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Stuck in Overdrive

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Legal Bill

Jedi Knight
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Hello Friends. Can any of you tell me what is wrong with my OD unit based on the following recital? The vehicle is an 1965 BJ-8.

1. After sticking in overdrive several times during a recent ride, where it would take several minutes of driving for overdrive to disengage, I started an investigation.
2. On my next test drive I put the car in overdrive and then attempted to disengage it. This time the overdrive refused to disengage. It stayed in OD in all forward gears. I operated the switch several times, but it would not disengage.
3. I drove nose first into the garage and parked it. To test the severity of the problem, I tried pushing the car forward and backward. I could not push the car backwards.
4. I started with a test of the electrical system. Dash switch, kick down switch, shifter switch and solenoid all work as they should.
5. I Removed tranny cover and verified operation of electrical components.
6. I removed the bypass valve assembly (it was full of oil, but no pressure) and inspected and cleaned all parts. They all looked good and the tiny hole in the valve body was not blocked.
7. I adjusted the solenoid arm per the instructions in the manual. When completed, I could push a 3/16 shaft through the hole in the lever and into the hole in the casing with no problem while the solenoid was activated.
8. I attempted to push the car backwards, but the OD was still locked up.
9. I ran the car on Jackstands in 3rd and 4th gear and switched the OD on and off several times. I heard no change in the rpm during this exercise.
10. I again lowered the car and attempted to push it backwards and it would not budge.
11. After reading an old thread on this site, I tried hitting the overdrive with a lead hammer in the area where the OD unit meets the gear box. The OD remained locked.
12. I then hit the OD where the conical section of the OD unit meets the cylindrical section of the OD unit. I heard a "ping" and the car immediately rolled backwards a few inches. The OD was unstuck.

Based on the above information, what do you think is wrong with the overdrive unit?

Thank you in advance for your time and thoughts.

Best regards,

Bill
 
I had the same thing with my OD (side shift transmission) several years ago. I turned out that that OD clutch was worn to the point that it would go too far into the OD brake ring and not come out. To get out of OD, I had to come to a complete stop, put it into reverse and gently apply a bit of throttle and it would pop out. When doing this, you don't want the car to move, but just enough to unstick the OD.

A rebuild is in order. It took the rebuilder a few tries to figure it out and fix it.
 
I think John gave the answer. How many miles on your O/D? I rebuilt mine a couple years ago at about 210K miles--150K by me--and the clutch lining was serviceable (I hoped; so far so good). The only clutches I know of for sale are relined ones by DWM.
 
Another (remote) possibility: Eight heavy springs hold the clutch together as a unit when in non-O/D. When you turn O/D off the springs push (pull?) the two halves of the cone clutch together, making it essentially a solid shaft, and unlock the sun gear. If they're not strong enough to pull the clutch from the brake ring and/or the clutch is worn it could remain stuck. IIRC, you are admonished, by both the shop manual and Magnus Karlsson in his videos to replace those springs when rebuilding the unit. Mine looked fine, but I sprung (heh) for new springs--about $90--because it seemed important, but no explanation given.
 
Thank you gents. The car has 60,000 miles on the odometer and I have no reason to doubt this is accurate. The speedo worked when I bought the car 30 years ago. It had been sitting in storage for many years at that time. The OD worked reasonably well, but did get stuck once before, maybe 10 years ago. I'm going to drive it around today and try shipping it in and out of OD at low rpms and see if it always sticks. This is sort of a last ditch effort to see if some usage might clean/free things up internally. Otherwise, my plan is to pull the tranny out, remove the OD, and send it to Autofarm for a rebuild.
 
Update. After trying a trick someone recommended last week (go hard up a steep hill and throw it into OD between 3500 and 4000 rpm) today the OD performed flawlessly in about an hour of mixed use. Highway and backroads, 3rd gear and 4th gear, on and off in quick succession and then on and off after several miles in OD. I started at relatively low RPM in 4th gear and slowly built up to higher RPM use. The system worked perfectly.

A long-retired Healey expert (my brother) listened to my story on Wednesday of last week and said "It could be lack of use." I'm not sure this will hold up, but I'm encouraged to keep using it! Now I need to pull the propellor shaft while the consoles are still out and have that balanced. I've been chasing a "scuttle shake" problem for a long while now and this is an opportunity to have the prop shaft properly balanced. Then I have a local Healey mechanic who told me he has a Snap-on wheel balancer and the proper mounting adaptors for wire wheels (made from a hub and and knock-off). Things are looking up!
 
If, after balancing the driveshaft and wheels, you still have scuttle shake, check the balance of your rear brake drums. They are commonly out of balance.
 
Legal Bill said:
Update. After trying a trick someone recommended last week (go hard up a steep hill and throw it into OD between 3500 and 4000 rpm) today the OD performed flawlessly in about an hour of mixed use. Highway and backroads, 3rd gear and 4th gear, on and off in quick succession and then on and off after several miles in OD. I started at relatively low RPM in 4th gear and slowly built up to higher RPM use. The system worked perfectly.

A long-retired Healey expert (my brother) listened to my story on Wednesday of last week and said "It could be lack of use." I'm not sure this will hold up, but I'm encouraged to keep using it! Now I need to pull the propellor shaft while the consoles are still out and have that balanced. I've been chasing a "scuttle shake" problem for a long while now and this is an opportunity to have the prop shaft properly balanced. Then I have a local Healey mechanic who told me he has a Snap-on wheel balancer and the proper mounting adaptors for wire wheels (made from a hub and and knock-off). Things are looking up!
Click to expand...
The prop shaft has a couple of stamped alignment arrows near the splined joint. Be sure they're aligned.
 
BobHaskell said:
The prop shaft has a couple of stamped alignment arrows near the splined joint. Be sure they're aligned.
Click to expand...
True, and those arrows are not very well aligned on my prop shaft no matter which of the two closest splines I use. Fortunately, the work shop manual tells us the joints must both be in the same plane. So when the arrows don't quite line up, you can look at the u-joints. Mine were on the right spline. But I think one or the other flanges might have been replaced 180* out when I did the u-joints. I'm not sure, but the balancing shop will let me know how far out it is. Even if it wasn't out, I figure I might as well do this as long as I have the tranny tunnel off.
 
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