Crawls Backward (When Alarmed)

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Saab c900 Seat Bottom Repair Completed

I finished sewing the rod/frame and its new fabric cover to the seat.  I did it section by section over several nights so as to keep my sanity. 

It seems to be attached tightly to the seat cover.

Now to attach it to the seat.

I punched holes through the new material in the locations where the clips will attach.  I did double check the locations prior to making the holes.

Here's the seat cover with the clips attached to the rod.

I had to do this twice.  The first time I found that one of the clips pulled up off the rod, so I went back and squeezed the the ends tighter around the rod so they'd stay in place.

Now to attach the clips and see if all this work was worth it.

This is one of the clips (there are 7 total) poking up through the seat foam.  There were slits cut in the foam to allow the clips to pass through.

What we need to do is just pull the clip up and attach it over the seat frame.

Easy to say, not quite so easy to do.

The two rear clips were easy, as were two of the side clips.  I just pulled the clip up with pliers while pushing the frame down, and hooked the clip on the frame.

Whoo hoo!

The arrows in this picture point to two of the clips, just in case you didn't believe I actually did this!

Note all the obstructions in the way...and hold that thought.

I'm sure this was originally done before the motors, wiring and seat bottom frame that bolts to the car floor were on the seat.

The three clips on the semi-circular part of the rod were difficult to attach.

I tried pulling them up with pliers, but I couldn't keep enough of a hold on them - they kept slipping off the pliers.

I pondered this for a day or so, then I got an idea.  I put the top of the clips around a piece of small chain.  I could then really get good leverage on the chain (and the clips) and pull them up.

I also used a block of wood wedged between the seat frame and the cushion to push the cushion down for more clearance.  See the arrows in the picture above for the chain and wood block.

Here's one of the clips after attaching it.  I used a relatively thin chain, so I could just clip it with nippers after the clip was attached.

The center clip is under the seat tilt motor bracket, so it's virtually impossible to get to from above.  I slipped my hand under the seat cover from the front, clipped on the chain, and then passed the chain through the slit in the foam.  It worked!

I reattached the side clip rods (previous post), as well as the clips holding the back and front of the cover over the cushion.

Turns out I lost a clip somewhere, so I just used some 18 gauge picture frame wire as a substitute.  It's not like it will be visible when the seat is in the car.

You may also recall the two cable ties that held the cover onto the front corners of the seat.  I had cut those off during removal, and left the cut ends on the cover to use as a guide.

Now I was able to replace those ties with new ones (red arrow).

You may also recall my grousing when taking the seat tilt motor mounting bolts off.  I needed a ratcheting box end wrench for that job, so I got one - actually 3: 8mm, 10mm, and 13mm.  Probably the three most common sizes on a Saab 900.

The wrench was great to have and made the job of remounting the motor go much faster.  Here's the whole assembly back together with the replaced drive cables.

Now for the moment of truth.  Let's turn this puppy over and see how it looks!


Much much better.  The center part of the seat bottom now follows the contour of the foam.  The seat's still pretty dirty, but I'll clean it up shortly.

Those creases and wrinkles in the material from sitting flat for years which you see in the picture have already beginning to relax more than the picture shows.  It looks pretty good.

Too bad I have another seat to do...sigh.  But now I know what I'm dealing with, so it will go much faster.


Sewing a Saab c900 - Seat Bottom Repair

This is the most tedious part of the seat repair.  That's the bad news.  The good news is that it appears that my strategy is actually going to work.

This is the rod that both helps to give the seat bottom its shape.  Originally it was covered by fabric (the light brown fabric you see in the picture).  The rod passed through the fabric, almost like a tunnel.

Then there are vertical clips that clip over the rod and onto the seat mesh frame below.

You can see how my fabric is torn up.  The plan is to make a new strip of fabric to function the same way the original did. 

Side note:  I am told this failure is not uncommon on c900s.  Oddly enough, the other three I have owned (still have one of them) never did this.

I procured some upholstery fabric - it's actually a bit heavier than the original material.  I hope the added weight will help keep it together over time.

I measured the original piece as best I could.  In this picture, you can see that the fabric tore.  One side of it is about 15mm, so the original was probably a bit over double that - maybe 35mm.

