Mercrusier Gimbal studs

[tank1949]

There seems to be some confusion concerning an earlier post: I cannot find any MC manual reference to the sealant used, Locktite, 5200, Permatex, etc., concerning the 8 7/16" studs used to secure the gimbal housing to a boats transom. I am rebuilding my transom and replacing many of the 8 7/16" bolts on the gimbal housing. Four of these bolts go all the way through the gimbal housing and their ends will be exposed to salt water on the front side near where the bell housing is located. MC manual indicated to use "Red" Locktite on the bell housing studs, but these studs bottom out inside aluminum. I cannot find any reference concerning the sealant used on these 8 bolts. Any suggestion? Attached is jpg. The four middle bolts pass all the way through. Help!

 

[harringtondav]

I'm guessing here. But all of this hardware is stainless steel, and, like the aluminum, is protected from corrosion by the numerous sacrificial anodes and continuity wires on the entire Stern Drive. Merc. also sells their "Mercathode" system for saltwater, using electrical charges to further counter the galvanic action.

The Loctite is for anchoring the studs in the gimbal hsg. And believe me, the red stuff will do it. It takes a very hot heat gun to remove them.

Again guessing, I think you'll be OK w/o any additional sealant. I just grabbed the Merc. Gen II installation manual that came w/my boat. This is for boat builders making the installation. Short instruction: pull through all hoses, cables and wires, install the external gasket and torque all fasteners to 20-25 ft. lb.

Also just pulled my #14 Gen II manual. The exploded assy. view shows just the studs and bolts, but no sealant or loctite flags as shown elsewhere.

Also, I believe all fasteners are inside that large gimbal hsg. - to - transom seal. It's designed to keep water out.

 

[tank1949]

I'm guessing here. But all of this hardware is stainless steel, and, like the aluminum, is protected from corrosion by the numerous sacrificial anodes and continuity wires on the entire Stern Drive. Merc. also sells their "Mercathode" system for saltwater, using electrical charges to further counter the galvanic action.

The Loctite is for anchoring the studs in the gimbal hsg. And believe me, the red stuff will do it. It takes a very hot heat gun to remove them.

Again guessing, I think you'll be OK w/o any additional sealant. I just grabbed the Merc. Gen II installation manual that came w/my boat. This is for boat builders making the installation. Short instruction: pull through all hoses, cables and wires, install the external gasket and torque all fasteners to 20-25 ft. lb.

Also just pulled my #14 Gen II manual. The exploded assy. view shows just the studs and bolts, but no sealant or loctite flags as shown elsewhere.

Also, I believe all fasteners are inside that large gimbal hsg. - to - transom seal. It's designed to keep water out.

Thanks for responding! Mercathode is a battery draining POS(my opinion). Better methods available...Former owner removed all traces of it. I have replaced all zincs. Removed studs are steel with some rust. A couple are badly rusted. No SS forund! There is some sort of finish on the remaining studs. My guess that they have been exposed to elements since 1995 (manufacture year of assemblies). My manual says 20-25 torque for the lock nuts but nothing, including sealant, for 7/16 gimbal studs inserted into aluminum. Hopefully, a lot of red loctite will hold and seal them from allowing water to come in. If I can access the other side, I will plug thread holes with 5200. Again, thanks for responding.

 

[harringtondav]

SS studs are available online. But if yours are rusty, water leaked inside that gimbal hsg. seal. Be sure to buy a new one before you install it. Several senior contributors add high test automotive sealants to this seal. Maybe one of them will advise.

 

[Bondo]

Ayuh,..... Ya better look again Dave,...... None of the studs are SSteel,.....

 

[harringtondav]

Bondo Aye Cap'n. My bad. I helped my bud clear his transom for rot repair. Since the Alpha II is all SS hardware, and my boat builder used 100% SS, including carpet staples - I assayouandme'd those studs. Medicare in Dec and I'm still learning.

 

[tank1949]

The side I pulled was the best side. I expect nightmares with the second transom assembly studs. THX to all!

 

[tank1949]

Bravo 1 Gimbal stud order

As I have described on earlier posts, I am rebuilding my transom and replacing any defective parts on my Bravo 1 Transom/gimbal assembly. 7/16"' studs were almost welded to old wood and aluminum housing. I couldn't use torch or I would have set my transom on fire. I had to double jam nut each of them. But, in my stress, I and forgot to mark where the 4.25" long went and where the 4.75" studs went. I assume the shorter four go on the bottom, but I hate to assume. If anyone can provide order, I would appreciate it. THX!

