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Overdrive working when cold


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My overdrive seems only to be responsive when cold. After driving for approx 10 mins the overdrive becomes unresponsive.

Usual checks made oil level ok. Click , clack of solenoid which seems good. Have gearbox tunnel off currently and considering options.

Has anybody any thoughts?

Thanks

Kevine

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I had this exact problem with my J type overdrive. I stuffed around with oil changes, filter cleans etc and then replaced the solenoid. The solenoid has two seals, they go hard with age and allow the oil when hot and thin to leak through. When the oil is cold it works, once it warms up it doesn't.

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I posted this a while ago....It might help as was starting from a point of knowing nothing and eventually managed to fix it!

 

https://www.tr-register.co.uk/forums/index.php?/topic/65938-another-a-type-overdrive-problem/?p=580758

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Thank you for input so far. I have checked some of the responses. I'am now moving to the thought of pressure. some time ago i replace the solenoid plate and recall no packing washer was in the accumulator sleeve where the spring is positioned so might introduce a washer to see if that helps. Also have been using Penrite GB40 gearbox oil which i believe is thinner that EP80/90 which i may try.

Following that it may be the Accumulator assembly is failing and noticed O ring which might be at fault.

Next question is can the Accumulator assembly be removed whilst still in the vehicle and any body have an idea on where to buy the the tool for the job.

Thanks

 

Kevine

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Kevine-I would start by checking oil level and maybe the filter screen (which would require draining the oil). Then check the pressure and the valve adjustment. Don't rely on the 3/16" drill method as it may not give enough valve opening for reliable operation. If the pressure is low ( below 450 psi)try shimming the accumulator spring. here is a link to the Buckeye article, if you don't have it- http://www.buckeyetriumphs.org/technical/AOD/AOD4/AOD4.htm Note the free length of a new accumulator spring is 6.3" for comparison. Also,be careful not to add enough shims to cause coil binding of the spring.

Hopefully, the accumulator can be accessed without removing the transmission by unbolting the rear mounts (and drive shaft) and jacking it the rear of the transmission.

Berry

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Hi Everyone,

just a quick update. Replaced gearbox oil with EP/90 which I think has made a small difference as it seems longer to fail if that makes sense. Re set solenoid but also added a washer inside the solenoid plate. I feel more positive now. Maybe when setting the solenoid using a drill bit in the lever arm perhaps I should advance this a little? Thinking of buying a gauge to see what pressure I have. Also somebody posted about the electric loom which controls switches/solenoid which they said was the answer to their problem. Currently the solenoid clicks and clacks as it should.

Still working to find solution but I now have a better understanding

Thanks

Kevine

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To make absolutely certain whether its something electrical or the overdrive itself....and if you have the gearbox tunnel off... Remove the solenoid altogether and tie piece of string to the overdrive operating arm and find a private road and either (preferable) get a passenger to pull it up and release it

 

Go VERY CAREFULLY of the exposed prop shaft when you do this

 

...On mine it proved the fault was electrical and indeed it turned out that a new gearbox overdrive loom provided a perfect fix!

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Looks like overdrive maybe faulty. Ordered pressure gauge from Sheffied together with a new Actuator spring in the first instance. Spoke to a chap called James who was very helpful.

Does anybody know if you can remove the overdrive without taking the gearbox out?

Thanks again

 

Kevine

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Does anybody know if you can remove the overdrive without taking the gearbox out?

Thanks again

 

Kevine

Its just do-able but TBH a lot easier with it out.

Stuart.

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I still think it is the solenoid seals. The solenoid might click on and off ok but when the oil is warm it gets past the seals and fails to properly engage the od. Borrow a solenoid first.

It is highly highly unlikely to be in the od.

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I removed and replaced the J type on my 4A without removing the GB with no problem but would imagine, as Pete says, if it's a A type putting it back would be very difficult.

Alan.

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Tried to upload the original Triumph "A type" overdrive manual but it didn't work.

 

The only cause mentioned in the manual for the overdrive dropping out is foreign matter under the operating valve seat.

 

My manual is for a TR2 if you want to look for it on the web.

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Elin Yakov has done a series of videos on a gearbox with A type.

Great to view to see what could be involved.

https://youtu.be/rmEbgmwMLfY

There are 12 parts. But a great series.

(You will have to find them within his channel listing. He does a lot of triumph resto videos)

 

Helped me a lot. If only to inform me that I needed professional help for a proper long term fix.

H

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kevine back again. Firstly thanks for input. I ordered a pressure gauge + new accumulator spring from Sheffied.

 

First reading was 400psi without overdrive. Then overdrive engaged dropped to about 250psi although it raised as revs increased.

Next I put in the new accumulator spring, firstly it was approx 7mm longer than the previous spring taking into account 2 washers.

The readings with the new spring went to about 450psi and the pressure with overdrive in to about 300psi all seemed to work ok but when switched off the oil pressure dropped very low very quickly. I'am now thinking accumulator O ring. All test were with the rear wheels off the ground and not road tested.

Think the pump is ok as it is consistent when o/d out.

I will post back with an update in the middle of next week.

Has anybody got any thoughts to add?

 

Many Thanks

kevine

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Kevine-It looks the link I gave for the Buckeye articles doesn't work. Try Googling Buckeye Triumph. I think you will find there is a wealth of info on the OD&trans. The accumulator o ring you are referring seals the acculator housing to the OD case. I don't it is usually responsible for pressure problems, but is cheap to replace. Remove the accumulator housing requires a special (or homemade tool) to extract it. Air pressure through the operating valve also works, sometimes. Leaks in the accumulator can also be caused the bore in the housing becoming scored.

Having said all that, I would check the operating valve adjustment (going beyond the drill bit method) and road test before removing the OD. My OD functions fine, but I did notice that the pressure drops off fairly fast after shutdown.

Berry

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My OD started dropping out when warm yesterday. I hope it's electrics /fluid level/ adjustment but if it's more serious I'll be very interested in the outcome of this discussion-it's springtime here so any major work will have to wait for next winter.

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Hi everyone Kevine reporting back.

In receipt of new Accumulator, piston, and rings and have now fitted a new Actuating valve.Firstly thank to Hamish a couple of post earlier with the link

which shows a tip in getting the accumulator out. Basically remove Actuating valve ,Ball, spring etc and then put the ball back in. Remove solenoid and plate to expose large spring etc. Use air compressor and the Accumulator with pistons eased out. I noticed the accumulator was scratched and looked a little worse for wear. ( previous history unknown) Anyway replaced all parts and fiddled around setting up solenoid and tested.

All oil pressures now read as per brown bible.

Parts fitted New Accumulator, piston and rings. New large spring (longer by about 7mm than the old one) and Actuating valve.new gasket for solenoid plate

All good in garage with wheels off, and then test drove for 1/2 hour.

I'am now so pleased as everything appears to be working as it should.

Thanks to all

Kevine

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