General Tech Overdrive--Afraid it's Serious

[KVH]

I just took a drive and used my overdrive for the first time since it was rebuilt in the shop 3 years ago. This was its first time in service. It seemed to run fine, but my transmission is now locked up. It will drive forward, but it will neither roll backward nor drive backward. Reverse seems locked. I was thinking my brakes locked up, but I'm certain that can't be it. This is a total lockup for anything moving the wheels backward.

Did I wire something up wrong? Do I need to take the entire interior back out and release a valve?

I can hear my solenoid working, and I'm not feeling any hot wires. I'll dive into the search tool, but wanted to get a jump on any thoughts you folks may have.

Thankfully, I'm retired. If I need to pull it all back out, I guess that's what I'll do. Thanks for any help or advice.

 

[CJD]

You MUST NOT try to reverse the car with the overdrive still engaged!!!

What has happened is the OD is remaining engaged, and this tries to spin the one way clutch backwards when you try to go into reverse. If you try hard enough, you will shatter the clutch and destroy the OD.

Things to check...

1) make sure the solenoid is releasing.
2) If it is, then release the OD, and then rap on the round barrel of the OD. Especially on new rebuilds, the drum tends to stick in the barrel, keeping the OD in gear. Rapping on the barrel should free it.

3) If the above doesn't do it, then you will need to check pressures to ensure the solenoid is adjusted properly

Finally, change to MT90 tranny fluid to prevent sticking.

 

[Geo Hahn]

Wow! I wonder if your overdrive is stuck engaged even though you hear the solenoid click?

I think you could tell if that was the case by observing the operating lever &/or working it manually.

Could be that the valve is gunked up from a long spell of disuse?

Don't rush into pulling it but I think you're going to have to get the tunnel off to see what's going on.

 

[CJD]

Yes, Geo is correct, if checking for the motion of the solenoid and rapping on the barrel doesn't release the OD, then more detailed work requires removal of the tunnel cover.

 

[KVH]

I did gently try to go into reverse. But gently with the clutch. Ruining something crossed my mind. Hopefully, I'm OK on that score. Can I try rapping from below with a plastic dead blow hammer? Will I hear something release?

I'll also check that solenoid lever, but I tested it before putting the cover back on, and it all seemed fine.

When you say to be sure the solenoid is releasing, you mean I should see the operating shaft rotate back?

 

[CJD]

I tried plastic, but a copper or brass hammer works better. You need to jar it. No, you cannot hear it release. To see if it did, genly rock the car backwards with the tranny in neutral. If it moves backwards, then it released.

If the OD was adjusted properly to begin with, then releasing the solenoid will release the pressure internally to release the barrel from the drum. But...it sounds like you don't know if it was set-up properly or not. What I mean by that is that the solenoid can release, but the adjustment arm is not positioned correctly to release the internal pressure.

Testing for pressure release normally requires a pressure gage...with the tunnel removed. But, you can allow the pressure to bleed down by letting the car sit over night. Then rap on the barrel to release it and try rocking the car. If it seems the OD remains engaged even with the solenoid releasing, then the solenoid arm needs to be adjusted.

 

[KVH]

I have the car back up on blocks. The wheels now rotate, but in opposite directions, and I'm assuming that is irrelevant to the overdrive lockup, correct? The wheels would rotate opposite regardless, but not together in reverse if locked up. Also, about that copper hammer--what part of the OD am I hitting, and does that require the interior be removed? Something I'm learning to dread. Thanks all.

 

[KVH]

Update: The operating rod and valve, and solenoid, are working properly. A few bangs on the OD housing "ring" we’re given. No luck. I'm totally locked. I’ll wait ’til morning to see what happens. Nothing in the online Laycock Manual is giving me much hope aside from the BFH technique that I'm rather hesitant about, and tried somewhat already.

 

[mezy]

You say the OD was rebuilt, was the gearbox rebuilt at the same time ?
There is one other thing which will lock up a gearbox, and give you no drive forward or backwards,
when you move the gear stick does it feel as it should, can you feel all the gears going in and out,
It may be possible you have selected two gears at the same time, if the selector pawls have not been fitted correctly or one is missing.
I am not familiar with this type of gbox, does it have a cover plate on top you can remove and see where the selectors are.