The original seams were all sewn as one piece - the brown fabric - the seam where the two leather pieces join - and a piece of foam padding.  We'll see this closer a bit later.

I decided to play it safe and use more material than I probably needed.  I can always trim of the excess.

So I cut strips about 40mm wide from the new material.

The original plan was to sew the material onto the rod and the leather seam at the same time.

I quickly found out that the rod wouldn't stay in place, and running a needle though the leather was going to be difficult.

I reverted to Plan B.  Instead of sewing the whole thing all at once, I decide to first sew the material onto the rod, then sew the material onto the seat cover.

This is a shot of sewing the material to the rod.  Piece of cake, and it got me some sewing chops in the process.  (Like practicing scales on the guitar).

I used a standard hand sewing needle - the thread is a #90 automotive thread, which is about the weight Saab originally used.

This part took an hour or so.  When I do this kind of work my mind goes into thoughtful mode.  This time, I decided the theme song for this would be Miles Davis' "So What," but renamed to "Sew What," or alternatively "Sew WHAT?"

I also recalled Toy Making Dad saying to me "99 percent of car owners wouldn't attempt what you're doing."  I'm still not sure if that was meant to be encouragement or a comment on my sanity.

Here we have the new material sewn onto the rod.  I never said it would be pretty.  At this point, I'm very encouraged that this will actually work.

The "X" marks are the approximate locations where the clips will connect to the rod.

You can also see that (fortunately) I had a "pocket" of the old material at each end that I could tuck the rod into.  This helped enormously for the next phase.

And here's the next phase.

I lined up the new material with the old.  One important thing the height of the rod.  If it's too far away from the seat, there won't be a deep contour on the other side.

Then I used a darning needle to sew the new fabric though the foam and the leather seam.  I have some leather needles with special points, but they're machine needles - the heads are too thick to go though the leather.

In the picture, the red arrow points to the seam where two pieces of leather come together.  You can also see that when the seat was made, the two leather seams, the foam insert between the leather and the brown fabric were all sewn together at once.  Since this was done on a big machine, it wasn't too hard to do.

I don't have that luxury, hence my somewhat piecemeal approach.  I'm also only running the thread through one side of the leather.  The leather's heavy, and I'm hoping it will work this way.  So far I have a nice tight join.

Finally, you see I have to use a pair of pliers to pull the needle through the thick leather.  It's slow going, but it's working!  I think it's going to work.  And I'm trying not to think about the second seat I have yet to do.


Saab c900 Seat Cover Removal

With the seatback cables replaced, it's time to remove the bottom seat cover.  I hope to be able to repair it so it will return to its original contour.

There are a number of clips that fasten the cover to the frame.  Here I'm pulling one of them off.

There are some cable ties that hold the two lower front corners onto the frame.  I just cut them off.

I'll replace them with new ties when the cover goes back on.

There are also two heavy rods that are on each side of the seat cover at the bottom.  These pull the cover down on the sides.

They each just slide over a clip on the seat frame - see the arrow.

This one pulled right up easily, while the other side needed some encouragement with a screwdriver to pry it off.

I should mention all of these pictures are looking "up" from the bottom of the seat.  The seat was turned upside down on a stool for this work.

With that side rod released, we can begin to slide the cover off one side.

I had a mixture of excitement and dread at this point.  Excitement that it was going easily and all was going well.   Dread that I'd forget how it all goes back together.

But I do have pictures!

The outboard side has to have the trim holding the seat controls removed.  It's held in by three Torx fasteners.

One's at the back.

One is on the side under the fore/aft/up/down switch.

There is a third under a plug on the rear side.  In actuality, I didn't have to remove it - I was able to slide the cover down enough to get to the rod.  I didn't feel like taking it all off if I didn't have to.

The switch knobs pull right off.

You can see there are 4 switches - for each motion for the seat bottom.

Pull the cover down and you have access to unclip the rod as we did on the other side.
There are also 2 clips and some upholstery tape holding the rear of the cover to the frame.

The cover just pulls off at this point.  Whoo hoo!

You can see the thin rod I've been referring to.

Originally, this was sewn to the seat cover, and the clips pass though the cushion and pull the cover down into the seams in the cushion, giving it that familiar (and lovely) shape.

There are 7 clips for the rod and cover, by the way.

The grey thing covering the foam cushion is the seat heater.

