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Ford Galaxy Mk2 - 6 speed manual gearbox shim fitting (& purpose of fitting it)

Started by insanitybeard, December 17, 2020, 12:55:29 PM

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NOTE: Most images can be viewed at a larger size by double clicking on them!


This procedure will apply to Mk2 Ford Galaxies, VW Sharans and Seat Alhambras with the 6 speed manual transmission built from around 2003 onwards providing that they have the black rubberised blanking cap covering the gearbox input shaft as seen in image 1 below. If the gearbox doesn't have this cap and is just a plain aluminium casing, the procedure will not apply - but the earlier gearboxes use a different bearing arrangement for the input shaft meaning that they're unlikely to suffer from the same issue that makes the addition of the shim necessary in the first place!

I carried out this modification to address a whine which I had started to notice when changing gear (particularly noticeable when changing into 5th gear), and at the same time, I hoped it might make a difference to another intermittent issue I have which is a hard to select 5th gear (it sometimes 'baulks' and will not select at first attempt). In my case, fitting the shim cured the whine but sadly didn't make any difference to the 5th gear selection issue, which I believe is a fault within the selector mechanism itself (and I have read a few reports over the years of people losing 5th gear entirely so it must be a weakness with the design, however as my Galaxy is now 15 years old and has at time of writing covered 160k, I'm not about to remove the gearbox and strip it to investigate, I just take a bit of care selecting 5th and don't force it in- if it won't select first time, I just shift back to neutral and try again and this usually works)

Gearbox end view.jpg
^ image 1: end view of the gearbox showing the blanking cap arrowed red

Why adding the shim is necessary

The earlier gearboxes without the rubberised end cap use taper roller bearings on both ends of the input shaft which are able to handle high axial (in the form of end thrust) and radial loads and are generally long lasting and trouble free. They will therefore not be affected by this issue.

In the later gearboxes this arrangement is changed for some reason (likely cost/ ease of production as is usually the case, it's certainly not for robustness!) and instead of taper roller bearings, a needle roller type bearing is used at the clutch end of the input shaft and an ordinary ball bearing is used at the opposite end (behind the blanking cap). The ball bearing is free to 'float' axially within the gearbox casing. Because of this, any end thrust of the shaft is only controlled by a flange on the inner side of the ball bearing and a circlip on the outer side (see image 2 below). The flange on the inner side of the bearing is reasonably large probably meaning that most of the wear is taking place and being caused by the circlip (which is located in a groove on the opposite side of the outer bearing ring), said circlip has a fairly small contact area against the gearbox casing and over time, the thrust and rotation (which must be intentional) of the bearing outer race within the gearbox casing causes the circlip to wear a groove into the soft aluminium casing, increasing the shaft end float and consequently increasing the force of the axial thrust. After extended mileages this can lead to an audible whine when changing gear and possibly difficult gear selection, and if left unchecked will eventually cause the ball bearing to fail when the wear and the increased axial thrust exceeds the maximum loading that the bearing is able to withstand. If the bearing fails, the debris created is likely to find its way into the various other bearings and gears within the gearbox causing further damage meaning that repair isn't economical. I believe that this issue may have been the cause of what was described in this thread.

Gearbox bearing 2.jpg
^ image 2: view of gearbox ball bearing showing inner flange (arrowed orange) and outer circlip groove (arrowed blue)

Parts required

I ordered the shim and end cap from Darkside Developments (link below) though at time of writing there are sellers on [eBay] offering them as well. Darkside Developments supply three shims with their kit, I couldn't see how it would be possible to use more than one (more on that later) so I have a couple spare. If you need one, I'm happy to send for the cost of postage, but you'll still need to source an end cap- these are available separately- note that in this case it gives a choice of 2 sizes of end cap and for the gearboxes fitted to these particular vehicles you'll need the smaller 79.35mm diameter one- VW part no. 02M 301 211B. The shim alone is part no. WHT001976.

Link to end cap and shim kit:
Darkside Shim Kit

Link to end cap only:
Darkside End Cap

The shims themselves were 0.65mm thick, but due to the manner in which the shim is used for this modification, the thickness isn't actually important (as long as it's a) thick enough to have sufficient strength to prevent it from being distorted by the thrust force acting on it and b) thin enough to allow you to refit the circlip after you've fitted the shim!). Image 3 below shows the shims and end cap as supplied:

new parts.jpg
^ image 3: cap and shims as supplied

The procedure

Before commencing, if fitted the undertray will need to be removed and the nearside front wheel removed. An axle stand is always a safer bet than a trolley jack! As long as the vehicle is slightly raised on the gearbox side above the 'normal' height it would be at if it was just sat on its four wheels, there should only be a minimal loss of residual gearbox oil from the bearing when the blanking cap is removed. The cap can simply be removed by driving an old screwdriver in between the gearbox casing and cap and just levering it out but I'm fussy and didn't want to risk damaging the casing doing this. The very centre of the cap is just rubber meaning that you can stab a decently sized screwdriver through it and lever against the metal liner of the end cap without risking any damage to the gearbox casing.

