF THE TRANNYS ( NOT COMPLETELY BUT PROP TURNS IN NEUTRAL) SO OUT COME THE MOTORS AGAIN, MAN I AM GETTING GOOD AT THIS.YA GOT TA LOVE THIS SPORT TO KEEP WANTING TO WORK ON THESE THINGS HA HA.

Out-drives!?--Trannies!?----If it's a TRS (or anything else) the prop SHOULD spin in neurtal. Pull yourself together! What is REALLY going on here? We can probably help. --- Jer

Oh, by the way; I don't know where you buy NEW "cryo-treated" stuff. The guys that do this process treat whatever parts you give them. If your used gears show "no" or "nice" wear patterns, then have 'em treated! After all, they are tested pieces, and you'll only make them tougher. --- Jer

Is the prop spinning in neutral and slipping on the top end?

If the clutches are going bad you will feel the trans start to slip at WOT and check the color and smell of the tranny fluid. Try to replace the tranny fluid before you go start pulling motors and doing a lot of extra work.

The trans is fairly simple to rebuild, but if you want a good strong trans with upgraded and additional clutch plates send it to BAM, he is upgrading one of mine right now.

Panther.

Ok jer Ill try, but heres what hppened. Befor the first run the props would Not spin in nuetral, after the run only R. prop was spinning in N. And with engines off and out of the water the R. prop was twice as hard to turn ( clutch plates warped and taking up clearance and draging), E-Mailed Marc at BAM and he said these trannys are marginal with this set up and sugested rebuilding with graphite clutches. I just want this thing to be relisble all summer, and would rather work on it now while it is all snowey and stuff.

Well, Marc IS the man to talk to on this but I just don't know why these units shouldn't turn fairly freely. (there is some drag cause you are turning all the TRS parts plus the output side of the tranny) When you water tested, did the boat tend to creep forward when in neutral? --- Jer

JP

Just the fact that panthers rpms dropped suggests that the props were slipping and that the cones helped.

Panther,

The nose cone issue does make sense, along with what kind of props are being run. Adding the cones simply cleaned up the water flow to the props and lessened the amount of slip, thus putting more stress on the drives. possible solution: go to 3 blades if you were at fours......

Every body loves and runs four blades these days for thier cruise speeds, but they just put more stress on the drive. Thats fine for most applications, but for those on the edge with power, it's not helping things. It's just like the guy who finally puts slicks on his street machine and starts breaking rearends, trans', and axels !!! He may have a better 1/4 mile time for bragging rights, but now he's gonna break **** thats "never broke before".....

I blew my single trs this winter (new boat to me) with 625 hp / 700lbs torque, huber 925 trans, with hydromotive 28P four blade, and nose cone. Previous owner got 3 seasons with this power and 28P Bravo one four blade(habits???)

I'm rebuilding that drive to keep as a spare, picked up another that I knew entire history of, and am now going to try a three blade mirage plus. I'll loose some cruise speed, but I don't want to be afraid of my drive all summer.

My previous boat was about 500 hp hooked to a bravo/nose cone with a three blade and I abused the **** out of it for 4 seasons without a single problem. No-one could understand why I wouldn't run a four blade. Meanwhile I was doing hole shots, hopping the boat out of the water just the throttle, etc. - You could feel alot more slip in that setup and I really don't think it would have lasted with a four blade prop......

Huber Transmissions does the same type of trans work. They are basically increasing the number of clutches in the pack and increasing the pump pressure that holds the clutches together. The grafite clutches can survive a little slippage unllike the "paper" clutches that may have originally been in the drive - once they slip under load, they tear and are done... I can only assume that running more pump pressure eats more hp, and that why the factory didn't do it??? Some body set me straight.
damn, I write too much.....

Actually Hubers trans a lower pressure spring (white) than a stock trans (black). The lower pressure does keep the heat down.
He can run a lower pressure because he uses a larger foward servo to compress the fwd. pack. The pump is shaved too and has a wear plate.

