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carsluTT
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a good friend of alex's here in dnever is a mad quantum owner and he told me bout this fix he did, thaught maybe somneone round here could use this..
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I knew I'd seen that evil blue thing before when I messed with the one on
>my (now Keith's) red QSW.. I was convinced when I saw that it was made by
>VDO too.. I didn't have the need on the red QSW or the time and patience
>on the blue one to try it, tho...
The one I bought was black. There was a little experimenting that I had
to do. Here's the summary of making one work:
1. The mercedes valves come with a plastic piece with a brass insert that
is crimped onto the valve shaft. That has to be cut off. I carefully used
a die grinder, but a Dremmel would be better.
2. The shaft also has to threaded. I forgot the diameter, but I used a
4mm die. (I had one and it worked).
3. I also had to make the connecting piece. I used 5/16 stock steel bar.
It comes in 1 foot lengths for $1.30 or so. I used a friends drill
press. I tried to find some hard nylon material in the same size (or
something close) but couldn't. It would have been a lot easier to work
with.
I tried a 1/4 inch square axle key, but it proved too thin to work with,
when using an old drill press as a milling machining. -- I'll look up the
drill bit size that I used and get back on it.
Most anyone would have to make this part too, because the link that comes
on the valve rusts in place or so -- It will have to be threaded. That was
a more tedious then anything else. I broke one tap in the first piece I
tried, because I was rushing it and not backing out the tap when it was
going hard.
4. I also had to find a small bolt to connect the valve to the lock lever.
That's another .80 or less. I expect that to break or rust out before the
new valve fails, and will replace it with a stainless steel bolt someday.
5. The mounting holes also have to be threaded. The bolts are 5mm. (.50
for the little bolts.) The VW valve comes with three mounting holes. The
mercedes valve only has two that match the positions. The third one could
not be tapped because, because its was too shallow. I used a threaded rod
that I made into a J-hook screw. I wasn't worth the time it took to heat
it so I could bend it. The valve is mounted with just two bolts and it
seems to be fine.
Other notes:
This same work would make a valve that would work on the front too. You
just don't have to make the connecting link. (The front valve has a nylon
piece that screws onto the valve shaft and it connects to a rod that goes
to the back of the transmission to operate the lock).
On my rear installation, I could not get the metal mount-housing for the
valve off the differential. The bolts were too rounded to get a grip on.
Others might be luckier.
I ended up drilling the pin out of the old valve, and then since the
screws mounting the valve to the housing were really rusted, I cut one
screw off, and sort of pulled the valve off the other two.
The plastic body-bolt holes of the old valve were essentially broken
anyway. (And that is one source of valve failure. More on that later).
After that, I had to use a cold chisel to loosen the ends of the rusted
5mm bolts, so I could get them out of the mounting plate.
After that, it was a matter of putting the new valve in position, and
installing the 5mm bolts, and bolt through the connecting link and lock
lever.
All of this would have been a bit easier with the center muffler removed.
I said before that the mercedes valve comes with a plastic connecting
piece for its locks. I cut it off, and then cut it down so I could use the
part that covers the rubber boot when its retracted (off position for the
differential lock). The plastic cuts pretty easy with a razor blade held
in vise grips.
Because I didn't have a VW connecting link where I could unscrew it and
measure the dept of the hole (for mounting it to the shaft), I drilled the
hole in the new piece deeper the VW did, and then adjusted the length on
the shaft (by screwing it on), until it was the same length as the
original VW valve throw length.
I had a spare differential IU could put on the bench to work with, so it
made the whole task simpler. -- That means keep these notes.
The VW mounting plate curves at the bottom. It has the appearance of being
shaped that way to allow room for the vacuum hoses (probably true), but
when I had the differential on the bench and was checking the setup, I
also found that if the mounting plate is not curved at the bottom (just as
VW designed it), the length of valve shaft travel changes, and the
differential lock won't work if the mounting plate is shaped any other
way. (Ask me how I know that?)
These mercedes valves go used on ebay for $10-15 dollars quite often. I
would not buy a used one for that. New ones list for $75, but I've seen
them around for $40. I just got a really lucky hit bidding on a a new
one for $12, plus shipping.
That's the short of it. --Ask me questions now guys, while all this is
fresh in my head. I would not have spent $40 for an experiment, but now
that I've done the basics, others can go for it if they need to replace
the valve.
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