Well nut size

I am starting to polish out the heavily oxidized paint on my OCC and want to remove the roof strips. I feel sure the well nuts are way past their prime. Does anyone know the size needed?

Check the thread size, and buy accordingly. I believe they are 6mm screws. You may find them in the motorcycle windshield section. If the wellnuts turn with the screws, turn them while putting slight pressure on the strips, and they will work their way out. Do a little at a time to keep from breaking the roof strips.

Be extremely careful removing the rack rails. They are held by rivnuts. The rivnits are notorious for spinning in the body, instead of the screws turning out. If they spin, the only way you can get a grip on them is by removing the headliner. The rivnuts are no longer available anywhere, unless there is a forgotten stock at a dealer. They are a bastard size only made by GM. You can use an SAE size that approximates the hole size in the body, but the screws are larger. The screws are stainless steel, and if the rivnuts spin, you will probably have to drill them out. If you take the rails off, and the rivnuts do not turn, super glue them, and put anti-seize on the screws. Reseal the top seam channels while the rack rails are off. I scraped the dried out sealant out with a screw driver, and filled the channels to the same depth with regular roofing sealant for houses. Do not fill them to the top, because the roof rack rails extend into the channel. It will help eliminate leaks that drain into the trays on top of the cargo bay interior.

Thanks Fred. I have read all the threads on roof rack removal but hadn't seen a definitive size for the well nuts. On the subject, can you take all the roof rack parts off without dropping the headliner? I have the GM service manual and it shows hex nuts being removed along the back of the vista glass where it meets the rack. I'm assuming those come out if you're taking the glass out?

You can if the screws do not cause the rivnuts to rotate in the roof. If the rivnuts rotate, you must remove the headliner to get to them.

What glass are you referring to?

Sorry I'm old school. I called it the vista glass. I meant the roof glass. They show regular hex nuts being removed where the front rail meets the roof glass, along with the screws that go into the rivnuts.

They are definitiely 6 mm thread on the 91 OCC. The 6 mm rivnuts I bought off E-bay fit well in the rear three holes but were too small for the front hole. Only changed one strip so not sure if this applies to all.

On both the junkyard car and mine the existing (factory) nuts spun freely and I wound up gently prying the strips upward. There is a nerf cut in the steel backing about halfway to permit them to conform to the gentle slope of the luggage rack body panel.

Walterf wrote:

They are definitiely 6 mm thread on the 91 OCC.  The 6 mm rivnuts I bought off E-bay fit well in the rear three holes but were too small for the front hole.  Only changed one strip so not sure if this applies to all.  

On both the junkyard car and mine the existing (factory) nuts spun freely and I wound up gently prying the strips upward.  There is a nerf cut in the steel backing about halfway to permit them to conform to the gentle slope of the luggage rack body panel.  

The rivnuts are only for the rails, not the rub strips. The well nuts are a different animal. I forget what size rivnuts fit the rack rails, but you should never use the well nuts for the rails.