4 door conversion 1959-60, differences

so a fellow hamber asked my help in making a decsion. he wants to take his 59 more-door and make it into a functional convertible. i figured if i would explain what i know, i may as well make it helpful for all.

So. the first thing to understand is your specific car. in this case, we r speaking ab a 1959 chevy. there were many different verison of this car, and many different details alot of people would not know. teh biggest thing that people do not know is that the 59"coupe" trunk is longer then that of the all other models. the two door biscayne shares trunk with the four door models.

next, the flattop, 4-window , impala, shares thhe same rough line with the convertible cars. has same windshield and size vent windows. the windshield can be reused with the convertible frame.

so here is a list of what you will need to do your own conversion.
from front to back....

1) convertible windshield frame...with all the trim pieces ( there are 7 pieces. 3 stainless,outside, 4 pot metal, normally painted on inside. on selected cars, Bonneville, Cadillac, Buick 225. all are stainless.

2)secondly doors.
you will need a set of 59 coupe doors. cadillac ,chevy, pontiac, i am certain are the same. i think oldsmobile and buick have a wing going through the doors. so they cannot be used.

3) vent windows and window frames. convertible vent windows and window frames are different then regular coupe window frames.the have a distinct curve to form to the top.

4) the next thing and most difficult thing to get is a "complete tub" you can but a tub, but people will have taken out the "quater windows" the window regulators, the snap trim, and have left it bear. when doing a conversion it is best to have all the pieces in becuase searching takes alot of time and effort and winds up costing alot.

when is comes time to start lining things up, having the windows in place as well as the convertible rack are crucial to how your project will turn out.

NOTE- i will get into the differences in tubs and cars later in the post.

5) lastly, your convertible rack. its hard to find rust free racks.usaullay in the rust belt you can get everything. but will need much work. so if you can find better starting material then you project will go along much smoother.

6)Lastly Patience,Patience and even more Patience. what you have to realize is that most floors of gm cars between 55 and 70 were on two year build periods. 55-56, 59-60, and so on. as time went on it moved to three years 66-68.look at cars and you can see how at first two years deisgns looked similar. and after 3 years designs.until late 70s and 80s , when creativity kinda just stopped existing.


pics are coming in next while

 

Man, I would love to have my dads old '59 Impala convertible that my mom sold in '69 for 10 bucks! I'll be watching this thread.

 

first thing you need to decide is what look you are goign for. if you want a true functioning convertible top. if you want a caron-phantom top design. or whether you want just a "roadster design". each are fine , but you must decide.
i have a 1960 4-window cadillac. has the convertible windshiled height which makes it a low rooof. being 6'8 it hard to get in and out of, so i have decided that the roof will be coming off. i have found a few pictures dealing with this particular design. it was going to combat what lincoln was starting in the early 60s.

 

next you have the 4-door covertible with a removable ragtop design.... here are a few examples...

 

Wow! I didn't know they made a 4 door convertible??? That red one is sliiiiiiick!!

 

here is the best "carson" top design i can find for a four door, the top has really good detail and a great look

 

they didnt!!! all these are customs. the only one designed by gm factory was the white 4 door. it was a concept to fight lincoln!

 

ok, now to task at hand, you look and see the 4-door models , and say thats not what i want. i want a real deal 59 convertible. so there are a couple things to consider here. if you want a direct fit, or just something that works and looks goood.

the most exact way to fit your 59 chevy, is with a 59 chevy vert project. every 59 convertible car (gm) has the same mechanism and tops bows. the quater window segments are larger on buick and cadillac. the tub has a "flat lip" for the snap trim to bolt to. in 1960 the lip was raise and stayed raise through 1965 when the second generation cars became more produced. the biggest change was from x-frame to box.

the also , stopped the stainless windown frame and began with just tempered glass. this glass has a curve in it, which makes the "convertible roof area" smaller.



here are the two different tub sections one from a 1960 and one from 1959

here is a project 1959 convertible....look at how the tub section runs flush with the wings...


here is the tub cut out of the car......the wings and section are all flat and run really flush with the wings.....



here is a 60 cadillac convertible. Cadillac kept the same convertible design as (gm)1959 models. cadillac has a longer wheelbase then the chevrolet , so the qauter window is longer which makes for a longer convertible rack. the bows and header can be used for chevy, but the tub section and lips are all wrong size for (swb) cars.


here is the 60 tub section i am using on my 59 project

 

now , here is where it gets quite touchy. in 1960 the first raised tub lip shows up. common on all bop models. buick 225 and cadillac stay with the flatlip design. after 1960, the raised lip stays around....i will try to breka it down really slowly.

first off here is the tub from a 1960 pontiac....


here is a cutout tub section.....notice the raised lip.....


another 1960...

 

Wow. A huge project. My hat's off to you for tackling it. I'll be watching this one!

 

here are some tubs and lips from teh earlt 60s

here is a 61 cadillac convertible....
notice the raise on the lip


here is a 62 impala..notice the raise on the lip

 

this is not a project, persay, i am trying to show the differecnes in convertible projects that are out there and available. and what direction is the best to take for each person.

 

so guys if you , can follow what i have been trying to say. there are two different usable tub methods for your 59 chevy. one will give you the direct flush look as if original. the next will give you teh raised lip, and show it is not original , but you will have the same fucntioning top.

 

going into further detail now, after you have decided your tub, you will need to figure out the best way to mount it. after studying these things for some time. i have noticed that it is all a big puzzle piece. if you think of it like this, then you can drop it into place without much hassle. the area to watch out for is the inner tire well on the rear wheels. there is a dent on the well that is there to allow the rack to laydown under the qauter panel without being seen. this is probalbly the toughest area to get clean. here are some pictures of how the convertible mechanism attaches to the rear tire well.

example...


exp2....



the difference in the height of the two wheel wells....


iin stalled.....


the difference in height....

