Simple TRS inspection
 

Are there any simple "sanity" checks to do on a a pair of TRS drives and gimbals before re-installing and trying them out?

The drives are off now and they turn very smoothly from the input shaft, but drives feel the same. There are no leaks from the seals and the paint (probably original) is in great shape. No noticeable play in either input or output shafts.

On one of the gimbals, the lower bearing has some play, maybe 1/16". The upper bearing is tight. On the other gimbal, both upper and lower bearings are tight. I plan to replace the bellows.

I've got the Mercruiser manual but no special tools.

Thanks for all your help, Randy

TRS drives had 2 types of steering arm shafts. One was round and splined the later and better was square with rounded off corners. Their steering arms had wear problems and the splined shafts where junk. The bellows are a judgement call, depends on how plyable they are. The bearings should be tight but smooth and free. Not tight from corrosion. The worn one should be replaced. 1/16th turns into alot of slop in the drive which could be dangerous. Don't forget to check the side pivots too. Everything needs to be able to accept greese and be tight and smooth. Side to side, up and down. By the way, you will need the proper gaskets for the outside gimble to transom mounting.

thanks
 

Great thanks. These gimbals have the U-bolts, which, by the manual, indicates it's a later square steering pivot. Do you have a good source for parts?

Any tips for the drives?

Thanks, Randy

For me the only sanity check is to check out the lower pinion. From what I know, that is the weakest link. I check the gears out every 2 seasons. Actally, I have a pair of gearsets on my desk that were out of our old mistress with stock 502's. Checked them out and found that the case hardening was broke through. Ever since then I started doing that..... Not a simple check. The only other thing would be to measure the rolling torque of the whole assembled unit and compare it to the spec in the manual....
Hope that helps.. Pm me if you have any Q's
Jr.

BustedBrick,
Didnt realize you had a mistress. I love those boats!!! One of the best ridding Cigs out there..... Post some pics of her..
Jr.

Thx Jr.

It was a non-runner when I bought her. Both 468's were built with eagle rods, forged cranks, merlin heads. One puked its raw water pump, clogged up the oil cooler, overheated, broke a valve spring and broke the intake manifold/head seal, dumped a load of water into the lifter valley. The dropped valve hit the piston once and jammed itself up against the chamber wall out of harms way. It was a huge mess in there.

I gotta work on some pics, too big to upload now.

Is there such thing as getting oil analysis on the drive oil to see if the gears are wearing like you mentioned?

It sounds like your pretty mechanicly inclined. I would just pull the bearing carrier and hava a look at the pinion... Not sure about the oil analysis..

tr/trs wisdom
 

In dealing with tr/trs, the first thing one must know is that Mercruisers preload specifications are incorrect. This was due to oil quality at the time, and engineers who were smoking their breakfast. If bearing bores are tight, longevity of use and proper support are accomplished only by exceeding maximum preload by about ten percent. Mercruisers high performance gear lube should be used exclusively in this instance. Lesser quality lube cannot handle the load.
The only truly problematic bearing in the tr/trs, is the forward drive gear support bearing; due to small diameter and length of travel towards the drive gear, this bearing loses load consistently, allowing gear chatter and the subsequent "bang". Upper failures seem far more common than lower issues, and this is a huge contributing factor. Be certain the check the aft u-joint shaft/yoke for "any" lateral play. This is a simple check for loss of preload, and if any exists, rebearing before disaster strikes. Loctite 660 is a excellent fix for the likely loose support bore.
The gimbal housing should be sealed on "both" sides of the mounting gasket with "boatlife lifecaulk" this provides a adequate cushion for the cork material to avoid being cut by the small surface above the lower trim manifold. While running forward all load is forced on this small surface by propeller torque and leaks; and even "sinkings" could have been avoided by this simple procedure. The exhaust seal "must" be replaced before gimbal installation for the same reason. An old exhaust seal invites leakage. If the lower swivel bearing is loose, be certain to replace it; it will only destroy the gimbal ring if you do not. The other "weak link" is the oil resevoir transfer hose, in front of the bell housing. Use type A fuel line (thick walled) with non-magnetic stainless hose clamps. The tr/trs has the distinction of being a "vented" oil system, and as such oil loss can a very common issue. The transfer hose is often ignored and can cause devastating failure if not maintained. The clearance betwen the top of the gimbal ring and the gimbal housing is also "critical", any gap larger than .005 is excessive, and a sign of upcoming steering issues, and possible u-joint failure. A gap at this critical juncture upsets alignment at a place where ujoints will not tolerate it. Be certain to use only high performance ujoints 75832T 1 ....any others are inviting disaster...

this must be Mr.Kc marine the merctrans wizard.

Interesting. This is all new to me..
Jr.