Help Finding Drive Shaft Centerline
 

I am trying to figure out a way to determine what my propshaft depth would be for new drives based on current engine height. My thought was if i knew the current TRS drive shaft centerline, i could then take measurements off this point for new drive. I cant find any TRS drawings with the measurements, so does anyone know what the drive shaft centerline measurement is in relation to the transom cutout? In pictures it looks like its about 4" or so from the top, or maybe in the center of the very top & bottom assembly bolts. But would like something more accurate than my eyeing of internet pics. Engines are out of boat & drives at shop. So the only reference point i have right now is the outline of the transom cutout.

I already know i will need to move the engines back, so now curious if i will need to change the engine mount height too.

TRS input shaft to prop shaft centerlines is about 24.5 inches.

What drives are you going with??

Right. But that in itself doesnt tell me where the input centerline is in relation to the drive cutout. If i knew all TRS Cafe's had propshaft at lets say 5.5" below hull, then yes i could measure up 24.5" to find input centerline, & then measure down again for the new drive length.

I just dont have any hull reference right now to know where to start my measurements. If that makes sense. lol.

Reason i am curious is i thought i was buying a pair of Konrad 540 PRS's as direct TRS replacements. What i received was a pair of ACE drives which are meant for Bravo replacements. I actually like the ACE package better since it has built in steering & extension boxes. And since i have a fresh transom without any cutouts, it wont take much more effort to use these drives. So i know i will need to move the engines back, & now just want to get an idea of the height change the engine will need.

A used pair of Konrad ACE's. They were delivered Mon & i only had time to move them into the shop. But from my initial viewing they look much more massive than my TRS- especially with those extension boxes. i will be back out at shop this weekend so thats why i wanted to try & get idea of my engine placement.

Are the new drives shorter than the TRS’s?.... with the boxes you’re going to want them higher than they were originally

I believe the regular lower is 1.7" shorter than TRS. I am pretty sure that's what is on them. Tomorrow I plan on getting the measurement to verify standard or shorty. Then the fun part of figuring out where my props should be, exhaust & transmission changes...

What you really need to find is what is the X dimension set at on the Cafe's with Bravos.
Then raise it another inch up for the ext boxes.
Then determine the difference in depth of the Konrad vs Bravo.

Does it have a notched transom ?

if not, you might try to get a hold of Carter and see if he has any info on the set up of this unit
as to where the prop shaft depth Is
https://www.offshoreonly.com/classif...35-o77771.html

https://cimg4.ibsrv.net/gimg/www.off...216265e5ea.png
https://cimg5.ibsrv.net/gimg/www.off...5443029a95.png
https://cimg6.ibsrv.net/gimg/www.off...f3d965898d.png
Originally from Full Force thread I believe.......I don't have a drawing from a TRS but the numbers seem to correlate from Image 1 to the SSM drawings as a visual aid

F.F. may have the actual drawing if you PM him

Found this on Konrads site

https://static1.squarespace.com/stat...+JULY+2016.pdf

it does show where the drive shaft center is in relation to the transom assy on page 15

Thanks for the help. If i would have known i was going to buy drives, i would have measured my TRS prop depth for a reference point before taking them off. But i still dont think these drives are going to cause me too much install grief (granted i said the same about replacing transom & stringers..)
I have been in contact with Kurt so once i send him some pics of the drives to verify the lowers, i think can then get recommendation of what depth to set the prop center & can be off & running again. Then i'll have questions regarding my Gil's & reversion if i take 9" or so off. :)

There is a lot of information already on this thread, and I don't want to muddy further, but crankshaft centerline is parallel to the hinge pin center location on gimbal-ring/transom-bellhousing. If you have or can locate a TRS gimbal simply measure the hinge pin location relative to mounts studs and then transfer to your TRS cutout stud location if still on hull. Hope this helps a little... Jason @InshoreOff

Are the exhaust holes already cut out??? If not, you could run the risers as is all the way through the transom.
Not sure what if anything you did to the engines as far as cams, but if stock cams, you won't have reversion issues with shorter risers.

Thanks JB. I didnt even think about gimbal/bellhousing. lol. those i do have.

So now i need to figure out what my xdimension should be with these drives. If my measurements are correct, i think this new drive is 18" from drive shaft to prop shaft. So i think these may be their x-factor shorty because a regular one is 22.5"

Griff- no the exhausts are not cutout. I was thinking i probably could too, just wanted to take it into account before i start going crazy with cutting holes. I was hoping i could cut off the 8 or so inches that we move the engines back, dam up the walls, & weld in a new water outlet bung & be good to go.

I also discovered my current Bravo props dont fit on the spline as is. The propshaft is larger on these drives.
https://cimg3.ibsrv.net/gimg/www.off...52c86e64a7.jpg
https://cimg2.ibsrv.net/gimg/www.off...d501e2e04c.jpg
https://cimg7.ibsrv.net/gimg/www.off...3ba8138798.jpg
https://cimg9.ibsrv.net/gimg/www.off...e5a5fb7087.jpg