Note: Once the end cap is removed, do not start the engine until the circlip and end cap have been refitted after fitting the shim, otherwise the rotation of the gearbox shafts is likely to cause oil leakage out of the end cap opening!

With the cap removed, you can now see the outside of the bearing depicted in image 2. Before removing the outer circlip, it is possible to gauge the amount of wear that has taken place by jamming your finger into the end of the hollow gearbox shaft and attempting to alternately pull and push it back and forth. Any end float should be immediately obvious. Moving on to circlip removal, there are two circlips - the outer one which locates in the groove of the outer bearing ring (which causes the wear to the casing) and the inner one which sits in a groove in the gearbox input shaft and locates against the inner bearing ring. It is only the outer circlip that needs to be removed. These circlips do not have lug holes meaning that you can't use conventional circlip pliers on them which makes them a bit of a pig to remove. I think that you can probably get dedicated pliers for this type of snap ring but they're not commonplace, in this instance I find a pair of long nosed pliers used the opposite way to normal (i.e. by pulling the handles apart to separate the jaws) will do the job even though inevitably the clip will keep springing off of the end of the jaws just when you think you've got it!

Image 4 below shows the outer circlip in question, with the circlip end gap circled red. It's not a fantastic image, not helped by the poor light (and the glare of the flash) and tacking the job in the gloom of December, but hopefully is good enough to illustrate:

cap off.jpg
^ image 4: end cap removed

Once you've succeeded in removing the circlip, you should be able to see the groove that the circlip has worn in the gearbox casing behind it. It's very difficult to show this in an image with the gearbox fully assembled but I have tried in image 5 below:

casing wear.jpg
^ image 5: gearbox casing wear

In the above image, the tip of the head of the blue arrow is pointing at the groove in the casing worn by the circlip. The groove is visible as a slightly darker shade of grey compared to the surrounding aluminium casing. The red arrow is attempting to show the amount of wear that has taken place, to the left of the tip of the arrow head is the circlip groove machined in the outer bearing ring. Fractionally to the right of the tip of the arrow head can be seen where the bearing ring meets the gearbox casing. The distance between the circlip groove and the gearbox casing is the amount of wear that has taken place, as when new the circlip groove should have been flush with the surrounding casing, allowing minimal end float (basically just enough to ensure that the circlip wasn't binding against the casing). I estimate that this amount of wear had caused in the region of 2mm of end float of the shaft assembly.

For reference, the next image (image 6) shows the removed circlip and the new shim. What I should have done was take an image of the circlip laid directly over the shim to show the slightly larger diameter of the shim in comparison but this didn't register at the time.

Gearbox shim and circlip.jpg
^ image 6: bearing circlip removed with new cap and shim

I found the next part a bit of a struggle, because the shim supplied is actually of a larger diameter than the circlip, which means that it doesn't sit in the groove worn in the casing but over it. By this I mean that the shim is sitting over the unworn portion of casing surrounding the wear groove, which means that it's actually reducing the shaft end float to less than it came out of the factory with. For this reason, I struggled to refit the circlip after installing the shim because there wasn't quite enough float left in the shaft to do it, and is why as I said earlier I don't see how it would be physically possible to fit more than one of the shims! A better solution would be if the shim actually fitted inside the wear groove in the casing therefore effectively 'replacing' the material that had been worn away and giving the circlip a fresh surface to run against without taking up all of the end float but possibly such a shim would be too small to manufacture effectively or too thin in section to be sufficiently strong, I don't know.

Anyway, with this in mind when refitting the circlip on top of the shim (once again using the long nose pliers, a bit of a fiddle to say the least), make sure that the circlip is positively seated back in its groove in the outer bearing ring before fitting the new cap. If it is a bit tight, it should 'free up' once the gearbox has run a bit and the shim settled into place. It's not ideal though in my opinion. Once you are satisfied that the circlip is properly located, give the surrounding casing a clean and ensure there is no debris or dirt around the bearing or cap seating surface. You can now fit the new end cap using a rubber headed mallet or similar to avoid damaging or distorting the cap when tapping it in - try to keep the cap as square as possible to the casing when doing this.

Hopefully this will have now silenced any gearbox whine that you were experiencing and depending on the amount of wear present may also make a difference to the gear selection, though not in my case.

Finally, below are a couple of parts diagram screen grabs to illustrate the difference between the pre-2003 gearbox and the post-2003 gearbox:

Pre 2003 gearbox.jpg
^ The above is a parts diagram for a pre-2003 gearbox. The input shaft bearings are no's 2 & 5, both described in the description as taper roller bearings (although the description for no. 5 is not visible in this screenshot)

Post 2003 gearbox.jpg
^ And here is a comparable parts drawing for a post-2003 gearbox. Here the input shaft bearings are no's 1 & 3, no. 1 being the needle roller bearing at the clutch end and no. 3 (which is the bearing shown in image 2) being the ball bearing at the wheel end.

Always learning..... Often by mistakes!