TRS rebuild specs
08-26-2022, 04:39 PM
#1
Registered
Thread Starter
TRS rebuild specs
I have the Merc manuals and tools for the TRS and Merctrans II.
One piece of info I saw on the old KCMarine website, was that the original pre-load for the TRS were outdated with the new fluids available.
These drives amd trans are getting long in the tooth...worse, is the lack of qualified mechanics.
There is a lot of valuable info here on OSO.
Bam Marine has posted many tidbits of TRS knowledge.
Maybe we can create a thread with condensed TRS knowledge on operating and rebuild.
Prop Selection: from what I've read, the TRS has a hard time with 4+ blade props. Likely too much bite for the hole.
Prop Shaft: using solid shims (Bravo shims fit) vs. The TRS Crush washer, prevents gear deflection under load.
Left hand drives are stronger than the Right hand. Gear thrust is on the solid fsolt of the bullet....vs the carrier for Right Hand.
Merc Trans: has fluid cooling issues. Wants fluid between 175f-195f. Has very small reservoir, so it does not have much thermal backup.
Better fluid cooling would help. There is speak of a gatling cooler. Assuming it's like a heat exchanger style with many tubes vs the stock large single copper tube.
Anything to increase fluid volume but maintain max level would help. Using the bottom cooler cover is likely the best option.
Crankshaft bushing in good health. Often overlooked. Merctrans has a sprung spline on a plate that bolts to the flywheel. Round for 454....and triangular for small block Chevy. The Merctrans input shaft must go through the spline, and nose into the crank end bushing for alignment and support. Bot sure if the upgraded roller crank bushing/bearing would be a better option.
TRS upper gear set is strong, and less likely to give any issues. Lower gears are far more likely to break. Cryogenic treatment of gears has benefited many. Don't have to be new...just not showing any indication of pulled metal from the teeth.
Always use Mercruiser branded U-Joints. Make sure they are in good health. Issues here can lead to exploding u-joints and damaged TRS Transom parts that are difficult to replace.
Play in the vertical Gimbal bushing needs to be addressed. Mine may have chewed chewed put the aluminum in the housing, requiring some machining and maybe a bushed solution to align it again.
Gimbal bushing and tiller arms. There are a few types. The square non splined are the best, and moat recent design.
Having tight steering is essential.
One piece of info I saw on the old KCMarine website, was that the original pre-load for the TRS were outdated with the new fluids available.
These drives amd trans are getting long in the tooth...worse, is the lack of qualified mechanics.
There is a lot of valuable info here on OSO.
Bam Marine has posted many tidbits of TRS knowledge.
Maybe we can create a thread with condensed TRS knowledge on operating and rebuild.
Prop Selection: from what I've read, the TRS has a hard time with 4+ blade props. Likely too much bite for the hole.
Prop Shaft: using solid shims (Bravo shims fit) vs. The TRS Crush washer, prevents gear deflection under load.
Left hand drives are stronger than the Right hand. Gear thrust is on the solid fsolt of the bullet....vs the carrier for Right Hand.
Merc Trans: has fluid cooling issues. Wants fluid between 175f-195f. Has very small reservoir, so it does not have much thermal backup.
Better fluid cooling would help. There is speak of a gatling cooler. Assuming it's like a heat exchanger style with many tubes vs the stock large single copper tube.
Anything to increase fluid volume but maintain max level would help. Using the bottom cooler cover is likely the best option.
Crankshaft bushing in good health. Often overlooked. Merctrans has a sprung spline on a plate that bolts to the flywheel. Round for 454....and triangular for small block Chevy. The Merctrans input shaft must go through the spline, and nose into the crank end bushing for alignment and support. Bot sure if the upgraded roller crank bushing/bearing would be a better option.
TRS upper gear set is strong, and less likely to give any issues. Lower gears are far more likely to break. Cryogenic treatment of gears has benefited many. Don't have to be new...just not showing any indication of pulled metal from the teeth.
Always use Mercruiser branded U-Joints. Make sure they are in good health. Issues here can lead to exploding u-joints and damaged TRS Transom parts that are difficult to replace.
Play in the vertical Gimbal bushing needs to be addressed. Mine may have chewed chewed put the aluminum in the housing, requiring some machining and maybe a bushed solution to align it again.
