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TR2/3/3A A type overdrive

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Graham H

Graham H

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My 3A has an A-type overdrive which I believe came out of a TR6 so is the later model with the smaller accumulator piston.
About six months ago I fitted a new oil pump and accumulator cylinder to try and fix a low or no oil pressure problem and after reassembly, the oil pressure came up straight away with instant engagement on a road test.
Last week I noticed there was no overdrive after running for about one mile but after 3 or 4 minuted running the OD came back and seemed ok. After stopping at the shops for about 20 minutes I tried the OD again and it would not work until I had driven for 3 or 4 minutes.
I have now taken the transmission cover off checked the oil level and all the electrics and lever adjustments and fitted my pressure gauge. No oil pressure until run in gear for 3 or 4 minutes then pressure came up to normal and OD engaged with a pressure drop off and recovery as it's supposed to. After shut down the pressure drops back to about 300lbs then slowly drops to about 100lbs and stays there for about two minutes. If I start it up again the pressure comes up straight away and it's all good, if I let it sit for about 10 minutes I have to wait for the same 3 or 4 minutes for the pressure to come back.
Does anyone have any ideas what could be the problem?

Graham
 
Thanks, Randall it may be as simple as a piece of fluff under the ball letting all the oil drain out of the accumulator circuit the only way to find out is drain the oil and take it apart.

Graham
 
Hi Phil,

The accumulator cylinder has an O ring that seals it in the casting when I first took it apart the O ring had a large bite out of it which was replaced with a new one. After the initial running of the OD, it lost pressure and I took it apart again and found the O ring was damaged as before so I may be looking at the same problem again.
This unit has been an ongoing drama it works for a while then fails again, it could be a lemon and I need to look at a replacement but I will persevere for now and see if I can't fix it.

Graham
 
graham
I m talking the small pistion thats inside the accumalator that has come out
pm me your number and I will call you
Phil
 
Phil

Sorry, I haven't got back to you I have been busy pulling the box out and after dismantling can't find anything wrong with it. Will report back after it's back together, about a week it's been a bit hot the last few days 35c.

Graham
 
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