How I build a Carson style roadster top.

Okay guys and gals, I've thought about this long enough to get started. I am going to build a canvas roadster top with a tubular steel frame for my roadster pickup. The top I will build is going to hinge at the rear and flip open to give me better access without bending too much, but the same plans will apply to any non folding roadster top, whether it hinges open or not. I am going to do complete step by step show and tell with digital pictures, solid models, and associated costs.
The reason I'm not going to buy from Lebaron Bonney or one of the other top manufacturers is #1---my roadster pickup is made from a cut-down sedan, so it has a unique shape that nothing would fit, and #2--I'm a cheap but creative old bugger, and want to see if I can do it.
The first step to this job will be detemining the shape of the top bows, to fit me comfortably, look esthetically pleasing, and not be too complex to fabricate.
I am attaching two solid models I have created. One shows the framework as made from 1" diameter steel tubing with 2 "people" setting in the car. There is no canvas yet, but you can see the general shape that the tubing will be, and the top header is made of pine, the sheet of transparent steel over top is #16 gauge, and the 2 flat peices at the top/rear of the steel body will be 3/4" plywood (with piano hinge between them on the rear side for my top).
The cheapest way to calculate the radius of the steel tubes is to use some 3/4" plywood to start with, as shown in the second model.
The end result will look something like the photo-shopped picture which I will attach.
-----more to follow----

 

I will be interested to watch you get this done, I don't wish to spend alot of money on the top for my roadster either. So if this can be done on a budget and have a good appearance I would like to see your build process, might be a good tech post.

 

Nice! I would ditch the pine in exchange for a hardwood for the header...maybe oak. The pine will probably warp and twist some and any screws will hold into a hardwood much better.

 

I used to think like you, that oak would be best. However, after talking to a few upholsterers,I have found that they actually prefer something softer like pine, as it is far easier to staple the canvas to.The pine will not really have any screws going into it, (or at least not many), and it will be about 3 1/2" wide x 1 1/2" thick, so strength isn't going to be a big issue.

 

Planning,planning----When I drive the roadster pickup around, I like to rest my left elbow on the top of the door and the area directly behind the door. Tonight I enlisted the help of my reluctant spouse to come out into the ice cold garage and take this picture.---The piece of tape is placed approximately 1” back from my elbow. This will establish the maximum "foreward” position of the ¾” plywood pieces that attach to the top/rear of the cockpit. (you can see that its not going to be quite the same as shown on the model). It also establishes the rear of the side window opening. The other attached “drawing” is based on measurements I have taken showing the position of my head relative to the rest of the car body. This gives me a starting point for making the patterns for the metal frame tubes.

 

Like that?

 

Because THIS is what I think of when you say Carson top and it's way sexy!
xxx

 

hey,

thats my heap of shit. the roof is totally crap but looks ok in that pic. my hole ride is crap but looks ok in that pic. if only i was in there too maybe i would have gotten some of that photo love...

dan

 

Yes that's right ladies and germs,

That there is our very own Psychobilly Boi's Av8 with soft top.
Nice lookin roadster, nice lookin top and nice lookin boy........

Maybe he'd be SO kind as to elaborate on it's construction?

xxx

 

Here is my top under construction. I did it like the thread but covered the mock up with fiberglass.

 

To start things off, I cut a peice of 3/4" plywood to the shape required for the "anchor" plate for my carson top, but leave it about 1/16" to 1/8" oversize all around the edges.
The area at the rear/top of the cab where I want to attach the 3/4" plywood "anchor" for my carson top is a compound curve. Not a huge compound curve, but enough of one that when I lay a peice of flat plywood on it there are some pretty signifigant gaps between the plywood and the car body.
To fix that, I will make a series of sawcuts as shown in the model, about 1/8" wide and 11/16" deep, 3/8" center to center. This will leave 1/16" of the plywood intact, which will make it very flexible in the areas where the compound curve is most pronounced.
Since the body is finish painted, (and believe me, I have no desire to screw it up), I will tape a peice of fairly heavy polyethylene sheeting over the entire area of the body where I will be working. In the area where the plywood will set I will set 3-layers of fiberglass mat, cut to shape, and coat them with resin. While the resin is still wet I will lay the plywood on top of the resin (with the saw-cuts facing up, away from the fiberglass) and then use every clamp in my garage to clamp the plywood down so that it follows the exact contour of the steel body, with the wet fiberglass cloth trapped between the plywood and the body.---this is horribly messy.
After the fiberglass has set up overnight, I will remove all but 2 of the clamps and use a putty knife to force "dog-hair" (polyester bodyfiller with strands of fiberglass mixed into it) down into all of the sawcuts. I will use a good bodyfill spreader to trowel the dog-hair filler smooth before it hardens. Once it has hardened for a couple of hours I will lay another 2 or 2 layers of resin soaked fiberglass over the top of the plywood.
I then remove all the clamps, remove the "part", and then sand all the edges untill I get an exact match to the roadster body.
Pictures to follow------

