1970 Buick GS 455 Frame

Discussion in 'Buick FAQ' started by bernhard, Dec 28, 2017.

  1. bernhard

    bernhard Active Member

    Is the Buick GS 455 frame different from the 1970 skylark frame?
    If there are different how do they differ?
    Can a 1970 skylark frame be converted into a 1970 GS frame?
    Thanks
    Bernhard
     
  2. DBS

    DBS Well-Known Member

    Lots running 455's on 350 frames and a simple change of the motor mount pads will allow this, but technically the front 455 frame horns are thicker metal so yes, they are different and no, you can't convert them.
     
  3. BUQUICK

    BUQUICK I'm your huckleberry.

    While there may be some differences, they will interchange with no modifications required except for the big block engine mount pads.
     
  4. bernhard

    bernhard Active Member

    Thanks for the reply's.
    Is the 1970 GS 350 the same as the GS 455 frame?
     
  5. Bernhard,

    The GS 455 frame differs from the GS 350 frame that is shared by the Skylark.

    Walter
     
  6. Rich Johns

    Rich Johns Platinum Level Contributor

    1970 Buick GS 455-GS Stage 1 frames are unique.

    They are stamped BW on rear frame rail.

    The C channel thickness of metal between firewall and where lower control arms bolts into frame is 50 thou thicker than any other Frame used in any other A body car in 1970.

    The front cradle in front of firewall and rear section housing rear axle to the back crossmember is standard regular thin gauge metal found on any other Buick or A body frame.

    From my research and observations there are only about 5 stamped dates ranging throughout 1970 model year for these special frames.
    Meaning, a batch of BW frames were manufactured, shipped to assembly plants and gradually used over a period of time.
    Thus, you will have the same dated frame in a range of stamped cowl tag assembly dates.

    I think Buick Chassis engineers were afraid that the torque of the mighty Buick 455 would hurt, twist damage the GS 455 -GS Stage 1 body infrastructure and therefore engineered a Heavy Duty frame for these special Big Block cars in 1970.
     
    Last edited: Dec 29, 2017
    mrolds69 likes this.
  7. 12lives

    12lives Control the controllable, let the rest go

    Did it carry over into 71-72, 73?
     
  8. hugger

    hugger Well-Known Member

    It did in 71/72 yes , 73 I have no idea, those cars were kinda beefed up everywhere anyway

    The 70/72 455 frames also have 3 holes in the top of the cradle also whereas the 350's have had st center punched hole

    I also had a Fremont built 70 Skylark with the 3hole frame, only 350 one I've seen with the holes, so maybe it was a plant thing, only Fremont car I've had too so,..
     
  9. Bigblock71

    Bigblock71 Member

    Why did my picture pop up upside down damn. It’s a 71 btw I put my sisters 72 grille on that’s all I got
     
  10. Stage 2 iron

    Stage 2 iron 480 IRON HEAD STAGE 2

    How about a 70 GS 455 convertible frame what would the code be would it also be BW ?
     
  11. TXGS

    TXGS Paint by numbers 70 GS 455 4spd

    I have a 70 GS350 that has the three holes in it as well. It was a leeds built car.
     
  12. mrolds69

    mrolds69 "The Cure"

    I just looked at my build sheet, in the frame box it says XV43. My car is a Fremont GS455 convertible. For my car, it's XV. It's interesting though, because other make A bodies, the convertible frames are usually boxed. A GS, I thought all the frames were boxed. I'm not sure why a convertible frame would have a different code. But...who knew what Rich said? Maybe there are other differences.
     
  13. Duane

    Duane Member

    Frank, for the 70-72 years,
    70-72 convertibles were the only frames that were boxed. That is why they carry a different frame number/letter code. Also for convertibles only, the same frame was used by Olds, Buick, Chevy, and possibly Pontiac.

    Also 70 convert frames carry a different number then 71-72 cars.
    Duane
     
  14. mrolds69

    mrolds69 "The Cure"

    Thanks Duane! I see...it's interesting stuff about the Buick GS. The extra body mounts in the front, the cross bars, the braces in the rear, and the axle bumper brackets. Now I'm reading about the thicker frame thing that Rich wrote. There's always something new to learn, isn't there?
     
  15. Stage 2 iron

    Stage 2 iron 480 IRON HEAD STAGE 2

    Thanks Frank and Duane for the clarification this will definitely help this week when I go to check out the car.
     
  16. ToddsGS

    ToddsGS Founders Club Member

    This came up on a FB post so I decided to dig into it a bit also. (2-3-2021)

    Here's my findings:

    Big Block Buick Frames ARE Beefier than Small Block Frames!

    After a lot of discussion and answers all over the board on this topic I think we can put it to rest today!

    Big Block Buick Frames are thicker than the Small Block Frames in regards to the C Channel section in the middle.

    We have 3) Buick’s in the shop – 2) Big Block Cars and 1) Small Block Car as well as 2) 1970 BB Chevelle’s.

    All 3) Buick Frames have been sand blasted and Powder Coated so the results should be pretty “fair”.

    The 2) Chevelle’s are clean cars with original – unmolested Frames. I figured I’d throw them in the mix as well.

    The general consensus in a recent post was Buick’s A-Body Frames are all the same other than the Convertibles being boxed in.
    A few of us figured there was a difference myself included because GM had issued the Big Block Cars (Frames) a different part number.
    1970 for example showed the 3300 – 4400 series as having Part # 3960733 Those are all Small Block Cars.
    The 4600 series has 2 parts numbers – 1 early and one later build. 3960798 & 1235413 (Later Build) This is the number my Stage 1 frame has which is part of this documentation.
    4600 series is all the GS / GSX 455 Cars. See my photos on this as well.

    So with all that being said here are the results . . . .
    The Small Block GS we have in the shop (Frame Part # 3992388 – which is correct for 1971 Small Block) had a thickness of 1/8”

    For comparison the 2) 1970 Chevelle Big Block cars we have in the shop were the same! So maybe Chevrolet didn’t use the beefier frames like Buick did!?!?

    The 2) Big Block Frames we have including mine were almost 3/16”. Our Metal Thickness Gauge would fit when using the 3/16” opening but not the 10 Gauge opening which is the next one in line after 1/8”. If you see them side by side you can see the difference with a naked eye!

    So the C-Channel from the #2 Body mount back to the Arch in the Frame towards the rear is almost twice as thick as the small block versions - more than likely the reason for different part numbers.

    Hopefully this clears up the confusion on Big Block Frames vs. Small Block Frames. Funny the Chevelles didn't follow suite! [​IMG]
     

    Attached Files:

    Dano, FirstBuickNut, Anas and 3 others like this.
  17. 12lives

    12lives Control the controllable, let the rest go

    Maybe that's why the dreaded "Frame sag" doesn't seem to affect BBB Buick GS but does BB Chevelles?
     
  18. Lou2

    Lou2 New Member

    I'm just starting a mild restoration of my dad's (early) 1970 GS stage1 455 convertible. I was reading this thread and it looks like i have a small block frame under this car. The frame code HAYES
    3960735 10 30 69 1
    20221115_173107.jpg 20221115_171408.jpg 20221115_173211.jpg
     
  19. Dano

    Dano Platinum Level Contributor

    My understanding is the convertible frames were all the same. Only the hardtop 455 frames were thicker.
     
    ToddsGS likes this.
  20. Lou2

    Lou2 New Member

    I guess alot of people would race the hardtops more than a convertible. So they got pushed harder.
     

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