Wrench Blog
Categories:

digitaldownpour.com:

Other sites:


Sat Apr 14, 2007
10:52
Ever been curious about the inner workings of the Volkswagen 020 transmissions? For the uninitiated, 020 refers to non-cable-shifted transmissions found in 4 cylinder Golfs, Jettas, Rabbits, Sciroccos, etc. During a recent trip to visit my parents down south, my dad and I spent one morning tearing down a 5 speed 020 transmission, just to see what kind of shape it was in and to give me sort of a crash-course in VW transmission rebuilding. This particular transmission came from an A3 (Golf/Jetta from 1993 through early 1999), and the A3 Bentley manuals do not cover the internals workings of the transmissions. Fortunately, however, the A2 Bentley manual covers transmission work in great detail... and the procedures and diagrams can be applied to the A3 transmissions (the differences are quite minor).

Here we start by removing the output flanges (the flanges that bolt to the inner CV joints). The first picture shows a small apparatus used to compress the flange so that the retaining clip can be removed (the flanges are spring loaded). The second picture shows a puller being used to remove the flange - the puller may or may not be necessary, depending on how snug the seals fit against the flanges.
Output flange compressed, circlip removed Output flange being pulled

Next, the selector shaft cover plate gets removed. The hex recess in the selector shaft cover plate is 27mm, and 1 1/16" is a nearly perfect fit as well. You can either buy the official removal tool or just fashion your own using hex bolts and nuts that are either M18 (for metric) or 5/8"-11 (for SAE). An impact wrench and some penetrating oil may be necessary to remove the plate. Here is the tool we used, along with the removed cover plate. We left the selector shaft itself in place for the time being.
Removal of selector shaft cover plug

The 5th gear housing is the small section bolted on to the very back of the transmission housing. This 5th gear housing also contains the throwout bearing. Remove the bolts that go through the fifth gear housing, and lift it off (it may stick, in which case you may have to work at it with a rubber mallet or deadblow hammer). In the first picture below, you can see the 5th gear housing being lifted, and in the second picture it is completely removed.
Removal of 5th gear housing 5th gear housing removed

Now remove the 5th gear lockout plug which threads into the selector shaft housing. In the first picture below you can see the lockout plug and the reverse light switch being removed, and in the second picture the selector shaft is being slid out of the housing.
Removal of reverse light switch and 5th gear lockout plug Removal of selector shaft

With the selector shaft removed, you now need to manually operate the shift forks so that both reverse gear and 5th gear are engaged at the same time. This is necessary to keep the innards of the transmission locked up so that the hollow bolt on the end of the input shaft can be removed. I don't have a picture of how the shift forks need to be manipulated, but it's pretty easy. Look down into the selector shaft housing with a flashlight, and you should be able to see the shift fork actuators all lined up in a row, side-by-side. 5th is on one end, and reverse is on the other end. Make sure all the shift forks are "even" (meaning the transmission is in neutral) and then press down on the two fork actuators on either end. Now both the input and pinion shafts should be locked in place and the hollow inset triple-square bolt that holds the 5th gear assembly on to the input shaft can be removed. You will need the correct size triple-square bit (the same size used for removing many VW cylinder head bolts) and an impact wrench. They are not only tight, but loc-tite'd in place.
Removal of input shaft bolt holding 5th gear in place

The 5th gear shift fork now needs to be separated from the shift fork tube. There is a special tool you can buy to spin the shift fork tube, which is threaded. We just used a pair of needle-nosed locking pliers (carefully!) to spin the shift fork tube out from the 5th gear shift fork assembly. In the first picture below, you can see a small locking plate being pried out of place - that is necessary before the tube will turn. In the second picture we are removing the forks from the tube using locking pliers.
Removal of 5th gear shift fork from fork rod tube Removal of 5th gear shift fork from fork rod tube

Now the two mating 5th gears can be removed. You may have to pry the input shaft 5th gear, as they can sometimes be a tight fit. The mating 5th gear on the pinion shaft is held in place by a retainer. In earlier transmissions (A1/A2), Eaton-style retaining rings are used, in A3 transmissions a special clip (pictured below) is used. The A3 style clip is quite easy to remove using a flat screwdriver. The Eaton-style clips can be difficult to remove, especially if you don't have flat-nosed circlip pliers. In the first picture below, the input shaft 5th gear assembly is being removed. In the second and third pictures, the mating 5th gear on the pinion shaft is being removed.
5th gear input shaft gear, shift fork, shift fork collar, and synchro ring being removed as an assembly Removal of retaining clip for 5th gear pinion shaft gear Removal of 5th gear pinion shaft gear

With the gears out of the way, we can now access the screws which attach the plate for the large input shaft bearing to the inside of the transmission case. They are smaller triple-square screws and are incredibly tight. The best thing to use for these is a hand impact screwdriver and a good, heavy hammer. In the first picture below you can see an impact driver being used to remove the screws. In the second picture below, the screw that attaches the top end of the reverse gear shaft to the housing is being removed (that makes the case halves a lot easier to separate).
Removal of input shaft bearing plate screws Removal of reverse gear shaft retaining bolt

Now remove the bolts securing the two halves of the transmission case. The gasket material used on these transmissions often causes the case halves to really stick together, so you may have to work at it with a rubber mallet and some prying. The first picture below shows the halves being split using a pickle fork and cold chisel. The second and third pictures below show a trick for separating the large input shaft bearing from the housing. Wedge the two halves of the case as far apart as possible using screwdrivers, chisels, or whatever, which will allow the weight of the input shaft to exert downward force on the bearing - basically, the shaft will be hanging from the bearing. Now use a good, hot torch flame to heat up the area of the case around the input shaft bearing. The more you heat the case, the more it will expand and start to release the bearing. You may also have to tap down on the input shaft while doing this - but many times the whole shaft and bearing will drop right out on their own.
Separation of transmission/differential case Using heat to separate the input shaft bearing from the case Using heat to separate the input shaft bearing from the case