 

Very useful info boom I was able to follow your entire thread with ease to pick you brain a bit more, I'm a but puzzled with the area between the snap trim on a 59 chevy vert to that of a 60 pontiac vert I kno it's flat on the 59 and raised on the 60 but it also looks broader on the 60 if u have close ups of this area please post as I looked everywhere but the pics I saw were not clear thanks!!

 

i got you last questions bro,and was thinking....its only metal ,right? there has to be a way to do it. or someone who has done it before....

so i looked and looked, and i found a guy who used a 60 lesabre, to do a 59 cadillac. now we all know, that the cadillac shared lengths with teh buick 225. not lesabre. the lesabre was shorter wheelbase car, ie. was more in touch with chevy and the other "smaller cars". so to answers your question i will try to show with pictuures how this guy fixed that issue.

so here is the car he used.....


here is the 59 cadillac for the conversion......


here is his tub cut out..........


just as a teaching point, to you guys, and for a later post i will make on this topic. loook at this tub and rack here and can you tell what the difference is in this one, and the on above it?

 

ok face-off, this is will help you with your question. the lesabre, was from 60 so the hump was present. not as bad as pontaic and other because of teh rise in the quater panel, but it was there. so, this guy took the "hump out" with cutting , filling, and massaging. here are the steps.....

one , line up your convertible tub to the car, always undercut, you know that already! lol....after look at where you think it should be, then make some preliminary cuts....


here i think he uses cardboard as a way to decipher how to get it flat....

(also , this area, is quite important because it anchors your vinyl/canvas top down in the reat. must be super pateint here.)

as you can see from picture, the two "lips" are at different heights


to lower the "hump", you must remove the "hump", and create your own new "lip". once again, this takes patience. but after, here is what you get with little bt of work!!!

 

ok, so you are asking me, "well boom, why is he cutting and grafting the tacking rail section onto the the rear deck lid. "

my answer is becuase he used a shorter wheel base convertible tub, for a long wheelbase car. when you use the SBW tub on SWB car, you will not need to "make up" for extra room. i will show you in the next pictures why....

 

here is what out guy came out with.....notice the distance between trunk lip and where the tacking rail will go. it is about 4-6 inches, i cannot tell. notice the below picture. it is of a "factory" 59 convertible. that same lip is much smaller.

our guys "lip"


factory lip

 

ok, so now you have another dilemma, one you are not building a cadillac. so you cannot use this guys idea. you have your trunk supports already connected to your tub. are you suppsoed to cut it all apart and then re-weld it so that it looks good???

well that is a possible option, but will take alot of work. you can do it the way this guy dd, but using your 59 rear deck and trunk supports. you can splice the tub in back , separating the tacking rail from the trunk supports.
* if you do that, you need to use the convertible "springs" that hold the trunk up. they have different weight and resistance for convertibles!!!

or you can leave the lip and just go down the road....and people will know you have a convertible thats a bit "off"....that is what i willl do with my flattop 60. i dont care so much about factory and numbbers matching, ii just know i love that car and want it to be a convertible.

but i must say. if you are going to be getting into a project this big, you can take an extra week and make it flush. you wont have this done in a weekend. but to eahc his own. i am not an expert at this , nor claim to be, i just want to share the wealth with what i know and give ideas.
the "true" Gurus of this science dont really talk so much ab it or share their pictures, so I THINK i can help out us little folk and try to steer guys in the rigth direction. more pics coming sooon

 

btw guys, i am sorry for the oversized picures, but the uploader on site doesnt ever work for me, so i am using tinypic and they just put em as big they can possibley be...pfff

 

Aww man I am so grateful that you are sharing your knowledge with me and all the HAMB followers "to each his own" is the correct quote to use I am under no type of deadline to complete this project and I am going to try my best to be as close to factory as possible. Reading your previous threads and posts I have learned a lot I have a pretty good plan as to how to approach this build after seeing your recent pics. Thanks again and I will definitely keep you posted

 

coool man, great attitude, if you are not under a deadline and want factory, remember that on your 59, the differences in the trunk need to be accounted for. other then that i think, you pretty much have it figured out!! i am also learning much as i go along as well, i will continue posting more things i find coool ab these swaps!

 

WOW !!!!!!!!!!! Lots of work.... Hat's off, to the guys doing these..... I seem to recall something to channel water away from the trunk area, on my 68 Caddy ?

Keep us posted,...These are great projects !!!

4TTRUK

 

i am in europe not , with my cars, but i know teh channel you speak of and has a drain hole on the inner fender, let me see if i can find some pics, and figure out what they do with that

 

Anything need to be done to the frame of a 4dr for stiffness after the roof is gone?

 

yes, there are a few thinsg you need to watch out for. the rocker panel has two set of reinforcing. a solid angle iron bar run through teh middle and a under support that can be welded on. that is for body.
for the frame, there are extra pieces of "reinforcemnets" added, also extra body mounts. on cadillac the number of body mounts stay the same. on chevy there are 4 extra mounts that need to be added.

 

here is a the view of the inner rocker panel on convertibles. it has an extra "rocker" but is more of just a really solid piece if metal. it is connected from the firewall to the under structure of the convertible support frame.

the next pictures are of the convertible "undersupport" it is welded under the rocker for extra support and to prevent flexing.

 

Too much good info to get buried. To the top.

 

Hello; Do You have a follow up to this post or more pictures to Look at, I enjoyed it, Thanks