F-body convertibles owners

[rohrt]

I have come to the conclusion that F-body convertibles are terrible when it comes to making them into a semi-protouring ride. They flex like crazy, creak and rattle going down the road. I can drive on completely smooth road and put my fingers in the door gap and feel the flex in the car. I have a poly suspension system but rubber sub-frame bushings and no subframe connectors yet. I don't hold out much hope that solid bushing and the hotchkis sub-frame connectors will make a dramatic difference. That will have to be a next year project for me.


Any F-body convertible owners out there that can share there thought?


MY 64 Tempest Convertible feels much more solid going down the road. A full boxed frame can make all the difference.

[rlodad]

With poly bushings and no subframe connectors, even coupes flex like crazy. I have a 1969 camaro vert with solid bushings (DSE) and Hotchkiss subframe connectors (welded) and Vert stabilizer and it drives great. Coupe solid? No, but great. Here's a link to my build:
https://www.pro-touring.com/threads/90846-My-1st-PT-69-Camaro-vert-build?highlight=notata+camaro
I don't quite understand why you have decided that making 1st gen verts into protruding rides can't work when you haven't turned yours into a protourer yet?

[rohrt]

With poly bushings and no subframe connectors, even coupes flex like crazy. I have a 1969 camaro vert with solid bushings (DSE) and Hotchkiss subframe connectors (welded) and Vert stabilizer and it drives great. Coupe solid? No, but great. Here's a link to my build:
https://www.pro-touring.com/threads/90846-My-1st-PT-69-Camaro-vert-build?highlight=notata+camaro
I don't quite understand why you have decided that making 1st gen verts into protruding rides can't work when you haven't turned yours into a protourer yet?

I call mine a semi protrouring since almost everything has be modified in some way. Lee quick ratio, Hotchkis springs, 1 -1/4 sway bar, 15x8 wheel vintique rims, 455, 2.5 exhaust etc...etc... I do what I can when I can. I never said you can't I just think the convertible is a terrible platform to start with, at least in comparison to full frame or HT cars.

Nice build. Good to hear that the solid bushings and SFC are working for you.

[68Formula]

I know exactly what you mean. When I first got mine, it still had the factory bushings, crossbrace support, and cocktail shakers in all four corners, and I couldn't rest my hand on the the header molding (even though it felt natural when cruising) because of the shake. Since I put the solids in, I haven't noticed it (and I still rest my hand there). And that's with the crossbrace removed for exhaust clearance, and still without subframe connectors (although I will someday add them just because).

I think if you put in solid bushings, subframe connectors, and keep the factory crossbrace (or aftermarket equivalent), you'll be pleasantly surprised. The bushings are a simple half day job or less with basic tools, so just don't wait, you'll be glad!

[ragtop1968rs]

I've got solid bushings, weld in coupe frame connectors(I notched out the conv bracing and welded connectors to it) and no crossbracing. Mine feels extremely solid. No flex that I can feel.

[rohrt]

I've got solid bushings, weld in coupe frame connectors(I notched out the conv bracing and welded connectors to it) and no crossbracing. Mine feels extremely solid. No flex that I can feel.

I would like to see pictures of that

[F-Body International]

Solid body mounts will lock the subframe to the body. This should make a dramatic difference for starters. After that is installed, then you should consider chassis bracing (cross braces, subframe connectors, firewall braces, roll bars, etc.).

[68Formula]

Did you install the solids yet, rohrt?

[rohrt]

I was looking at purchasing Global West body bushings. I like the interlock design and stock height.
https://www.globalwest.net/800.html

Does anyone know who sells these body bushing insulators? I really don't want to deal with SC&C again if I can help it.
https://scandc.com/product/scc-body-mount-isolator-kit-for-use-with-aluminum-body-mounts-67-81-gm-f-body-68-74-x-body/

[SPG]

Getting those insulators would somewhat defeat the purpose of getting solid bushings as you would be reintroducing possible flex (very minor, but still there)

[68Formula]

Honestly don't think those will be of any benefit. If anything it's a source to trap moisture and cause corrosion. But if you really want them, you could probably find something at Home Depot to cut to fit.

Dude, it's been almost 6 years that you've been missing out. Get them solids installed! You'll wished you did it 10 years ago.

[srode]

Do you have the door wedges installed? Those are supposed to help keep the body more ridged.

[rohrt]

I talked with with someone here that has them on his car. He seems very happy with them. They are around 1/16 of inch thick so I don't think there will be much flex. As for noise vibration, if it helps at all, I would open to it. I think there may also be some benefit for galvanic corrosion, maybe.

What are you guys using for solid bushing? Anything better I should consider?

