Mercruiser TRS gimbal bearing replacement

Does anyone know how to change the gimbal bearing on a 1981 Mercruiser TRS drive. I have done Alpha I drives and pre Alpha drives but never a TRS. At a glance it looks like there are a several bolts holding it in place. Any insight would be appreciated.
Thanks

Jon

Re: Mercruiser TRS gimbal bearing replacement

Those bolts your looking at (7/16" hex) hold the rear motor mount snug to the gimbal housing while the actual motor mounts keep it nailed down.
There is no gimbal bearing! The trans probably close to being junk! You won't know until, 1 troubleshoot it installed 2 pull it out & have qualified trans people look at it.

The bolts you see have to be loosened about 3-4 turns. With everything else prepped for engine removal it will come out. DO NOT LIFT the front anything than you have too. 1/4" off the stringers is all you need, slide engine forward & once clear of gimbal hsg, transom plate & decking etc lift it out.

The "tail stock" on the trans is cast aluminium & NLA. Most of the parts for those units are NLA. IF you have any luck in putting this unit back into service, make sure you replace the "pilot bushing" & check the splines on the input shaft!

Re: Mercruiser TRS gimbal bearing replacement

What you have is a Merc Trans ll transmission. 1981 was the last year for them. Actually what you are seeing are 6 nuts on studs which hold the bearing retainer and tail stock bearing in place. As mentioned the engine and trans must be removed if you want to replace the bearing which is in the tail stock. Tail stock it self won't need removal or replacement. What makes you think it needs replacement? Reach in there and spin the bearing with your fingers and see if it spins smoothly and is firm and not loose. If you look closely the retainer with the 6 nuts also may have a grease zerk between 2 of the nuts for greaseing the bearing. If there is no zerk than someone has replaced the bearing with the newer style permanently seal one. The bearings are availiable though Merc but most of the other parts aren't. Their the same bearing as a Bravo gimble bearing. However you can still find parts if you know where to look. You see them on ebay every so often and other boat sites classified sections. Also theres a guy that rebuilds and sells them as well as parts. KC Marine
http://www.kcmarinetr.com/Default.aspx

Re: Mercruiser TRS gimbal bearing replacement

I assume the bearing is bad b/c when you put the drive in gear (forward or reverse) it grinds. At first I thought it was the u-joints but turning one dirrection or another doesn't change the sound and after removing the drive I realized the bearing has a little bit of play in it and it feels slightly rough when you spin it. I'm suprised it makes this much racket. I don't know if you would even here it in an Alpha drive, but its the only problem I can find. The u-joints feel fine and so does the lower unit when you spin it. The gear lube is clean and so is the tranny fluid. The bearing does have a grease fitting on it so I greased it and it feels better. I'd like to put the drive back on and start it to see if that helped at all, but even if it does I'm thinking it should still be replaced. I'm guessing it whent bad because there was a little ATF in the bottom of the bellows that probably washed some of the grease out of the bearing as it went by.

Re: Mercruiser TRS gimbal bearing replacement

If you do decide to replace it then while it's out you should replace the rear seal in the trans while your at it if there was trans fluid in the bellows. If it was just a little I doubt it would have washed the grease out of the bearing. The bearing is pretty much sealed except for a couple small holes where the grease enters it from the fitting. You could start it up with the drive off and shift it forward and reverse just to see if it makes any noise. If so then it's probably in the tranny. The seal is part #95 in this diagram.
http://www.perfprotech.com/store/as...LY-(STERN-DRIVE)-PAGE-2,988-220.aspx#assembly
It's NLA from merc but is a common seal you can have a auto parts store order for you. About 6 bucks. Let me know if you do and I can give you the part number. Don't have it here at the house with me right now.

Re: Mercruiser TRS gimbal bearing replacement

All together I may have soaked up 2 oz of tranny fluid from the bellows and what was on the inboard side of the bearing. I did start it with the drive off and shifted it, there was no noise at all so I greased the heck out of the bearing turned it back and forth and greased it again. I don't think it feels like a good bearing should but I put the drive back on, started it, shifted it, turned it, trimmed it, and didn't hear any noise. I think I'll try running it for the summer, if it starts rumbling again I'll put it back on the trailer, otherwise i think I'll wait until winter to deal with it, I just don't feel comfortable with a questionable bearing. I just don't want to damage anything else on the transmission.