Here's the bottom of the seat cover itself.  You can see the material that was sewn around the rod - the brown cloth.  It's ripped/torn/rotted away.  The cover then just began to sit flat across the cushion with nothing holding its shape.

My plan is to get some new material, and sew it up as it was done originally.  I don't think it will be too difficult, but who knows.  I haven't used a sewing needle for 30 years. 

But I do have a heavy needle and some automotive thread. 
Here's the Scandmec stamp on the seat heater.   

Scandmec is now known as Kongsberg - based in Norway with plants around the world.

These particular heaters were made at their plant in Mullsjö, Sweden.

Isn't the internet fun?


Saab 900 Seat Tilt Mechanism Repair, Pt. 2

The whole time I was taking the gearbox/drive off the seat, I was eyeing that big green spring and hoping I wouldn't have to remove it.  Ha.

Turns out it has to be removed to give the drive enough clearance to be removed.

The spring holds a lot of tension - it's a big part of how a human person is held up when sitting in the seat.  Finally I remembered I had a smallish pry bar.

I used that, along with some fairly stout pliers to pull the spring hook off the seat bottom webbing.  I undid some of the cross supports, and pulled the spring toward the center of the seat while pushing the side bar of the mesh outward.

It worked!

Then I could just pry the gearbox off the splined shaft, and remove it from the seat.


On the top you see the original, broken drive and housing.  The one at the bottom is the replacement.

The inner cable slides right out of the housing.  It would be easy to use some sort of steel conduit or even a heavy, thick-walled rubber hose to slide over the housing as a fix.  I suspect it would work well.
But since I have a good replacement in hand, I'm not going to test that theory!

Replacement is straightforward.  Slip the drive over the splined shaft on the seat.  You can also see there is a locating pin on the seat frame - the drive housing slides over that.

You can also see the 8mm bolt that holds the housing onto the drive.  I had yet to tighten it when I took this picture.

Last step is to put the plastic cover - the one marked "V" - back on.

I was wrong about the "V" being an arrow, by the way.

When I went to reconnect the drive back to the motor, I had to remove the cable on the other side.  And in the process, I found that it too was broken!

Good thing I have a lifetime supply of these parts, huh?

Now that I had done one side, the second side was very easy.

This is the gearbox cover.  You may recall my musing about the "V" stamped on the cover for the other side.

This one has a "H" instead of a "V."  Ironically enough, Sven of Argapa Ukuleles had known right away what the "V" meant and emailed about it.

This "H" is for höger - Swedish for 'right.'  And the "V" is for vänster - 'left.'  Makes perfect sense to a native speaker.  Thanks for educating me, Sven!

(Be sure to check out the amazing ukuleles he makes).

Since I knew what I was doing, the höger cable took a mere ten minutes. 

Recall the seatback is still twisted at this point.  I need to realign it so it will work properly - meaning that both sides will move in unison - before I connect the cables back to the motor.

I sat the seat on the floor and used a socket to drive each of the cables manually until the seatback was fully upright.  There is a mechanical 'stop' where the seatback is upright.  I just turned the cables until I reached that point.

I don't have any sockets smaller than 6mm, so I wound up using a 3/16 socket to match the square drive on the cables.  Worked fine.  I'd guess the cables are about 3mm, but anything close will work.

Oh.  Here's one picture I wanted to throw in if you are contemplating this yourself.  (Out of order in terms of the reassembly but there you have it).  The green arrow points to the spline drive on the seat mechanism.  I referred to it a number of times, and this is it.

The mating spline gear in the gearbox housing slips over it.

Now we can connect the cables back to the motor.

I had a hard time pulling the cable ends upright off the motor and the clips that hold the cables onto the motor mounting plate.  The cables go into the motor horizontally, so it's difficult to pull them out.

It dawned on me that the proper way to connect - or disconnect - them would be to unbolt the motor from the plate it's mounted on.

In the picture above, you can see me using an 8mm wrench to remove the 2 bolts for the motor.  (Note to self:  Wouldn't this have been easier with a ratcheting wrench?)

In that same picture above, the red arrow points to one side of the motor where the drive cable enters the housing.  There is another cable connection on the other side.  The two green arrows are the clips that hold the ends of the cable drive housings.