"Dude, it's been almost 6 years that you've been missing out. Get them solids installed! You'll wished you did it 10 years ago." Your not wrong! I had a serious blowby issue and decided if I'm going to pull the motor I'm going to fix all the issues. And there is a lot of issues. I have been driving my 64 Tempest so I still had a ride. Turning 50 this year so Its my goal to get my bird back on the road.
I have 8.5 rear to put in.
I have a different sub frame to put in
I have a spare 455 to put in but will need to see if mine can be re-ringed
AGR box leaks:(
Transmission leaks:(
List goes on but going to hit it heavy this year and see if I can get it rolling again.

[srode]

GM put those wedges in convertible door jams from the factory for a reason obviously.

[mikedc]

It's simple engineering. Picture a convert body shell with the doors removed. There isn't enough metal height in the middle of the structure. A unibody convertible is never really going to be stiff without having tall rocker boxes or a tall center tunnel.

You can put thicker steel in the rocker or tunnel structures, but that only helps once the metal is already bending (like in a crash). It doesn't help flexing rigidity from normal bumps & vibration. Rigidity only improves when the rockers or tunnel get bigger dimensions.


Body-on-frame convertibles are not immune to the problem either. They just keep the body isolated so the flex is less obvious & annoying. It's still there in the chassis/handling sense.

[Mark@lateral-dynamics]

Body-on-frame convertibles are not immune to the problem either. They just keep the body isolated so the flex is less obvious & annoying. It's still there in the chassis/handling sense.

1000% agree. And also agree with the overall comments. We are completing a 69 'vert and have installed subframe connectors similar to the DSE style (we fab'd them). I would highly recommend the same for any other car, integrating into the floor pan helps increase the rigidity over underslung style, might not be much, but either approach will help.

For SURE the GW body mounts are really nice. We grabbed a set from a customer build we are doing (first time we had ever put hand on them), they are very well thought out and high quality. We will likely just use these on our stuff going forward rather than designing our own.

One other item that may, or may not be in play - rust. It's a four letter word for a reason. I grew up in the snow-belt where they salt the roads in the winter. Even when the cars we built way back when were only ~10 years old, rust was a huge issue. Putting a solid body mount on a compromised body, won't help..... Just sayin'.

[rohrt]

1000% agree. And also agree with the overall comments. We are completing a 69 'vert and have installed subframe connectors similar to the DSE style (we fab'd them). I would highly recommend the same for any other car, integrating into the floor pan helps increase the rigidity over underslung style, might not be much, but either approach will help.

For SURE the GW body mounts are really nice. We grabbed a set from a customer build we are doing (first time we had ever put hand on them), they are very well thought out and high quality. We will likely just use these on our stuff going forward rather than designing our own.

One other item that may, or may not be in play - rust. It's a four letter word for a reason. I grew up in the snow-belt where they salt the roads in the winter. Even when the cars we built way back when were only ~10 years old, rust was a huge issue. Putting a solid body mount on a compromised body, won't help..... Just sayin'.

Thanks Mark that was very helpful.

If I can get this car back on the road the DSE subframe connectors will be next on the to do list. I think some others have installed them in their convertibles.

Did you cut right through the convertible bracing? I thought it would be cool if there was a way to slice the DSE SFC in half and sandwich it between the factory bracing. Been so long since I have been under the car I don't remember if this is an option or not or if it would add of any benefit.

[Mark@lateral-dynamics]

You know, I don't actually know what the convert bracing is! This car had a bit of floor rust so we cut the floors completely out and swapped with re-pop metal. Knew we were going to do more cutting so didn't think about it to be honest, and of course we did a 3-Link, DSE tubs on it too so the SFC's were done at the same time. Cocktail shakers are also long gone though the car actually still had them when we got it.

[dhutton]

Thanks Mark that was very helpful.

If I can get this car back on the road the DSE subframe connectors will be next on the to do list. I think some others have installed them in their convertibles.

Did you cut right through the convertible bracing? I thought it would be cool if there was a way to slice the DSE SFC in half and sandwich it between the factory bracing. Been so long since I have been under the car I don't remember if this is an option or not or if it would add of any benefit.
I notched the convertible braces and set the DSE subframe connectors in the notch. Then welded the connectors to the braces. The notch was roughly half the depth of the brace if I remember right.

The biggest improvement I made was installing Hotchkis handlebars to brace the cowl. Completely eliminated the dreaded cowl shake. I had to modify them to fit around the LS motor.


Don

[rohrt]

The biggest improvement I made was installing Hotchkis handlebars to brace the cowl. Completely eliminated the dreaded cowl shake. I had to modify them to fit around the LS motor.
Don


I would love to do something like that if I could keep it stealth, I like the a stock look for the most part.