Ok, something that I REALLY should have done much earlier was test the functioning of the overdrive (I know, I'm an idiot).
It's not working. I've tried all the standard tests, checked the oil level, bled the air, tried operating the actuating leaver whilst on the move and with the rear wheels off the ground all to no avail. Only fix left to try is removing the sump plug, draining the oil and tapping the pump to see if it frees off. Other than that, it's looks like the only alternative is a rebuilt unit.
The question is, is removal of the overdrive doable from inside the car? Looking at it, I believe so but don't want to get half way through trying only to find it's impossible.
Yes they are a fickle thing, only because you cant get to them easily..if they were presented on a plate they would never go wrong. Not heard of anyone taking just the overdrive off in suitue, not sure
Questions:
Is it an A or J type
what oil are you using
has it been "touched" or just washed and fitted
A good person to run your thoughts past is Tom at Pete Cox Sports Cars. He rebuilds all mine (I have a spare spare on the shelf if you want to buy ) and he might have some ideas you may not have tried.
It's an A type o/d and filled with the correct (according to all info I've read) oil. Can't remember exactly but it's probably SAE 90.
I did contemplate calling Tom as PCSS reworked my top cover to accept a switch for the reversing light (you may recall this conversation).
I actually took the box (with o/d fitted) to a local trans shop who checked it over for me and declared it in good nick. TBH, the box works fine and there are no issues there. Looking back, I think it's doubtful they checked the o/d. If they did, they should have realised it's not operating.
I really, REALLY don't want to pull the whole engine/box out and can live with the o/d not working for a while but it's still something I'd want to get sorted in the longer term.
I'm a bit surprised that I've not had someone get back to me on the viability of removing the o/d in situ, I would have thought that someone somewhere has tried it. It looks like it should come out easily enough. Take off the prop shaft and it looks as if it would lift out easily but who knows?
Is your spare A type? If so, what would you be looking for? Outright purchase or exchange?
The overdrive unit needs to slide straight back about 8" before it can be lifted or turned so I doubt very much it could be done while in the car. You need to source a pressure tester and check to see if the unit is building any pressure. There is a 7/16 nut on the top right side if the overdrive. Below is the operating lever. This is where the tester is screwed in.
I saw this pressure tester on a youtube video (someones rusty beauties? Something Eastern European?). But despite searching, I can't find one in the UK. The only available item I've seen for sale is in the USA. I have, however, slackened the bolt you speak of and there is pressure as the oil pushes out past the bolt if it's not fully tightened.
Mike, a little alarmed to your hazy memory to what oil you may have in it. I have always used SAE 30 in mine and it works very well. SAE 90 IMHO opinion would be way to thick?
In fact, I did actually speak to Tom at PCSS yesterday and mentioned SAE90 and he was ok with that although I should have said HYPOID 90 which I pretty sure is what I have in. Quote from the Duckhams website "For all A Type o/d gearboxes, 40 grade gearbox oil is best but if you can't get any then Hypoid 80/90 will work. The overdrive likes this but the gearbox might have a heavier change due to the higher viscosity. "
Anyways, he suggested a number of tests which I'll try and, specifically, getting a pressure gauge to check the oil pressure in the box. He also suggested a couple of contacts one of whom I called right after speaking to Tom. He's given me other tips including how to check the operation of the pump without removal of the o/d AND how to use a right angle (blunt) pick or similar to check if the steel ball on the pump plunger is free. Apparently, this can be another problem area.
As this would necessitate draining the oil, I may take the opportunity to change to a lighter grade.
Not sure when I'll get around to all of this so may be motoring on just the 4 speeds for the foreseeable but I'll keep th site posted.
One thing Tom did say was that you'd need a minimum of 9 inches clearance to remove the o/d (preferably 10) so it looks like it would have to be an engine and box out job if I eventually need to replace the o/d.
Here is a link to a web site of a UK company I buy parts from to rebiuld ODs. They have the gauge set up for 60 lbs. In reguards to the oil to use, if it is a gear oil it should be the GL4 designation. GL5 and above has an additive that is corrosive to yellow metal. That would include the Syncros and several bushings in both the trans and the OD. I use a synthetic oil from Redline, MT-90. There are other brands that make the GL4 in synthetic as well. Most of the racers in the States are using the Redline variant.
The best web site I have found to read and understand the A and J overdrive units is the Buckeye Triumph website. Link provided. They give you the information you need to test your unit.
I actually spoke to a guy from o/d repairs yesterday and he offered me a money saving tip. I don't need a gauge to check the pressure. With the rear of the car on stands and in 1st gear, remove the plug that the gauge would go into and check to see if the oil pushes out (which it should do) , if you put your thumb over the hole and oil still pushes out, there's enough pressure. If not, pumps not working. But there are other fixes he's suggested before pulling the box.
Re oil type for the box & o/d, I've had as many opinions as people I've spoken to ranging from Nigel's SAE30 right up to SAE80 with everything in between. An that's from guys who specialise in either od/ repairs or parts.
Frank, I'd be really worried if the pump fell out from the sump because, by all accounts, it shouldn't.
The other tip I got from Overdrive Services (whom Tom at PCSS directed me to) was to remove that sump plug and strainer, drain oil. With the car on a ramp and working from underneath, elevate the rear wheels and have someone rotate them. Shine a light up into the sump plug hole and check for up and down motion in the pump. If it moves, it's working. Next test is to get the pump in it's topmost position and, using something narrow and right angled, check that he ball that sits at the end of the pump plunger is free. Apparently, these can stick if left unused for a long time (as mine has been).
So, lots to try before I resort to robbing the piggy bank for a recon.
One final suggestion I was given, and this sounds a bit brutal to me, was to drive the car and drop the clutch pedal as if you were trying to free off a sticking clutch plate. Might free off the cones??? Not sure about that one.