Self Machining Syndrome?
I have heard a lot about this lately. OK, exactly what happens in the tranny
when this happens? My rocco has aprox 150,000 miles on it and I pray that
this will never happen. Can you tell it is going to happen before hand, are
there any signs that it is about to happen? I consider myself to have an
excellent tranny for its age, No grinding, smooth shifting, syncros seem
good. is there anything that can be done to prevent it, like frequent oil
To those who have had this happen to them, what fluid were you using? Were
you using Red line? I have heard people swear by Red line that it makes the
shifting real smooth and I have also heard it can cause problems later down
the road. I have not done the switch yet.
What type of driving do you do., city, Highway, balls to the wall at every
light, never reving past 5000. I am just trying to correlate these things to
see if it can be prevented.
Brian 86 16v
There's been a few questions lately concerning the dreaded 020 tranny
Self Machining Syndrome (or SMS) and which years and or transmissions
*will be* affected. It just so happens that the April 1990 edition
of VW & Porsche can answer these questions. There is an article
called 'A brief look at the 020 5-speed transmission', with an
information chart showing all the production years, codes and gear ratios.
It has a multi page side-bar entitled 'VW 020 Gearbox Failures: Causes &
Cures'. This is what I'll be typing in. ON WITH THE SHOW ALREADY!
The problem has become a classic one for VW owners with close-ratio
gearboxes: sudden & catastrophic failure of the normally well-mannered
and durable gearbox. The 020 is a tough tranny, one that stands up well to
the abuses of hard driving and the added torque from such upgraded powerplants
as a Techtonics Tuning 2020 motor or a turbocharged engine. Now, stock
transmissions, carefully driven, are failing when the differential eats
it's way through the case.
IDENTIFYING THE CULPRIT
Those transmissions built with serial numbers up to 14102 (gearboxes
up to October 14, 1982) have snap rings installed on the differential pinion
shafts. Those boxes do not usually have any problems. Cars with the wide-
ratio gearboxes do not seem to have the problem.
The cars affected include GTIs and GLIs from 1983 to 1986 (both A1
and A2 chassis), 8-valve Sciroccos from 1983 to 1986, and 1984 to 1986
Cabriolets. These cars had close-ratio gear boxes starting with serial
number 15102 (gearboxes built after October 14, 1982) and up, and did not
have the snap rings installed. The grooves are still there, but apparently
some engineer at VW dreamed up the idea of using a larger head on one of
the rivets as a retainer and doing away with the 15 cent circlips. The
special rivet is simply not able to properly retain the pinion shafts.
Under even normal driving conditions, there's a chance that the pinion
shaft works itself out, let's things tilt around and eventually machines
a hole in the transmission case. Shop supervisor Paul Boot at New Dimensions
said that most of the failures they've seen occur between the 50,000 and
120,000 mile mark.
One somewhat limp "cure" that VW has incorporated is to use rivets
with a thicker head. This still won't provide the positive location of the
shaft afforded by the circlips, but at least it takes longer for the pinion
shaft to pound it's way through.
No one we've talked to has taken apart a late-model non-16v close-
ratio box, so we're not sure if VW continued with the rivets or has returned
to using the circlips. On the gearboxes used with 16v motors, VW has
resorted to using the circlips again.
For VW's service differential repair kit (#171-498-088) used when
replacing the ring & pinion (either when changing ratios or as a service
replacement) the rivets are replaced. The kit included eight studs and
nuts (to be used in place of the rivets), washers, retaining bracket -
and two circlips.
IDENTIFYING THE DAMAGE
The first symptom that your beloved car has been attacked by this
design flaw is a gear oil leak under the transmission and, perhaps, strange
noises from the gearbox. An alert driver will notice it right away. Most
gear oils have a distinct appearance. (It's thick smelly stuff) Note
that a failed differential side gear retainer is not the only source
of a gear oil leak. Leaky side seals or a worn-out output shaft seal are
other potential sources. Both of those tend to be slower, smaller leaks
then a case that's ground through.
Don't worry - if you miss the first hint, you'll get a second
chance. Like most second chances, this one can be a bit more expensive
than the first. You'll notice it when all of a sudden, your clutch fails,
but strangely, when you check the adjustment, it's okay. One symptom of
a slipping clutch occurs on a long upgrade, when the engine revs climb
but the road speed stays the same. Is it all over at that point? Will
everything in your tranny be trashed?
At this point, we would hate to call it a credit to VW engineering,
but here we go: When to retainer rivet fails, the hole is ground high
enough up on the case that it does not immediately drain all of the gear
oil. With time, it will continue to pump more and more out. The first
damage is "just" the clutch and pressure plate. As the gear oil level
drops, the next thing to go is fifth gear, soon followed by the rest of
the gears. In short, many of the affected transmissions are repairable,
if you stop driving the car immediately. That includes towing with
the front wheels on the ground too.
So, you noticed that puddle and it's definitely gear oil. You
checked your tranny case and it has one of the "problem" numbers. What
If you call a dealer thinking that they will take care of it
for you, you might want to have smelling salts handy. First of all,
VW does not consider this a design fault or any kind of warranty problem
if it occurs after the standard warranty has expired.
Will VW repair your defective transmission under warranty? It
depends. All the cars that suffered from the problem are out of the
factory's two-year 24,000-mile warranty. If you let the dealer sell you
an extended warranty, it will probably cover everything but the clutch.
We feel that your dealer should hear about the problem from you, and
the VW district office should hear about it as well. It might not do
any good, but at least it's a reminder.
You will pay full rate on this one. A new transmissino case, to
replace the one with the hole in it, lists for over $500. On top of
that, you'll have to add the cost of removing and replacing the gearbox,
and also throw in the bucks for a new clutch and a complete transmission
rebuild. Any guesses on what the bill will be?
You can lower the cost of having it repaired at the dealership
a bit if you're willing to remove the transmission yourself and
take it in for repair. You'll still need to replace your oil-soaked clutch
Yet another way to save some money is to purchase an entire
replacement gearbox. Note that when you do buy a
replacement close-ratio gearbox with a serial number in the problem range,
it will probably not have the retaining clips either.
There is another way to go, which is definitely more cost-effective.
Darrel Vittone at Techtonics Tuning offers a service for customers who have
suffered the Self Machining gearbox syndrome. If you are certain that you
discovered the problem before there was any major damage, the easy way
out is to remove your transmission, clean it up and ship it to Techtonics.
For a charge of $300 Techtonics will disassemble the transmission and
repair the case damage using a specialized welding procedure called TIG
welding. This type of welding uses a tough tungsten electron and an
evelope of inert gas to keep oxygen from entering the weld area. It makes
it possible to weld aluminum alloys like cylinder heads and tranmission
cases and have them be as strong or stronger then new.
Techtonics then puts the trans back together for you, using
the circlips that VW should have used in the first place.
As one might expect, the tranmission repair job is not simple.
The entire tranmission and differential, every last piece, must be
completely disassembled before any welding is possible. The welding
job itself is straigtforward. The location of the hole is far enough
away from anything cricical that warping is not a problem.
There's a few more paragraphs, but you get the gist (and then some).
Sorry this was so long, but I hope that this puts the question of
if your affected or not away forever. I think I'll post this to
the VW newsgroup too, many people seem to have questions about this.