Hello everyone, I remember seeing in the Oldsmobile Chassis Service Manual pictures of front frame braces used on the Cutlass wagons for 70-72. Has anyone ever seen these on the cars? Just always wondered about that. Thanks

 

If you are talking about the diagonal cowl braces used on the Vista Cruisers, yeah, every 1970-72 Vista came with them. Note that the page from the PIM says "4800 only", which is the Vista Cruiser model designation.

 

 

I am aware of the upper fender braces, seen them before. I remember seeing lower braces attached to the frame in the front of the car, also not the rear frame braces on some four speed cars. Thanks

 

Are you talking about these, used only on 455 2dr cars?

 

No, I have those on my 442 and four speed car, I will find the picture later on, they are under the car in the front of the frame under the motor to strengthen the frame.

 

Here is the pics ...

 

These are for big body cars.

 

B-body is the Delta 88
C-body is the Ninety Eight.

 

Just curious about the frames in the first picture, my Vista has them and the drive side brace interferes with battery maintenance/removal although minor. My question is this, why are the necessary?

 

My 82 Custom Cruiser has them. I had to remove the rears to clear long tube headers.

 

Dan, I've always assumed they took visible shake out of the fenders/hood. But I'm no expert in this area of engineering.

I will be interested in Joe's take. Mr. Structural Engineer always gives us a logical explanation.

Gary

 

My thought is that the longer wheelbase of the Vista, coupled with the higher probability that the wagon would be actually used as a wagon (hauling stuff), led to the use of those diagonal braces to stiffen the front end against a torsional mode. Frankly those struts aren't particularly structural. More likely they are there to raise the natural frequency in torsion to avoid a suspension mode that might hit resonance and cause an NVH issue.

 

I think I’ve asked this before, but while we’re on topic of firewall / fender / radiator support braces…

Is there any point in adding them to my ‘66 big cars? My ‘66 98 convertible shakes a bit on the freeway, I’ve been curious for years as to whether braces might help that. I’m not too optimistic though, since convertibles are, well, a structural compromise. And really, how much could a couple of 1/2” or 3/4” tubes really reduce shake?

Hypothetically, if I were to brace the radiator support or fenders to the firewall I’d put a support piece on the firewall to thicken it a bit, but it’s probably all for nought.

It’s just that I’ve observed braces in C*ddies and other GM’s of similar & later vintages and wondered whether adding them could do me some good.

Joe P, if you choose to indulge me, many thanks. I believe you’ve weighed in in the negative before. And I have every reason to trust a structural engineer on these points.

Cheers
cf

 

Joe, that does make sense. I don't see those two long rods doing too much structually to the front fenders/core support over a stock installation and the wheelbase difference between coupe/sedan/wagon is mostly after the firewall if not completely; so your theory of resonance makes more sense.

 

This is especially true when you remember that the attachment of the core support to the frame is rubber bushings, so these do exactly nothing structurally. Non-structural engineers frequently don't understand the difference between stiffness and strength. Glass is stiff but not strong (usually). A willow is strong but not stiff.