DP-SM not shifting easily OUT of gear

[st0n3]

With the engine running, shifting into forward and reverse works perfectly. The gears engage nice and smooth. However, when returning to neutral from either forward or reverse, the control handle sometimes needs to be wiggled back and forth for the gears to disengage.

Based on my diagnosis, it looks like the problem might be slop due to a worn shift link mechanism, but not sure.

What do you think?


Engine: Volvo Penta 8.1 Gi-F (2004-2005)
Transom: SX-MHP
Drive: DP-SM 1.78 (M22)

Gear oil:
The exact specification Volvo Penta brand synthetic gear oil (75W-90 API GL-5) is all that has ever been in this drive. Gear oil is changed each season before winterizing. Levels are correct.

Shift Cables:
The shift cables were replaced in 2017. When disconnected from the shift linkage mechanism on the drive, the cables move smoothly and easily. The travel from forward to reverse is 70 mm and, when in neutral, the travel is at 35 mm (centered). The cube nut is adjusted to be centered in the shift link mechanism when in neutral.

Shift Link Mechanism:
The shift link mechanism (number 13 in this diagram) has about 3 mm of slop travel when measured at the point where the cube nut attaches. This slop appears to be keeping the shift actuator from clicking into neutral from either direction. The shift actuator almost makes it to the centered position on neutral, but a nudge is necessary to click into place. The various rods and holes don't appear excessively worn, but each adds just a little bit to the overall slop. Is this normal?

So, what do you think? Replace the shift link mechanism or something else?


- Brad

 

[dypcdiver]

That is exactly as I adjust mine each year, however I always use a small paintbrush to apply water resistant grease to each of the joints in the mechanism and as a result I don't have as much slop.
I would be inclined to replace the shift linkages on the outdrive, Alternatively check that the throttle linkage is not also worn.
If you fancy a little bit of engineering remove the outdrive linkage and drill out and fit brass bushes to all the links.

 

[Horigan]

What I've done to minimize the slop is to install several washers in each of the link points to minimize the slop at each joint. You'll notice much of the slop is associated with lateral movement of the linkage, which the washers eliminate. I had to go this route since I could not remove the pin that the mechanism rotates about. Something to consider.

 

[st0n3]

Update:

I ordered and replaced all of the parts associated with the shift linkage:

• Link rod kit (bellcrank assembly)
• Link rod bar
• Associated washers and pins

Using a digital caliper, the new and old parts were measured. There was no discernible wear on the old parts, but all parts were replaced anyway.

There was no measurable change in the slop after reassembly.

Then, I tried Rich's suggestion in the previous post and put two 1/4" stainless washers on the linkage arm. I also followed dypcdiver's suggestion and added waterproof grease to all the moving parts on the linkage.

The slop was cut in half with the addition of the washers!


[IMG alt="Two 1/4" stainless steel washers added " type="full"]https://drive.google.com/uc?id=12rietsWP2PSNYsb4MfwKTiC2QOq-5ElZ[/IMG]

Unfortunately, reducing the slop did not improve the original problem as evidenced in an on-water test yesterday.

With the engine running, shifting into forward and reverse works perfectly. The gears engage nice and smooth. However, when returning to neutral from either forward or reverse, the control handle sometimes needs to be wiggled back and forth for the gears to disengage.

Next steps:

I think that the next thing to try is to re-shim the shift actuator housing. The instructions in the Volvo Penta DP-SM Service Manual seem pretty straight forward.

What do you think. Will this help solve the problem?

Any tips on the shimming process?

Is the Volvo shim bracket (sets position of arm) necessary?

I assume that this can be done without removing the lower drive assembly (as shown in the manual), correct?

 

[st0n3]

The plot thickens... Hopefully this write up will help others.

Today, we checked the shimming on the shift actuator housing. We even were able to track down the elusive Volvo bracket (3850057) to ensure that the arm is in the correct position.

The shift actuator bolt was removed with the six shims. Note that the shims are stainless steel and the shift actuator arm is brass. The last shim was stuck to the face of the arm, so if your face is silver instead of brass, you still have a shim to remove. By carefully using a razor blade, the last shim popped off.

You can see the back end of the shift shoe (dog) in the hole. There is nothing in the hole between the bolt and the shift shoe. Because the cone clutch is not round, the shift shoe moves in and out in this hole as the propeller shaft is turned. From what I understand, the back end of the shift shoe will tap against the shift actuator bolt when properly shimmed.

The propeller shaft was moved so that the shift shoe was in the maximum "out" position. The depth of the screw hole with no shims was measured using digital calipers. This measurement was more than the entire length of the shift actuator bolt.

Even with no shims, the shift shoe does not reach the shift actuator bolt!


Shift Actuator Housing Problem?
With the shift actuator arm in the shimming position, it can be pushed in quite a bit which then springs back out. Time to investigate whether the excess play is in the shift actuator housing.

With the shift actuator housing removed, excessive wear can be seen where the pin slides across the rear of the housing. There appear to be divots worn where the surface should be flat. These divots are at the location where the shift actuator arm would be during the shimming process. Thus, it appears that the arm is not pulled in far enough so that the shift shoe is not moving out far enough.