Here's the motor up off the mounting plate, with the two cable drive ends slipped onto the motor.  The red arrows point to the two ends of the cables.

We just push the cable ends down onto the clips and the cables are held in place.  Then we bolt the motor back down and the replacement of the cables is done!

Now we'll remove the bottom seat cover to (hopefully) repair the places where the cover has come apart from the rod and has made the cover lie flat instead of following the contour of the seat cushion.


Saab 900 Seat Tilt Mechanism Repair, Pt. 1

With the seat out of the car, we can take it to The Dungeon and find out what's wrong with the tilt mechanism for the seatback.

Here's the seat from underneath.  There are four (!) motors to make it all work.

The motor at the top drives the seatback tilt via two cables.  The motor on the left with the green connectors is for the fore-and-aft adjustment.

The second motor on the left is for the rear of the seat bottom rise/lower, and the motor on the right is for the front of the seat bottom rise/lower.

Here's what is causing the seatback to twist.  The cable housing for the left side of the seatback tilt is broken.  This is a very common issue on 900s with power seats.

The housing is a thick plastic tube.  You can see it has to make a fairly sharp turn when it goes from the motor back to the seatback.  Over time, it can break, which causes the cable itself to bind.  With one side not working, the seatback becomes twisted as a result.

Replacement is the repair - although after looking at the broken housing I would think you could slip a flexible steel rod over the housing and it might work also.

Looking down from the top of the seat, you can see that the left side of the seatback is further back than the right.  The left side has the broken housing - its cable won't move.

The right side can move, and in this instance it was moved forward, twisting the seatback.

The driver's side seat has the same issue...I'll fix that one next.  But first let's fix this one.

I've managed to procure two motors, two left-side and two right side cables in good condition.

You can see how the tilt adjustment works by studying the whole assembly. 

A switch on the side of the seat controls the tilt motor to run in a forward or backward motion.

The motor drives both seatback cables at the same time.  The cable rotates in its housing.  The end of the cable is connected to a gearbox that contains a gear driving a splined bushing, or hub.  The cable thus drives the bushing in a circle.  You can see this gearbox and the splined gear in the shots of the assemblies on the workbench above. 

The bushing fits over a mating splined shaft housed in the bottom of the seatback which runs horizontally.  That shaft is connected to a geared wheel which in turn is attached to the seatback.  The rotation on the cable goes through the shaft, and tilts the seat backward or forward depending on the direction of the motor.

This will hopefully become clearer as we see how everything is installed in the seat.  It's a very simple, yet clever design.  But I still prefer manual seats.  I suppose I am stoopid.

So let's get the assembly out of the seat and replace it.

First thing we do is remove the outside plastic cover.  This takes a T-30 drive.

This is the easiest part of the whole job.

There's a plastic cover over the gearbox.  We need to pull back the upholstery a bit to get to it.

There's a clip holding the side of the seatback upholstery at the bottom.  You can see it here.

Before I started this job, I figured I might need some special tools.  (You can never have enough tools anyway, so this was an excuse to get more).

Here I used a pair of Osborne fabric stretching pliers to pull the upholstery up and off the clip.

On the left you can see the outside of the big gear connected to the seatback frame.  That's what gets driven to move the seatback forward or backward.

The arrows in the picture to the right show where the gearbox cover is located.  It's clipped on to the gearbox itself.  We need to pop that off.

Note the big blue-green spring.  There are four of them which hold the corners of the seat mesh to the seat frame.  I was hoping to not have to remove it when taking the gearbox out.

Silly me.

It's harder to see, but this is a portion of the cover viewed from the outside of the seat.

I was able to push the cover off the gearbox from this side...

...and then pop it off from the rear.

Here's the inside of the gearbox cover after removal.  You can see the three tabs that clip onto the gearbox.

I'm pretty sure that molded "V" on the cover is to point to the top side of the cover to aid in assembly.  Clever.

Or it's just a random artifact from the molding machine.  You decide.

Now we can access the 8mm bolt that secures the gearbox drive to the splined shaft in the seat.  Finally we can see the gearbox clearly.

From this picture you should be able to visualize how the tilt mechanism works. 

This is a very tight clearance - I couldn't get a socket in there, so I used a closed-end wrench.

Tool Note to self:  procure a set of ratcheting closed-end wrenches before you do the driver's seat.