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View Full Version : Gimbal Ring Wear - How Bad?



Knot 4 Me
03-23-2009, 10:36 AM
Have a friend with a '96 303 SR-1 Formula with 7.4L's/Bravos. Boat has between 400 - 500 hours on it total. Motors were pulled a couple of years ago and built up to 465 HP by Baker Eng. At that time, Imco hydraulic steering was added. We pulled both drives yesterday to service them. While the drives were off the boat, I grabbed both bell housings and moved them both vertically and horizontally to see how much play was in the gimbal ring. On the starboard side, I could move the bell housing up and down quite a bit and you could hear it clunk. There was also slop in the side hinge pins where you could make them clunk. On the port side, I could not really move the housing up and down and there was just a little bit of movement in the hinge pins.

My question is two part. First, was my grabbing the bellhousing with the drive off and moving it around an OK method of checking the health of the gimbal ring. Second, how bad off does the starboard side sound? I did not attempt to mess with tightening the nuts on the u-bolt to see if it took some of the play out for fear of snapping the u-bolt. My friend asked how bad the starboard side was and my feeling is there is too much play but I wanted to get some expert opinions. Thanks.

MOBILEMERCMAN
03-23-2009, 12:37 PM
First the up and down is set by the nut on the upper swivel shaft inside the boat. Usually when the distance increases and the ring falls it is from corrosion on the ring. Generally you need to remove the assy or cut the access holes to tighten. The clearance is something like .025. Maybe less I would have to look it up.

Second the hinge pins should have no play. Slight side to side parallel to pins only. None in and or out up or down.

The u -bolt torque is light at 23-25 lbs. That wont fix it.

When the ring settles it tends to mis align the cross bearings and adds a side load to the gimble and input bearings. When the hinge pins wobble loose a bell housing { the part the drive boats to } failure is immanent. I am sure you have heard the stories of drives breaking off and hanging by cables.
I would be most concerned about the hinge pins.

If your transom assemblies need major repair buying new assemblies are worth considering. They show up priced right from time to time

Knot 4 Me
03-23-2009, 02:14 PM
Thanks for the reply, Jim. Yeah, I figured the swivel shaft nut is what set the up and down play. I didn't know if maybe the nut was loose, the washers have worn (13, 15 in the diagram), or if the housing itself has worn and that is where the extra play is coming from. You could really see the bellhousing move up and down when I pushed on it. Seemed way to loose to me. As for the hinge pins, yes I could move them side to side parallel but I could also feel up/down and in/out movement in them. If there should be zero movement in them, then you have answered my question that there is too much play. The scenario you describe above with the drive breaking off is what has me concerned. You mention input bearing load. I assume you are referring to the driveshaft input bearing?

Thanks for your help. I will recommend he has the starboard side addressed immediately. If the assemblies are in good shape, can the bushings be replaced to remove the play in the hinge pins?

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=880951%2000&ivar=images/COMMON/30828.png&inbr=5398&bnbr=70&bdesc=GIMBAL+RING+AND+STEERING+LEVER

MOBILEMERCMAN
03-23-2009, 02:45 PM
The bushings can be changed, but I have found the threads in the bellhousing are often the worn part. There are a few different bellhousing out there. The early with threaded hinge pins, the late with threaded pins and a inset Stainless washer, and the HP pins. The early the threads wobble and junk the bellhousing. Don't bother trying heli coils. Make sure you get the bellhousing with the washers. The second seems to hold up pretty well. The if the threads are good and the bushing whole is not egg shaped you can re bush with success.

On the gimble ring settling. I have found the ring erodes the swivel is steal and the ring is aluminum. .. I recently did a dropped ring. After drilling the access holes I was able to replace the upper swivel shaft and bushings and reuse the ring. I replaced the shaft because the seal surface was pitted and would not make a good seal surface and the seal was gone. If the ring and the bellhousing need replacement by chance a complete assembly may be better spent money.

MOBILEMERCMAN
03-23-2009, 02:53 PM
This pic shows the late bellhousing with washer

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=891748001&ivar=images/COMMON/5476.png&inbr=11296&bnbr=90&bdesc=Bell+Housing

Knot 4 Me
03-23-2009, 03:00 PM
Thanks so much, Jim. I do want to double check the amount of hinge pin play. Can this be done with the drive on? Can I just grab the drive and start moving it around checking for play or will the tie bar and steering rams give too much resistance? Should the bar and the rams be removed first and then move the drive to check for play?

