This article covers a new convertible top installation on a 1972 Oldsmobile Cutlass Supreme Convertible. This is a two piece GM style top common to nearly all A-body cars, including a Chevelle. It also touches on repairing the frame, tacking strip, and trunk areas.
The top on our Cutlass was believed to be original to the car, and certainly had a number of issues. There were signs of water damage into the trunk, and tears along the sides of the top. The hydraulics didn’t sound great, and the top frame had signs of rust. It was time to address these issues properly so we could have a reliable convertible cruiser.
In this article I won’t tell you exactly how to install a top, as you should follow the instructions from your top manufacturer or your body manual, but I will show you some areas to look out for, provide pictures for reference, and provide a general outline.
Total install time is over 30 hours for a first timer. Be prepared and BE PATIENT. This is a frustrating and fragile process, and the directions are usually not very clear. Also, every time you remove a part, you’ll find another issue underneath it. Decide ahead of time how deep you want to go, and please put the effort into DOING THE JOB RIGHT.
Disclaimer: This is my first convertible top install. If you see something you don’t like, or that looks incorrect, please leave a comment and let me know!
PARTS LIST AND SCOPE
Because the entire top was going to be removed, including the frame and hydraulics, I decided to inspect and restore the trunk area as well. I’ll break the parts I needed into two sections, top and trunk.
I opted for a complete top package from https://www.convertibletopguys.com. Please note there are many options for convertible tops, especially for GM A Bodies, which are relatively common cars.These tops come in two parts, the rear curtain and the top section. You’ll probably need both.
Options for you to consider prior to your top purchase:
Vinyl or canvas? Vinyl is original to this car. I opted for canvas because I like it more. You research and decide what’s right for you. Canvas costs more and is arguably slightly more work to maintain.
- Plastic or glass rear window. Some cars come original with plastic. I opted for glass, which to me is a no-brainer.
- Zip-in rear window? This is an option. I chose it because it was only 20 bucks more. This option can provide good ventilation, especially if you have a non-AC car.
- Manufacturer. All tops are NOT created equally. Check with who you buy from, as they are probably not the direct manufacturer for the top. Ask about their return policy for fitment issues and warranty info.
In addition to your top package, you may need the following:
- Weatherstripping condition – mine was shot.
- Rain gutter condition – Located in trunk and drains water away. Mine was broken. Replacement gutters are hard to find and cost over $200. Be careful when you remove yours as they are flimsy.
- Tension cables condition – mine were OK but had surface rust. I replaced them.
- Hydraulics condition – Mine seemed to be OK. Rebuild kits are available, as well as new parts, but they are expensive. DO NOT break your hydraulic lines when removing them. They look like cheap plastic but cost over $100 to replace.
- Tack strip condition. After you get your old top off, you may find you need new tack strips.
- You need two sizes, 5/16″ x 3/8″ for the front (easily available), and 1/2″ x” 1/2″ for the top rear bow (I couldn’t find this size for sale anywhere).
- www.TopsDown.com sells tack strips and is knowledgeable.
- Top pads. They may be reusable, but more than likely you should order new ones with your new top. These are important and are visible from inside the car, so condition matters.
- Rear well liner. Mine was torn. Save yours if its in good condition as a new one is $80 plus. Either way, make sure you use one to protect your new top.
- Basic tools, and an electric or air staple gun for installation.
- STAINLESS STEEL staples. Galvanized staples will rust. My previous top was patched with some galvanized steel staples, and many were completely rusted away.
- Rivet Gun with aluminum rivets. These are cheap and available at most hardware stores.
Overall review of my kit from TheConvertibleTopGuys. Here are the highlights of my issues with their product:
Overall: 5 out of 10.
- Their install manual that costs $15-$30 is poorly written. A couple steps are a beneficial reference, but mostly the instructions are too vague to be useful. Don’t pay extra for this.
- They included galvanized staples in the kit that I paid extra for. Stainless staples are only a few $$$ more.
- The top seemed too narrow in the front, and the rear window zipper seemed too far up based on dimensions from my original top, which limited placement of the rear curtain later in the install. This COULD have been a result of me completely removing the frame for restoration, and installing it in a slightly different position, however I can’t confirm one way or the other.
- They did not include enough tack strip to do the job. They assumed only small patch sections would need to be replaced, which is a bad assumption for 50 year old cars with paperboard tack strips. Two sections of 5-6 foot each will arrive, however you will need about 8 feet of each size to do the whole top. They could have simply included an extra 3 feet of each size.
- The tack strip included for the rear was the wrong size. They shipped 3/8″ x 3/8″ which is too narrow and short for the rear top bow and would not have worked. I called and they claimed “we’ve never had anyone comment on the size before? Just use it” which is complete B.S. The forums are full of people with this issue. The real problem is that no-one seems to repro 1/2 x 1/2. One option is to buy the 5/16″ x 3/8″ size and stack multiple layers. If this kit is specific to a Cutlass/Chevelle etc, it should fit, or they should note the sizes included. Period.
- FYI, if you use tack strip that is too shallow for the groove/channel in the rear top bow, you will not be able to drive in the staples. This was very bad advise.
- The staple gun they recommend (Arrow T50ACD) was not powerful enough to drive any staple over 3/8″ into the tack strip that they also sold. You’d think they would test this? The rear trim stick requires 1/2″ staples. It also struggled with 3/8″ staples at times. It did get the job done; however, try to find a more power alternative.
- The side section of the top did not have a second row of stitching where the top wraps around the frame. This stitching was present on my original, as well as every other new top I’ve seen. It appears to be an oversight that I did not catch until finishing my install.