In the first picture below you can see the bearing starting to drop out from the case. In the second picture, you can see the whole rear section of the case being removed. The pinion shaft, input shaft, reverse gear shaft, and differential are now in plain view.
Input shaft bearing dropping out from the case Transmission/differential case completely separated

A3 020 transmissions are notorious for having reverse gear problems. The gears are prone to getting physically chewed and torn up. In the first picture below, you can see the damage to the reverse gear on the reverse gear shaft. In the second picture, you can see damage to the mating reverse gear on the pinion shaft.
Damage to reverse gear on reverse gear shaft Damage to reverse gear on pinion shaft

Now carefuly remove the shift fork assembly, as seen in this picture.
Shift forks, shift fork rod, and shift fork rod tube being removed as an assembly

The gear now on the end of the pinion shaft is 4th gear, and you will need to slide it off while removing the input shaft at the same time, as shown in the first picture below. The gear may slide right off the pinion shaft, or it might be a very tight fit which requires prying. In the second picture below, you can see another bearing plate at the base of the pinion shaft. We need to be able to get to those bolts underneath the pinion gears.
Input shaft and associated gears/synchros being removed as an assembly Lower pinion shaft gears are in the way of bolts for the lower pinion shaft bearing plate

While you are removing gears from the pinion shaft, you may want to check for end-play where applicable. Any place you see these Eaton-style retaining rings being used, you can use feeler guages to measure the gap between the retaining ring and the gear surface, and that's the end-play. In the first picture below you can see my dad measuring an 8 thousandths gap. If adjustment is required, retaining rings of different thickness are available. I am told they are color-coded. In the second picture below, you can see the pinion shaft with only first and reverse gears remaining. They may need to be pried loose, which can be a little bit of a pain.
Measuring end-play of 3rd gear on pinion shaft 4th, 3rd, and 2nd gears removed from pinion shaft

In the first picture below, you can see the pinion shaft stripped bare. The bearing plate can now be removed, as seen in the second picture. After that, the pinion shaft itself is free to be removed, as seen in the third picture.
All gears removed from pinion shaft Pinion shaft lower bearing plate being removed Pinion shaft removed

It is pretty common to see the large pinion shaft bearing show a lot of wear. In extreme cases, as shown in the first picture below, the bearing case will wear completely through so that the rollers are no longer retained. This is a weak point in the 020 transmission design. The second picture below shows damage to the pinion gear, likely caused by debris from either the pinion bearing or reverse gears.
Lower pinion shaft bearing, completely trashed Pinion gear damaged

The first picture below shows the differential removed from the case (it just lifts out). The second picture shows damage to the differential ring gear (which mates with our damaged pinion gear shown above). The third picture shows the rest of the transmission case, nearly stripped bare.
Differential removed from housing Differential ring gear damaged Case stripped of nearly everything

This is the point where you'd want to decide whether the transmission is worth rebuilding. In our case, perhaps not (because of the ring and pinion damage). If so, it's a matter of getting your hands on any replacement parts needed (synchro rings, bearings, gaskets, gears, etc), then thoroughly cleaning everything, then reassembling.

I am currently working on an A2 transmission, and the disassembly is complete (at the same stage that we left this A3 transmission). Luckily, the A2 transmission has no reverse gear damage, no ring/pinion damage, and no bearing damage. As I clean, repair, and reassemble it I will try to document the process so that y'all can see the rebuild.

9751 views 4 comments, click here to view them!



Post your comments below. Please note that your comments will not be visible until they have been approved by a moderator (me).
Your name:
E-mail address or website URL:
Your comments:
Captcha response: testing


Date: 05/22/07, 19:44:10 PDT
From: Kai
Comments: Great write-up! I need one for the O2J... :)

Date: 08/18/07, 19:32:45 PDT
From: diego
Comments: Very interersant , I have never done a transmission but I love close ratio transmission ,and I have never had good look with volkswagen becouse always coming with open ratio .I just bought a sirocco s week ago with a ff transmission ..Any way thank you

Date: 11/19/07, 20:28:46 PST
From: jeff
Comments: Does the selector shaft come out easily? I has been trying to get mine out for several days and it will only slide about 2cm in each direction. Any advice

Date: 12/05/07, 04:12:19 PST
From: Mitch Jones
Comments: thanks this was very helpful, my 020 was totaly trashed, i thought the clutch was bad......guess what i was wrong, i pulled the drain plug out and all that was there was chunks and chunks of metal from the diff coming apart.
A1 parts for sale:
intake air preheater hose
Item: Intake air pre-heat hose (from exhaust manifold shroud to air box), for Scirocco 2 (1982+)
Condition: New
$12


A2 parts for sale:
A2 GTI dual round grill, with inner lights
Item: GTI dual-round grille with inner lights, bulbs, and lower trim strip
Condition: Used, lower trim strip is weathered.
$35

parcel shelf strap
Item: Parcel shelf strap, 3 available
Condition: New
$3.50 ea.

A2 valve guides, 8 valve
Item: 8 (eight) valve guides, German, standard size, for 8 valve head
Condition: New
$24

wheel cylinder
Item: Wheel cylinder (for rear drums, obviously), 2 available.
Condition: New
$12 ea.


A3 parts for sale:
parcel shelf strap
Item: Parcel shelf strap, 3 available
Condition: New
$3.50 ea.


A4 parts for sale:
ALH water pump
Item: OEM Water pump, ALH engines
Condition: Used, 130,000 miles
$20