MOBILEMERCMAN
03-23-2009, 03:02 PM
You can check it assembled . You just need to use more muscle. Take the pin covers off to see if it wobbles or moves in the bushing.

Knot 4 Me
03-23-2009, 03:59 PM
Will do. Thanks again! By the way, the serial numbers are:

O.D. 0F814903 0F814906
TRN. 0F860644 0F860646

Blue Thunder
03-23-2009, 07:29 PM
First the up and down is set by the nut on the upper swivel shaft inside the boat. Usually when the distance increases and the ring falls it is from corrosion on the ring. Generally you need to remove the assy or cut the access holes to tighten. The clearance is something like .025. Maybe less I would have to look it up.




.002-.010 on the gimble clearance setting.

I'm pretty sure the u-bolts are 50-55 ft-lbs not the 23 mentioned.

MOBILEMERCMAN
03-23-2009, 10:55 PM
You are likely correct on the gimble clearance. I haven't taken the time to look . I thought it might be less. But I can assure you that cheap metal 3/8 u-bolt won't take 50 lbs. It was misprinted in the manual in the past. I have broken one before. No fun doing the ring install twice.

Sorry, I did not edit your post. I hit edit on my screen by accident.

Blue Thunder
03-24-2009, 05:29 PM
I have always torqued them to 50. I just rebuilt two and they are at 50. Never a problem. The standard toque spec on a 3/8"-16 bolt, grade 5 is 35-40 so 50 does seem rather high unless it is a grade 8 strength. Then it would be close at 50-55. BTW, that is still the merc spec. I'll post it up.

Blue Thunder
03-24-2009, 05:32 PM
Here you go..... ft-lbs and newton meters. Ubolts are 53ft-lbs. Maybe this spec is for new ubolts only or ones with no material loss due to corrosion.


Torque Specifications
DESCRIPTION lb-in. lb-ft Nm
Shift Cable Core Wire Anchor Screws 20 2.3
Hose Clamps 35 4
Trim Wire Clamp 95 11
Hinge Pins 150 203
Bell Housing Studs
Steering Arm Nut
50 68
Rear Engine Mounting Bolt 37 50
U-Bolt Nuts 53 72
Transom Stud Locknut 25 34
Pivot Bolt
Sterndrive Attaching Nut
23 30

MOBILEMERCMAN
03-24-2009, 07:48 PM
Dave,
I know what the manual says. You are quoting it correctly. I have been round and round with this before. At some point you will break one.

Blue Thunder
03-25-2009, 12:56 PM
No I won't because I won't go that high any more. I would recommend if you are only torquing them to 20ft-lbs you loctite the threads or use nylon inserts. You won't have enoungh fastener stretch at that torque for them to stay tight on thier own.

Thanks for the warning. :) I can imagine the aggrevation created if one of these snaps on a installed asembly :(

How you know my name?

MOBILEMERCMAN
03-25-2009, 01:02 PM
No I won't because I won't go that high any more. I would recommend if you are only torquing them to 20ft-lbs you loctite the threads or use nylon inserts. You won't have enoungh fastener stretch at that torque for them to stay tight on thier own.

Thanks for the warning. :) I can imagine the aggrevation created if one of these snaps on a installed asembly :(

How you know my name?

Dave,
I put red loctite on everything. If you contact Mercury they will likely recommend 23-25 lbs. It is the only mistake in their manuals I am aware of in over 25 years.

I checked your profile.

We appreciate your input. Thanks

Knot 4 Me
03-25-2009, 01:51 PM
I didn't mess with the nuts on the u-bolt due to the age of the boat and knowing it really wouldn't solve anything but could create a big problem. I would think those nuts really shouldn't be messed with after initial assembly. Anyway, thanks to everyone for their help. The boat goes into the shop at the end of the week to have our friend who is a certified Merc tech take a look at it and if need be, pull the motor(s) and replace what is necessary.

MOBILEMERCMAN
03-25-2009, 05:07 PM
There are two ways to attend to it. You can service it with out pulling motors.

Blue Thunder
03-25-2009, 06:32 PM
Dave,
I put red loctite on everything. If you contact Mercury they will likely recommend 23-25 lbs. It is the only mistake in their manuals I am aware of in over 25 years.

I checked your profile.

