Ed's 1990 Porsche 928S4: Winter Wheels / Windshield Scratch / Broken TT

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January through July 2001

Well, upgrades are slowing down for awhile.  I seem to be doing more maintenance than upgrades now.

New Winter Wheels and Tires

Wheels are Mille Miglia Cup 2, 17x7½ front, 17x9 rear.

Tires are Bridgestone Blizzak LM-22, 225/45-HR17 front, 245/40-HR17 rear.

Package purchased from 928 Specialists.

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View from My New Office

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Fixing a Windshield Scratch

What Happened

Sometime over the winter, a tiny pebble embedded itself in my passenger-side wiper blade.  Unfortunately, I didn't notice it until I had used the wipers a few times.  It left a rather nasty arc-shaped scratch approximately 20 cm long, as you should be able to see in Figure 1 (it's the mostly vertical scratch in the center of the photo; don't confuse it with the horizontal border of the dashboard inside the car). picture
Figure 1:  Scratch, viewed from outside 		picture
Figure 2:  Scratch, viewed from inside

The Solution

Having heard good things about some products from The Eastwood Company, I decided to give one of their products, "Glass Polishing Kit Pro, item 40011", a try.  It worked great!  It seems that as long as scratches aren't too deep, this approach should work.

What You'll Need

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Figure 3: Stuff you'll need		 Figure 3, from left to right:
  • beverage [optional]
  • drill or polisher to spin buffing wheel
  • Rhodite polishing compound (from the Eastwood Glass Polishing Kit)
  • buffing wheel (from the Eastwood Glass Polishing Kit)
  • container to mix polishing compound (it's a powder) with water (I started with these clear plastic bottle bottoms, but these turned out to be too flimsy and too irregularly shaped; I later switched to a margarine tub) and some kind of mixing stick (I used a straw, but a popsicle stick would have worked better)
  • masking tape and plastic sheeting (not shown) to mask off areas not being worked on
  • sponge, paper towels, and glass cleaner to clean up the mess

What You Do

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Figure 4: Mask around work
area and tape inside of
window to mark scratch		 picture     
Figure 5: Polish, polish, and
then polish some more		 picture     
Figure 6: What it looks like
after a couple minutes of
polishing (don't let it get
hot and/or dry)		 picture     
Figure 7: A closer view

It's really pretty easy:

  1. Mask off the area you're not working on [Figure 1].  You definitely don't want the polish getting on your paint, and it will splatter and spin off the polishing wheel.
  2. Apply some masking tape inside the window [Figure 1]; once you get polishing, you probably won't be able to see the scratch anymore (it'll be obscured by the polish), but you'll be able to see the tape.
  3. Mix up a batch of polish, following the directions on the Eastwood Glass Polishing Kit.
  4. Apply polish to the scratch area.
  5. Polish with the buffing wheel [Figure 2], but don't let it dry or get hot.  Recommended buffing wheel speed is no more than 1500 RPM.
  6. Periodically, sponge or towel off the polish and inspect scratch area.
  7. Repeat steps 4 to 6 until scratch is gone, pausing to take sips of optional beverage if desired.  Based on the extent and depth of the scratch, this may take some time.  Mine probably took at least 15 minutes.
  8. Remove masking tape and plastic masks.
  9. Do final cleaning with glass cleaner and paper towels.
  10. Finish remainder of beverage. [optional]

Broken Torque Tube (Drive Shaft, Actually)

On June 26, I had just left home when I hit the go pedal and the drive train let go.  It felt like and sounded like the torque tube broke.  It did.

picture       The shaft broke at the rear between the splines and the smooth part of the shaft.

 

Closer view of the shredded shaft.

Hmmm... it looks like the left side of the shaft might be loose.

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picture       It was; I was surprised to pull out a rather long shard of shaft.

 

Same shard flipped over to view the exterior side.       picture

 

picture       Thanks to 928 International, I had a replacement torque tube in a couple of days.  Actually, this isn't the one that wound up in my car.  The one that finally went in my car was a second one 928 International shipped me because the shop messed up this one.  The one that was finally installed was the older constant-diameter-shaft type, which I understand is not as subject to fracturing.

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