95cab

My drivers side cab transmission 'went' and the motor managed to pull the weld for the mount out of the chassis. Anyone seen this? Repair includes rewelding mount and replacement of transmission...not cheap.

Mike J

Did the transmission case crack? Do you have pictures? I have not heard of this failure before...

Cheers,

Mike

vjd3

This is all-too common ... the weld breaks, it gets out of alignment a little, gets worse and then bad things happen. You don't notice because the other two (?) welds are holding it on. My former C4 cab had a nut inserted behind the sheetmetal for the transmission where the weld had broken, but I'll be damned if I know how they got it in there as it's an extremely narrow space. There was a thread a couple years ago about this ... it seemed to me that you should be able to get some sort of threaded clip in there to accomplish what the weld did. I gave up and used the top manually.

nile13

We did this on mine and Riche's (Monkey Boy on Rennlist) car about a year ago. He has details on the inserts and insert tool.

That welded nut on the back of sheet metal is one of the dumbest designs I've seen. and I've seen some dumb designs

95cab

Tried, but can't get a picture with tranny in - and not prepared to remove - it's just too tight in there. Vic - sounds like you have seen this before. My weld isn't really broken - its in the process of going - it's probably only caused a 1mm shift - do you think that it enough to cause the transmission to get out of alignment enough to cause a break? Proposed fix (in addition to new tranny) is to re-weld both sides (cautionary on other side) with a fish plate through to the wheel well (as I understand it).

vjd3

It could be so many different things ... mispositioned microswitch allowing the arms to turn too far, cables getting shorter due to wear, friction in one or the other transmission because the grease has worn thin ... it's really a terrible system and a lot of it dates right back to the 1983 911SC cabriolet.

I like the insert fix better than trying to re-weld it. I still would recommend forgetting all about it, disconnecting the arms and removing the cables and transmissions and just putting it up by hand. Then all you have to worry about is the power latches up top.

MonkeyBoy

Do a google search for rivnut. Great product for solving the welded nut problem, if that's your issue. I had a snapped transmission housing welded as mine was cracked and also used a rivnut to replace the missing welded nut and it did the trick.

nile13

Rich, did you get the things reconnected and re-synchronized? If so, what's teh procedure?

I should have my roof replaced nex week and would like to get the stuff back in order.

briefescape

When I refurbish my cab I had a right mount (transmission ) issue , got that fix and two new cables plus install new roof (OEM ) all for less $1900 . The top looks great and now works well .
I also don`t believe it is the best system as far as smoothness goes but at least it works well now

MonkeyBoy

I did it myself - just eyeballed it. My top was due for the recall that replaced the long pins with short ones so I brought it to the dealer and asked them to check the synchronization and I believe they said it was fine. Unfortunately I had to sell the car a few months later so I can't say how well everything held up.

nile13

Rich, which pins are we talking abou here? The back pins that leave vampire teeth holes? The only recall I knew about was for the top motors.

When you eyeballed yours, did you somehow line up the big transmission arm before tightening the center bolt? What else is adjustable there?

Thanks! I do owe you more Sierra's

chet

For alignment, there is a rectangular indentation in the center of the transmission gear. On the lower arm that bolts onto the transmission, there is a rectangular protrusion across the inside of the bottom of the arm with the bolt hole. The tightened bolt locks the gear to the arm, so that when the gear turns the arm turns. When you loosen that bolt so that you can operate the top manually, that just allows the locking pieces to disengage.
If you tighten the bolt when the indentation isn't lined up with the protrusion, is doesn't lock the two together.
I found it easiest to leave the lower portion of the arm attached to the transmission, and make a mark (or put a piece of tape) on the transmission housing showing where the arm needs to be pointed when you are going to be reattaching the transmission. Before putting the new cable with worm gear into the transmission, get the arm lined up with your mark. Once the worm gear is in, the only way to get the arm into the right spot is by spinning the cable, but if you have it in the right position before you put the worm gear in, it's pretty easy.

MonkeyBoy

Follow chet's advice - I think that's pretty much what I did but don't remember exactly. As for the pins, part of the locking mechanism recall was to replace the back pins with slightly shorter ones, IIRC.

nile13

Thanks, guys!

The problem is that I've disconnected the driver's side tranny to replace the cable and did not indicate where the arm should be. So I'm aftraid that the gear might run out of teeth at the end of travel... Any thought?

chet

Just before you get ready to put the transmission back, attach the lower arm to the transmission without the worm gear from the cable inserted yet. You will be able to freely move the arm in a full circle. Hold the transmission up to the spot where it will sit, and move the arm in a semicircle along the path it will follow when it's working. If the teeth from the central gear are engaged with the little gears that connect to the worm gear (which isn't in yet, or you won't be able to turn the arm), the arm is attached right side up. If not, loosen the bolt holding the arm to the transmission, turn the arm 180 degrees, and tighten it up to the transmission again. Now you don't have to worry about running past the teeth.
Get the top into the position it is going to be in when you reconnect the cables (it has to be mostly closed so that you can get the cables into the motors behind the back seat, but I think there may be a bolt holding the transmission to the body that you might have trouble getting to if the top is completely closed), hold the transmission up to the where it bolts on, and now you can see where the arm is going to have to be to connect back to the top. You want the arm to be in that position when you put the worm gear in, because you can't rotate the arm once the worm gear is in other than by turning the cable.