We appreciate your input. Thanks

Ok, Jim. Thanks for the poop on the ubolts. I still wonder why yours fail and will consider that further. My guess is corrosion or unequal/improper torquing. The surface prep of the torque surface and lube applied to the threads (or lack of) makes a world of difference in actual torque values Where do they snap? At the threads?

MOBILEMERCMAN
03-25-2009, 07:20 PM
It has a number of years ago. it broke at the threads. It was not brand new but looked good. It is just stainless. A friend of mine broke one too. The Race boat I used to run had broke on at one point. It had the lower number torque value etched on near the nuts to ensure no one broke another one.

Blue Thunder
03-25-2009, 08:04 PM
It has a number of years ago. it broke at the threads. It was not brand new but looked good. It is just stainless. A friend of mine broke one too. The Race boat I used to run had broke on at one point. It had the lower number torque value etched on near the nuts to ensure no one broke another one.

Good info, thanks.

MERPerformance
03-25-2009, 08:46 PM
Why don't you just pull both engines ,remove the gimbal assy,rebuild with HP style kits from Merc cost $1175.00 retail $1600.00, sounds like you have a problem thats going to return over time. I perform this all the time

MOBILEMERCMAN
03-25-2009, 10:01 PM
There were some complete new assemblies offered out around $2300 not too long ago.

ROGUE
03-25-2009, 10:11 PM
Oh boy, this sounds all too familiar. The fact is, merc screwed up by not making the torque requirement a standard maintenance item, my 11 manual (1989) says 45 lb/ft. The merc shops all claim ignorance.

ROGUE
03-25-2009, 10:20 PM
And, wanting to sell you lots of new parts at high dollars. There are good people around who sell gimbal repairs, good shafts and good u-bolts because of this Merc ignored problem.

Knot 4 Me
03-26-2009, 08:22 AM
There are two ways to attend to it. You can service it with out pulling motors.Correct, but it is not my boat and the owner prefers the motors be pulled to perform the work if necessary. To be honest, if it was my boat I would pull the motors too. I'm not a fan of cutting access holes that could eventually leak.

Knot 4 Me
03-26-2009, 08:24 AM
Why don't you just pull both engines ,remove the gimbal assy,rebuild with HP style kits from Merc cost $1175.00 retail $1600.00, sounds like you have a problem thats going to return over time. I perform this all the timeI will recommend the HP kits to the owner. I agree, beef it up now and hopefully be done with it for a long time. At the end of the day, it will be his decision on what he wants to spend. He is not cheap so my guess is he will throw the best at it if a repair is indeed needed. Thanks!

Revd Up
03-29-2009, 11:54 PM
Dave,
I know what the manual says. You are quoting it correctly. I have been round and round with this before. At some point you will break one.

I usually torque my u-bolt to 53lbs about once a year. Should I loosen it up a little? Going to have to make that correction in my manual.
Glad to see this post before I broke it.
Thanks

MERPerformance
03-30-2009, 07:58 PM
I keep hearing you guys talk about the U-bolts, if you have to keep them tight, I would guess to say; maybe you have a problem with the steering you are using such as stock and the conditions you are running or power you have. The pin and arm have such a load on them that they are over stressed. To solve this problem, I would at least add and external ram, meaning a 1/2 system instead of a full hyd.

MOBILEMERCMAN
03-30-2009, 09:19 PM
The gimble ring settles on the upper swivel even with hydraulic steering. Tightening the u bolt has no effect on that after the pieces are worn or corroded in my experience.

The u bolt needs to be tight when assembled and as part of maintenance. But they are not intended to be used to tighten worn parts. IMO

Revd Up
03-30-2009, 10:42 PM
I have full hydraulic steering. I only torqued mine because I saw it in the manual. Usually check it when I pull my drive to check alignment and doing yearly maintenance. Think I might loosen mine a little now that I know its too tight.

Ryan8886
03-31-2009, 07:07 AM
I will recommend the HP kits to the owner. I agree, beef it up now and hopefully be done with it for a long time. At the end of the day, it will be his decision on what he wants to spend. He is not cheap so my guess is he will throw the best at it if a repair is indeed needed. Thanks!

