C4 Suspension Components in a 1st Gen

[hamrhed97]

With the demise of Wayne Due and his C4 compatible subframe, has anyone here thought about (or actually tried to) modify a stock 1st Gen subframe to accept the C4 suspension pieces? Opinions? My thought would be to see if the C4 "K member" (which has all the control arm mounting points) could be "spliced" into the stock 1st Gen frame to replace the existing frame cross members. More work than its worth? Thoughts?

Hamrhed97
67 Firebird Convertible

[almcbri]

https://lateral-g.net/campbell/

https://lateral-g.net/campbell/DSCN0097.JPG

Here is a stock frame with C5. I am not a big fan of that mounting point for the LCA's, but here is a frame that has been modified

[Beach Cruiser]

I'm in the same boat as you, I was set to pull the trigger on one of his frames when he closed shop. But I've done tons of research and on the road to building my own frame. First, for what you asked for, the stock vette k member has the engine set back about 6 inches from the camaro location. If you try to move the engine forward with that then you have problems with the rack which sits too high on the vette k member to clear the engine. Most aftermarket subframes use a variation of the ford, (yikes!) rack and pinion because its more compact. I have my design based on a later model mustang rack. I've borrowed different ideas from the various manufacturers to build into my frame. I have it all drawn on cad and am checking the design with the Mitchell suspension software. I'm building the frame jig this weekend. I will post some pics later in the week.

[hamrhed97]

Thanks Andrew for the link to the C5 installation, I love the creativity exhibited by the folks building these cars. I am however focused on trying to use the C4 parts I already purchased.

Beach Cruiser, I have not done anywhere near the homework that you have done. Have you tried to maintain the identical suspension mounting points (UCA & LCA) dimensions in relation to each other? I am anxious to see your pics and follow your progress. Obviously I would welcome any details of your design that you would be willing to share.

Hamrhed97

[Beach Cruiser]

Here's a picture of the two front ends before I pulled the car apart. I'm using the 84-85 components because they are a little narrower than the later years. Mine measures 59.5" hub to hub without the rotors. My camaro measures 60.5" hub to hub. My subframe has been upgraded to 70's vintage Monte Carlo brakes, rotors and Spindles. so the track may be a little different. (I did that in the 80's before all this new PT stuff was out on the market) I havn't gotten all the info back from my friend who is a Nascar Engineer on the new design, but no it's not the same as the stock vette. It's not far off, but I put the roll center about 2 inches above ground. I don't want to send you off in the wrong direction, because I havn't built the subframe yet, nor do I have valid numbers back from my friend. You can check on my progress in the Updates section. I'll be posting some pics tommorrow of the frame jig I built over the weekend.

[Bowtieracing]

This is intresting!!!

I have been wondering the same thing and watched really close this thread with lots of good info : https://lateral-g.net/forums/showthread.php4?t=5109

But the question is , how in earth i can fab correct mouting points on old frame when orginal vette part can be used ?? its really easy to miss mount em and get wierd front end geometry and wheel location. I understand at some kind of jig must be made but how how how how

Something like this i liked to try

[hamrhed97]

Beach Cruiser

Thanks for the picture, I see what you are saying about the stock rack location in the Vette K member. I understand now why Wayne would cut off the stock steering arm from the spindle and bolt on one that allows a lower tie rod attachment point and hence a lower rack position. Are you planning on something similar with your design?

I also have '85 Vette components I am planning to use. I will have to measure the hub to hub distance in my car. The previous owner of my '67 Firebird swapped out the stock front drums for discs from a '72 Nova (I believe). I pretty sure the spindles in my car are the original drum brake parts however.

I wonder if it still could be possible to use the Vette K member (I like the fact that it contains all the correct mounting points in the correct relationship to one another) if you could relocate the rack to a lower position because you are willing to go with different steering arms (i.e. WD's type of set-up)? I don't think that I would be ambitious enough to take on re-designing the suspension geometry. I definitely agree with your approach in building a frame jig and I look forward to seeing the pics when you post them.

Hamrhed97

[Steve Chryssos]

Please note that the modified factory subframe that appears in the Campbell gallery was junked long ago by the present owner. The subframe suffered from a variety of problems. For example, the picture below shows how far forward the rack is located. The steering arms are at the absolute limit of their travel. Less obvious is that the UCA inner pivot points were too high. Fixing the subframe would have required new crossmembers as well as modifications to the frame rails. Since there would be very little OE frame remaining, the decision was made to install a 21st century clip.

I just don't want folks to get the idea that it's okay to duplicate the original Campbell clip.

[Bowtieracing]

Thank you Steve... I had to say the idea looked allmost "too easy" even me. And i was thinking about it...

Sorry for some offtopic but i am still really confused what to do with my front end. I have a good and straigt subframe and i really want to go with 18" x 9,5" to get 275s at front. Sofar my plan has been to go with DSE coilovers,BRP front mount rack % pinion and then notch the stock frame to get more turning angle if needed. Do this sound crazy to you ? Is the total cost too close for art morrison clip allready...

Sorry the ot...

[Steve Chryssos]

My opinion keeps getting me into virtual fist fights with the resident suspension gurus. I'm the first to admit that my viewpoint is based almost entirely on subjective experience.

I get to drive a wide range of cars back to back. Life is good. I'm lucky enough to share shop space with a variety of different pro-touring F-body cars (As well as the Fairlane built by Charlie Libby). I get to hop out of one car and into the next for direct comparison. It's all street driving, but fun and useful nonetheless. Here's a picture:

And here's the list:
-Red 69 Coupe: 21st Century C5 clip; one-off torque arm rear, 8 point roll cage, 255/335, aluminum SBC 400, 4L80E paddle shift.
-White 69 vert: Stock clip with full DSE upgrade, ATS spindles and steering box; Hotchkis leafs rear 245/255, 383/T56.
-Green 69: Pro Street. Does nice burnouts.
-Gold 68: Modded C4 tubular clip, full cage, DSE 3" leafs rear; 255/275 all iron 406/4L60E paddle shift.
-Fairlane: Channelled body over tube frame with truck arms; 315's all the way around; 392 Stroker/Richmond 6 speed.
-Blue 68: Just started this one. Will have AirRide Street Challenge kit 255/275 (40's!) Not sure about engine/trans. probably 4L80E paddle shift.

I don't care what any of the "theorists" say about geometry similarities between modded-stock and aftermarket clips. The two clip'd cars (gold and red) are WAY easier to drive than the modded stock clip car. I can therefore drive them faster with confidence. I suspect the difference has more to do with rear-steer steering box (stock clip) VS front steer R&P (aftermarket clip) than anything else. It's important to note that the upgraded clip car (white) is a convertible. Soon I'll have an Air Ride Street Challenge coupe for comparison as well. And some day I hope to convert the gold car to an AME full frame car with 3 link.

If you're doing the welding and fab work yourself and choose quality parts, then it makes sense to extensively mod a front clip as you've described. Just be sure to use ATS spindles. If you're paying for labor, the dollars add up real quick. Even if the difference in cost is $1000, I would still go with an AME or DSE clip.