Gimbal bushing and tiller arms. There are a few types. The square non splined are the best, and moat recent design.
Having tight steering is essential.
The following users liked this post:
Bennerich (11-07-2022)
09-20-2022, 08:30 PM
#2
Registered
Art;
Got your email/PM but OSO is preventing me from responding due to low post counts. So here goes a response;
I did a lot back in the day with the FMX. It was all about getting the tires to chirp back in those days, 1to2 and 2to3 shifts (cars obviously). I designed my own full manual valve body and used the vacuum modulator case opening as access to a psi bleed off adjustment screw in the valve body, then over sprung the regulator. It worked like a champ but I soon discovered that even though I could dial in 600psi, it put huge amounts of wear on the pump and often times blew the ring lands off the front clutch basket and bent the front band anchor tab in half. It simply wasn't worth the effort and anything above 300 was a waste so I dialed in 250-300 and just left it. It was good only for compensating for worn sun shaft seals in the end. I always ran only 2 disks in the clutches. It just hit harder and they never slipped. I think if the psi was stock that would've never worked. Anyway, I also like you thought about a power steering pump but the psi just wasn't enough if I recall and there is no way those v belts could have driven it back in the day.
As far as the Merctrans go, I haven't played with mine much but also haven't had too either. Its been pretty reliable but I like you have heard of the electric shift between gears stories and cooling woes. Mine now has a stroked BBC in front of it with an honest 500hp pushing a 10klb '82 Sea Ray 255 Amberjack. With a full load I have never felt anything slip yet going to WOT to get on plane. I went through the trans when I redid the the stock 454 to stroke it up and replaced all the seals in the clutches and outside seals. I did not touch the sunshaft seals as they were the preferred Teflon gapless seals and usually never need replacing. I will also say that I have yet to do any long range cruising and really build up a lot of heat in the trans. The lower is a TR with a 15" "ceiling fan" prop. I know I'm loosing about 10mph on top end easily with that TR lower but I'm not really concerned with going over 40mph anyway on that boat, its just for cruising to the islands for RnR.
If I had to fashion a cooling system it would an electric pump through an external automotive type cooler w/ built in fan and definitely a temp gauge. Hope that helps, if you have any other questions post it here or... BL at BLmicro
-BL
Got your email/PM but OSO is preventing me from responding due to low post counts. So here goes a response;
I did a lot back in the day with the FMX. It was all about getting the tires to chirp back in those days, 1to2 and 2to3 shifts (cars obviously). I designed my own full manual valve body and used the vacuum modulator case opening as access to a psi bleed off adjustment screw in the valve body, then over sprung the regulator. It worked like a champ but I soon discovered that even though I could dial in 600psi, it put huge amounts of wear on the pump and often times blew the ring lands off the front clutch basket and bent the front band anchor tab in half. It simply wasn't worth the effort and anything above 300 was a waste so I dialed in 250-300 and just left it. It was good only for compensating for worn sun shaft seals in the end. I always ran only 2 disks in the clutches. It just hit harder and they never slipped. I think if the psi was stock that would've never worked. Anyway, I also like you thought about a power steering pump but the psi just wasn't enough if I recall and there is no way those v belts could have driven it back in the day.
As far as the Merctrans go, I haven't played with mine much but also haven't had too either. Its been pretty reliable but I like you have heard of the electric shift between gears stories and cooling woes. Mine now has a stroked BBC in front of it with an honest 500hp pushing a 10klb '82 Sea Ray 255 Amberjack. With a full load I have never felt anything slip yet going to WOT to get on plane. I went through the trans when I redid the the stock 454 to stroke it up and replaced all the seals in the clutches and outside seals. I did not touch the sunshaft seals as they were the preferred Teflon gapless seals and usually never need replacing. I will also say that I have yet to do any long range cruising and really build up a lot of heat in the trans. The lower is a TR with a 15" "ceiling fan" prop. I know I'm loosing about 10mph on top end easily with that TR lower but I'm not really concerned with going over 40mph anyway on that boat, its just for cruising to the islands for RnR.
If I had to fashion a cooling system it would an electric pump through an external automotive type cooler w/ built in fan and definitely a temp gauge. Hope that helps, if you have any other questions post it here or... BL at BLmicro
-BL
Last edited by B.Leonard; 09-20-2022 at 08:34 PM.
