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Triumph TR6 - tranny fluid

I am a new triumph owner, 75 tr6. thought I was changing the oil and I believe i emptied the transmission fluid. I inscrewed the plug under the motor, I know it was stupid. How can i replace the fluid, I don't see anywhere to pour it back in, can anyone out there help a rookie ?
DH Hutton

Hi DH

If you unscrewed the plug from the bottom of an aluminium part, then you drained the gearbox. If the plug was in the side of the black pressed steel sump, it is engine oil.

The fill plug for the gearbox is on the driver's side (assuming you have a LHD car), and is a square head plug. You might be able to see it if you look up from directly below, but if you are stuck (like me) with axle stands, you may have to feel around for it. Then comes the fun part - you have to get the oil up and into the fill plug. There are various pumps you can use, or you can use one of the oil cans with a thumb lever - this will strengthen your thumb, I can assure you.

The oil you need is something that is friendly to your yello wmetal gearbox parts, and it is, of course, not readily available. You need EP90 (I think). You can get it from The Roadster Factory, and occasionally from places like NAPA. You can also go with a synthetic from Redline (MT90?), which may be easier to get hold of, but will cost you...

If you have an overdrive box, then this all changes, and you need something else. Someone with a fancy overdrive gearbox will no doubt come along and advise...

If you drained the engine, then the Castrol GTX 20W50 (the legally required oil of all British cars) goes into the filler on top of the rocker cover.

Hope that helps.
Cheers
Alistair
A Hewitt

Perhaps this will help. If you did pull the tranny plug, the fill plug is on the side of the gearbox about 2/3 of the way up.

SteveP1

MR DH, do you have a manual?

Hey, since I am 6-less.
Am I still allowed here?
Don Kelly

For the engine oil, the Castrol 20w50 is OK although you might want to toss a little ZDDP in there with it. Shell has an oil in their Rotella line that still has a reasonable amount of ZDDP in it, but even that will go away eventually. Your flat tappet engine will thank you for it.

On the gear oil, it's more than just being "yellow metal friendly" and that "EP" is extreme pressure aimed at the types of loads seen in differentials. There are GL5 gear oils oils out there that are acceptable for the yellow metal parts, but still not something that you want to run in a transmission. The EP additives in GL5 for lack of a better term, plate onto everything and play havoc with the syncros. Running a GL4 means that you don't have to worry about those EP additives. Don't let anybody bamboozle you with the GL4/GL5 rating, it's really a GL5 that's yellow metal friendly. By specification there is an upper limit in GL4 on the additives that aren't yellow metal friendly, but no upper limit on the yellow metal friendly EP additives that aren't friendly to syncros and that is where the GL4/GL5 rating comes from in that it meets the letter of both standards. These cars are somewhat more tolerant of that than others, but still not a place that I want to go. If your shifting is notchy and difficult, you should consider replacing the gear oil with some fresh dinosaur GL4 or non-detergent motor oil, the Redline MT or the Motorcraft synthetic (see below on these). Note it might take a while for the additive to wear off the syncros, some folks see results quickly while others take a few hundred miles. In your diff, GL5 is no problem.

The Redline MT is pretty good stuff, I think the MTL is a little light for these cars. If you have a non-overdrive you might also consider the Ford/Motorcraft Full Synthetic Manual Transmission Fluid. It was originally developed for some German transmissions that Ford used and has become reasonably popular with the Miata and S2000 crowd along with a few other select elixirs. I run the Motorcraft in the Miata. The top item in the image is the transmission fluid, the bottom is for diffs. Note the part numbers and specification numbers. You have to watch them sometimes as I have heard of, and had happen to me, where the guy gets the wrong stuff but tries to tell you otherwise. Forewarned is forearmed...

If you have an overdrive tranny, synthetics are probably out and there are multiple schools of thought out there. Some subscribe to 90 wt GL4, others to non-detergent 30wt motor oil while others go with non-detergent 20w50 motor oil. I'm in that last bunch using Valvoline 20w50 non-detergent racing oil with an A type overdrive.

SteveP1

Still trying to get the gearbox filler plug off, she isn't budging, i am just stripping the square bolt. any other way to fill the gearbox? any suggestions on how i can get this bolt out, metic 12 wrench fits but it almost seems welded in, help please ?
DH Hutton

You can get an 8-point socket at Sears - I forget the correct size, but I think 7/16? I know I tried to use a socket and allen key (with the socket reversed so the square side was on the plug, if you see what I mean) and it didn't fit, so I think that rules out 3/8 or 1/2 inch sizes.

Alternatively, you can get a tool from Joe Alexander with two square drive ends - one end fits the gearbox (and sump) plugs and one fits the brake adjuster. You can get them from him directly (http://the-vintage-racer.com//index.php?main_page=product_info&cPath=8&products_id=13) or TRF, Moss et al sell them.

If you have already rounded the fastener off beyond the use of a square socket, then you are faced with either taking off the gearbox cover to access the plug from above (a lot of hassle) or you coudl try something like a spiral-type bolt remover (again, Sears has them), though I can't think of a time one of those has done anything beyond chewing the head up some more. Would a stud remover work? Not sure how much access room you have there, but might squeeze one in.

Hope that helps
Alistair
A Hewitt

Hi Folks
I cut an access panel in the transmission cover which allows me to check fluid level from inside the car, I also had a 3/4 nut welded onto that pesky square plug
Hope this helps
Charlie

Charlie B.

This thread was discussed between 18/07/2012 and 29/07/2012

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