928 windows not working
07-26-2015, 09:49 AM
#16
Rennlist Member
The pod guy used to have a great write up about this. It is no longer available but I had it copied to a word file that I am pasting below. I don't have the pictures and the text format does not help, but here it goes.
Door Windows
The power windows on the 928 are simple and reliable. The most common wear items are the guides. Without direct experience window repairs can be time consuming and frustrating. Observing a few critical procedures and the windows will continue to operate like new forever.
Components
The window. The 928 windows came in two different tints - green and bronze. The window is typical tempered glass with a metal support fitted to the bottom of the window.
Motor. There are two version of the electric motor that must be mated with the regulator. The older 8 tooth and newer 10 tooth motor. in 1983 Porsche added a one touch feature to the windows that allow the windows to be rolled up or down with a single touch of the button.
Regulator. The regulator has a spring that acts as ballast when the window is rolled down to aid the motor in raising the window. The regulator attaches to the track on the bottom of the window with a plastic roller. The motor moves the regulator arm up and down in the track raising and lowering the window.
Guide Bar. The guide bar is a curved vertical bar in the middle of the door. The window is attached to the guide bar by two plastic guides.
Bumpers. There are two adjustable felt covered bumpers on the top edge of the door that help guide the window into the window tracks.
Window Tracks. The window is sealed by two gaskets and the upper window track.
Repairs
Upper Bumpers. The two upper bumpers are attached to the door top inside of the door.
Put the window all the way down.
Remove the inner weather striping on the bottom of the widow by prying up with a screw driver and pulling away from the door.
Locate the two hex bolts in the top of the bumpers just inside the rim of the door.
Loosen the hex bolts but do not remove.
Slide the bumpers towards the outside of the door and down through the access hole in the door.
Quick Tip: The bumpers from Porsche are expensive - especially if all four are replaced. Over time the felt will wear and the rubber parts deteriorate. The bumpers can be repaired from common parts found in a hardware store. Select some stick on rubber feet about the same size of the rubber portion of the bumper and some stick on felt. Clean the metal base to the bumper and stick on the rubber feet. Using a bench grinder or a sander shape the rubber feet to match the original. Cut the sticky felt to a size big enough to cover the rubber and wrap over to the back side of the metal. When installed the extra material will help hold the bumpers in place.
Plastic Guides. The plastic guides are probably the most over looked component of the window system. There are two guides that ride on the vertical bar. New these guides fit snugly on the bar eliminating any rattle and causing the window to operate smoothly. If the window jumps when first starting down or rattles when part way down the plastic guides are probably at fault.
Put the window down a few inches until both plastic guides are visible in the access hole.
Brace the window with a piece of wood (locally grown) from the inside of the door.
Locate and remove the two recessed hex bolts at the top of the door that hold the vertical bar.
Push the vertical bar side to side until it comes free from the bottom.
Twist the bar in a horizontal fashion and draw it out the access hole with the plastic guides.
When removing the plastic guides make note of the direction that they were installed.
The plastic guides should be inspected very carefully. They will look healthy even when they are worn out. The upper guide has a small ridge in the center of the guide. If this is worn irregularly then the guide needs to be replaced. The lower guide has small bumps that directly contact the vertical bar. Often these are completely worn off.
Quick Tip: The lower guide has a split ring with a rubber piece that acts as an expansion joint. Even after the guide is worn down it still can be made to work by increasing tension on the split ring. The easiest way to expand the split ring is to insert a tooth pick or match stick behind the split ring increasing the tension that would normally be provided by the rubber insert. This repair can be made with only removing the access panel on the door panel while the rest of the door remains assembled.
Vertical Bar. The vertical bar is held in place by tow hex bolts at the top and a rubber bushing at the bottom that slides over a pin mounted in the bottom of the door. The bushing is made out of rubber and can over time deteriorate.
Put the window all the way up and then back down about an inch.
Grabbing the bottom of the vertical bar try to move it back and forth.
If there is play in the bottom of the bar then the bushing is shot.
Remove the vertical bar per above.
The rubber bushing pushes into the end of the tube. It may take a little rubber lubricate like silicon or Armor All to help get the bushing in place. Do not use oil or other hydrocarbon products.