The shift shoe is also showing slight signs of wear. Probably need to replace the pin too. The seal is the original (2004) and will need to be replaced.

Volvo sells the entire shift actuator assembly that contains all of these parts (3855787) and is a four bolt replacement for the worn unit. It was ordered and should be here later this week.


I assume that after the new assembly is installed, the shift actuator screw shimming should be checked, correct?

 

[st0n3]

Problem solved!

The new shift actuator assembly (3855787) arrived. It came as a complete unit and included the o-ring, shift shoe stop screw and 8 shims.

Compare the new housing with the old to see the wear.

New:

Old:

The o-ring was lubricated with gear oil and the shift actuator housing assembly was replaced. Next, the shift shoe stop screw was shimmed.

The shift shoe stop screw was removed from the housing. The propeller shaft was rotated to the point where the shift shoe was the furthest out (least depth in the hole). Using digital calipers, the following measurement were taken and compared to the depth on the old housing:

New depth: 11.38 mm
Bolt length: 12.17 mm
Old depth: 12.30 mm

When trying to shim the old housing, even with zero shims the propeller shaft turned freely. The bolt wasn't long enough to reach the old depth.

The new depth is 1 mm shallower. Now, the propeller shaft can be stopped with the bolt in part way.

By carefully turning the bolt and rotating the propeller shaft, the bolt could be set at a position where the shaft can be rotated 360 degrees with a slight tap on the screw. At this point, the feeler gauge measured .026 inches of clearance.

One shim = .007 inch
Three shims = .022 inch
Feeler gauge = .026 inch
Four shims = .029 inch

The measurement fell between three shims and four shims. We chose four shims because 1) it was slightly closer to the feeler gauge measurement; and 2) we wanted to error on the side of more clearance rather that the more disastrous results of not having enough clearance.

The Volvo Penta DP-SM manual says to add an additional 3 shims for a total of 7 shims.

The threads of the shift shoe stop screw were coated with Permatex 80019 (substitute for Penta 1161099) and installed to 10-12 ft.lb (14-16 Nm) of torque.

After reconnecting the shift linkage, the boat was first tested in the driveway and then on the water. The boat now shifts perfectly!

A video of this process was made and uploaded to YouTube for others that may be interested in how we tracked down this problem, or how to shim the shift shoe stop screw.

Thanks to everyone for their help!

 

[crenche]

Love your write up on this. I'm having problem with my DP-SM drive shifting out of forward and reverse.
I changed out my clutch cone and lapped my cups because I was getting delayed forward shifting.
My problem is that it will shift fine in and out of forward and reverse on land with no problem. When I place in water then I cannot shift back to neutral.
I was noticing that the service bulletin states that the shift shoe needs to be a certain one. My question is the shift shoe is the proper shift shoe or do I need to update the shift shoe. My shift shoe I believe has a 3 stamped on it.

I'm having similar problem with the shifting screw is not touching the shift shoe even with all the shims removed.
The shift housing does not have divots in it like your old one did..
Any suggestions. I'm stumped and wanting to get out on the lake so bad.

Problem solved!

The new shift actuator assembly (3855787) arrived. It came as a complete unit and included the o-ring, shift shoe stop screw and 8 shims.

Compare the new housing with the old to see the wear.

New:

Old:

The o-ring was lubricated with gear oil and the shift actuator housing assembly was replaced. Next, the shift shoe stop screw was shimmed.

The shift shoe stop screw was removed from the housing. The propeller shaft was rotated to the point where the shift shoe was the furthest out (least depth in the hole). Using digital calipers, the following measurement were taken and compared to the depth on the old housing:

New depth: 11.38 mm
Bolt length: 12.17 mm
Old depth: 12.30 mm

When trying to shim the old housing, even with zero shims the propeller shaft turned freely. The bolt wasn't long enough to reach the old depth.

The new depth is 1 mm shallower. Now, the propeller shaft can be stopped with the bolt in part way.

By carefully turning the bolt and rotating the propeller shaft, the bolt could be set at a position where the shaft can be rotated 360 degrees with a slight tap on the screw. At this point, the feeler gauge measured .026 inches of clearance.

One shim = .007 inch
Three shims = .022 inch
Feeler gauge = .026 inch
Four shims = .029 inch

The measurement fell between three shims and four shims. We chose four shims because 1) it was slightly closer to the feeler gauge measurement; and 2) we wanted to error on the side of more clearance rather that the more disastrous results of not having enough clearance.

The Volvo Penta DP-SM manual says to add an additional 3 shims for a total of 7 shims.

The threads of the shift shoe stop screw were coated with Permatex 80019 (substitute for Penta 1161099) and installed to 10-12 ft.lb (14-16 Nm) of torque.

After reconnecting the shift linkage, the boat was first tested in the driveway and then on the water. The boat now shifts perfectly!

A video of this process was made and uploaded to YouTube for others that may be interested in how we tracked down this problem, or how to shim the shift shoe stop screw.

Thanks to everyone for their here