Hey Knot! I don't beleive in going cheap either....but HP rings seem to be a lot of overkill for 7.4L's. Unless he likes spending cash for the fun of it, why not just replace with standard Merc rings? Unless he's planning to yank those motors and replace with big horsepower, they should last another dozen years just like the first set and cost less. Even tweaked, you can't pull much more than 400 hp out of the old 330's.

txriverrat2001
03-31-2009, 08:15 AM
The gimble ring settles on the upper swivel even with hydraulic steering. Tightening the u bolt has no effect on that after the pieces are worn or corroded in my experience.

The u bolt needs to be tight when assembled and as part of maintenance. But they are not intended to be used to tighten worn parts. IMO

I agree - I've never seen an improvement by tightening the U-bolt.

Check with Victory and see if they have some non current assemblies laying around. You'll probably just need to update the fitting for the oil resevoir as the new one just clip on vs. clamp on.

It's a much safer and easier option if the funds are right.

Knot 4 Me
03-31-2009, 08:45 AM
Hey Knot! I don't beleive in going cheap either....but HP rings seem to be a lot of overkill for 7.4L's. Unless he likes spending cash for the fun of it, why not just replace with standard Merc rings? Unless he's planning to yank those motors and replace with big horsepower, they should last another dozen years just like the first set and cost less. Even tweaked, you can't pull much more than 400 hp out of the old 330's.The stock 7.4L's were re-worked by Baker and dyno'd at 465 HP. Brodix II aluminum heads, a healthy Crane roller cam, Merlin single plan intake, Nickerson modified 850 Holley's, CMI E-Tops, MSD ignition, etc. Eventually all those top end goodies will be placed on a 502 or 540 short block. So, I don't believe the HP rings are overkill.

Ryan8886
03-31-2009, 09:02 PM
The stock 7.4L's were re-worked by Baker and dyno'd at 465 HP. Brodix II aluminum heads, a healthy Crane roller cam, Merlin single plan intake, Nickerson modified 850 Holley's, CMI E-Tops, MSD ignition, etc. Eventually all those top end goodies will be placed on a 502 or 540 short block. So, I don't believe the HP rings are overkill.

Ahhhhhh....in that case, I'd have to agree. That's interesting too....all anyone has ever told me was that the 7.4's aren't worth hopping up. Glad he's had some fun with them!!

Knot 4 Me
04-01-2009, 08:38 AM
Ahhhhhh....in that case, I'd have to agree. That's interesting too....all anyone has ever told me was that the 7.4's aren't worth hopping up. Glad he's had some fun with them!!I personally wouldn't have put all those goodies on the stock 7.4 cast internal short blocks but he has put 80 trouble free hours on them to date. Boat is propped to top out at 5,000 - 5,100 RPM and he doesn't stay in the throttles for long periods of time. He knows the bottom ends won't last forever and is planning to upgrade the short blocks in a year or so. The cam and heads will make more power if he has them on a motor he can spin to 5,400 RPM. He is leaving HP on the table only turning 5,000 RPM but knows the 7.4's would be short for this world at 5,400 RPM.

MERPerformance
04-01-2009, 09:10 PM
About 6yrs ago, we upgraded two 7.4 MPI 28 or 29 Baja. The owner was a true Merc owner no H.P. stuff for him! Well about 1 1/2 yrs of new ownership he started to have a piston rapping noise, tore them down and found the pistons pins getting tight, the pins were tappered wall and not round. Also found the cam was just a stock 330 hp cam not the 385hp he paid for. Called the area Merc rep. found out that sometimes the engines going down the line don't always get the up-graded cam if they run short, thats what I was told. Passed that one to the customer, along with out-a-warrenty. Well those engines were built back with Eagle rods, CP pistons, Canfield heads, different cam, new lifters, ECMs re-mapped, they made right at 490hp haven't touched them in 6yrs except for drive repair. The owner is an X US Air pilot, so he keeps up on maint. He likes H.P. now. The foundation of the block and crank, and MPI worked fine with some change of major parts.

Thunderstruck
04-01-2009, 10:28 PM
The gimbals can be rebuilt for a fraction of the cost of even used stuff and a heck of a lot less work than pulling the motors and transom assemblies. Look at www.jrmarine.com and call Ron Bender. He can weld up and CNC the upper swivel area and the side pins. He has a stainless upper swivel shaft that is top notch and all the parts needed.

He has a kit that gives you a template to drill out the back of the transom assbly with special cut down wrenches to gain access to and remove the swivel shaft nut and the steering lever bolt. Much easier than the Merc kit and has a nice stainless plate to cover the hole. Ron is great to work with and is available by cell phone for questions/problems.