09-24-2022, 05:48 PM
#3
Registered
Thread Starter
B.Leonard,
Thank you for the detailed info. Sounds like you really got after that FMX to get the most out of it.
Glad to hear you're not having any issues with the 500hp BBC powering through the Merctrans. 10k 255 is no joke for a single. The 15" TR prop likely isn't very forgiving and bites hard....a further testament.
Stock Merctrans pressures are around 115 psi ish?
I just read that the Type F ATF has zero friction modifiers in it. Perfect for this application. Therr is mention of Type FA as well....but need more investigation. I've heard it was a bridging ATF...and some versions may have fric modifiers in it. Others have reported good success and avoided rebuilds for using Type FA.
I suspect a good brand of Type F would be best...and change often. No need to go synthetic.
I'm planning on having a pressure and temp guage. As well as warning lights with audible alarms for over temp and pressure loss.
I was also considering the electric atf pump for fluid cooling. This would also increase volume. The one caveat is the elec motor in the bilge area, and Coast Guard approved etc. I also prefer not to add complication. Maybe fabricating an additional reservoir off the coolant cover. With a far more elaborate raw water cooling.
A failed elec pump would mean issues...but a failed raw water pump is just a rubber vane impeller change, spare on-board.
Haven't opened up my Merctrans yet. But I'll likely do a complete re-build. It only had the 280 HP SBC pushing it, with a 14p alum prop. Formula 233. Hoping the gears are in good shape.
Thank you for the detailed info. Sounds like you really got after that FMX to get the most out of it.
Glad to hear you're not having any issues with the 500hp BBC powering through the Merctrans. 10k 255 is no joke for a single. The 15" TR prop likely isn't very forgiving and bites hard....a further testament.
Stock Merctrans pressures are around 115 psi ish?
I just read that the Type F ATF has zero friction modifiers in it. Perfect for this application. Therr is mention of Type FA as well....but need more investigation. I've heard it was a bridging ATF...and some versions may have fric modifiers in it. Others have reported good success and avoided rebuilds for using Type FA.
I suspect a good brand of Type F would be best...and change often. No need to go synthetic.
I'm planning on having a pressure and temp guage. As well as warning lights with audible alarms for over temp and pressure loss.
I was also considering the electric atf pump for fluid cooling. This would also increase volume. The one caveat is the elec motor in the bilge area, and Coast Guard approved etc. I also prefer not to add complication. Maybe fabricating an additional reservoir off the coolant cover. With a far more elaborate raw water cooling.
A failed elec pump would mean issues...but a failed raw water pump is just a rubber vane impeller change, spare on-board.
Haven't opened up my Merctrans yet. But I'll likely do a complete re-build. It only had the 280 HP SBC pushing it, with a 14p alum prop. Formula 233. Hoping the gears are in good shape.
11-05-2022, 04:27 PM
#4
Registered
Hey guys,
nice to see that there is an actual thread about the merctrans and that the knowlegde about it does not die.
I refitted my whole 22ft boat and also have a merctrans II MCM-A in it powered by a 350 Chevy.
Do you guys know where to get the seals or a complete seal kit?
I think it would be nice to achieve something like a part catalogue. Also with other parts from other applications that can be used like from the FMX trans.
I have the problem that my trans is leaking and I don’t know where. I just pulled the cooler and tried to seal it with selfmade gaskets. I assume that it leaks there.
Is this a critical spot where I should use only the original gasket? The whole transmission runs empty when I let the engine run for 5 minutes without going into gear.
Maybe you have an idea.
Thank you in advance!
nice to see that there is an actual thread about the merctrans and that the knowlegde about it does not die.
I refitted my whole 22ft boat and also have a merctrans II MCM-A in it powered by a 350 Chevy.
Do you guys know where to get the seals or a complete seal kit?
I think it would be nice to achieve something like a part catalogue. Also with other parts from other applications that can be used like from the FMX trans.
I have the problem that my trans is leaking and I don’t know where. I just pulled the cooler and tried to seal it with selfmade gaskets. I assume that it leaks there.
Is this a critical spot where I should use only the original gasket? The whole transmission runs empty when I let the engine run for 5 minutes without going into gear.
Maybe you have an idea.
Thank you in advance!
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The following users liked this post:
Bennerich (11-07-2022)
