Window Parallelism Adjustment

[Superman]

I've got a 1978 SC which seems to be missing the fasteners and adjusters that it is supposed to have. The first pic below is from the Bentley manual, showing the proper fasteners and adjusters. Also shown below is a URL to a thread here showing the proper fasteners.



Installing Door Window & Regulator - 911 Cabriolet Targa - Leveling - Parallelism

[Superman]

Here are pics of the door with stickies showing where these fasteners should be, and without stickies showing the fasteners are simply not there. This door is the mirror image of the Bentley picture and the pics in the URL thread.

[Superman]

What gives? This is a 1978 SC WITH electric windows. How does it not have the parallelism adjustment?

[Jack Stands]

What do the three slotted Allen head fasteners adjust?

[Superman]

Good question, Mr. Stands.

[76FJ55]

It appears that you have the earlier parallel arm window mechanism. the Bentley I think is showing the later cross arm mechanism.

[Superman]

Originally Posted by 76FJ55

It appears that you have the earlier parallel arm window mechanism. the Bentley I think is showing the later cross arm mechanism.

Maybe so. Perhaps in 1978 they used some leftover parts. The windows are motorized. I am left wondering how I can parallelize the driver side glass. There is wind noise.

[Superman]

Bump. How can I adjust window parallelism on this door?

[Jack Stands]

I’d try to loosen the three Allen screws and try to move them back and forth to see how they move the window glass. I’d assume that they will give you the adjustment you need.

[Superman]

Thanks Jack, or whatever your name is. grin

I suspect this is a known (mid-year) type of motorized window regulator setup. If so, then somebody has the manual for this car. My Bentley is for SCs. If I have to use trial-end-error, then I will. But.....trial-and-error has its own risks.

Hoping someone will just tell me how to make this adjustment.

[dannobee]

https://www.pelicanparts.com/More_Info/91154293628.htm?pn=911-542-936-28-M1000

[Superman]

Thanks dannobee, but I hope to avoid drilling holes and replacing both window regulators. I am hoping someone can tell me whether this regulator can be adjusted for parallelism and, if so, how.

[dannobee]

The only way that I can think of is to loosen up the four attaching bolts that hold the regulator to the door, then move the regulator around to where you need it. If that's not enough, you'll need to either fix the play in the regulator or slot the holes.

[Superman]

Thank you again dannobee. Loosening up the four bolts and jostling the mechanism might be the solution, but I've also got three Allen head adjusting screws here which very possibly allows the adjustment I need. Somebody must know.....

[Superman]

After consulting with Dr. Walker I now see the early regulators simply did/do not have the fine adjustment feature for glass parallelism. Apparently, I can loosen the mounting bolts and try to jostle the mechanism to get the top of the window glass as level as possible. Beyond that....I would need to do some drilling on the doors and swap out the regulators.

The problem I am trying to solve is a bit of wind noise coming into the car between the glass and the top of the channel/frame at the uppermost rear corner of the glass. I am posting this for others to find/learn in the future.

[Jack Stands]

Do you have the factory booklet on the early Targa top adjustment? It does mention that the mounting holes may need to be enlarged.

[filoudebruxelle]

Hi Superman! I'm trying to refurbish my electrical windows from my 911sc also from 1978 and came across this thread. I have the same doors but the previous owner had the new regulators fitted and drilled new holes. The problem is the motor can barely pull the window down or push it up this happens somewhere half way. I'm wondering how to make this smoother. With no adjustment possible (remember no predrilled slots), what options do I have? Wonder how your experience was. Many thanks!
Filip
Brussels - Belgium

[john walker's workshop]

New felt often helps.

[Superman]

Update: I discovered that the later SC mechanisms were adjustable but early SC mechanisms are not. Still, by loosening fasteners and tweaking the mechanism pieces while tightening the fasteners I was able to get the mechanism to work better. Including faster up-and-down operation. Particularly down. Down was very slow, and then was much better after adjustment. New felt is also great, as John mentions.

[filoudebruxelle]

Originally Posted by Superman

Update: I discovered that the later SC mechanisms were adjustable but early SC mechanisms are not. Still, by loosening fasteners and tweaking the mechanism pieces while tightening the fasteners I was able to get the mechanism to work better. Including faster up-and-down operation. Particularly down. Down was very slow, and then was much better after adjustment. New felt is also great, as John mentions.

@superman & @john walker many thanks for the tips. I opened up the door last night and took out the window regulator to operate the window manually. It became clear that the window was getting stuck in the frame when it was half way down/up. Had to apply too much force to move the window up or down. (had already repaired the broken spring slot before but to no avail)

So I took out the window frame to verify the felt. The felt was in ok condition (minor pieces missing), BUT when I checked the frame curb or camber (to check if there was no tension between frame and window) I noted that the window frame close to the b-pillar was not bent with the same curb as the window causing the window to get stuck in the frame, hence the slow movement when lowering or lifting the window.

Had to manually bend the frame to the correct camber. This was in no means perfect as I wanted to avoid putting a dent in the frame. So long story short: window slides better up and down in the frame (not perfect but way better than before).

Thanks for pointing me in the right direction.