Introducing myself

Hi Michayos...
I guess the "bump" in the rear crossmember is for the fuel tank filler neck...but, oddly, the original shop manual image of the frame does not show any curved section...
The rear body and rear bumper of my Catalina were not damaged so I think it was never involved in any major accident...

Thanks Vittorio.  I suspected as much.  The filler neck for the gas tank on my car not only clears the front of that brace between the frame rails but also clears the trunk floor support in front on it.  In fact I have a very annoying tube in my trunk that encloses the filler neck as shown in these pictures.

https://i.servimg.com/u/f73/18/49/56/13/dsc01614.jpg
https://i.servimg.com/u/f56/18/49/56/13/dsc01729.jpg
https://i.servimg.com/u/f56/18/49/56/13/dsc01731.jpg

I thought all the 59 Pontiacs were the same length.

So now I have to ask if anyone knows if the 2 door hardtops are shorter than the 4 door sedans or is the gas tank bigger on the 2 door versions?  There would have to be a good 4 inch difference somewhere between my 4 door sedan and Vittorio's 2 door hardtop to explain this.

Thanks!

Michael

Michael…..no, all of the Catalina body styles are the same length overall (213.7"), except for the Safaris (214.3"), and of coarse the Star Chief and Bonneville (220.7"). The wheelbase for all of the Catalinas and Bonneville Safaris is 122". All of the Catalina Frames are basically the same dimension, but some, like the Safaris and convertibles had extra brackets and cross members for support. They also had boxed side frame rails behind the rear axel kick-up.

Vittorio…..I think that the cross member should not have that hump in it. I would measure the distance between the side rails. It should be 57 3/16 inches +or-1/16 from outside to outside at the spot where the cross member meets the rail. If it's not, the cross member needs to be straightened to reach that dimension. Also check the other dimensions to be sure the entire frame has not been diamonded. You don't want the car "crab walking" down the road. With the body off, now is the time to check and correct any issues All the measurements are in the shop manual……John

Thank you John
I checked the measurement of the frame before sandblasting and painting..and they were ok but I'll check again next weekend...the rear crossmember is better then it looks in the picture.
I mean, some "smart" guy probably hooked a towing cable (or something like that) to the crossmember to pull the car and bent it rearward..I already put it back in shape as much as I could before painting...
But the body and bumper were correctly bolted to the frame when I got the car so I did not insist much...
I attach a picture (taken from the old thread of a 1959 StarChief ) where the hump in the rear crossmember is clearly visible ...

Thanks for the info John but in answering my question you've given me two more.  

You said the frames on the Catalina's are all the same.  So if the Star Chief and Bonneville are longer is their frome longer somewhere too?

The rear cross member looks to be in the same place on Vittorio's Star Chief as it is on my Catalina.  So... If the gas tank filler tube is the same on the Star Chief as it is on my Catalina then it should easily clear that cross member and the hump would not be needed.

The hump in the cross member looks too perfectly centered to not be from the factory.  Is there any record of that hump on the 59 Pontiac models?

Vittorio, do you by any chance have a picture of the trunk before you stripped down the car?  I'm curious to see where that filler tube goes.

Michayos
My car is a Catalina too...2 dr Htop, the last picture I attached is another member's StarChief I found on this forum...just to show the crossmember hump on another car frame...

According to my shop manual the StarChief/Bonneville frame is 2" longer in the center section...somewhere between the front body mount and the rear axle area....

I attach a picture, It's a 1959 Bonneville rear crossmember and guess what?
No hump!!
Different assembly plant might have used different shape frames...who knows?

Sorry about the confusion Vittorio.  I thought you had a Catalina too and your last picture caught me off gaurd.

Ok, so we have confirmed that the hump is on SOME other cars and different models.

As an engineer, I know that this hump would increase the strength of the cross member.  So maybe it was added to some models for that purpose.  But why wouldn't it be a standard on all cars of the same model?

There is a thread on this forum named "Production differences and anomalies you've found! "
Sounds like this is material for that thread.... 

Vittorio…..you just reminded me of something when you mentioned different assembly plants. No, the frames were not made at the assembly plants, but they were supplied by two different outside suppliers. One was the A. O. Smith Co. mainly from the Detroit Mi. area, and the other was the Parrish Co. from the Reading Pa. area. That would probably account for the dip in some cross members and not in others. I used to know how to tell which company made the frames, but old age has crept in. One had a continuous weld of the two "C" sections that formed the boxed rail portions of the frame. The other company stitch welded 4" sections, then skipped about 4" sections all along the joint.

Michael…..Pontiac claimed that they used 8 different frames. This was true in the sense that there were some extra brackets, braces, and cross members depending on the needs of a particular body style. I'm sure they ordered 8 different frames from their suppliers and had 8 different part numbers. However, they basically had two frames, a long wheelbase (124") and a short (122".) Bonnevilles and Star Chiefs were 124" and Catalinas and Bonneville Safaris at 122'. Vittorio is correct that the 2" difference is in the center section somewhere between the "X" and the beginning of the axle kick-up. The long wheelbase frame is also about 5" longer from that point to the end of the frame. As far as the 7" difference in overall length, about 2" of that was between the "B" pillar and the beginning of the wheel opening. The rest was in the length of the quarter panel and the trunk lid. Remember, the interior dimensions were all the same. That's why trunk lids, trunk floors, and quarter panels of Bonnevilles don't fit Catalinas, while doors, glass, roofs, and floors do, style for style.

Thankyou John..
I really appreciate this knowledge you share!!

Vittorio, sorry to go off on a tangent here. Curiosity just got the best of me.

Great info John! I eat this kind of stuff up and I'm always hungry for more.

The boxed areas on my frame have one continuous weld.

Some updates ...

Upgraded later design front crankshaft seal....

The engine looks great!

Thank you Michayos...
It is now already back between the framerails!!

Good job !

Bad news for me.....

Started working on the heads....found one small crack on a valve seat.....
guessing what to do: look for replacement head(s) or try welding this one?

Looking good! (Except for the cracked head of course.) Really enjoy the progress pictures so please keep them coming.