Extra line pressure is not the answer (been there done that many years ago), the material and number of plates is more important. We have found the cut down pump causes more problems then it solves. No oil flow through the cooler at idle, inadequate pressure when the trans is hot. It is however worth about 5-7ft lbs less loss in the trans. Actually the standard plates are brass which will last a long time in a cruiser application but have a low coefficient of friction (they are slippery). There was a few years that the transmissions that came from Merc with the TRS had the paper clutches and white spring.

Marcs right, its better to have the right flow to the cooler. After a hard run when your idling the trans flow to the cooler is low. So its better keeping the pump's mass. I quess what happens is the oil bypasses between the pump, plate and rev/fwd. adaptor pump face when its hot on the shaved pumps? Am i right Marc?

Not so much that it bypasses in the pump, but the cut pump has less displacement. The flow is diverted to the cooler once the pressure regulator starts to open, and with less displacement there is not enough pressure/flow at idle to open the regulator. We run the fluid through a clear lexan block on our trans dyno so we can really see what happens.

That makes plenty of sense Marc. I got a question for you. It seems like the 2.10:1 71 and 72c has very little flow to the cooler a idle. Is this because the oil from the cooler returns onto the rear planetary and not to the usual place? We noticed it on every test run in our dyno stand with the 2.10.

3 VS 4 blade on TRS
 

When I boat on Lake Michigan (about half the time) I switch out my 25 Mirage 3 blades for the 26 Bravo 1 4 blades. When things get a little lumpy on Lake MI I would have top be on and off the throttles with the 3 blades, but with the four I stay hooked up.
I would think a constant load is better than unloading and reloading of the drive , no?
It's really not much of an issue with my current under 450 HP engines going thru the TRS.
By the way I loose 3mph and 400 RPM with the Bravo 1s
(obviously overpropped).
DS

DS,

Sounds like a 24 bravo 1 might be worth a try?? Should be an easy size to borrow. I see your your point about loading and unloading the drive. I've also heard the arguement that the 4 blade has less vibration along with less cavitation which is better for the drive, but I was thinking more for those times in rouph water when the prop breaks loose and your not quick enouph on the stick - that re-entry in a high hp situation would be gentler with the three blades.

Well, now we've moved this to a prop discussion. But YES, Zanie; I have also experienced that a Mirage on a TRS will give you the best GPS reading under "ideal" conditions. It took Mike Spinelli four trys to get one of his 4 blades to get to the Mirage speed. But when he got done, it was about 1/2 to 1 MPH faster and performed far better in all other areas. And yes, loading and unloading will kill drive systems. --- Jer

ok, back to the drive itself. Is "Cryo-treated" just a fancy word for heat treated?? Guys in my area have told me they've had bad experiences with this route in the trs - that heat treating can make the gears too brittle so they just break easier?? better to just let them wear?? JP??

NO!! Actually it's a controlled time/temp freeze down to as close to "absolute zero" as is possible in the liquid nitrogen chamber and then a transfer to oven during the warm up process to heat to a specified high temp and back to room temp. I'm over simplifying here but I've got to believe that anyone who had a "bad experience" with cryo-treating didn't get REAL cryo-treating. The guys that do the REAL process have some VERY expensive equipment and are not heating and quenching your parts with a torch in the back yard. (which, of course WILL make them very brittle). --- Jer

Thats what I wanted to hear. Neither of them refered to it as "cryo", just heat treated, and went through this about 10+ years ago with thier race boats. They finally gave up and went to bravos which had only been out a few years (without much better luck). I've still got to rebuild the trs I blew to use as a spare, so I'll go that route with the lower gears. Thanks.....

Lookup www.diversifiedcryogenics.com

They have a pretty cool website that explains the process pretty well. You can send them your gears and shafts for treatment. It is pretty reasonable, $5.00/pound with a 20 pound minimum of something like that.

I have been told by John at Doller that all the new replacement gears from Merc are now Cryo treated from the factory.

Kurt.