Window Regulator. The window regulator uses the motor to operate an arm to raise and lower the window. The arm connects with a small plastic roller to the track on the bottom of the window. By moving the arm up and down the window moves up and down on the vertical bar. As the window moves down it contracts a spring that counter balances the weight of the window and aids the motor when raising the window.
The plastic wheel can deteriorate over time and break. When this happens the window will clunk and not move smoothly up and down. Replacement wheels are sold in kits with a bolt to replace the factory rivet.
The spring can fatigue and break. When this happens the window will move down rapidly but need a manual assist to go back up.
(This needs a review and test)
The regulator is held in place by four bolts directly through the door.
Before removing the bolts on the regulator support the window in the full up position with a piece of wood.
Remove the four bolts and slide the regulator toward the rear of the door sliding the roller out of the window track.
Once released use the power to contract the regulator in the down position.
Disconnect the wires from the motor.
Slide the whole assembly back and out of the access hole.
Reconnect the motor and uncompress the regulator by putting the regulator in the up position.
Motor. The motors used by Porsche are robust and fail infrequently. When the window fails to operate it is more often the switch or physical problems with the mechanism. Pre 1983 used an 8 tooth motor. This was switched to a ten tooth motor in later years. The new motor supports single touch operation. The motors and regulators are matched and can not be mixed. A complete motor and regulator can be swapped as a pair.
Remove the four bolts holding the regulator.
Disconnect the wires from the motor.
Slide the regulator back to gain access to the bolts holding the motor and slide the motor out the front access hole in the door.
Window. The window is really only held into the door by the single roller on the regulator and the plastic guides on the vertical bar. Window glass for the 928 came in two tints - green and bronze. Be sure to determine the tint before replacing any windows.
Use a screw driver to pry up and pull off the inner window gasket in the top of the door.
Put the window down a couple of inches to gain access to the bolts on the plastic guides.
Remove the four bolts holding the plastic guides to the window.
From the outside grab the back of the window and gently push forward forcing the front portion of the window downwards.
Operate the window slowly lower while continuing to push the window down in front.
At about the half way down position the window track should slide off the roller. When it does hold the window from falling by hand and operate the window regulator the rest of the way down.
From the outside of the door pull the window up and out from the back side of the window tilting it away from the car as it come out.
Adjustments
There are six separate adjustments for the window. These all have to be adjusted correctly for the window to operate properly. Before adjusting the window the vertical bar should be cleaned and lubricated with a thin coating of white grease. The track for the roller and the gears for the regulator should be lubricated with white grease. Oil the pivot pins on the regulator - spraying with these areas with Liquid Wrench with Teflon first is also a good idea.
Before making any adjustments all of the components above should be inspected and repaired.
Window Guides
Use a screw driver to pry up and pull off the inner window gasket.
Roll the window down several inches until the bolts on the plastic guides come into view
With a 5 MM hex wrench to loose the upper bumpers - do not remove.
Check the four bolts holding the regulator to be sure they are tight. A check on the motor is probably a good idea too.
Locate and loosen the two recessed hex bolts that hold the top of the Vertical Bar.
Loosen the four bolts on the plastic guides.
Roll the window down about have way and then roll it all the way close.
Loosen and then tighten the bolts on the plastic guides and the vertical bar.
Operate the window a few times to be sure that it is tracking correctly. If it is not loosen the bolts again and repeat the adjustment procedure again.
Rubber Bumpers
Roll the window have way down. Using a 5 MM hex wrench push each rubber bumper out until it contacts the window. Try to get a balance between the two and then tighten them up.
Operate the window to see that it tracks correctly. The window should not hit either side of the upper window gasket, but instead make a clean hit in the center of the upper window track as it closes.
Readjust the bumpers until the optimum adjustment is obtained.
Regulator Stop
Slowly roll the window down until all of the glass disappears into the door.
Look on the bottom of the where the regulator is exposed. There will be, held on by a hex bolt, a sliding stop. Adjust this stop as far up as possible. This will prevent loading of the window regulators when it is in the down position and releases stress on the door.
Hope it helps
Door Windows
The power windows on the 928 are simple and reliable. The most common wear items are the guides. Without direct experience window repairs can be time consuming and frustrating. Observing a few critical procedures and the windows will continue to operate like new forever.
