Sunroof Crank Mechanism Demystified

[Dana67Dart]

I'm working on a project for @Davecuda to Reverse Engineer the Guide and Gear on an A Body Sunroof.

He sent me the crank mechanism and me being me, well you know...

The Parts

From left to right

1. Cable Guide
2. Plate
3. Gear
4. Crank Shaft
5. Brake Spring
6. Housing
7. Shoulder Bolts

I suspect there 2 star lock washer not shown

This is the assembly (The crank would be in the car and the guide would be up in the sunroof assy channel)

Cable Guide

The sunroof cables run inside the guide one on the top and one on the bottom (I don't have the cable but the drills are sitting in the channels and the flutes of the drill represent the spiral winding on the outside of the cables)

The cables look kind of like the covering on the E brake cable

The image is from this video Dave shared with me.


The Plate
It appears to be a spacer and goes between the Guide Plate / Sunroof Channel and the Housing
It does not retain the Gear

Be careful on reassembly not to pinch the plate under the shoulder of the shoulder bolt, I suspect that's how the Guide broke originally from the factory

Blue points to pinched plate

Red side is pinched, green side is not

The Gear

The gear assy services 2 purposes

1. It causes the cables to move
2. It presses on the ear of the Brake Spring to make the spring looser in the body of the housing so the crank can turn (more on the brake function later)

Note the Tab on the Gear plate.

The Crank Shaft
The crank shaft has a large opening and a small opening. The opening interlocks with the tab on the gear and the brake spring to allow the handle to turn the gear.

The large opening has witness marks that the brake spring tabs ride on the two flats. (In the video the producer says the Brake Spring tabs go into the small opening on the crank assy. This would render the Brake Spring useless as it would make the OD of the spring smaller and there would be no braking action)

Continued

 

[Dana67Dart]

The Brake Spring (and function)

The Brake Spring serves 2 purposes

1. It holds the Sunroof in position
2. It prevents the sunroof from being slid open from the outside of the car

Your door and quarter windows have a similar mechanism, otherwise the glass would not stay up or in a position and someone could just pull down on the glass and it would open.

Function
When forces is applied by the Tab on the Gear Plate to the Brake Spring ear (blue arrow) the spring winds up slightly making it slightly smaller in diameter (green arrows) and can slide in the Housing

Cranking the Sunroof or glass works the same in either direction since there are 2 Brake Spring ears

When the Sunroof is attempted to be moved by sliding the glass (or gravity in the case if the side and quarter glass) the Gear rotates and force is applied to the Brake Spring ear (blue arrow). This results in the Brake Spring unwinding and becoming larger in OD (green arrow) and drags on the Housing

Forcing the Sunroof or glass works the same in either direction since there are 2 Brake Spring ears

The Housing
The Housing also serves 2 purposes

1. It supports and contains the Crank, Gear, and Brake Spring
2. It is the bearing surface for the Brake Spring

You can see the wear on the inside where the Brake Spring contacts the Housing

The Brake Spring inside the Housing

The Shoulder Bolts

They sandwich the assy to the frame of the Sunroof by bolting to the Guide

There are witness marks n the Housing that a star lock washer was under each head of the Ssholder Bolts

Cross section of how the assy is installed on the Sunroof frame

The silver plate to each side would be the Sunroof Channel

CONTINUED

 

[Dana67Dart]

Some photos Dave Sent me of his Sunroof Mechanism


The guide would fit slot side down over the cables and onto the Sunroof Channel

The Crank assy bolted through the Sunroof Channel and into the Guide above it.

The Sunroof Channel fits between the red Arrows