Window Regulator Preload

[JHZR2]

Hi,

Can anyone explain the purpose of window regulator preload? Is it to effect the angle of the window glass, because it shifts the bottom of the track that the window slides on relative to the top, or is it more to adjust/prevent how far the window and regulator "flexes" when the window hits a door seal?

Im really talking about frameless windows... I suppose there is no need for preload in a framed window...

Thanks!

 

[mechtech2]

It's to seal against the door gasket.
The window goes mostly up, then over a bit.

 

[Tegger]

Framed windows slide into an internal channel all around the frame; or else they have a pin-and-channel assembly to hold the window against the seal, if the window rides on the outside of the frame. "Preload", therefore, is not necessary to prevent air- and water-leaks.

Frameless windows rely completely on how hard they press against the rubber seal on the roof and pillars; alignment and "preload" are all that keep the window from leaking water, or whistling from air leaks. Plus there are manufacturing tolerances, so each frameless window is adjusted at the factory for proper fit.

 

[JHZR2]

So I'm assuming that you want the bottom of the window as far outboard as it can be, so that the top angles towards the weatherstrip to catch? Too far and I guess it would hit too hard and be stressful on the glass and regulator. But you still want the top of that glass angled towards the car a bit, right?

 

[Tegger]

Originally Posted By: JHZR2
So I'm assuming that you want the bottom of the window as far outboard as it can be, so that the top angles towards the weatherstrip to catch? Too far and I guess it would hit too hard and be stressful on the glass and regulator.

In my experience, the bottom of the glass (when raised) stays fixed; it's the top of the glass (when raised) that moves in and out. That movement is effected by adjusting the CHANNELS at their BOTTOMS, deep inside the door, while the glass is raised up all the way.

Originally Posted By: JHZR2
But you still want the top of that glass angled towards the car a bit, right?

Yes. Exactly how much is a bit of a fudge. The "gauge" I'm familiar with involves a strip of ordinary printer paper trapped between the glass and weatherstrip. The strip ought to have about the same resistance to pulling, all around the glass edge, and should not be loose in any one spot.