Tom Chatterley- Cox Posted September 6, 2022 Report Share Posted September 6, 2022 15 hours ago, Nobbysr said: i'm curious why no hypoid oils, have you had issues ??? Hypoid is designed for use in "Hypoid" gear sets, ie. differentials. My understanding is that Hypoid Oil is optimised to reduce wear when two surfaces are sliding over one another under extreme pressure. In a gearbox + overdrive unit, the synchro rings and the cone clutch in the OD rely on friction/pressure to function. Use of hypoid may reduce the effectiveness of these parts. Quote Link to post Share on other sites
RogerH Posted September 6, 2022 Report Share Posted September 6, 2022 16 hours ago, Nobbysr said: i'm curious why no hypoid oils, have you had issues ??? Hi Steve, try and organise your oil for the job Engine GB/OD Diff They are all made for their particular job and do not necessarily interchange. The GB oil is not an area for Hypoid oils or EP oils. However in their wisdom TRiumph put EP in the TR4-6 GB's The gear structure does not need it. The Diff definitely DOES need a Hypoid type oil as the gears do not work in the conventional way. Because of the odd loading special additives are add that may not be happy in the GB/OD. Roger Quote Link to post Share on other sites
Nobbysr Posted September 8, 2022 Report Share Posted September 8, 2022 Some background on gear oils An sae 30 oil is roughly the same viscosity as an 80w-85w gear oil, the current additive technology for a branded oil API GL-4/GL-5 will not compromise the clutch material in an overdrive but will improve gear performance and bearing life . There used to be issues with some of the active Sulphur additives and brass/bronze gears/material and some of the E.P additives but again that's really old technology. Companies such as Shell, Castrol, Exxon Mobil, BP etc have moved away from these additive technologies. I have uses an 75w/90 gear oil in my 3A for the past 20 yrs with no issues but Also its worth noting that the "W " in the spec refers to the Winter viscosity, which has to be within certain parameters, which for say an 85w is 500 cSt at -12 C. the other important aspect is also the viscosity at 100 C. Essentially the viscosity of all oils reduces as the oil get hot, so the viscosity at 100 is important in gear oils The other factors which also impact on performance is the additive technology and base oils. Some engine oils do contain some gear oil performance but that depend specs as engines re formulated to deal with the environment within an engine, as we know there is some gears present in the engine but the load is much lower than in a gear box ..Some engine oils are formulated to cope with gears and they tend to use specs such as FZG and 4 ball tests .. hopefully this makes sense, i happy to share my industry knowledge if any one want message me On 2/21/2022 at 7:13 AM, Ralph Whitaker said: I had a similar problem with my O/D which was caused by the lever under the solenoid slipping on the operating shaft so it was not fully opening the overdrive valve. The procedure given in the workshop manual for setting does not always work on older units due to wear, and I found with mine that using the setting hole and a rod would not work. I had to advance the operating lever a fraction and it works fine now. Also they seem to work best with SAE30 rather than SAE90 oil, and definately do not use HYPOID oils Ralph On 8/2/2022 at 6:40 AM, Ralph Whitaker said: Just going by what Laycock, and now Overdrive Services, reccomend. I originally put in Hypoy 90,which Triumph themselves advised for the TR4, but then noticed that for the TR2/3 they were recomending Castrol GTX. After discussions on this site I changed to Morris Oils GB30 and found that the syncromesh worked better and the overdrive operation was sharper. Ralph Hi Ralph the reduction in viscosity would help with shifting as an sae 30 oil about is the same viscosity as an 80w to 85w so the thought process is correct its one of the reasons O/D operation can be sluggish in the the depths of winter Quote Link to post Share on other sites
Ralph Whitaker Posted September 8, 2022 Report Share Posted September 8, 2022 48 minutes ago, Nobbysr said: Some background on gear oils An sae 30 oil is roughly the same viscosity as an 80w-85w gear oil, the current additive technology for a branded oil API GL-4/GL-5 will not compromise the clutch material in an overdrive but will improve gear performance and bearing life . There used to be issues with some of the active Sulphur additives and brass/bronze gears/material and some of the E.P additives but again that's really old technology. Companies such as Shell, Castrol, Exxon Mobil, BP etc have moved away from these additive technologies. I have uses an 75w/90 gear oil in my 3A for the past 20 yrs with no issues but Also its worth noting that the "W " in the spec refers to the Winter viscosity, which has to be within certain parameters, which for say an 85w is 500 cSt at -12 C. the other important aspect is also the viscosity at 100 C. Essentially the viscosity of all oils reduces as the oil get hot, so the viscosity at 100 is important in gear oils The other factors which also impact on performance is the additive technology and base oils. Some engine oils do contain some gear oil performance but that depend specs as engines re formulated to deal with the environment within an engine, as we know there is some gears present in the engine but the load is much lower than in a gear box ..Some engine oils are formulated to cope with gears and they tend to use specs such as FZG and 4 ball tests .. hopefully this makes sense, i happy to share my industry knowledge if any one want message me Hi Ralph the reduction in viscosity would help with shifting as an sae 30 oil about is the same viscosity as an 80w to 85w so the thought process is correct its one of the reasons O/D operation can be sluggish in the the depths of winter You obviously have a greater knowledge of the subject than I. What I take from the above is that you are saying that the problem with additives attacking brass/bronze items is historical, and that it will not happen now with current oils, and that GL5 is perfectly acceptable, as are all EP Hypoy oils. Is this correct or have I not understood correctly? Ralph Quote Link to post Share on other sites
