Installing HP Transom Assemblies
 

Picked up some new HP transom assemblies...have a few questions:

1. Some people recommend 4200 when installing. Others install dry. What are people recommending?

2. What are the torque values on the studs inserted into the plate? What are the torque values of the nuts on the studs?

3. What are everyone's thoughts on glassing the cut out vs leaving it alone?

Thanks.

25 ft lbs and i would use a bead of 5200. also either smear quick dry 5200 over the cut out or paint with oil base paint to seal it up

use 4200,,if or when the seal on the steering shaft goes,your gonna want to be able to remove the transom assembly.5200 will be a royal pita to remove later on.

25ft lb on the stud into the plate or on the nut.

i just replaced a transom assembly on a omc king cobra last week.the studs just get screwed tight into the assembly,omc called for 22 lbs torque on the nuts in a circular pattern.i usually don,t use 5200 on anything that may need to be removed at some point.

I ran a light bead of 4200 just inside seal. Torque to 22-23ft lbs. kind of x pattern starting with inner 4 then outer 4. 5200 is permanent and will damage fiberglass if you need to remove again. I went with HD assys also.

yep,i have seen gel coat ripped off the boat with 5200 applied to transom assembly.

Nuts are 25 ft lbs - start with middle nuts with one pass of tightening in small lower torque moving to an X pattern for torqueing in 3 or 4 passes till 25 ft lbs is obtained on all 8 nuts. Do not tighten all at 25 ft lbs again in small X pattern passes obtaining 25 ft lbs.. Merc has the diagram of torque patterns in their service manuals..

The studs themselves are 15 ft lbs - into the bell housing

Are you talking about where the round rubber gasket goes? If so I would just use something to hold the gasket in place for assembly.

Installed a new HP transom assembly dry, still dry

If the cutouts are not already sealed, I would use penetrating epoxy on them. No need to glass.

Bob

On the fence on sealing up cutout and applying 4200 on transom assembly...will be tackling this project in a few weeks.

Assuming you mean the foam gasket, as long as the transom is flat you shouldn't need any sealer. A little bellow adhesive in the corners between the gasket and transom assembly to help keep the gasket in place is all you need.

I agree, if your transom is flat you don't need any sealer. When I redid my transom I installed my new transom assemblies dry, still dry!!

Below the waterline, possibility of rotting the transom if it leaks, tough to see if it does, I'll put a thin layer of sealer on it vs worry about it or even think about it.

The sealant for me was added peace of mind. I know it isn't necessary and many don't use it. A little extra sealing can't hurt.

I'm removing one now that was installed dry, gasket shrank up and now it leaks BAD

Guess there is a first time for everything but never heard of a gasket shrinking. Most time it starts to leak is when the transom gets soft.

Boat has 200 hours, been out of the water for 4 years. Transom is solid and flat

Gaskets and any rubber material for that matter shrink, dry out, crack and eventually leak over time. What is everyone using 4200? Or something else? Thanks for the insight.

As before and still current, never seen it happen. Have heard of it happening but have not seen anything which verifies. Not saying it doesn't happen, just no proof of it happening with a properly installed assembly. Its always an opinion, just like mine

No way you should ever use 5200 to put one one. You will need to cut it out with a saw! Even 4200 is going to be a pain. I would go with something less then that. All I am going to do is put some around the studs to keep water out of the transom. That is all Formula did when new. Even the 4200 that they put under my steering and transom assemblies ripped off some of the laminate not he back of the boat. Luckily it will be covered back up.

Installed assemblies last night. Everything went as expected with the exception of a small crack on the bottom of the inner plate. Crack didn't go all the way thru...cracked on the thin side of the plate. Probably gonna leave it but man those inner transom plates are cheap garbage. These were essentially brand new plates. Junk.

This isn't our plate but image of where it cracked..

https://i.imgur.com/V70OnVw.jpg

Put a wide washer on surface which has an angle, the washer will deform before the stud or bolt breaks. Install the same washer on a flat surface, the washer will stay flat until the stud or bolt breaks.

The plate doesn't need to be strong only flat. If the plate is installed on a flat surface, the plate would not crack. I would suggest removing the plate and use a straight edge and feeler gauges to see what the variations are. If this is not an option, remove the nut and use a feeler gauge behind the plate to see what the gap is, noting the plate has been cracked and will not rebound fully. might be able to get away with shim stock

Just my pinion

My new TA came from the factory with the gasket damaged so I added a bead of 4200. I would not have added anything if the gasket was ok but it was not.

ended up buying a new plate and shimming it. wasn't off much but it worked.