1971-76 BUICK LESABRE AND CENTURION, CADILLAC,
CHEVROLET IMPALA AND CAPRICE, OLDS DELTA 88 ROYALE, PONTIAC
CATALINA AND GRANVILLE
Convertible Service carries a full line of replacement
parts for most 71-76 G.M. FULL SIZE convertibles. Visit our
online store for pricing and availablility.
GM FULL SIZE CONVERTIBLE TOP MECHANISM
TROUBLE SHOOTING TIPS
FROM CONVERTIBLE SERVICE:
here to download our Scissor Top troubleshooting sheets
(Click to open or right click and select "save
as" to save) (.pdf format, requires Adobe Reader)
Slow or inoperative scissor
top: It’s easy to
assume that the problem is the motor, but, friction from worn
parts is the most common cause for a good motor to not be able
to operate the top. Often it’s not just worn side rails or
side gears, but a combination of several of them being worn at
once. See “Worn Side Rail test”, “Worn Side Gear test” &
“Bad switch, relay or motor” tests below to be sure.
Bow folds incorrectly when raising top
(one side goes forward toward the header bow): Two
things control the position of the #2 Bow; See “Worn #2 bow
side brackets” & “Side Hold Down cables” below.
one side of top operates:
Cable may be loose
or broken. Inspect both, first at the side gears, then at the
motor behind the rear seat back. If drive cables are
functioning, perform the “Worn Side Gear test” below,
on both sides.
guide pins won’t
reach forward enough to drop into holes on the windshield:
1. Side rails not adjusted or bent. Follow Fisher Body
Manual adjustments. If problem persists, bent side rail may
need replacing. 2. Top material may be too tight at the
header bow, in the rear quarter, or both. If it is, loosen the
top, if possible, or install a new top after properly
adjusting the frame. Also, see if tightness of rear window
curtain on the #4 bow is holding the outer rear rail assembly
back. 3. If only one guide pin can’t be pulled into
it’s hole, try resyncronizing drive cables so that the bad
side comes up to the windshield a little sooner than the other
TO HELP YOU FIND WHICH PARTS ARE BAD:
Side Rail test:
top lowered 2 feet back from windshield, one side at a time,
grab the front of the side rail and move it up and down. If
there is more than 2 inches of play (caused by slack at the
side rail elbow pivot), the side rail has too
Side Gear test:
With the top folded all the way down, disconnect the drive
cables and unbolt the side gears from the 3 inch siderail
links. Grab the side gear appendage and force it through it’s
travel, all the way forward and all the way back. A worn side
gear will either bind up at one or more points (going in
either direction), or, will move too freely
in either direction. A good side gear will have constant firm
resistance throughout travel in both directions.
#2 Bow Side Brackets:
Check for play where pivot ball/rivets swedge to the bracket;
also, see if bracket is bent.
Hold Down Cables:
side cable should have a 2” shunt cable attached to the #2
bow. See if it’s disconnected or broken, or, if the ends of
the #2 bow core substance can no longer hold the cable screw.
Replace side cables or #2 bow.
switch, bad relay or a bad motor?:
This is a little more complicated. Call our info line,
626-285-2255. We’ll help you, free!