Nobbysr Posted September 11, 2022 Report Share Posted September 11, 2022 On 9/8/2022 at 1:58 PM, Ralph Whitaker said: You obviously have a greater knowledge of the subject than I. What I take from the above is that you are saying that the problem with additives attacking brass/bronze items is historical, and that it will not happen now with current oils, and that GL5 is perfectly acceptable, as are all EP Hypoy oils. Is this correct or have I not understood correctly? Ralph Hi Ralph That's pretty much the case, we used to see similar problems with Phosphor Bronze bushes pitting but i haven't seen any issues for many years now however most of the products i have looked at are from the Oil majors, Castrol, Shell, Mobil etc Some small blenders do buy cheaper additive packs and cheaper base oil so I have alway stuck with what i trust . Must of the oil companies i have worked for have their own test beds but also use data from Ricardo Eng and testing completed by additive companies such as Infinium, Lubrizol and others. Attadive companies do sell low spec off the shelf additive packs formulated for more basic requirement in market in Asia but some will often find their way into the UK market via local blenders, primarily due to price The issue of thickness or viscosity of the oil is a little complicated but the W refers to Winter performance but the most important factor is the Viscosity (thickness) at 40 Celsius and 100 C although the oil reduction is not linear, the Pour Point is also important as is the Viscosity Index as i have put together a comparison chart which should give an idea of the typical figure. The base oils used are mostly Paraffinic Mineral oils and wax as they get colder so additives such bas Pour Point Suppressants are used, synthetic oils have a much broader temperature range Some of the antiwear and EP dont start to work until at higher temperature which where some of the significant wear takes place .Manufacturers often use gear oils with chemically active EP additives that cope with running in after which time you move to a hand book oil. I have just noticed that someone in the US is now selling steel synchro cones with a carbon lining which should, if claim are to be believed, improve shifting .. However I prefer Phosphor Bronze gearbox bushes rather than steel as they to be kinder to the more expensive components if oil runs low or out GL-4 oils are formulated to cope with Spiral Bevel and hypoid gears for moderate speeds and loads, with exception of LSD applications., but GL-4 oils can be use in manual gearboxes and transaxles. But some of these oils have added antioxidants and other components to cope with wet brake application in agricultural vehicle. its worth noting that much of the test equipment for this specification is no longer available. So suppliers will have to purchase known technology additive or read across additive performance which is not always accurate!!! However i would suggest that GL-4 spec oils are considered for General Tr Driving gearbox's and GL-5 for axles GL-5- oils are formulated to cope with high speed hypoid and high torque applications but it was mainly driven by the US MIL-L-2105C specification, they are also compatible with the latest Viton and Nitrile seals . These oils also meet SAE J2360, which cover elastomer seal swell, Oxidation (thichening) and Detergency (Cleanliness) the idea being that any insolubles are held in suspension and not deposited in the gearbox but changing the oil is important These oil also have meet many specific manufacturers specs and some will need to meet ZF, some Merc some VW etc and the additives useds may not be miscible or compatible which is why there are a number of the same viscosity gear oils. I haven't seen or heard or anything that would cause overdrive wet clutch problems or experienced any issues myself but the linings available today should compatible with todays oil and i have used Semi synthetic and mineral 75w/90 gear oil which does make gear changes easier at lower temperature (see attachment) There is a case for stating that a GL-5 oil is paying for performance not required in a TR box but a GL-5 oil does help protect the gears and the O/D unidirectional clutch and be worth considering for competition uses but that as requires consideration as to what issue is trying to be resolved , Some engine oils can be be used in gearbox applications as they have Anti-Wear additives but they lack the the load carrying properties of the gear oils but it can be argued TR boxes don't require that level of protection but to me anything that extends the life of the gearbox should o be considered. I have attached something which will show how multigrade gear oils viscosities compare with mono grades i can add specific makers products if people let me know and ill try and do the same for engine oils hope this is of some interest and hopefully not to wordy Steve Gearoil comparisons.xlsx Quote Link to post Share on other sites
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