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View Full Version : TRS vs Bravo Dimensions



MDonziM
12-20-2010, 09:43 AM
Anyone know the exact height difference driveshaft to propshaft between the two? I know it's around 3" but I'm trying to figure out a swapout.

Thanks - Marshall

LKSD
12-21-2010, 08:50 AM
If my memory is correct on what I have measured in my shop over the years:

The Drives (my measurements based on memory) from the input shaft center to prop shaft centers:

Alpha aproximately 22.5"
Bravo aproximately 22.5"
TRS aproximately 24" to 24.5"
OMC Cobra aproximately 22.5"
Volvo penta 270/280 & SX aproximately 22.5"

Keep in mind that the X dimension mountings may be different boat to boat and drive model to drive model.

Jamie / Lakeside

MDonziM
12-21-2010, 09:29 AM
Thanks Jamie,

I found the bravo dimension from the merc website, 21 13/16".
The TRS appears to be about 24 1/4

MM

Conquistador_del_mar
12-25-2010, 01:23 AM
Thanks Jamie,

I found the bravo dimension from the merc website, 21 13/16".
The TRS appears to be about 24 1/4

MM

Marshall,
If you want, let me know if you want me to check those measurements. I have both a Bravo and a TRS sitting on stands right now. Bill

MDonziM
12-25-2010, 07:14 AM
Marshall,
If you want, let me know if you want me to check those measurements. I have both a Bravo and a TRS sitting on stands right now. Bill

Thanks Bill, Merry Christmas. My TRS's are at my mechanics' but he said he measured 24 1/4 drive shaft to propshaft, so the TRS is 2 3/8' deeper than the bravo. I'm probably safe raising the X that full amount, just not sure. Trying to figure out all the measurements for the best x-dim while hopefully leaving enough room under the hatch for small weiand blowers... stay tuned.

Marshall

Conquistador_del_mar
12-25-2010, 11:57 AM
Thanks Bill, Merry Christmas. My TRS's are at my mechanics' but he said he measured 24 1/4 drive shaft to propshaft, so the TRS is 2 3/8' deeper than the bravo. I'm probably safe raising the X that full amount, just not sure. Trying to figure out all the measurements for the best x-dim while hopefully leaving enough room under the hatch for small weiand blowers... stay tuned.

Marshall

Marshall,
That sounds like a cool project. Won't you have to build a new transom to accomodate the switch from TRS to Bravo even if you could leave the X at the same height (I realize you will be essentially raising it by the 2 3/8" by doing the change)? Certainly the cutout is not the same - correct? The sound of a blower winding up is hard to beat, and the 100+HP gain makes the effort worthwhile. Bill

MDonziM
12-25-2010, 02:10 PM
Yes the entire cutout will be filled with overlapping rectangular cores and reglassed. The bravo cutout is slightly smaller and bolt pattern different also. I'm hoping the motors will go from 420 to at least 550hp. I'll post up some pics in a few days. For now I just have engines out, drives off and most of the hardware removed. Suprisingly, everything so far has come out/off quite easily.

Peterjfinch
12-26-2010, 03:53 PM
Yes the entire cutout will be filled with overlapping rectangular cores and reglassed. The bravo cutout is slightly smaller and bolt pattern different also. I'm hoping the motors will go from 420 to at least 550hp. I'll post up some pics in a few days. For now I just have engines out, drives off and most of the hardware removed. Suprisingly, everything so far has come out/off quite easily.

Hi, Iīm not sure if this will make a difference to you but, as I am trying to work out the reverse calculations, I was under the impresion that the TRS sits further away from the transom (about 5 1/2 inches), changing the X. Please donīt hold me to this as I am also trying to find the answers.

Pete

MDonziM
12-27-2010, 06:08 PM
Hi, Iīm not sure if this will make a difference to you but, as I am trying to work out the reverse calculations, I was under the impresion that the TRS sits further away from the transom (about 5 1/2 inches), changing the X. Please donīt hold me to this as I am also trying to find the answers.

Pete

Not sure, haven't heard that one. We will be doing glasswork, prep and paint for 4-6 wks so I have some time to check into that.

mrfixxall
12-27-2010, 06:47 PM
or if you can find speed master # 2 lowers that may work for you.

heres a pic..http://www.offshoreonly.com/forums/drives-lower-units/195348-these-speedmaster-2s.html

Peterjfinch
12-28-2010, 12:02 PM
Not sure, haven't heard that one. We will be doing glasswork, prep and paint for 4-6 wks so I have some time to check into that.

All my measurements are from an Alpha 1, not a Bravo but I am told the measurements are similar to the Bravo. I have been advised to go up 1 inch, to take into account the extra setback of the TRS drives.

Hope this helps

Pete