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Switch to a slightly thinner gearbox oil. Go for a fully-synth.
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Had the same problem with a MK2 Mondeo, I have found that after adding Molyslip it has made the situation much better. I am generally against additives but this seems to be a situation where it offered genuine merit.
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Does this Molyslip stuff realy work and would you guys recommend it?
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I have exactly the same problem with my 1994 Peugeot 306 1.9 TD, struggle to engage 2nd gear when first starting out, especially in these cold mornings of late but after being on the road for 10 mins or so, the change from 1st to seconds becomes one hell of a lot smoother. All other gears are fine, its just engaging 2nd until the oil warms up.
Martin
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Having much the same problem on an 04 sxi corsa,its still under warranty,can anyone advise if vauxhall would consider changing the gearbox oil to a synth?
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Does Molyslip realy work and would you guys recommend it?
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I would emphatically advise against the addition of any molybdenum compound to oil lubricating high speed rolling bearings. This is because it's possible for the particles to coalesce, which would cause a rolling element to jam by wedging action. As an addition to grease in sliding joints, or very large rolling elements (such as CV joints) it's fine. In a gearbox, there is an additional risk that synchromesh action will be compromised due to coefficients of friction being outside the operating range for the synchronising system being used.
The common misconception that a lowered coefficient of friction is a good thing neglects the fact that in a gearbox, all critical moving surfaces roll, not slide. Thus, ball/roller bearings are used, and tooth forms are involute, which gives a rolling contact. The sliding action takes place in the synchromesh, and here a defined degree of friction is a necessity.
As Aprilia suggests, a synthetic gear oil may help, as long as it is to the required viscosity and duty, but bear in mind that for some older transmissions with a high oil level, foaming has been a problem with the use of these oils. It's best to follow the makers' recommendations as mistakes are costly.
659.
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659FBE is correct.
I would never add moly to a gearbox.
A synchro system is like a little clutch - every time you move the shift lever you are pressing the clutch into engagement. Obviously the correct oil (in terms of viscosity and frictional properties) is critical to correct synchro action. Moreover, the oil characteristics vary with temperature - hence a 'box which is crunchy and baulky when cold will operate slick and smooth when hot.
I would use a top-quality oil specified for the 'box. If its the MT75 Ford box then several oil co's do a specific oil for that box.
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A FWD Ford will be a MTX75;MT75 were RWD.I know it sounds pedantic but it may help you find the right lubricant.
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I agree with 659FBE in his advice.
However, I would like to add a point of pedantry - I hope that 659 will be able to forgive me.
The gears are only truly rolling at the pitch point, at all other points during the engagement of a pair of involute teeth, there is a combination of rolling and sliding.
Of course, in hypoid gearing, there is always sliding, even at the pitch point.
Number_Cruncher
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My '97 Mk2 Mondeo (2L petrol) suffers from the same gear stiffness when cold - and from the replies, it seems as though this may not be confined to Mondeos. Maybe it's like arthritis - not (usually?) life threatening, but one of those things that you have to put up with as you get older. The measures to alleviate it may have undesirable side effects!
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Agreed, NC, of course, but gear design is generally such that at near peak torque, allowing for the deflection of shafts and other components, the maximum tooth pressure occurs at the point of true rolling motion. As the expression for contact pressure in a helically cut gear contains the factor cos^2 (helix angle), the pressure reduces very rapidly indeed on either side of the rolling point for this type of gearing. Books have been written...
Hypoid gearing, with its attendant sliding motion and consequential need for an EP lubricant thankfully does not now generally arise in passenger car transmissions. I was always most unimpressed by the high temperatures and attendant losses achieved by the very heavy duty drives I used to deal with.
659.
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>>Books have been written...
Now there's an understatement!
I agree with your point about tooth pressure - the maximum combination of tooth stiffness occurs at the pitch point. As the teeth are effectively cantilevers, the stiffness falls off rapidly as the point of contact moves out beyond the pitch circle.
I have been surprised, virtually every time, to see the footprint test patterns of aircraft gearboxes that I've been involved with the stressing of. Despite the attempts made to account for casing, bearing, and shaft deflections, post footprint test adjustments to the mesh were the rule rather than the exception.
Number_Cruncher
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