Components
The window. The 928 windows came in two different tints - green and bronze. The window is typical tempered glass with a metal support fitted to the bottom of the window.
Motor. There are two version of the electric motor that must be mated with the regulator. The older 8 tooth and newer 10 tooth motor. in 1983 Porsche added a one touch feature to the windows that allow the windows to be rolled up or down with a single touch of the button.
Regulator. The regulator has a spring that acts as ballast when the window is rolled down to aid the motor in raising the window. The regulator attaches to the track on the bottom of the window with a plastic roller. The motor moves the regulator arm up and down in the track raising and lowering the window.
Guide Bar. The guide bar is a curved vertical bar in the middle of the door. The window is attached to the guide bar by two plastic guides.
Bumpers. There are two adjustable felt covered bumpers on the top edge of the door that help guide the window into the window tracks.
Window Tracks. The window is sealed by two gaskets and the upper window track.
Repairs
Upper Bumpers. The two upper bumpers are attached to the door top inside of the door.
Put the window all the way down.
Remove the inner weather striping on the bottom of the widow by prying up with a screw driver and pulling away from the door.
Locate the two hex bolts in the top of the bumpers just inside the rim of the door.
Loosen the hex bolts but do not remove.
Slide the bumpers towards the outside of the door and down through the access hole in the door.
Quick Tip: The bumpers from Porsche are expensive - especially if all four are replaced. Over time the felt will wear and the rubber parts deteriorate. The bumpers can be repaired from common parts found in a hardware store. Select some stick on rubber feet about the same size of the rubber portion of the bumper and some stick on felt. Clean the metal base to the bumper and stick on the rubber feet. Using a bench grinder or a sander shape the rubber feet to match the original. Cut the sticky felt to a size big enough to cover the rubber and wrap over to the back side of the metal. When installed the extra material will help hold the bumpers in place.
Plastic Guides. The plastic guides are probably the most over looked component of the window system. There are two guides that ride on the vertical bar. New these guides fit snugly on the bar eliminating any rattle and causing the window to operate smoothly. If the window jumps when first starting down or rattles when part way down the plastic guides are probably at fault.
Put the window down a few inches until both plastic guides are visible in the access hole.
Brace the window with a piece of wood (locally grown) from the inside of the door.
Locate and remove the two recessed hex bolts at the top of the door that hold the vertical bar.
Push the vertical bar side to side until it comes free from the bottom.
Twist the bar in a horizontal fashion and draw it out the access hole with the plastic guides.
When removing the plastic guides make note of the direction that they were installed.
The plastic guides should be inspected very carefully. They will look healthy even when they are worn out. The upper guide has a small ridge in the center of the guide. If this is worn irregularly then the guide needs to be replaced. The lower guide has small bumps that directly contact the vertical bar. Often these are completely worn off.
Quick Tip: The lower guide has a split ring with a rubber piece that acts as an expansion joint. Even after the guide is worn down it still can be made to work by increasing tension on the split ring. The easiest way to expand the split ring is to insert a tooth pick or match stick behind the split ring increasing the tension that would normally be provided by the rubber insert. This repair can be made with only removing the access panel on the door panel while the rest of the door remains assembled.
Vertical Bar. The vertical bar is held in place by tow hex bolts at the top and a rubber bushing at the bottom that slides over a pin mounted in the bottom of the door. The bushing is made out of rubber and can over time deteriorate.
Put the window all the way up and then back down about an inch.
Grabbing the bottom of the vertical bar try to move it back and forth.
If there is play in the bottom of the bar then the bushing is shot.
Remove the vertical bar per above.
The rubber bushing pushes into the end of the tube. It may take a little rubber lubricate like silicon or Armor All to help get the bushing in place. Do not use oil or other hydrocarbon products.
Window Regulator. The window regulator uses the motor to operate an arm to raise and lower the window. The arm connects with a small plastic roller to the track on the bottom of the window. By moving the arm up and down the window moves up and down on the vertical bar. As the window moves down it contracts a spring that counter balances the weight of the window and aids the motor when raising the window.
