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Overdrive Operating Valve Question

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Bob McElwee

Bob McElwee

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This is a follow-up to my previous questions about an overdrive that would not disnegage.

Today I removed the interior and tranny tunnel in anticipation of swapping out the transmisson to a 5-speed later this week.

I followed the check out procedure Dave R. had sent. When I removed the valve parts I noticed a definite 'dimple' on the upper spindel where it rides on the ball. There was also a 'dimple' in the underside of the cap screw where the other end of the spindel meets it. The long spindel that rides on the operation cam was clean with no obstruction in the relief hole or hollow center.

After putting the operating valve back together I took the car for a ride. (I made sure there were no loose ends to be caught in the driveshaft) The overdrive worked fine, as it did before, but I didn't drive it long enough to duplicate the previous conditions.

Are the tolerances such that the two dimples could be causing the problem? I don't see how because it doesn't happen until I've driven for 3 or 4 hours. I've had adjustment at the solenoid before but never something like this.

Thanks for your thoughts.
 
Hi Bob, I am not sure I understand your comment, however here goes my thought regarding the dimples. There should not be any contact from the operating valve parts and the cap screw. This is because beginning at the top of the operating valve shaft with its dimple comes the ball,followed by a plunger which fits inside the last and only part which should be in contact with the cap screw. consequently, if these parts are not in place as defined it could cause a problem.---Fwiw--Keoke
 
Hi Bob,
Not sure what you are describing here:
"There was also a 'dimple' in the underside of the cap screw where the other end of the spindel meets it."

One seal is between the top of the spindle (J) & the ball (G). The other seal is between the lower aluminum seat (F) & the ball (G). See the attached pics with explanation. Make sure that the parts are assembled exactly as shown.
D
 

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Gents,
Sorry for the confusion. All parts are present and assembled as described in Dave's attachments.

Using Dave's attachment #5646:

Spindle 'C' it has a dimple on the flat surface on the bottom where it comes in contact with Ball 'D'.

The top part of Spindle 'C' appears to also have put a dimple in the bottom of Cap 'A'. If Spindle 'C' is not suppose to touch the underside of Cap 'A' what is missing? There is also a small spring that fits around the top part of Spindle 'C'.

Hopefully this clarifies it a tad.
 
OK Bob, If the plunger/spindle Item C has a dimple in its face it is worn. If the plunger shaft is hitting the cap perhaps the spring is weak.---Keoke?
 
Hi Bob,
In my above post I was refering to spindle (J) only. I have reworded that post.

I would consider what is called spindle (C) to be a spring follower & it's only purpose is to provide a smooth contact surface with the top of the ball (D).

Since the spindle (J) is kicked up pretty hard by the solenoid operation, it may over travel against spring tension & momentarily drive the top of spindle (C) into the cap (A) bottom & then rebound onto it's seat (G).This momentary spindle (C) contact would be intended to prevent overly compressing the spring.

The dimples in the bottom of spindle (C) & the underside of cap (A) are likely to be due to wear & tear & should have no effect on the OD operation.

The OD operating arm should be adjusted so that when the solenoid is operated, the ball is lifted .030" to .040" off of it's seat (G). The factory method of anchoring the setting lever on the RH side with a pin & then tightening the clamp on the solenoid lever is often not the correct adjustment on worn parts. Thus the method of measuring actual ball lift as stated above.

If the spindle top (G) is seating well against the ball (D) & the ball is seating well against the aluminum seat (G) & the ball lift is set correctly, everything should work.

I have found cases where the O rings which seal the through/transverse rod which operates cam (K) have excessive friction. This can prevent the spindle (J) from fully returning when the solenoid is released. (No seal between (D) & (F). This would prevent the OD from releasing. IF so, slightly stretching the spring (about 3/16") under the cap (A) will restore correct operation.
D
 
Thank you both, I'm beginning to lean towards the spring either being weak and/or O ring having excessive friction. Both might become more pronounced as the unit heats up from a long run. I realize that is a SWAG on my part but it helps me understand what is actually happening.

After looking at Moss and Vicky B ($80 to replace all the operating valve stuff), I think I will use the 3/16" stretch recommendation first.

I'm trying to come up with a backup plan for the trip to Conclave in case I can't get the 5 speed in before we leave. Running without OD is costing me 3-4 MPG on the highway, which is adding up with the cost of premium today.

Again, thanks to you both.
 
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