C4 Suspension Components in a 1st Gen

[hamrhed97]

Beach Cruiser

I can tell you have done your homework. You point out some clear considerations that would need to be addressed to successfully engineer the adaptation of the C4 suspension parts to the 1st Gen frame. I am also an engineer by trade and I definitely need to do more homework to see if there are feasible solutions to the issues you point out, that would bear out continuing with the stock 1st Gen subframe. Best of luck with your project and I look forward to following your progress.

Hamrhed97

[Beach Cruiser]

Here's some pictures of the frame jig my loyal apprentice fabricator Ed B and I made over the weekend. First we leveled and squared the stock subframe using jackstands and shims. Then we built the jig above it to locate all the body mounts and engine mounts. Keeping the new jig square and level, we built in all the cross braces and knee bracing that you see. Before we unbolted and unclamped everyting, we pulled strings and marked the frame center and the front axle centerlines. these marks and the ground location (with respect to ground clearance at ride height) are what all the suspension pickup points are based off of.

My plan is to remove the jig from the subframe and flip it upsidedown. I'll level it and secure it to the floor so it can't move. Then I'll lay in the frame rails from back to front and square them up. Then I can start locating the suspension pickup points and building the fixtures to hold them in place. I've already built the back half of the frame with the transmission mounts in place, so I'm halfway there as far as the frame rails go.

Hmrhed97 If you'd like to give me a call I'll be glad to share with you what I've learned along the way. pm me for my number.

Mills

Ps, Yes the jig is full of parts of old exercise equipment that I've scavenged over the last month or so. The engine is actually located by the remains of an old stairmaster! You just can't walk into home depot and by any real steel...

[hamrhed97]

Beach Cruiser,

What is the old saying?...Necessity is the Mother of all invention! I'm sure the StairMaster would have been proud to give it's life in the pursuit of Hot Rodding!

I'm going to be on a business trip for the next two weeks, I contact you when I'm back.

Thanks,

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.

[Mean 69]

Nice, Steve. How would you describe the difference in driving the rack cars versus the stock frame cars? In other words, "why" is it easier, is steering effort, feedback, combination of all things?

I am looking forward to driving Steve's car with the 21st piece up front. One thing that I can share to the discussion of the front stuff, for certain when I moved from a 235 front tire, to a similar style 275 front tire, the drivability of the car changed a fair amount. Kind of hard to describe, actually, "heavier" feel maybe? The grip level went way up, and on the track (smooth surfaces, fast speeds) it is completely at home, but it does feel different on the street. Not "bad" at all mind you, but different. Sure looks damn cool too.

Mark

[Steve Chryssos]

"Turn-in" on the rear-steer cars feels delayed--not sloppy, like with a stock box, just disjointed. As for tire width, I personally prefer smaller, lighter wheel and tire packages. The Fairlane has humungous 315's up front. even worse, the wheels have almost no backspacing. Their coming off and getting replaced with 275's. Narrower wheels with a touch more backspacing.

[Bowtieracing]

Steve thank you ( and Mark too!!) for good and easy to understand reply and comments.What opportunity to test different suspension choises. Do you have any idea how will BRPs rack&pinion work with stock frame(its a front mount) . You both must be right at wider fronts steering feel might be heavier but i am worried about braking.There are lot of cars with powerfull engines and huge 14" brakes but - cmon!- 245 tires. It must mean something when there is a need for heavy brakeing.

[Steve Chryssos]

Originally Posted by Mean 69

.....I am looking forward to driving Steve's car with the 21st piece up front....Mark

You will love the 21st Century clip. Are they outta business? I can't wait to drive one of your 3 links.