 

[Bondo]

As I have described on earlier posts, I am rebuilding my transom and

Ayuh,..... So lets keep the whole project in one project thread,.....

 

[tank1949]

Ayuh,..... So lets keep the whole project in one project thread,.....

Do u know stud pattern? Does Iboats sell 4.25" STUDS?

 

[achris]

Bondo Aye Cap'n. My bad. I helped my bud clear his transom for rot repair. Since the Alpha II is all SS hardware, and my boat builder used 100% SS, including carpet staples - I assayouandme'd those studs. Medicare in Dec and I'm still learning.

I've installed MANY Alpha One Gen IIs, and none have had SS mounting studs. A quick lick of paint over the outside exposed end, and keeping the anodes in good condition is all that's require to protect them...
As for sealing them as you install new zinc plated MILD STEEL studs, the manual doesn't call out any requirement, but if you REALLY need to seal them up, use Perfect Seal...

BTW, Do NOT use SS studs. They accelerate corrosion on the aluminum housing and the anodes, and are weaker than steel.

Chris.......

 

[AShipShow]

I just used blue loctite on mine... then I coated the exposed metal of the stud on the drive side with a few layers of paint for good measure...
make sure you put the correct length studs in the right spots.. I had to fix mine in the middle of the install.. I have my install video below if it's of any use.

 

[tank1949]

I just used blue loctite on mine... then I coated the exposed metal of the stud on the drive side with a few layers of paint for good measure...
make sure you put the correct length studs in the right spots.. I had to fix mine in the middle of the install.. I have my install video below if it's of any use.

Excellent video explaining the "pitfalls." I experienced similar while rebuilding an old Proline a couple of years back. I couldn't find information concerning short bolts either!!!!!

One thing that you didn't mention (or I didn't hear) was the importance of your rebuilt transom thickness and parallelism. It is important, or your inner transom plate (also rear motor mounts) after torqueing will be canted too much port or starboard.
The inner transom rebuild needs to be almost perfectly flat too or after torqueing lock nuts, gaps between inner plate and inner transom skin may cause metal fatigue later on.

If transom builders don't try to adhere to the previous transom's thicknesses, on V8s, front motor mounts may have to be relocated or adjusted forward or backward. Mercruiser provides some "wiggle-room" but not much. I don't know how critical this is for 4 cylinders.

Any imperfections between inner plate and transom can be minimized by applying thickened epoxy or poly onto transom where inner plate will be attached. Be sure to use a releasing agent on metal, or you will not be able to remove plate later on (especially if epoxy was used). Draw up the four inner lock nuts to squeeze out excess. Once cured, you will have a perfect fit. Imperfections can also be minimized by not overlapping fiberglass seems close to transom plate. I made this mistake too! Ok to over lap but not near plate area or you will have to do a lot of grinding to make thickness parallel.

The former owner of my boat must have run out of gimbal studs when he retrofitted Alpha drives with Bravo 1 drives. . He used (4) 4.25" and (4) 4.75" studs. I cannot find any 4.25" studs on the WWW. I suspect that I will have to buy 4.75" studs, shorten and re-thread.

If my memory serves me correctly, the (2) shorter studs are needed so that they don't bind against the y pipe? I don't know where the remaining (2) short studs go. I guess I will have to "trial and error" it.

Excellent video and lots of work!!!!! THX! You didn't mentioned how you cleaned up all the 5200? Lots of acetone...

 

[AShipShow]

Yup.. I didn't cover it in a video, but I checked all of the Merc specs on transom dimensions. I actually noticed that the inner transom had quite a dish to it from factory so I had to fill the low spot with thickened resin and basically "screed" it flat. Then I checked that the thickness was the same all around the keyhole to verify parallelism.

Suprisingly, I've seen quite a few examples on the resto forum where the factory transom was quite a bit out'o'whack.

As far as the studs, not sure if your still talking stainless, but I had no trouble sourcing the two different length studs. I just struggled to put them in the right spot, lol.

 

[Rick Stephens]

Mad, you 'n tank crack me up.