dead power top
Thread Starter
8th Gear
Joined: Oct 2002
Posts: 8
Likes: 0
From: New Hampshire
dead power top
I have a '90 Cab which in the 10 years I've owned it has had the power top break 3 times. This last one was catastrophic failure..one side started up without the other (bad sign to begin with) and before I could stop LOUD pop and the thing basically crumbled. The scissor portion of the frame on the passenger's side broke (very heavy casting) and the passenger's side window frame buckled. According to my body shop guy the entire works of the top have to be replaced as the individual frame parts are not avail. separately. I've also been told that you can convert it to a manual top..this seems like the plan since the top is not very heavy and the motorized part of this has now failed 3 times. It seems way over-engineered to me. I am looking for advice about: a)am I wrong about this whole issue b)who would you have replace the works..body shop, mechanic? c)am I stupid to do this..will it lower the car's value? Thanks. I'm in central NH where we don't have Pcar wrenches on every corner. I do have a guy who is pretty capable but don't know if that is the best way to go. I love the car but I don't love the top. Appreciate the help. 
1st Gear
Joined: Apr 2006
Posts: 1
Likes: 0
From: Portland, Maine
I have an 88 cab that is operated electricly for latching and unlatching at the windshield and manually for opening and closing. The replacement parts I would think are availabel through a juck yard. After all the hardware is fixed and frame is operable by hand I had an automotive electrician wire a 3 pole toggle switch (20amp I think). He was able to bypass the convertible control box (under the pasanger floorboard) and mount the switch left of the ignition switch. I did supply the tech with a bentley manual but he also pulled wiring diagram from the net. hope this helps
Rennlist Member
Joined: Jun 2004
Posts: 1,081
Likes: 62
When replacing the top on my 87 cab I discoverd the RH main folding top bow was cracked; basically a thin aluminum casting. I TIG welded the bow and put it back together. Along the journey of the replacing the top I learned that there a few things than can cause a few failures. I'm no expert but here are some things to look for:
A) drive cables on between the electric motors and the gear drives (Bimmer by the way), when the cables break the "sync" or "timing" between the LH and RH sides opening and closing is not in unison; causes several types of failures, such as: gear boxes, frames, etc.
B) worn worm gear and planetary gears between the gear drives and the drive cables, same type of failures as "A" above
C) lose bolts holding the gear drives to interior body side panels, gear drives get out of sync and you get the same type of failures.
Thinking about the car is nearly 20 years old, I guess we can't always have egg in our beer.
I came across a CD video, believe it or not, that illustrates how to set up the top with respect to adjustments and timing. The CD is a bit funny to watch however it along with a written manual makes you 80% wiser in the job.
A) drive cables on between the electric motors and the gear drives (Bimmer by the way), when the cables break the "sync" or "timing" between the LH and RH sides opening and closing is not in unison; causes several types of failures, such as: gear boxes, frames, etc.
B) worn worm gear and planetary gears between the gear drives and the drive cables, same type of failures as "A" above
C) lose bolts holding the gear drives to interior body side panels, gear drives get out of sync and you get the same type of failures.
Thinking about the car is nearly 20 years old, I guess we can't always have egg in our beer.
I came across a CD video, believe it or not, that illustrates how to set up the top with respect to adjustments and timing. The CD is a bit funny to watch however it along with a written manual makes you 80% wiser in the job.
