Primary Input Shaft

[simpleur2]

I'm installing a new motor into my boat. It's a 1991 Volvo Penta 570A with a DP-A 290 outdrive.
I always overthink stuff, so while assembling the flywheel, flex plate and bell housing I decided to check to see how far the primary drive shaft (PDS) engaged the flex plate. It only in engauges is about three quarters of an inch, possibly a full inch pretty sure it's less. I replaced the bearings and seals on the PDS and think it would be impossible to install the primary shaft in the wrong position because the aft bearings position on the shaft is dictated by a snap ring, and then the bearing is driven into a seat in the housing, then the subsequent snap rings and seals go in place above that. If the PDS were in the wrong position none of the subsequent parts would fit along with the snap rings that hold them in place.

Is that normal to have such a minimal amount of spline engaugement on the shaft that links all of the engine power to the drive components ?

 

[Scott Danforth]

Yes

 

[simpleur2]

Yes

Simple answer , Your sure on that?? Scares me!

 

[Scott Danforth]

I'd you rebuilt the PDS correctly, you can put well over double the power your 5.7 is putting out

I now have a big block in front of my 1988 DP290 (technically a DPA1)

The weak link is the input shaft end in the gearbox in the input gear. NOT the 1-5/32 inch diameter 26 spline version plugged into the drive plate.

 

[simpleur2]

Simple answer , Your sure on that?? Scares me!

I also need to find the torque spec for the clamp ring that seats the two-giant o-rings on the bell housing and transom plate

 

[Scott Danforth]

I also need to find the torque spec for the clamp ring that seats the two-giant o-rings on the bell housing and transom plate

It's in the manual (you tighten until you seat the ring)

Get new o-rings (also in the manual)

 

[simpleur2]

I'd you rebuilt the PDS correctly, you can put well over double the power your 5.7 is putting out

I now have a big block in front of my 1988 DP290 (technically a DPA1)

The weak link is the input shaft end in the gearbox in the input gear. NOT the 1-5/32 inch diameter 26 spline version plugged into the drive plate.

View attachment 404341

 

[simpleur2]

Don't think I'm going to be putting a big block in soon, man that wrecked that shaft in the upper gearbox. Guess 3/4" engagement is enough !

 

[simpleur2]

The Volvo Penta dealer told me the manuals are no longer available, and they don't have them anymore either (could be BS). I have some used ones coming from ebay

 

[cyclops222]

That excellent large picture of the Splined Shaft appears to have major damage to it.
Ripped out section of the shaft above the tapered end of the splines.
Tapered end of splines are twisted out of shape.
If true ? A major jam up has occurred.

 

[Scott Danforth]

A major jam up has occurred.

Yep....Was on a buds boat I was following.
Sheared gear tooth came between the input gear and forward gearset in the transmission at WOT. Split the transmission. Instant 4800 RPM to 0. I could smell the gear oil from 300 ft away. He got a rebuilt drive for a bit over $10k.

I bought the carnage, a trans shield, new bearings and built it back up to my spare drive with a new to me rebuilt transmission and a pile of parts I sourced.