I refurbished both gimbal rings, new swivel shafts, gimbal and shift bellows, new shift cables, new steering levers all for <$2,000 for both sides.

PM me and we can discuss if desired.

Before the JR Marine rebuild:

http://www.youtube.com/watch?v=yEC9jtJ3KFg

Thunderstruck
04-01-2009, 10:35 PM
Pic of the hole in the transom assembly:

Thunderstruck
04-01-2009, 10:44 PM
Stainless plate to cover the hole with repaired gimbal ring.

MOBILEMERCMAN
04-01-2009, 10:54 PM
Thunderstruck,

I know many people are happy with that procedure. I would just like to say I prefer the Merc way. I feel better about the pipe plugs sealing and like the way it is not so obvious it has been repaired. I have done countless jobs over the years and have created a few special tools to turn the swivel lock nut.

I would choice the engine pull method on my personal boat. I know I am old school. I can't help it.

Thunderstruck
04-02-2009, 08:06 AM
Certainly gain access to the upper swivel pin nut and steering lever bolt by whatever means makes you comfortable. Just wanted knot 4 me to know that there is a method to refurbish the gimbal rings instead of replacement, depends on the budget. I also like the stainless upper swivel pin. Much more functional than the Merc one. Also, Bender's pin is $152, Merc's is ~$333 list or ~$300 online.

Thunderstruck
04-02-2009, 08:08 AM
Mercman,

Heard there are snow flurries in Austin today??

Knot 4 Me
04-02-2009, 08:37 AM
The gimbals can be rebuilt for a fraction of the cost of even used stuff and a heck of a lot less work than pulling the motors and transom assemblies. Look at www.jrmarine.com and call Ron Bender. He can weld up and CNC the upper swivel area and the side pins. He has a stainless upper swivel shaft that is top notch and all the parts needed.

He has a kit that gives you a template to drill out the back of the transom assbly with special cut down wrenches to gain access to and remove the swivel shaft nut and the steering lever bolt. Much easier than the Merc kit and has a nice stainless plate to cover the hole. Ron is great to work with and is available by cell phone for questions/problems.

I refurbished both gimbal rings, new swivel shafts, gimbal and shift bellows, new shift cables, new steering levers all for <$2,000 for both sides.

PM me and we can discuss if desired.

Before the JR Marine rebuild:

http://www.youtube.com/watch?v=yEC9jtJ3KFgThanks for the info, Thunder. I'm aware of this method for repair along with the Merc method with the threaded pipe plugs. The owner prefers to pull the motors as would I if it was my personal boat. Not saying one method is better than any other. Comes down to personal preference. I've been sending the owner links to the 540 short block ad that KEPP has been running. Heck, if you're going to pull the motors to make a gimbal ring repair might as well upgrade those bottom ends while you are at it!

Griswald
04-02-2009, 04:05 PM
Mercman,

Heard there are snow flurries in Austin today??


Nope..........just W Texas dust.


p.s. Jim repaired my boat last year the way he is describing. He worked so hard that I felt sorry for him and drank all his margaritas! :drool5:

Quinlan
04-05-2009, 09:51 AM
First the up and down is set by the nut on the upper swivel shaft inside the boat. Usually when the distance increases and the ring falls it is from corrosion on the ring. Generally you need to remove the assy or cut the access holes to tighten. The clearance is something like .025. Maybe less I would have to look it up.

Second the hinge pins should have no play. Slight side to side parallel to pins only. None in and or out up or down.

The u -bolt torque is light at 23-25 lbs. That wont fix it.

When the ring settles it tends to mis align the cross bearings and adds a side load to the gimble and input bearings. When the hinge pins wobble loose a bell housing { the part the drive boats to } failure is immanent. I am sure you have heard the stories of drives breaking off and hanging by cables.
I would be most concerned about the hinge pins.

If your transom assemblies need major repair buying new assemblies are worth considering. They show up priced right from time to time




I have serious play in the gimbles at the hinge pin and top shaft as you guys are discussing. Looks like gimbles are on the list but the question is how to tell if the transom assmblies need replaced also?

Boat in T/S gun w Stelling boxes, so I dont THINK in need to pull motors to replace these but what do you guys think? Any advice would be great.

Quinlan