 

Hey---this is working good!!! It didn't take nearly as many saw cuts as I had anticipated to make the plywood conform to the compound curve of the body. It becomed very flexible with the number of sawcuts that you see, and the fiberglass cloth, once applied, will make it hold the exact shape that I want. You will see a second peice of plywood setting in the car----I used the first one as a pattern to cut the second one, which will be the hinged part of the carson top. Contrary to what I said in the previous post, I didn't cut the plywood oversize. I made a heavy cardboard pattern, trimmed it to an exact fit with a box knife and heavy duty scissors, then transferred the pattern to the plywood and cut out the exact shape.
Next comes the stinky part----fiberglass work. I am working in a garage under my front bedrooms, and I just know that my good wife is going to have my ass for stinking the house up.

 

You're not related to Colonel Angus are you?

 

Tman----I'm not sure who colonel Angus is. My last name is Rupnow. My second name is Angus.----Hows that for a weird heritage. Ancestors on my mothers side were Irish/Scottish and on my dads side were Russian/German.

 

Using pine may be a convenience for upholsterers, but I'd be inclined to use oak where a top is involved.
Pine . . . ok for interior stuff, but the flapping wind puts quite a strain on the top material and I'm not sure pine is up to the job.

 

How about a shape more like this? And better yet, white...

 

Woops!!!!!----slight design change here. I spoke to the man who will sew the Carson style top this afternoon, and he said that on original early roadsters the top was attached with canvas straps to the folding mechanism above the doors on each side of the car. My original design with the sheet metal peice between the header over the windshield and the front-most top bow did not have any frame member there to tie the sides of the top to.-----he says that will make the canvas flap around in that area above the doors on both sides of the car.
-----So, I've dumped the sheet metal and added a tubular peice on each side of the frame between the header and the front-most top bow.
The canvas will extend about 1/2" an inch below this tube on each side of the car. He said that there was no requirement for a framing tube at the rear of the side window openings.

 

I learned the hard way (in a TR-3 I think, or an MGA) that it's extremely painful to have a top bow directly over your head if your seat belt isn't real snug all the time! Set it up so when you go thru a dip in the road your head hits only soft cloth.

Also, Hardwood is definitely the way to go but Oak doesn't stand up to weather outdoors as well as Maple, Ash , or Hickory would. (learned this the hard way too...)

If you added a bow it would give a better Model A look instead of a Model T s bow look and then you could space the bows so they aren't directly and dangerously over head.

I wish I knew how to do cool graphics like that!!!

 

hahahahahahahaahaha SAy it 10 times fast, with your wife in the room.

 

OK, I'm patiently waiting! I will be up against the same thing with my car.

Kathy

 

instead of slicig the 3/4" plywood for the curves you can do what the skate boarders do to make ramps, Use a few pieces of thin plywood & layer it.
they also make a very bendable plywood.A friend of mine used it on his T bucket, but it was given to him (3/8" thick)so i don't know where to buy it.Sure they would know at home depot or lowes.
Another thought would be do it like the old days, make a frame out of conduit weld it & cover it with chicken wire , padding & canvas, it'll still tilt & be alot lighter.
jimV

 

Jeez---what a yucky, slimy, mess. Anyways, as promised, here's the first step in the fiberglass dance. I cut the plywood to the exact shape I needed, positioned it exactly where I wanted it with clamps, then drilled 4 holes through it and the top of the roadster body rail with a 1/4" drill bit. I then tool 4 round peices of rod (make that 2-peices of 1/4" rod, one-1/4" hex bolt, and one old spade wood bit with 1/4" shank), and ground a very sharp point on one end, then coated them with paste wax.
I removed all the clamps and the wood, and worked some paste wax down into the holes I had drilled in the car body, and then covered everything with clear polyethylene sheeting.
I used the wood as a template to cut out 3 peiced of 1 1/2" fiberglass mat (the mat was cut about 3/4" oversize all around.
I taped the first peice of fiberglass into position on the car body with a bit of masking tape, then mixed up a batch of resin and hardner, and used a 1 1/2" cheapo paint brush to soak down the single peice of fiberglass. (there is polyethylene sheeting under that peice of fiberglass, so it won't bond to the toprail of the car body).
I then layed the second layer of fiberglass mat on top of the first one, and wet it down with resin, then the same for the third peice of cloth.
Then it was time to wet down the mating surface of the plywood with resin, and lay it in place on top of the 3 peices of wet fiberglass. I then performed my amazing octopus stunt, and while holding the plywood in place on this gluey snotty mess with one hand, took my other hand and shoved the sharpened peices of rod through the plywood, the 3 layers of wet fiberglass, and the rail at the top of the car body, and took my other hand and tapped them into place with a hammer.
---Then I took all of my clamps, and 4 that I borrowed from my neighbour, and clamped the plywood down into place.
With the clamps holding everything in place, I mixed up a batch of "dog hair" bodyfiller and worked it down into the sawcuts in the plywood (thats the nasty green stuff in the picture).
T his entire mess can now set overnight, and the fiberglass will "set" and hold the plywood in the exact shape that the clamps have pulled it into.
Later this week I will pull the plywood off the body and put another 3 layers of mat on the top side, to give it extra strength and gaurantee that it will hold its shape.

