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Topic at hand is: GM Big cars with VentiPane windows from 65 until whenever GM discontinued them for noise & manufacturing complexity.
Can we make them water seal (as delivered) and quiet 55 years later?
I’ve got a thing about wind noise and water ingress in my ancient cars. So I go way out of my way to keep the rubber fresh, add extra seals like Caddy did and I’ve even replaced door hinges on the 98 (Covid project), Each year, I burn a day or 2 seeing how good I can make these cars.
I’m lucky enough to maintain a 66 98 convertible & a 66 Starfire coupe. Both have the GM big car (B & C body) standard VentiPanes, known to most people as front door vent windows. It’s well known that they contributed to wind noise as designed. 55 years later, at the car wash (high pressure water blasting at the car…) they leak a bit too. My cars are drivers, so yeah, I use the car wash - also because in my town there ain’t much water. The car wash recycles. I don’t, so washing cars there saves me time & water bill $. And as a “driver guy” I really believe that these cars should be able to withstand a run through the car wash with no leaks.
Last night I installed oversized roof rail seals in the hardtop (‘66 Starfire). I wasn’t satisfied with ‘66 88 offerings from Soffseal, Metro, or Steele, so eventually I got some oversized generic extrusions from Steele. I installed them last night and they seem to have quieted the car by maybe 10-15%. Which focused me on the noise from the vent windows.
As an axiom when you’re in the noise reduction game: once the big noises go away, the little ones come out. In this case vent window noise.
Today I put in orders for VentiPane (vent window) seals from both Steele & from Metro. Soffseal doesn’t offer this big car part. It will be interesting to see which are better. I know the factory seals (from 55 years ago..) had brass inserts cast in against the A pillar. I’ve tried reproduction before. Thus far, none have had the brass inserts. O.k., then of those available, which are the quietest?
Parts should be here in a week or 2. Watch this space for the eventual experience. No idea when I’ll get around to installing the best parts. Getting these parts in means pulling door panels, water barriers, and messing deeply with the front window adjustment (Massive Time Suck…). 8 hours is a decent guess. Or maybe more.
Net net, it will be interesting to see if Metro or Steele make better vent window seals for the big cars. I have no affiliation with either company, I just want a quiet car. Will pass along what I learn. What ever information I gather should be useful to GM B & C bodies (hardtops & convertibles) from 65 to 68 or so. Hope this helps someone down the line.
Cheers
cf
PS: If anyone is interested in the part number for the oversized roof rail rubber for the ‘66 Starfire (more or less same as the 88/98/Starfire from 65-66), hit me up. I don’t recall the number, but can chase it down pretty easily.
I got the Steele vent window seals in the other day and received the Metro Parts today. Disclaimer, I'm just a hobbyist and not affiliated with either vendor. I spent the retail $ to get the same parts from each.
GM used these vent windows (called Ventipanes back in the day) from 65-68, so what is below should pertain to big Oldsmobiles, Pontiacs, Buicks, Caddys and Chevies in those years. In 1969 GM discontinued the ventipane for most of those cars since the little windows contributed a lot of wind noise into the cabin. It is exactly that wind noise and a little water ingress (only at the car wash!) that I'm interested in getting rid of. Or at least minimizing.
These little triangle windows have two seals I'll refer to as front and rear. The front is the larger of the 2 and a fairly complex angular shaped casting. The rear is just a little strip of metal with a "L" shaped seal that the vent windows close against to seal. GM retained the front seals in the chrome castings with a set of brass clips which bite into the rubber and hold it in place. The rear seal is retained in the division channel (front fuzzy holder) by a set of "ears" that you bend into holes in the rear channel - kind of like how some chrome trim is retained.
Several years ago I replaced the vent window seals in my '66 Starfire believing that new rubber would beat 55 year Old GM rubber. That turned out not to be true. In fact I disliked the reproduction stuff so much, I never changed away from the original GM seal in my '66 convertible. The problem was I couldn't remember which reproductions I _didn't_ like. The big difference from GM original rubber seals vs. the reproductions is that the factory used a brass brace inside the leading edge of the front seal to make it hold its shape. Neither of these reproductions have that steel brace. Which means that the stiffness of the rubber is what will do the job.
If you can find original NOS GM seals, they will still be the best quality assuming the rubber is not all cracked and dried up, which it may be after 50+ years. I haven't put the stuff on yet, but my bench test clear winner here is Steele.
Here's why:
First up, the front seals. Bottom line Steele is using stiffer rubber and I believe has a more true-to-GM-shape casting. Steele vs. Metro vent window front seal. Steele has stiffer rubber and I believe more correct casting indentations.
Getting picky, I think that Steele has an indentation for the seal retention clip that the Metro part is missing. GM may have varied the clip count for cost or other reasons, but I believe the Steele part is closest for my '66 big Olds's
Steele provided indentations for more seal retention clips.
Getting even pickier, I'm a believer that the shape of the seal might make a difference in noise and/or water ingress. I give the nod again to Steele here since they've shaped the line where the window pivot is. Metro just kind of drew a line.
A view of the front seals from the outside. These are driver's side. I believe Steele has better contours.
Rear Seals: Advantage Steele - brass insert, better extrusion, curved like our windows
Here's an overall view comparing Metro vs. Steele rear vent window seals.
The windows on our cars are curved. Steele seal is, Metro is not. I think Steele will be quieter and a better seal.
If you're like me, you probably never noticed a tiny flap of rubber at the top of your vent window rear seal. Along the way these little flaps get pressed into the the seals they're a part of an most never notice them. Metro didn't cast them into their extrusion, understandably. Steele did, so I give them the nod for sticking closer to the GM original design.