These are for reference. If you can’t remember how yours went together, hopefully this helps.
Disassembly of the whole top cage assembly is pretty simple. Since I was removing the whole frame for rust repair and coating, I did the below.
NOTE: Before removing the old top, rear curtain, or pads, there are measurements you need to take! If you don’t know what the below is referring to, now’s the time to research it.
- Measure distance from rear body deck to center of the rear top bow. This is your rear bow height and is critical.
- Measure distance from the rear top bow to the center bow. This is for reference so you have two points of reference for your rear bow height.
- If not re-using the top or rear curtain, mark where the top overlaps the rear curtain near the rear window. you can then match this with your new top. If you are reusing either section, only mark to the rear of the rear deck near the rear trim stick, since this area isn’t visible. you’ll have to do some of the disassembly below prior to having access to this area.
- Note the position of these adjustments if you are dissembling your top frame. They should be reinstalled in the same place to start.
- Remove rear seat and rear quarter interior panels.
- Disconnect hydraulic hoses. Don’t make an oily mess, this will interfere with the painting you may do.
- Disconnect rear well liner from rear seat.
- Remove the rain gutter CAREFULLY.
- Unbolt the rear trim stick from the top’s side brackets. There is one bolt per side, facing outward. This is a floating rear trim stick and not bolted directly to the body (the A-Body instructions mentioned above had this wrong).
- With a helper, unbolt the three bolts holding the top hinges/brackets to the body on each side. The top is now completely separated from the car.
- Lift top out of car as whole assembly. Place padding over painted areas to protect them. The whole top weights approximately 100 pounds as an estimate, so have at least three people handy.
Top frame disassembly
Before removing any component of the top frame, take lots of pictures and draw diagrams. The top frame is complicated, and it is VERY easy to forget the order of assembly for the hinge areas especially. Which way did that bushing face again? During Disassembly place each bolt assembly into its own plastic bag with labels/diagrams. I also assembled all the bolts/washers/bushings etc in the correct order before placing it into each bag.
If you’re having your top frame coated/blasted you’ll need to remove the old tack strips. Save the old pieces and label which section they came from, because you’ll need to know the dimensions to purchase new tack strip. If your tack strip is aftermarket and held in with rivets, you’ll need to drill each rivet out and re-rivet later. A quality top install starts with a solid foundation, and you don’t want this top coming loose in the future or letting in water.
Disassembly Reference Pictures:
TOP CAGE REPAIR
I had my top media blasted for inspection. If you can, find a blaster that uses media less harsh than sand, such as soda. The bushing are bronze/plastic and the handles appear to be magnesium or aluminum. I had mine sand blasted because they were the only ones in town, but there is some sand in the hinges and some pitting in the metal from the sand. Definitely not preferred. Sand blasting was ~$150.
After blasting, I sent the cage parts to a powdercoater for better protection and appearance verses paint. Powdercoat is attracted to the metal with static charge, and is much easier to get into the nooks and tight spaces than paint. The powdercoating price for the whole top frame was around $300 and I went semi gloss black.
Installing new tack strips is most of the work associated with the new top. For the front, there are little metal tabs which bend to hold the tack strip in. These are usually rusted away. Alternatively, you need to use stainless steel screws or aluminum rivets to hold on the new tack strip. This will require drilling into the front panel and through the new tack strip. Remember that this tack strip MUST be securely fastened, as the top is under a lot of tension when installed. I opted for rivets or screws every 2-3 inches, and adhesive behind the tack strip as I went. The screws or rivet section that extends through the frame piece will need to be ground flush with a grinding wheel so it doesn’t tear your new top. Make sure to re-paint and seal areas with penetration or where you grind for waterproofing. Use clamps to hold the tack strip down while the glue dries.
Some people use stainless #6/#8 machine screws vs rivets. If you do, you’ll need to countersink the screw heads into the tack strip using a larger drill bit. An exposed screw head will wear through your installed top eventually. Rivets are the traditional method.
The tacking strip installed in the rear top bow and rear trim stick should fit tightly, be secured with glue, screws/rivets, and should be nearly flush with the top of the channel, although slightly recessed. Ideally, the tack strip should be 1/16″ to 1/8″ recessed from the top of the channel. If the tack strip is too high, it will show a bulge in the installed top. If it is too low, it will make stapling difficult and collect water.
While the top is out, look for rust on the underside of your rear quarter panels. Look for rust holes in your trunk floor pan, and in the lower areas near the wheel wells. Also look for rust in the area where the lower trim stick meets the body. this is the area below the rear window where the rain gutter bolts to the body. If you find any rust or issues, this is a great time to address them.
I decided to strip the trunk, repair the rust, and repaint from the rear seat frame back to the rear bumper.
Parts I used:
- Wirewheels, paint strippers, sandpaper etc. Standard paint prep stuff.
- Metal repair stuff. Welding/bodyfiller etc. Seriously, don’t be ridiculous with body-filler and use it only as intended.
- Eastwood Rust Encapsulator Black Aerosol 15 ounce 16060Z x2 from www.Eastwood.com
- Eastwood Self Etching Primer Black Aerosol 16 oz Net 16114Z x3
- EW Trunk Paint Gray Black Aerosol 12 oz 10009Z x3. This is the speckle paint the came originally in the trunk. Order an extra for future touchup. MUST be painted on primer surface and must be clear coated to be water proof. This is water based paint.
- Eastwood Diamond Clear Gloss Aerosol 16105Z x3 (doing this again, I would use semi-gloss)
Continue to the install on PAGE 2 !!