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Triumph TR3 - Type A overdrive

I have dismantled my gearbox and overdrive because I was observing a grey color in the oil for some time already. I knew the brassy colour is normal, but not the grey.
Everything was working fine with no particular noise. But this was a good decision.
The cause for the colored oil is that the thrust washer (brass) between the sun gear and the planet carrier had totally gone (worn) and the sun gear was starting to grind into the planet carrier (when OVD engaged). Its teeth are now slightly rounded on that contact edge and the planet carrier has a 0.5 mm deep groove. I will however re use these parts as the damage is not compromising their function. Similarly, another thrust washer placed behind the unidirectional clutch has worn beyond limits and the larger planet pinions (3 each), the ones that gear with the sun gear, were just starting to rub against the annulus gear side face.
These are the only marginal observations I made, everything else is okay. I will rebuild my gearbox and overdrive with the usual replacement parts (bearings, sleeves, thrust washers (of course), layshaft, etc).
I wanted to share my experience with other happy owners of overdrive, if the oil has a dark color, it is telling you something. If it is only brassy, it tells you you still have some time. If the amount of brass is considerable, you probably have less time before you need to do something. Has anyone else had this thrust washer gone into powder?






























Jean Louis Lafont

Bonjour Jean-Louis - I replaced the lower straight cut gear (non-synchro) layshaft in my gearbox during a total re-build at 15,000 miles in 1962, all done again at 80,000 miles (1990) and since then I've driven "TRusty" over 78,000 miles. I change the oil every 3000 miles in my gearbox with overdrive using Valvoline 20W50 motor oil. I use the 20W50 "R" (for Racing) when I can get it. The oil always has brassy particles when I drain it, but the oil is still clear - almost like new.

Merçi et bonne chance !

Don Elliott, Original Owner, 1958 TR3A

http://www.tr-register.co.uk/images/memberscars/trusty.jpg
Don Elliott

Bonjour Don, Thanks for your advise on the oil. I have read several things about the oil, and have always questioned myself about the best to use. Since it is gears, I personally have always used gearbox oil (EP80 or EP90). But I have read articles about oil types and there is a type (GL4) that may damage brass parts due to high sulfur contains. I do not know if the EP80 I use is GL4, it might not be classified this way in oils available in France..? But now that I have dismantled my gearbox and seen that these two thrust washers (mentioned in my initial thread) are worn (one is actually GONE), I wonder if I was not using a high sulfur oil.
However, I know that several owners use engine oil and I will try it after I rebuild my GB and OVD.
I also note the oil change frequency you use; quite frequent when you compare to the gearbox oil change frequency on more modern cars.
I was doing frequently too (4000Km) because I knew for some time that oil was getting dirty.
Merci
Jean Louis Lafont

J-L - Ken Gillanders from So. California told me to use the Valvoline 20W30 "R" in my gearbox with overdrive in 1990. Ken has been an expert on TR's since he bought his TR2 almost brand new in 1954 from a Triumph dealer in France who had this TR2 modified for racing but Ken was the first person who bought it. Ken was in the US Forces and he shipped it back to California in 1955. Hence he is also "an original owner".

Last summer, when I saw all the brassy particles in my oil, I also thought about GL4 and GL5 gear oils. The newer GL5 attacks brass, bronze and other "yellow" metals. I filled the gearbox and overdrive with GL4 gear oil which does not attack brassy parts. But after 3,000 miles, I drained it and it was just as brassy. I called Ken and he said that GL4 or GL5 gear oils will cause the cone clutches in the overdrive to slip. So I went back to 20W50 "R" Valvoline. Except for this one period of 3,000 miles I have used the Valvoline 20W50 for the last 78,000 miles from 1990 to 2003.

From new in 1958, I had always used straight SAE #30 oil like it said in the TR owner's manuals. But this oil wore out the bearings and my layshafts after 14,000 miles, then again at about 72,000 miles from new. I limped to 80,350 miles with the gearbox like this when I re-did it all during my total body-off restoration from 1987 to 1990.

Don Elliott, Original Owner, 1958 TR3A
PS - where are you located in France ?
Don Elliott

Don, I have experienced the overdrive cone clutches slip occasionally, at high torque demands. I could have suspected accumulator pressure also and I will measure it when I reassemble my OVD. All hydraulic parts are good, no scores on pistons, cylinders or pump, so I think it will be okay, unless the accumulator springs lost force. The measurement of pressure will tell me. But I will definately use 20W50 oil.
I am living in Toulouse area, and I am there half of the time. The other half, I am commuting abroad (Brazil for the last 11 years) in the oil industry.(talking about oil!)

JL Lafont 59 TR3A ownner since 1992
Jean Louis Lafont

I don't think the accumulator springs would lose any force. The original overdrives (as for the early TR2's) had smaller pistons which provided less pressure than for the TR3A overdrive. The older ones also had steel piston rings that can wear out or break and you will loose more pressure.

If you have a newer overdrive with the larger pistons and rubber o-rings, the overdrive should not slip. If it does, it is usually only when you click into overdrive. If it only happens here, just let up a bit off the gas pedal and it should engage solidly.

If it slips at other times, it may be an older overdrive from a TR2. Of if it is a later overdrive, the rubber o-rings may be worn. I have also heard that the small o-ring that seals the shaft that goes through from the solenoid lever to the rhs may be too tight, and the extra resistance (friction) of this small o-ring seal (or seals) can delay the rotation of the shaft and make the shifting into overdrive a bit sluggish. Bill Piggott of England reported that one he drove in California was like this. It took 15 minutes for it to shift into overdrive after he clicked the solenoid switch.

I have always (45 years and 160,000 miles) kept my foot on the gas pedal when shifing into or out of overdrive. If you let up on the gas pedal, the overdrive will go clunk and this cannot be good for the mechanical parts. Many TR6 owners have told me that they step on the clutch pedal when they shift into or out of overdrive. This is not necessary, but they say they do it just to be safe. Not necessary.

Don Elliott, 1958 TR3A
PS - I have been to France about 20 times and visited many regions, Bretagne, Normandie, Lille, Strasbourg, Alsace, Provence, Cannes, Carcasonne, Lyon (Sister-in-law lives there), Toulouse (Bendix Automotive Electronics for ABS Brakes), Anjou, Bourgogne, Cote de Rhone, Cahors, Perpignan, Jura, Gorges du Tarn, etc.
Don Elliott

This thread was discussed between 08/01/2004 and 11/01/2004

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