Flap or no flap? GM seals had a flap, Steele does. Metro does not.
This is probably way, way more about vent window seals than anyone ever wanted to know, but I just wanted to note the head to head here since these parts are expensive and you really have to have a thing about noise & water to spend 2x normal just to know what's best.
Also, in case I forget what I did this time.
Concluding -- if you can find good NOS GM seals that have been well maintained, that may be best. If not go with Steele, but remember GM gave up this design in 4 years or so due to noise. Meaning even if you have a perfect seal, it'll still make more noise than modern cars.
Part III - Installed new vent windows seals in my ‘66 Starfire Coupe today. Quality of the Steele stuff is on point. Small advice - if you’re replacing vent window seals, you might as well replace the front fuzzy (division channel) too. Good time to grease up the window tracks, check your teflon window rollers and so on.
I started the day by removing the rear bench, front door panels, interior quarter panels and water shields. I pulled the interior just in case I needed to to window adjustments before or after adding new seals for best fit.
Upfront I took an hour or so to adjust the rear quarter windows, just a little to get their verticals parallel to the front windows and tight to the seals. Conventional wisdom with car window adjustment of these cars is do the rears first since they have less adjustment latitude and finish with the fronts. I wanted to be sure my rears were as good as possible before conquering fronts with new seals. Turned out I didn’t need to adjust my fronts much at all.
On to the seals. It turns out you can remove the entire vent window assembly on either front side without disturbing the main front window. The ‘66 vent windows are held in with 1 1/2 head bolt, and 2 7/16’s adjusting screws. I marked my adjusting screws depth with a silver sharpie just to be sure I had them set the same way they were before I removed them. To get the vent window out, you have to remove the big bolt at the corner and you _must_ remove the front 7/16”’s screw, but you can leave the lower 7/16”s screw if you’re clever about turning & twisting the assembly as you slip it out the front door. It probably helps to have the main window part way down.
So I pulled the vent window and discovered that in my zeal for quietness, I’d torqued the cr*p out of the crank handle & bent some die cast parts. And cracked the division channel connector to the front cast chrome. I sistered a screw in there to solve the crack and repaired the overtorqued crank on the workbench. I greased up all the moving parts with lithium grease as the factory did.
Getting the seals in is a trick. The rear (simple L seal) is pretty easy, but you have to remove the division channel (front fuzzies) to get at the retaining ears. Frankly you’ll have to disassemble the whole vent window assembly anyway, so this is just 1 step. The front seal is a little tricky - there are 4 retention spring steel clips which are so old that they break on removal. I made do with weatherstrip adhesive and a couple of clips. With that big “V” or angle shaped seal, he big thing to notice is that the bottom of the “V” shaped front seal is supposed to be threaded through the horizontal part of the division channel.
Unless I miss my guess, the best process is put the front chrome in a vise (below the visible parts), clip/glue the “V” seal in, then route the division channel bottom onto the “V” seal. 3 screws hold the assembly together - 1 at the top of the window, and 2 at the bottom. I highly recommend doing the top screw first. If you secure the bottom 2 first, getting the top one done is not fun. I spun them in with a screwdriver, but torqued them in with a small ratchet just for tightness which may translate to a better seal.
I think I’ve goofed this before. This time I had the driver’s side in before I realized the need for threading, so my driver’s side is wrong, but snug. My passenger side is correctly installed but seems less snug. I’ll have to test drive to see which sounds quietest.
On reinstallation, marking the depth of the window adjustment screws saved me a bunch of time. When messing with windows, draw a silver sharpie line around where you started. It’ll save you hours of guesswork.
I burned 60 minutes or so hitting all the chrome and visible parts with my buffer. I don’t dig into this stuff that often, so why not take the opportunity?
On reassembly I added some aluminum-backed closed foam insulation to make the car quieter. I’ve had a roll around for a year or 2 so I thought I’d glue it in to make things yet quieter. I’ve heard it called Volara, but its a swap meet purchase. It’s white 1/4” closed cell foam with an aluminum backing which claims all kinds of heat & noise reduction. I took an hour or so to fill the door voids and glue it to the water barrier. With luck it will be better. Not sure I’ll notice, but it’s light weight & can’t hurt.
Tomorrow I’ll wrap up the interior reinstall and looking forward to a test drive with the new seals!
I love in depth instructions/guides like this and I read it all thru. I don't even have a big Olds but I enjoy reading tech articles, etc. Thanks for all your trouble to post this. I'm sure it will help others.
I've done a little road testing for the past few days and noise from the vent windows is down by a lot. Hard to say how much, but maybe by half? Once the noise is gone, it's hard to remember how loud it was.
What's weird is I did the driver's side incorrectly and it made a tighter seal than the passenger side. After a couple of days, I redid the passenger side just as wrongly as the driver's side and it's better (tighter). I can't recommend going against the design in good conscience, but it's working for me so far.
One trick that seems to be helping it to stick some closed cell foam under the "skirts" of the V seal that extend down in the door. I used short lengths of this stuff, on the inside and outside: Closed cell foam can help balloon the V seal door skirts and reduce noise.
It's hard to visualize, but by ballooning the skirts, it forces the edges of the rubber above tighter to the window edges and reduces noise.
Oh - one last thing. When you install the V seals correctly or incorrectly, they don't seal quite as nicely as I'd like.
My driver's door came out perfectly, but I'm going to have to use a bit of closed cell foam to shim the last 3/8" gap between the lower front corner of my passenger vent window and the seal.
__Almost__ perfect, but then these cars weren't all that perfect when new.
April 22nd, 2022, 07:39 PM
