Frame question Olds Delta 88

[Homer86]

Hello together,

My first question
Is the frame from the cabriolet Oldsmobile Delta88 1970 the same as from the Hardtop Olds Delta88 1970?

Thanks
Dennis

[66400]

According to Hollander Interchange books convertible and hardtop frames are not the same.

Henry

[Kennybill]

The difference between the 1970 Delta "convertible" frame and a 1970 Delta 2-door hardtop frame is the convertible frame is "boxed" for extra strength.

[joe_padavano]

As noted, the convertible frames are reinforced to make up for the lack of rigidity when the metal top is removed. The hardtop frame will physically bolt up, but over time it will sag, doors won't close right, etc. Not the best choice.

[Olds64]

Can gussets be added to the hardtop frame for extra strength?

[joe_padavano]

Originally Posted by Olds64

Can gussets be added to the hardtop frame for extra strength?

Yes, but...

When one says "boxed frame", most people immediately think of the common practice of adding flat plates to the inside of street rod frames to turn the C channel into a box. Unfortunately, the boxed frames on later model convertibles are significantly more complex. Having said that, it IS possible to turn a HT frame into a convertible frame with a lot of work. The "boxed" part in question refers only to the section of the frame rails under the rockers. The front frame horns are already boxed from the firewall forward, as are the kickups over the rear axle.

The 60s and 70s GM convertible frames started with the same rail stampings as the HT frames, which have an open C section under the rockers. Additional C-shaped sections were fabricated and welded to the open end of the existing rails to complete the box. These are not flat or even rectangular sections, but are formed, tapered, and notched to clear the floorpans and other parts. Replicating these parts would be extremely complex and time consuming.

A more feasible, though still very labor intensive, option is available if the convertible frame in question is only rusted in the parts that are common with the HT frame. In that case, one could start with a good HT frame, cut out the unrusted reinforcements from the bad convertible frame, and weld them into the HT frame. This essentially replicates how the factory built the convertible frames.

[Homer86]

Mahlzeit,

Ok, thanks for our Answers.

Dennis