Date: Sat, 2 Sep 2000 22:40:54 -0500
Reply-To: John Rodgers <inua@HIWAAY.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@HIWAAY.NET>
Subject: Speedometer Failure
Content-Type: text/plain; charset=us-ascii
Well, it seems my 88GL has suffered the famous speedo failure. A little
famous potmetal gear slipped on the shaft, allowing the shaft to slip
out of the hole it rides in, dis-engaging the wormgear that drives the
thing , and causing the wheels to tip into mis-alignment.
What to do? What to do?
I have read a good bit about a potmetal wheel that comes loose from the
shaft and how you have to take all the little wheels loose, and fasten
the potmetal wheel back to the shaft by crimping or using a little super
glue....risky business - both. A slip and you have cracked the pot
metal. To much super glue, and you have glued the works.And besides
that, there is a light coat of light instrument oil all in there. Glue
won't hold.
After dissasembly to identify the problem, I found that I didn't want to
have to fool with the glue and squeeze routine. So here is how I fixed
my Speedo.
QUESTION - HOW DO YOU FIX A 1988 VANAGON GL SPEEDO WHEN THE WHEELS STOP
TURNING?
TOOLS - Screw Drivers - 1 small Phillps, 1 Small Common, Small intrument
technician screwdrivers - 1 Phillips, 1 Common. 1 pr needle nose pliers,
1 jewelers file or fingernail emery board, 1 pr sharp scissor like
cutting instrument capable of cutting sheet brass to 1/32nd inch. 1
drill - dremel tool, Foredom, the like, some small drill bits, and
maybe a grinding burr.
MATERIALS: Sheet brass (hobby shop) 1/64 to 1/32 or so. ( I used a
piece of scrap...not sure exactly what thickness, but easily bent). It
must be sufficiently thick so as to have modest resistance to bending
or flexing.
1) Begin by disconnecting the battery.
2) Sit in the driver seat.
3) Remove the instrument panel cover - Sit in the driver seat, and with
both hands feel for the slots in the back of the instrument panel
cover--toward the windshield. Pull up with the fingers. Should pop
loose. Sometimes a little difficult, but can be done. Learn how...it's
where you have to check and service the brake and clutch fluid anyway.
4) On the left side of the panel is the head lite switch - on bottom,
and a warning lite fixture on top. Both have locking tabs that can be
depressed to release them from the panel. Press and remove ...no need to
disconnect the connectors. Do the same on the right side of the panel.
5) Now remove the two panel anchor screws holding down the left side,
and the one screw towards the windshield on the right side. DO NOT
REMOVE - LOOSEN ONLY - the 4th screw - right front corner.
6) Now jiggle the panel to the left while slightly lifting the left end
of the panel. This will allow you to work the panel to the left a 1/4
inch so it will clear the screw you only loosened. Now the panel is free
from the anchors holding it to the dash.
7) Reach behind the Speedometer and disconnect the wire that is fastened
to the Speedo. It is a slip off connector, easy to remove. You might
want to look at it through the windshield before removal to see exactly
where it is and how it can be slipped off. Easy to do in the blind, once
you see it.
8) Now lift and tilt the panel toward the windshield. There is a large
connector underneath the panel. It is easy to reach now. With forefinger
and thumb pull the connector down to free it.
9) Now the panel is free except for the speedo cable. You can manuver
the panel slightly to press the release lever on the cable connector. Do
that, and the panel should now be free from the vehicle. I did the
speedo cable last since I have big hands and have a hard time reaching
into the little space provided for connection/disconnection. I also
connected it back up first. Easy to do.
10) Lay out a clean white towel on the work table....helps keep things
clean, and you can keep track of little pieces better. Have a good
directional light handy.
11) Remove the four fastening screws from the back of the instrument
that hold the instrument into the panel. DO NOT REMOVE ANY OF THE
ELECTRICAL CONNECTION SHEET MATERIAL FROM THE BACK OF THE INSTRUMENT.
12) Carefully remove the instrument, being aware of the pin sticking out
the front through the glass in the panel. Lay it on its back, dial face
up, on the instrument panel.
13) Remove the needle or pointer. Before you do this. Use tape to mark
where the back of the needle is relative to to the face. That way,
reinstallation of the pointer will be exactly the same. A watchmakers
gear puller was used in this case. Nice to have. However, a shim made
from styrene plastic or this brass or aluminum stock should protect the
dial face under the needle block while you exert a little upward
pressure with a screwdriver blade.
14) Remove the two screws in the dial face that holds it on. Set aside
with the screws.
16) The operating mechanism can now be seen. On the 88GL the mileage
counter wheels are mounted on a shaft with a pot metal gear on one end
of the shaft. On the other end of the shaft is a spacer bushing that
provides proper clearance and separates the teflon gear on the end from
the shaft support. The teflon gear engages a teflon worm gear.
The potmetal gear is locked to the shaft and serves as a stop for all
the counter wheels on the shaft. If the gear loosens, it walks,
increasing the spacing between the wheels. This results in an increase
in the shaft endplay. The shaft then can move toward the worm gear
side and the potmetal gear end slips from its detent. Once that
happens, the shaft cocks over, disengages the worm drive and the speedo
no longer clocks mileage.
17) First setting the shaft back into it's detent, a handled socket was
used for support on the pot metal gear end, and punch and leather
mallet on the other, the Teflon gear end of the shaft was tapped. This
action drives the shaft a tiny bit through the potmetal gear, resulting
in a closing of the spaces between the counter wheels.
18) Noting the screw and plastic pin in the upper left corner of the
cover for the counter wheels, a support finger was designed and
installed.
19) Remove the screw. Using the bit of sheet brass (must be non-ferrous
metal) cut to an "L" shape. This "L" shape must be cut so that the
foot of the "L", when bent 90 degrees along the long side, would fit
over the screw hole and the pin. The screw will hold it in place, and
the pin will help lock it. So two holes need to be drilled in the sheet
brass. They need to be a good fit...no slop.
20) Cut the "L" to size, mark for the pin hole and screw hole, drill and
ensure the fit, then bend the foot.Now the long side of the "L" will be
along side the little teflon wheel, and the other part of the foot will
be over the screw-hole and pin.
21) Bend the long side of the "L" so it is in the shape of a "V". The
assembly should be set so the bottom of the "V" is against the end of
the shaft with the teflon gear. This "finger" should be adjusted by
bending, so that the pressure on the end of the shaft is minimal. When
the finger is correctly installed and adjusted, the shaft will never
move out of position again.
22) Re-assemble in reverse order.
23) When installing the speedo needle be very careful. You may need the
slighest tap to get the needle to seat, but it doesn't take much.
I did make pictures of this process, but it may be a while before I get
them, and I have no idea if they will be good enough to post somewhere.
If someone has the drawing skills, I will be glad to sketch out this
"finger" fix and scan it and email over so it can be redrawn and posted.
Best of luck to all who have to deal with the Vanagon Speedo Fix.
John Rodgers
88GL Driver, Birmingham, AL