 

I just spent the morning in the garage doing more fiberglass work, but it looks like a big horrible mess right now, so there's no point in using up bandwidth posting a picture.-----Things will start getting real interesting in another week when I get the hinge mechanism sorted out and start forming the top bows.
I spent some time last week and installed a small "fan in a box" in the garage window, with a trap-door that I can open and close. This fan is a bit like a computer fan on steroids that I had hooked up in my last house to blow heat from the wood-stove in the family room into the heating ducts for the rest of the house. ( I never throw anything out if there is even the remotest chance that I may someday use it again)
The fan provides enough negative pressure in the garage that the worst fiberglass smells don't stink up the entire house. (my garage is under the front bedrooms) and my wife gets rightously ugly when the house smells like a fiberglass factory).

 

Progress,progress----the garage is quiet today, and some of the fiberglass stink has abated. I am about to start sourcing the steel tubing that I will use to make the top bows, so have been spending part of today verifying the accuracy of my solid models, and adding in the loft of the canvas top and correctly positioning the driver. This is necessery to enure that I have good vision through the "side windows", as well as adequate head room. I have tried different lofts to the top material by moving the highest top bow closer to and farther from the windshield posts, but this shape is the one I like best.----It is an interesting "shot" because it shows the position that the top canvas will occupy, and defines the position of the "side window openings", and I have made it transparent to show the actual positioning of the top bows. (the header over the windshield posts will actually extend about 3" beyond the front of the posts, I just noticed that I have it shown flush)

 

What is it costing???? Well, so far I've paid $80 for 4 yards of 1 1/2oz. fiberglass mat and a gallon of resin. This week I have talked to a number of fabrication shops about bending the tubing for me, and a surprisingly great number of them refuse to bend thinwall tubing!!!! The one outfit that said they can bend it wants $120 (thats for 4 ninety degree bends with a 9" outside radius).----and no, I won't do it myself. I don't have a tubing bender, and I've tried bending the damn stuff myself, using all of the tricks (sand in pipe, radiused dies, etc) and it always kinks.
I estimate that I will use about 30 foot of 1" outside diameter DOM seamless mild steel tubing with a 0.065" wall, and today I was quoted $26 per 10 foot length.
---How did I determine the radius----a little bird told me that the outside radius of the tubes should closely match the radius at the rear of the cockpit.
If your adding, and include the $600 I was quoted for the canvas top, and all the taxes us lucky guys in Ontario get to pay, were up to about $900 and that doesn't include the header or latches.

 

I tried the plastic drop cloth trick when I built mine . It did not work. The resin went thru the plastic and got the paint. I found that al. foil is not affected and I also had good luck with masking tape. I only have one piece of steel in my top. The side openings have plywood and the header is oak. I put a reinforcing loop of steel tubing arround the back above the seat. This was added 10 years after the top was originally made. It moved a little and this was the fix. I bent the tubing by putting sand in it and heating over a form.

 

Andy---really nice job. The top looks great, and yeah, the resin got my paint a bit too.

 

Don`t you think 1'' tubing is kinda overkill? I am not knocking your plans , but think that is a little bit much for a top! Most of the other tops I have messed with use maybe 3/4'' at most. Why not use aluminum? Just asking, that`s all.

 

Well, actually, I've never done this before. I chose 1" because it seemed reasonable to me. I talked to a couple of top manufacturers, and they told me that aluminum wouldn't stand up to the wind buffeting at sustained 60 MPH speeds. Another top manufacturer I spoke with uses 7/8" outside diameter tubing. You could very well be correct, but when I model things to scale, it doesn't look unreasonably big to me. If it looks too big, I'll know better next time.

 

Lke I said, just asking. I am always too quick to critic someone elses work and it`s not a very appealling atribute! I too, am going to make a similar top for my RPU, and am paying close attention to this thread. Keep up the good work and please keep us posted when you can. Thank`s Vic