The plastic wheel can deteriorate over time and break. When this happens the window will clunk and not move smoothly up and down. Replacement wheels are sold in kits with a bolt to replace the factory rivet.
The spring can fatigue and break. When this happens the window will move down rapidly but need a manual assist to go back up.
(This needs a review and test)
The regulator is held in place by four bolts directly through the door.
Before removing the bolts on the regulator support the window in the full up position with a piece of wood.
Remove the four bolts and slide the regulator toward the rear of the door sliding the roller out of the window track.
Once released use the power to contract the regulator in the down position.
Disconnect the wires from the motor.
Slide the whole assembly back and out of the access hole.
Reconnect the motor and uncompress the regulator by putting the regulator in the up position.
Motor. The motors used by Porsche are robust and fail infrequently. When the window fails to operate it is more often the switch or physical problems with the mechanism. Pre 1983 used an 8 tooth motor. This was switched to a ten tooth motor in later years. The new motor supports single touch operation. The motors and regulators are matched and can not be mixed. A complete motor and regulator can be swapped as a pair.
Remove the four bolts holding the regulator.
Disconnect the wires from the motor.
Slide the regulator back to gain access to the bolts holding the motor and slide the motor out the front access hole in the door.
Window. The window is really only held into the door by the single roller on the regulator and the plastic guides on the vertical bar. Window glass for the 928 came in two tints - green and bronze. Be sure to determine the tint before replacing any windows.
Use a screw driver to pry up and pull off the inner window gasket in the top of the door.
Put the window down a couple of inches to gain access to the bolts on the plastic guides.
Remove the four bolts holding the plastic guides to the window.
From the outside grab the back of the window and gently push forward forcing the front portion of the window downwards.
Operate the window slowly lower while continuing to push the window down in front.
At about the half way down position the window track should slide off the roller. When it does hold the window from falling by hand and operate the window regulator the rest of the way down.
From the outside of the door pull the window up and out from the back side of the window tilting it away from the car as it come out.
Adjustments
There are six separate adjustments for the window. These all have to be adjusted correctly for the window to operate properly. Before adjusting the window the vertical bar should be cleaned and lubricated with a thin coating of white grease. The track for the roller and the gears for the regulator should be lubricated with white grease. Oil the pivot pins on the regulator - spraying with these areas with Liquid Wrench with Teflon first is also a good idea.
Before making any adjustments all of the components above should be inspected and repaired.
Window Guides
Use a screw driver to pry up and pull off the inner window gasket.
Roll the window down several inches until the bolts on the plastic guides come into view
With a 5 MM hex wrench to loose the upper bumpers - do not remove.
Check the four bolts holding the regulator to be sure they are tight. A check on the motor is probably a good idea too.
Locate and loosen the two recessed hex bolts that hold the top of the Vertical Bar.
Loosen the four bolts on the plastic guides.
Roll the window down about have way and then roll it all the way close.
Loosen and then tighten the bolts on the plastic guides and the vertical bar.
Operate the window a few times to be sure that it is tracking correctly. If it is not loosen the bolts again and repeat the adjustment procedure again.
Rubber Bumpers
Roll the window have way down. Using a 5 MM hex wrench push each rubber bumper out until it contacts the window. Try to get a balance between the two and then tighten them up.
Operate the window to see that it tracks correctly. The window should not hit either side of the upper window gasket, but instead make a clean hit in the center of the upper window track as it closes.
Readjust the bumpers until the optimum adjustment is obtained.
Regulator Stop
Slowly roll the window down until all of the glass disappears into the door.
Look on the bottom of the where the regulator is exposed. There will be, held on by a hex bolt, a sliding stop. Adjust this stop as far up as possible. This will prevent loading of the window regulators when it is in the down position and releases stress on the door.
Hope it helps
07-26-2015, 12:36 PM
#18
Rennlist Member
If you find your motors are bad (both of mine were) Roger sells an alternative that is way cheaper than Porsche OEM and you get a new motor vs used. I ordered both new switches and motors and did a one by one replacement to make sure the failed component was isolated prior to simply replacing everything. Roger is good about returns so if you find it's a switch you can return the motor. One of my switches was functional but replaced anyway primarily for aesthetics. Good luck!