 

[TR4nut]

I had an overdrive that would stick on, in my case the hammer blow helped. One thing you could try before tearing everything apart - I drained the oil and put in ATF then ran the overdrive with the car on Jack stands. Then put in fresh oil - I think I used MT90 synthetic. The fluid flush solved my sticking problem. Might be worth a try for you before more serious work is needed.

 

[mastaphixa]

Where you hit the overdrive with your hammer does matter. There is a steel plate that is sandwiched between sections of the overdrive and usually looks darker than the aluminum housing. Its approximately 5/16" thick. Whack it on that steel ring like you mean it. I ran into that on a fresh rebuild while bench testing the unit.

 

[philstr6]

Update: The operating rod and valve, and solenoid, are working properly. A few bangs on the OD housing "ring" we’re given. No luck. I'm totally locked. I’ll wait ’til morning to see what happens. Nothing in the online Laycock Manual is giving me much hope aside from the BFH technique that I'm rather hesitant about, and tried somewhat already.

pull the operating valve out and see if the tiny hole is plugged and if so clear the hole so the oil blows thru,when you are in overdrive and you come out of overdrive if the hole is plugged it will no release pressure with the hole plugged and you will have a stuck clutch

 

[sp53]

I am learning about ODs myself, so any pictures you can post on this problem would be appreciated.
thank you steve

 

[KVH]

I can’t even get the car out of the garage because the wheels are locked from reversing. If I jack the car up and put it on the wheel dollies, I could push it out onto the garage apron. If I do that, do I dare drive the car?

The Laycock Manuel says not to drive the car because damage could result. Do they mean only if you try to go in reverse, or can damage result just from driving forward. I can’t imagine the latter, because I was several miles from home when this lock up would have occurred, and I didn’t notice any issue until I had reached home. I found a few posts from folks who got their overdrives to release by driving the vehicle. Not sure I should try that.

I’m hoping for a solution that avoids taking a Triumph interior out for the “umpteenth” time. Maybe I’m dreaming.

 

[KVH]

Guys I meant to add: While driving, and before I noticed this lockup from reverse, I definitely felt the OD disengage when I turned the OD switch off, and I don’t ever recall putting it back in overdrive after that disengagement.

 

[mezy]

Guys I meant to add: While driving, and before I noticed this lockup from reverse, I definitely felt the OD disengage when I turned the OD switch off, and I don’t ever recall putting it back in overdrive after that disengagement.

Have you attempted to drive it forward, is it locked up when you try to drive forward

 

[mezy]

I have just found this on a british forum, someone else had the same problem,
they sugest an Italian tune up,
i have coppied one of the post here.

• 22.7k If the clutch is sticking stuck on its cone maybe an italian tune up will clear it up ???
  Do some changes under power to make it work out without trying to kill it
  Have a read of the troubleshooting in here http://www.odspares.com/phdi/p1.nsf/supppages/odspares?opendocument&part=3
  It also suggests a bit of hard use,

 

[titanic]

It defintely sounds like the classic sticking of the clutch to the brake ring. Here is a link to the Buckeye OD articles. https://static1.squarespace.com/sta...933/1560385068892/A+Type+Overdrive+Part+V.pdf
The stuck brake ring is discussed on page 7/8.
Berry

 

[KVH]

The car operates fine going forward. Locked for anything reverse. Sounds like today is “hammer day.” I don’t have a good hide hammer, but it seems I’ll be assured there’s an Italian Specialty Shop nearby with a broad selection.

 

[CJD]

Driving forward will not hurt the OD, but any attempt to move in reverse can hurt the one way clutch. With both rear wheels off the ground, when you turn one, the differential will allow the other side to turn the opposite way. This is independent of what the tranny is doing. You would have to get someone to hold the other wheel to see if you can turn the tranny backwards.

You want to tap the round portion of the OD, where it bolts together. Tap around the ring. If the pressure is released, then the barrel should drop out of the drum to release the OD.

If it does not release, then there is a valving issue that will need to be addressed, which is causing the pressure to remain in the barrel pistons to hold the barrel into the drum...therebye holding the tranny in OD.