Overdrive A type problem

[Tom Chatterley- Cox]

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. 

 

[RogerH]

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

 

[Nobbysr]

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

[Ralph Whitaker]

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

[Nobbysr]

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