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Supra Restoration Fore/Aft Engine Placemant


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I am doing a floor/stringer restoration on an 87 Supra TS6M Comp.


It is time to drill motor mount holes reinstall engine/trans. YEA!!!!!!!

How critical is the fore/aft engine placement. By looking at the propshaft/cutlass bearing wear I can get the engine within 1/4" with no problem. Is that close enough??????


Edited by RickRSupra
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Here are a few items to consider:

- the fore aft position will slightly alter the shaft angle relative to the fixed attachment in the shaft strut. There could be slight bearing wear due to that (or you could have just set the engine closer to the true position depending on tolerance variation at the factory). You might try to obtain the dimension and tolerance from somebody at Supra to see how close and critical that dimension actually is.

- I would assemble w/o drilling the holes and check the system out, particularly spinning the prop by hand in both positions (current and as dissasembled) and see if there is any additional rotational drag.

- the fore aft position will also slightly affect the prop distance to the rudder, should not be a big problem assuming no issues with that model of boat. That would have to do with the hydrodynamics of the prop to rudder distance. That you won't know until the first (hopefully extremely enjoyable) first ride.

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One of my buddies had a 1986 TS6M. He had the same problems that you are fixing. The water leaks in around the exhaust traps on the transom and soaks the foam. The foam stays wet and never dries so that is what rots the stringers. The Supra plant rebuilt his during the winter while their business was slow. They pulled the cap off of the boat, removed the floor and foam, and replaced or rebuilt the stringers. They did not foam around the exhaust. Actually they built a wall around the exhaust and built drains so that any water that leaked in the traps would drain to the bilge. If you want more information I can put you in touch with my buddy and he could give you better details.

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The angle relative to the propshaft will be the same after alignment. I have plenty of adjustment available on the mounts, I did not think about the prop/rudder gap affecting prop wash on the rudder. I think I can get within 1/8" and the minimum prop/rudder gap is >3" so I would not expect a handleing problem. Supra has the rudder offset from the centerline of the keel?????? I do not know if all skiboats are llike that? The TS6M has a history of snapping propshafts while doing spin turns.


Thanks for the offer (of contacting your buddy) but the hull is already done :) The "Supertraps" did leak but the entire floor was gone and much of the srtngers so I restored all. I wanted the Supra to be wisper quiet. To do this I installed 3' under deck ski boat mufflers (with fabricated mounts) and reinstalled the "Supertraps" with large amounts of 5200. I also made numerous, large drain holes and did not refoam. We'll see how that works out. Have your buddy check out the thread, It's been a BIG project.


Edited by RickRSupra
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