1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

[JTKelleyiii]

I have a 1975 135Hp Johnson, model 135ETL75E.

Recently, the clutch dog will pop sometimes when I am shifting into Forward.

It does not do this all the time. Following one of the popping episodes, once it gets in gear and stays there it runs without issue all the way up to 5000 rpm.

I have looked through my service manual, Johnson, and it does not shed much light on this situation.

My questions to you professionals are:

- Is this an indication of the clutch dog starting to go out?
- Seems to me if the dog was going it would pop out at high rpm, high torques scenarios, which it is not.
- Could this simply be a cable adjustment since when it occurs is when I am shifting into forward at low rpm? If so, any advice on this? The manual is not really helping me, maybe I just have not found the info yet.

Any thoughts would be appreciated.

Thank You,

John

 

[Joe Reeves]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Try adjusting the cable first. If that doesn't help, It would appear that you're faced with a lower unit repair (dog/gear).

(Centering Shift Cable)
(J. Reeves)

When all is as it should be, the proper method to adjust the shift cable is to disconnect the cable from the engine. Move the shift linkage on the engine to find the center of the play in neutral, and when found, leave it centered.

Now, grab the end of the shift cable sleeve, push and pull it to find the center of the play there, and center that play.

Adjust the trunion on the threaded portion of the shift cable so that the centered play of the cable lines up with the centered play of the engine's shift linkage. Install and lock the shift cable with the retaining clamp in that position. That's it.

(Jumping Out Of Gear - Manual Type)
(J. Reeves)

This pertains to lower units on all OMC manual shift outboard engines, or any OMC engine with lower units defined as a Shift Assist or a Hydro Electric Shift unit which incorporates a "Shifter Clutch Dog".

Within the lower unit, splined to the prop shaft is what is most often referred to as a clutch dog, hereafter simply called dog. The dog has at least two lobes protruding from it on both ends, facing both forward and reverse gear. The forward and reverse gears also have lobes built into them near their center area. When the engine is running, in neutral, the gears are spinning constantly via the driveshaft being connected directly to the powerhead crankshaft, but the propeller does not turn due to the fact that the dog is centered between the two gears, and the dog lobes are not touching either of the gear lobes.

When the unit is put into either gear, shift linkages force the dog (and its lobes of course) to engage the lobes of the gear. The lobes of the spinning gear grab the lobes of the dog, and since the dog is splined to the prop shaft, the propeller turns.

The lobes of the dog and gears are precisely machined, most with right angled edges that could be installed in either direction, and some with angles slightly varied that must be installed in one direction only (one end only must face the propeller). Dogs that can be installed in one direction only, if reversed, even if the dog and both gears were new.... would jump out of gear almost immediately. Keep in mind that the lobes are precisely machined with sharp angles!

Due to improper adjustment or worn shift linkages, but usually due to improper slow shifting, those precisely machined sharp edges of the lobes become slightly rounded. Now, with those lobes rounded, as the rpms increase, the pressure of the gear lobes upon the dog lobes increases to a point whereas they are forced apart (jumping out of gear), and due (usually) to the shift cable keeping tension on the engines shift linkages..... the unit is forced back into gear giving one the sensation that the engine has hit something, and the cycle continues.

Some boaters with manual shift engines have the mistaken belief that shifting slowly is taking it easy on all of the shifting components..... Wrong! Shifting slowly allows those precisely machined sharp edges of the dog and gears to click, clank, bang, slam against each other many times before they are finally forced into alignment with each other..... and this is what rounds those edges off! The proper way to shift is to snap the unit into gear as quickly as possible.

 

[JTKelleyiii]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Thank You Joe.

I appreciate it and the info.

Will try the adjustments per your recommendations and go from there.

 

[JTKelleyiii]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Checked cable and no significant adjustment required.

However, I noted that when pushing the throttle lever forward two things were occurring:
1. Engine fully shifts into gear and as throttle lever is pushed further the warm up lever starts to comes up.
2. As I continue to push the throttle lever forward I hit a spot where there is some resistance. If I push through this the spot the shift lever on the engine "jumps" down partially. This indicates to me that I have a control box issue.

I found that if I hold the warmup lever down in the run position and pull it slightly amidships while advancing the throttle lever, everything works properly. Went fishing last weekend and used this technique and the engine shifted perfectly and I never experienced the clutch dog pop I had the weekend before.

Looks like its time to go into the control box. Fortunately I do have a manual.

Has anybody ever experienced or heard of something like this?

Thanks.

 

[Joe Reeves]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Engine fully shifts into gear and as throttle lever is pushed further the warm up lever starts to comes up.
As I continue to push the throttle lever forward I hit a spot where there is some resistance. If I push through this the spot the shift lever on the engine "jumps" down partially.Looks like its time to go into the control box. Fortunately I do have a manual.

Disconnect the throttle and shift lever from the engine. Now, advance the throttle lever while observing that warm up lever. If it doesn't move as you explain above the problem is not within the control box. The problem would be that one of the cables is adjusted too tightly at the engine end and is causing a binding action that is being transferred to the control box.

 

[JTKelleyiii]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Thanks Joe. I will check this.

 

[JTKelleyiii]

Re: 1975 Johnson 135Hp - Clutch Dog or Cable Adjustment?

Disconnected cables and bind went away. Reconnected and adjusted cables at engine and cycled several time. At first it appeared that the problem was resolved, i.e. warmup lever stayed down and shift linkage did not partially jump down. After continued cycling the problem came back.

Disassembled the Command Center (not as hard as I thought) and found the following:
- Warm-up Lever Roller was missing. Shaft on lever was there but no roller.
- Shift Lever Assy had issues. One of the plastic teeth was broken off and another was seriously deformed.
- Detent Ball was laying in bottom of housing. Spring end was crushed from hanging up on and or going under the Shift and Throttle Plate.

Other than that it looked fine. All other components greased and intact. Going to replace the components and properly adjust the cables. I suspect that should resolve the issue. I think the broken/crushed shifter gear teeth were the major contributor to the symptoms seen.

After working on this motor and boat I no longer get surprised by anything I find. On the up side she runs and gets me where I need to go. Slowly but surely I am resolving the problems. This website is nothing short of awesome in helping with this effort. Thanks.