lower units

[425Ronald]

Can anyone help me out. I have installed an XR6 150 EFI powerhead on my XR4 150. I bought this project in pieces and am not absolutley sure of the years,I think the xr4 is a 1990 and the xr6 is a 94. Now, my problem is that the lower unit shafts are slightly different in spline size at the engine end and Ineed a new lower unit and don't know what exactly to order. Where do I find the part or casting numbers. does anyone know what units will fit.

 

[425Ronald]

Re: lower units

Sorry I made a mistake in my earlier post. On the engine end of the shaft the splines are the same but there is a pin sticking out and the other one doesn't have this. Is this a centering pin?

 

[Ken G]

Re: lower units

That is a pre-load pin. I have no idea what it does but I do know that it affects how you check the backlash in the LU gears. The presence of the pin determines if you push down or pull up on the driveshaft when you check the backlash.<br /><br />Obviously I can't say what will happen if you remove the pin if everything else fits. Hopefully someone else knows.

 

[achris]

Re: lower units

Right, the pre-load pin is specifically for the style of gearbox, nothing to do with the power head. <br /><br />The one with the pin is earlier. The top bearing on the driveshaft, in the gearbox, is fitted in such a way that it requires the drive shaft to be constantly pushed down, hence the spring loaded pin.<br /><br />In the box without the pin in the driveshaft, the bearing is installed the other way round and requires the driveshaft to be pushed up, this is done by the gears in the box as they come under load. They try to seperate, hence the shaft tries to go up.<br /><br />Hope this helps a bit,<br /><br />Chris.............

 

[425Ronald]

Re: lower units

Thanks guys that helps alot. Now are there some part numbers or casting numbers on the housings hidden somewhere so Ican find out exactly what I have. thanks agian Ron