Hurth HBW 150 on a M25XPB

[brober29]

My HBW 50 is shot and I just found a good deal on a rebuilt HBW 150. Is there any reason an HBW 150 couldn't be used on a M25XPB? I was planning on going with an HBW 100 (ZF 10) but the 150 is a good price.

[brober29]

I should also mention that I am replacing the shaft so shortening the shaft will not be an issue. I know the HBW 150 protrudes back another 1.5" or so. Other than that, there looks to be plenty of room to accommodate to larger gear box. Just wondering what other implications there may be using this gear box with the M25XPB.

[Ron Hill]

brob : If the Hurth 150 will mate with the M25XPB there should be no problem, but check with Westerbeke's Joe Joyce (508)823-7677 to be sure.

You need to not only look at the bolting-on to the bell housing, but more importantly will the splines mate to the damper plate inside the bell housing???  
I'm sure that you can make the shifter connections work, but those splines are a show stopper!!

Check number groves on the splines!!  A thought

[brober29]

Thanks Ron. I did make sure the input shaft was 10 spline. I'm thinking I can just pull the bell house off the old box and bolt it onto the new box.

[Ron Hill]

brob: The bell housing on the M25xpAengine had the transmission bolted to it form the INSIDE.  On all of the M25xpB that I've seen has the transmission bolted into the threaded holes on the bell housing, thru an adapter plate and held on with bolts from the outside.

My drawings show that the HBW 150 might have a differant adapter plate than your old HBW 50 !??!  I don't know, but it's something you might want to check !!  Those cap screws that holds the transmission on to the adapter plate are a special cap screw so don't replace them with just any substitute look-a-like.  

Also make sure you use Locktite and any bolts/nut threads that are inside the bell housing - as you sure don't want anything backing out inside with the fly wheel and damper whirling about!!
A few extre thoughts