Gearbox Repair

Golf GTi Mk3 Restoration, Jul-2019

Been using the Mk3 Golf GTi as an everyday runabout and enjoyed every minute of it. However, the car became afflicted with the 2nd gear crunch problem that apparently affects almost every VW with an 020 gearbox/transmission with more than about 90K miles on the clock. It started with a very occasional crunch on selecting 2nd gear but steadily got worse until around every other gear change into 2nd would crunch horribly.

I tried Redline MT-90 synthetic gear oil and this improved matters considerably but did not clear the issue. Doing some research on the various VW forums, it became clear that the culprit is most likely the 2nd gear synchroniser ring.

Here’s a schematic overview of the gearbox, showing the components relevant to the crunch problem:

An exploded view of the output shaft showing the synchro hub and the synchro ring itself:

Reproduction rings are available for around £25 each, so decided to remove the gearbox and have a look.

I won’t go into how to split the box apart, but here’s the site I used for most of the information needed: BrokeVW.com . This superb site explains the workings, dissassembly and rebuild of a VW 020 far better than I can. What I would say, however, is that the special tools shown in this site and in VW manuals are not strictly necessary to do a limited repair such as the 2nd gear synchro ring replacement that I did here. I got by with a standard gear puller (to remove the LH drive shaft flange) and an assortment of pry bars and bracketry made from steel scrap. Only one special tool was really needed – shown below. You will however need a collection of good quality 12 point spline & torx sockets/keys.

Here’s the innards with the case, selector forks and selector shaft removed:

Once the 4th gear wheel upper retaining ring is removed, the gear wheel along with the complete input shaft can be removed together. The 3rd gear retaining ring can then be removed but must be put back in the same place when reassembling. This retaining ring is selected to provide a tight fit.

No special tools were required to remove the 3rd & 4th gear wheels and the 2nd gear synchro hub – they slip off fairly easily by hand. The 2nd gear synchro hub can be dissassembled to expose the synchro ring. Here’s the little bugger:

The synchro ring was badly pitted and the friction surface was worn through. The new reproduction ring was quite different in design – it didn’t have the spiral oil groove for example. This was a slight concern but could equally well be an improvement – time will tell.

The gearbox was put back together along with new gaskets, oil seals and end cap. A new clutch was installed and the left rear gearbox mount was replaced too. I left the left hand driveshaft flange off until the gearbox was mounted back on the engine. This made it a lot easier to manoeuvre the gearbox into position – I found the flange was easily snagged on the subframe during removal. Again, no special tools were needed to press the flange into position – an M10 threaded rod and an M10 nut, some spacers and a large washer are all you need to wind the flange back onto the splined shaft.

I refilled the box with Redline MT-90 and took it for a couple of miles test drive. Pleased to say the clutch & gearbox performed beautifully – not a hint of crunch on 2nd gear no matter how harshly I tried. Obviously, will need a few hundred miles to confirm the adequacy of this repair, so will report back if any problems arise.

P.S. Here’s the only special tool I had to fabricate. It’s a 27mm hex key made from 10mm steel with a nut welded on. This is needed to remove the end cap on the selector shaft.