Maintenance

[elansprint71]

I have been using a mixture of gear oil and Molly grease which seems to have worked fine for me over the last 15 years, I have now discovered the semi fluid greese intended for landrover front swivels which seems ideal for the job.

Do you have a product number/name for that stuff? Sounds like it is just the thing.

I use oil in a second Wanner grease gun, just for the trunnions, never remove the nipples and leave them "dirty" after lubrication as this stops the ball/spring from rusting; I just give them a good clean before the next lube. As the oil will drain out I think this is one job you cannot do too often.

[Galwaylotus]

Injection of a little engineering into this discussion is always good. Exploring the "semi fluid" grease theory versus oil or common grease is also interesting

Right. Here's what was in the archives:
Front Suspension Trunnion Lubrication - Lotus Elan / Europa

Steve Lennox
5th December 2006

There are many opinions and options for lubrication of these components in the Lotus?s. The factory recommends the use of Gear Oil 90, personal and shared experiences have shown grease to work effectively as well.
Recently there has been a move towards using semi-fluid greases for this application, so what are the pros and cons for each of these solutions.

Components and Metallurgy

The basic metallurgy is based on steel on bronze, set as a threaded section (steel) into the mating bronze (brass) trunnion. This set up allows the articulation of the front stub axle for steering.
As such with a set up such as this it is essential to maintain the correct lubricant film thickness between the mating surfaces; this is always related to the lubricant viscosity at the operating temperature.

Lotus OEM Recommendation

Lotus has recommended the use of Gear Oil 90 for two main reasons;
1) This oil provides the correct viscosity for the required oil film between the mating surfaces. This is essential to ensure smooth and frictionless articulation of the steering.
2) Rationalization and availability of lubricants (ie. Gear Oil 90 is recommended elsewhere on the vehicle).
An SAE 90 viscosity specification will have a viscosity at 400C in the range of 140cSt to 240cSt. Typically the commercially available oils have a viscosity of 190 -220cSt.

Oil Lubrication

PROS:
Oil has the correct viscosity for this application.
As the componentry only turns through a maximum of 900 the oil is sufficiently mobile within the housing to be refreshed in the load areas.
CONS:
Oil can drain out if sealing substandard
Oil does not have self sealing (as with greases) so there is a risk of ingress of contamination (dirt/water etc.)

Grease Lubrication

PROS:
Gel nature of grease minimizes leakage due to poor sealing
Grease provides better self sealing properties to exclude contaminants (dirt/water etc)
Most lithium soap EP (Extreme Pressure) greases have a base oil viscosity of 150-220cSt.
CONS:
Grease is not very mobile within this application, and as such will not refresh or replenish in the load area, due mainly to the lack of rotation of the components. Whereas in bearings the continuous rotation applies shear to the grease causing it to momentarily thin and feed the load areas.

Semi-Fluid Grease Lubrication

PROS:
Provides self-sealing capabilities of grease
Sufficiently mobile within this application to replenish loaded areas
CONS:
Most commercially available semi-fluid greases have very low base oil viscosity (30 to 70cSt).
However, checking product technical data from some of the major oil companies has highlighted the following products that will meet these lubrication needs;
Caltex EPC00 (base oil viscosity 153cSt)
Shell Alvania EP9LF) 00 (base oil viscosity 189cSt)
Retail availability may be an issue with these grades

Custom Made Lubricants

This is the best solution, as with little effort, and even less knowledge, anyone can make suitable semi-fluid grease at home.

Recipe
1/3 good quality lithium EP grease1
2/3 gear oil 90 (or 80W90)

Place both ingredients in a mixing vessel (tin) mix with paint mixer until smooth and homogenous. (Being careful not to lift mixer out of ingredients, as this will spray lube all over the garage)

This will provide a semi-fluid lubricant with a base oil viscosity of about 150-200cSt.

Notes:
1 Moly based grease can be used, and they will provide better extreme wear protection. Ideally any good Extreme Pressure (EP) grease will work. Make sure that it is a lithium soap (Lithium hydroxystearate, or lithium complex). Grease with tackifier will also enhance the quality of your semi-fluid lubricant.

Some of the greases that are recommended are;
BP Energrease LC2T
BP Energrease LSEP 2
Castrol APXT
BP Energrease LC2M
All these greases have base oil viscosities in the range of 155 ? 220 cSt.
NOTE: ?T? denotes tackifier
?M? denotes Moly (MoS2)


How Do I know This?

I have been in the lubricants industry for 20 years, and have formulated, sold and provided technical support to heavy industry for these 20years.

During this time I have encountered problems with heavily loaded worm drive gearboxes, and when these boxes are loaded they generate a lot of heat. This heat then destroys the seals, the oil leaks out, and the gearbox fails.
I found that by adding about 1/3 grease to the gear oil (usually a moly grease to help with the over loading) the gearbox performed better, the temperature dropped, and the seal didn?t leak as badly.
I believe that the lubrication issues encountered with these worm drives is similar to the trunnions in the front suspension of the Lotus.

Steve Lennox is a member of Lotus Club Queensland, Australia and owns an immaculate original S2 Europa.