311 SR1 TRS Failure
 

Had a pretty big failure - threw a driveshaft on one of the engines/drives (420/TRS). I wasn't on the boat at the time but I think operator may have mistakenly trimmed up into trailer mode and tried to plane out. They reported hearing a loud sound the the engine stalled. Came back and found water leaking in from a cracked inner transom plate. U-joint separated. Engine took on water and hydro locked but I was able to free it up and compression is good. Will need to replace driveshaft and inner plate at a minimum. Stock 420 w/ TRS never abused, hardly run over 4200RPM w 28P 3 blades. Surprised as TRS drive is solid when left stock, guessing had to be operator error?
Might as well do gimbal while in there - any other suggestions/comments?
Thx

There is no gimbal bearing on a TRS, they have two sealed bearings inside the tail stock of the transmission. You will likely have to pull transmission and tailstock to replace those.

That makes this make more sense to me. This is my first experience with TRS drive work, and I was having a hard time seeing how the hell the inner transom plate got cracked. The tail shaft of the velvet drive is about an inch or so long right? So there must be another shaft that connects the transmission to the outdrive input shaft with the U-Joint on it correct? If that does even exist, could it have broken apart and cracked the inner transom plate? Trying to find some diagrams or photos online, but I might just start pulling it apart and figure it out.

lol "velvet drive" - sounds like the name of actor in a bad 80s adult film.

Once you pull the drive off, you will see whats left of the double cardan joint. If it was flailing around it could do some damage

How did the engine get water in it? Separate issue?
Did the drive seize up causing this or is it ok?
I had water come in throuh a ripped bellows. The input shaft rusted to the tailstock bearing allowing no shaft movement. This took out the ujoints which destroyed the transom assembly

You might be right on the money. There is some corrosion on the broken U-joint. If I was on the boat when it happened I'd probably have a much better idea, but I'm going off of my wifes description of what happened. It came back to the marina with the drive almost all the way trimmed up (trailered up), while the other drive was lower (low as it could be with the other one that high, but only one side failed). I just don't know if she trimmed it up after it failed trying to start it, or if it was up while she was planed out and caused this whole thing. I need some free time to get up there and get the drive off.

Drive itself seems OK aside from driveshaft.

I think the water intrusion is from the engine being stalled from 4000RPM at probably 30-35MPH, I'm guessing it came up the exhaust. Engine runs fine now and compression on all cylinders is good so hopefully it didn't hydrolock, but got water in after it turned off and just couldn't be cranked afterwards.

Ugh. This ones gonna be BOAT dollars.

I guess this is where trim limit switches come in handy.

Do the trim limit switches do anything when you press the “trailer out” switch? Because that’s what she hit. The limit switches work when you press the trim up buttons, stops the drives from coming up any higher than they should, way lower than trailer mode while will raise them almost to the point the prop is out the water.

The boats on a slip. I’m probably going to disconnect the trailer out switch just so it doesn’t happen again. I’m the only one who puts it in the trailer anyway.

I wish there was something to alert or not allow power to be applied if the drives are raised past the trim limits.

Do you have mechanical drive trim indicators?

Mine won't let me raise them via the trailer switch unless they are already maxed via the drive trim switch... I guess they take the inverse of the limit switch. So the limit switch has to be tripped for my trailer switches to operate the UP direction.

My old boat didn't even have separate switches, it was one did everything. operator beware.

Yeahhh but the cables got pinched getting caught up on the trim rams and broke them. Stupidly never got around to fixing the cables. Trim tab indicators work. I told her drives all the way down and just use the trim tabs, don't even mess with the drive trim. 4 years of problem free operation with just standard maintenance, and the first ride she takes alone it comes back with a catastrophic failure. Gotta love boating.

My limit switches appear to have never been hooked up. There are switches on the drives, but the wiring is capped off and appear to have never gone to the black control box under the starboard gunwale. Once the ignition is on, the trailer switch is disabled. This is by design so unless yours has been modified, the trailer switch should have been inoperable with the engines running.

Sucks to hear about your situation. Hopefully, this does not open up a huge can of worms (i.e., transom). You've got a big repair job in front of you. If the transom plate is cracked, there is a good chance that the transmission got hurt when it blew up. I would be prepared to replace the tailstock and output shaft, and then rebuild the transmission. If the transom is bad, yank everything and reevaluate the situation in terms of work required and cost (transom, stringers, bulkhead, etc). If a transom is needed, this would be the time to convert to a Bravo set-up.

**I'm not suggesting dumping the TRS. You guys know I love them, but if a lot of hard parts are broken and the transom is bad, it's a valid consideration.

Get some posts under your belt and post pictures. There is a also a great resource available on FB... Formula SR1 (powerboats). A lot of us on here are resident members of that FB group. Good luck with the repairs.

-Tom

Tom -
Much appreciated input! I definitely have some serious work in front of me. As much as I love the butter smooth shifting BW/TRS setup - if there ends up being that much damage converting it to a Bravo setup will probably make more sense financially - now and with any future repairs. I'm going to be sooo devastated if the transom got damaged, but it certainly might have. I'll update when I know more.