Transom ideas .
02-27-2022, 10:50 AM
#71
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Thread Starter
Well that changes things , you do have #6 boxes. So yes the switch would be pretty easy , I`ll see if Jeff has a number 6 drawing .
02-28-2022, 07:41 PM
#73
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Right, I get that Dan. I would have the option of welding up my boxes bolt pattern, and re-drilling it to match the #6 bolt pattern transom assembly.
Do you have the #6 pattern just like the #5 pattern you just posted? That would tell me how much modification would be needed. I have "#6" boxes but drilled for a #5 drive (or enough real estate to land the #6 drive and bolt it up). It may not be as bad of a switchover as I originally thought. Running drivelines and drive shafts now. I saw the prop shaft to drive shaft input dimension is within a 1/16" from a 5 to a 6. That makes the install pretty simple for me, just re-drill a pattern (and all the hydraulics. But all of that runs through the box for me right now anyways, so no real transom work needed.)
Unsure if my transom could handle the forces though. It was built pretty stout as-is with the #5s on boxes setup. What's minimum reinforcement, transom thickness, or any bracing required for the #6 setup?
Do you have the #6 pattern just like the #5 pattern you just posted? That would tell me how much modification would be needed. I have "#6" boxes but drilled for a #5 drive (or enough real estate to land the #6 drive and bolt it up). It may not be as bad of a switchover as I originally thought. Running drivelines and drive shafts now. I saw the prop shaft to drive shaft input dimension is within a 1/16" from a 5 to a 6. That makes the install pretty simple for me, just re-drill a pattern (and all the hydraulics. But all of that runs through the box for me right now anyways, so no real transom work needed.)
Unsure if my transom could handle the forces though. It was built pretty stout as-is with the #5s on boxes setup. What's minimum reinforcement, transom thickness, or any bracing required for the #6 setup?
03-02-2022, 04:06 PM
#74
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Looks like your transom is already drilled for a #6 gimbal assembly, you would just have to drill the same pattern on the outside flange to bolt the #6 where the #5 is currently. As Dan said you will pick up some more length with the #6 vs the 5 you mighty want to space the whole assembly higher on the transom -- easier to space the lower down. Is there room on the boxes to drill another pattern 1" or even 2" higher?
03-03-2022, 11:22 AM
#75
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Yes it is, I have #6 inner transom dry sump plates.
I can do the conversion pretty easy, I think just a modified driveshaft and bolt everything up. Figuring out whether to keep the boxes or not, all this is hard to do without parts in my hands. I can go up 1" with the boxes, or bolt #6s to the transom. Drives are already mounted pretty high as-is. I think it would be setup pretty good if I bolt up to the boxes.
I can do the conversion pretty easy, I think just a modified driveshaft and bolt everything up. Figuring out whether to keep the boxes or not, all this is hard to do without parts in my hands. I can go up 1" with the boxes, or bolt #6s to the transom. Drives are already mounted pretty high as-is. I think it would be setup pretty good if I bolt up to the boxes.
03-03-2022, 11:27 AM
#76
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you will probably lose a bit of speed with the #6 compared to the #5, depends if you are concerned about the 5's holding up... I've heard of 900hp going through them -- but everything can and will break sooner or later...
03-03-2022, 01:03 PM
#77
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Thread Starter
Biggest advantage for me was getting on plane easier , more neutral trim and the large cavitation plate gets it on plane easier.
If you don`t use the boxes you will have to move the engines more than likely .
The box makes things way easier .You can use a driveshaft to connect to transmission.
03-03-2022, 02:34 PM
#79
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I`ve heard the opposite, kirk said he picked up 11mph when they switched from 5`s to 6s .
Biggest advantage for me was getting on plane easier , more neutral trim and the large cavitation plate gets it on plane easier.
If you don`t use the boxes you will have to move the engines more than likely .
The box makes things way easier .You can use a driveshaft to connect to transmission.
Biggest advantage for me was getting on plane easier , more neutral trim and the large cavitation plate gets it on plane easier.
If you don`t use the boxes you will have to move the engines more than likely .
The box makes things way easier .You can use a driveshaft to connect to transmission.
03-03-2022, 02:50 PM
#80
Charter Member #40
Charter Member
Back in 2012 or so, I went to change from 5"s on boxes and was planning on doing 6's on my 39 Sutphen. Richey Sutphen (RIP) talked me out of it based on expected loss of performance due to drive weight, footprint of gearcase and corresponding drag in water and parasitic hp loss due to internals. I am guessing we were thinking wet sumps. I am guessing he was basing his opinions on boats he had built with both. ??
