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TR6 overdrive stuck on ?


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Dear All,

Yet more issues with my TR6  ::(

Was enjoying a few hours driving yesterday, got home and was manoeuvring into my garage, and then when in reverse the car didn't really move anyway, just spun / whirred. 

I have since realised that my overdrive may well be stuck on. 

Without the engine running, but ignition on, when I flick the OD switch I can hear the solenoid clicking in all gears plus when in neutral

All was working so well for many years. FYI i do have OD in 2nd, 3rd and 4th gear. 

So question time:

  • Has anyone out there had this issue ?
  • What would be the course of action  Checking the OD switch first for electrical issues ?
  • Are there any reputable OD specialists within Essex and Herts areas ??
  • Hoping that major damage as not be done by reversing, didn't hear any crunching fingers crossed !

 Thanks, Neil T

 

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Sounds like one of the inhibitor switches (on top of gearbox) stuck on.

As you know, don't reverse the vehicle.

You're going to have to remove the gearbox tunnel to get to the switches & see what's what. You'll also probably want to drain the gearbox oil and check the filter for foreign bodies.

Not doing anything else today are you?

Jerry

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Thanks Jerry,

Sounds a good option to start with. 

A call to Overdrive Repairs Service this morning suggests a more expensive route, of the OD clutch plate worn out, but to my mind it happened so suddenly. 

I will start to stripping out this coming weekend...again !!

Neil  

  

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My car was wired some time in the past to engage overdrive in all gears including reverse. The inhibitor switches were simply  bypassed in what might have been a 1970's fad.

Because I did not make a practice of engaging overdrive in 1st or reverse I did not know this had been done until I removed the tunnel for other work.

Thankfully nothing was damaged.

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Hi Neil,

            a duff inhibit switch should not cause the problem unless the column switch is set to OD.

The cone clutch inside the OD can get jammed on.  Sometimes a rawhide hammer blow to the casing may shift it - be careful tho'.

Check the oil is worth while.

I would not think it is a worn OD clutch but the OD may well end up at ORS for other reasons.

If you need to hand push it backwards then I can;t see that destroying the casing - if you feel a resistance then stop - undo the propshaft bolts.

 

Roger

 

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Thank you RogerH.

I will try the hammer method (!) next weekend, I have a rubber mallet somewhere that should be ok to use (with care!). Will also check oil.

All was working very well until i was back home, so as you mention, really hoping the OD clutch is still ok. Cant think that something like that would suddenly just fail. 

Thanks Had17462 for the Carlow Engineering info..

Neil 

 

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Neil

Don't want to be a party pooper, but I had exactly the same symptoms as you when my OD hydraulically locked on, and I reversed and had a similar noise as you describe, rather like your wheels spinning on grass - net result, OD destroyed inside. Mind you, I was still able to move/drive car.

Coincidentally, had it rebuilt by Carlow.

Hope it's not as drastic as mine was, but it will be a gearbox out job whatever - I may be able to help you with a replacement  - PM me if you are interested - I'm also in Essex so not far away, I'm guessing

Cheers

Rich

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  • 2 weeks later...

Hi,

I had the same problem when I purchased my car, the unit was still under warranty from the last rebuild, the company claimed it needed "running in",

not being at all helpful or true !!!!

DO NOT TRY TO REVERSE THE CAR, EVEN BY PUSHING!!! (very difficult if you are parked facing a wall)

If you jack the car up front and rear, on the nearside, please use axle stands for safety, a smart tap on the annulus ring should free it, but it is difficult to see the right place to hit it.

A fresh rebuild of the O/D unit by a reputable firm, cured the problem.

The original rebuild was obviously rubbish.

I hope this is helpful.

 

Richard Logan.

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Sorry to butt in - but just in case !!! can you not move the car forward or back whilst in neutral and or clutch in without damage ?

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Hi Hamish,

                No.

                      the clutch (between engine and GB) has no effect on the OD functioning.

Inside the OD there is its own (cone) clutch, this drives a unidirection drive roller bearing race. This is on a tapering slope. 

In one direction it will rotate. In the other direction the rollers ride up the taper slope and then lock in - if in reverse the forces can burst the casing.

Not explained well - but don;t do it.

Roger

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Thank you. 

Of course the clutch has nothing to do with the wheels - axle - OD gearbox drive train 

Doh !!!

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Possibly the easiest way to move a car with a locked overdrive is to undo the prop at the diff.  Then move in neutral. 

Tim

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