1955 Pontiac chassis

[fomocomav]

I was wondering, would the Monogram 1955 Convertible be my best choice for using as a 1955 Pontiac chassis, given that it has an X member like the only picture of a '55 Pontiac chassis I can find?  I've seen drawings in the dealer brochure that show this X frame member, so I'm assuming that all the 1955 Pontiac cars had it?  I know the wheelbase is different, I just want something close.  And is there a model that had a similar motor that I could use?  I haven't found any builds yet that show this, so I thought I would ask.  Any help would be appreciated!  Thanks!

[High octane]

If you're not going to display the car upside down, and are really just lookin' for a chassis. I would use one from the Tri-Five Chevy kits.

[Ace-Garageguy]

I was wondering, would the Monogram 1955 Convertible be my best choice for using as a 1955 Pontiac chassis, given that it has an X member like the only picture of a '55 Pontiac chassis I can find?  I've seen drawings in the dealer brochure that show this X frame member, so I'm assuming that all the 1955 Pontiac cars had it?  I know the wheelbase is different, I just want something close.  And is there a model that had a similar motor that I could use?  I haven't found any builds yet that show this, so I thought I would ask.  Any help would be appreciated!  Thanks!

After researching the subject at length several months back, I decided to do exactly that for a '55 Pontiac gasser build I'm planning, based on an old Johan shell that got stepped on, which made it a natural for a chopped-top.

The Poncho frame is indeed similar in appearance to the Chebby convert frame. This is a '55 Poncho.

This is a Pontiac frame from the top (AFTER the independent front suspension has been removed).

   

Below is a '55 Chebby convert. The main visual difference is in how the Pontiac rails are forked just at the forward intersection of the X-member, and the fact that the Chebby rails are heavier, and boxed. Also notice the Chebby lower control arms are a different design, and have a kink in the leading edge that the Poncho units lack. The Pontiac control arms, from the bottom, look very much like the parts from a '49 Mercury, also available in kit form from both AMT and Revell.

As far as the engine goes, I think the old Revell parts-pack Pontiac engine kit is among the best there is. Only main visual difference is that the early Pontiac engines (through '59 I think) had the water connections in the front of the heads, rather than in the more-typical center location, due to Pontiac's "reverse flow" cooling system for the first few years.

Though the kit says it's a 421, all the Pontiac OHV V8 engines of the first-generation series look very much the same...other than details like intake manifolds, generator brackets, etc.

NOTE: Check out this build thread for a lot of shots of the guts of a '55 Pontiac.      http://www.jalopyjournal.com/forum/threads/1955-pontiac-gasser-build.501387/          

 

 

Edited April 18, 2017 by Ace-Garageguy

[Ace-Garageguy]

 COPYRIGHT NOTICE: Photos above taken from open internet sources under "fair use" definition in copyright law 

[fomocomav]

Thanks for all that information.  And the pictures!  I'm thinking I may not open the hood, so the 55 Chevy motor will work, too, since the oil pans are very similar.  If I DO open it, I'll look for a 421.  This has been a great help!

[oldnslow]

I believe the pontiac has a longer wheel base the the chevy , but it may be unnoticeable in 1/25 . The difference is 9" , 115" to 124" .( numbers from the internet )

[my66s55]

55 Chevy  and Pontiac frame:

[fomocomav]

Oldnslow, that's 9 mm.  It will definitely be noticeable.  I think I can manage that splice (I hope).

 

my66s55, that is awesome!  My Google-fu is not up to your level. 

Thanks again, for all the info!

[Art Anderson]

The 9" difference in wheelbase certainly will make a difference--that's 9mm, or in English Measure .360".   Now, the easy part of this is that  wheelbase difference is all forward of the firewall, as Pontiacs used the same GM A-bodies as Chevrolet.  With this im mind, and considering that the only 1/25 scale Pontiac plastic models were made by JoHan as promo's back in the day--a '55 or '56 Pontiac done from that tooling might possibly be just a it undersized--due to a quirk in GM Marketing's specification that alll promotional models of GM cars back in those days simply had to be packaged in the same exact-sized boxes.

With this in mind, it might be worth checking out the chassis (and floorpan) of the Revell 1950 Olds 88 kit--as that is also an A-bodied car, and the chassis comes with a ready-made X-member.  With both the Pontiac and the '50 Olds, the overall length and wheelbase differences vis-a-vis Chevrolet was in the front clip.

Just a couple of thoughts.

Art

[fomocomav]

Art Anderson, I had already bought the '55 Chevy Convertible by the time I read this.  But, just to be on the safe side, I checked them both.  Either would work, and the Olds DOES have the different attachment points up front like the Pontiac does.  However, there are 2 things that are swinging me to the '55.  First, strengthening ribs on the floor pan on the '55 look closer to the Pontiac floor pan, and the frame rails at the rear are closer on the '55.  The Olds frame rails flare out, where the Chevy rails remain parallel.  In the end, this is, I think, going to be easier to do closer with the '55 Chevy.  But the "in front of the firewall" information is most welcome!  I wasn't sure where to put the extensions.  Now I know, and that will save me a bit of work!

[MrObsessive]

Funny, I had this same question in mind as I bought a junker Johan '55 Pontiac at NNL East. It's missing its roof (Revell '55 Chevy would work), and this answers questions I had about the chassis. BTW, seems to me that the "X" member in the frame was used just for the convertibles and hardtops. The sedan's bodies would have been a bit tougher due to the center "B" pillar.

When I'll get to restoring the Pontiac is anyone's guess, but one can't have enough pictures and info!

[Greg Pugh]

Now with reference to the wheelbase difference, I know that the Star Chief was longer than the Chieftain and the lower models. So if the Star Chief has a 124" wheelbase, anybody know what the lower models had? Would they be the same as the Chevy's?

[MrObsessive]

Now with reference to the wheelbase difference, I know that the Star Chief was longer than the Chieftain and the lower models. So if the Star Chief has a 124" wheelbase, anybody know what the lower models had? Would they be the same as the Chevy's?

Greg, the Chieftan had a 122" wheelbase as opposed to the Star Chief's 124". With the '55 Chevy coming in at just 115", some definite surgery would be needed on the chassis from the firewall forward on the Chevy kit.

The two inch difference in wheelbase between the Star Chief and the Chieftan probably was located more in the rearward part of the quarters, with there being just a bit more real estate from the trailing edge of the doors (two doors for instance), and the leading edge of the rear wheelwells (Star Chief).

Of all the pics I've seen of '55 Pontiacs, all of the front fenders were of the same length, particularly between the trailing edge of the front wheelwell and the leading edge of the front door. Interestingly enough, I believe there was no increase in front seat legroom despite the Pontiac's longer wheelbase, comparing that with the Chevy.

Frankly, I sure wish cars today had those type of proportions, especially FWD ones. I hate how a lot of cars have the front wheels so close to the front of the doors, it gives some cars a "constipated dog" look when viewed from the side. Not to mention the annoying protrusion of the wheelwell into the interior footwell area of the car!! 

[BubbaBrown]

Wasn't there a article in S.A.E. a few years ago saving a 55 Pontiac wagon with Chevy parts?