Thread: Old 'vette rear suspension...

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Greetings...
While surfing for suspension modifications that might help a street driven '61 corvette I have decided that I have only succeeded in confusing my self because of the many options available these days.

Perhaps this is the place to find some common sense application that can be fabricated cheaply. I am a a veteran mechanic, welder etc. and even though semi retired, I have a well equipped home shop in the country.

Being a product of the performance '60's culture..I have owned and built many street cars, pickups and the like. Just seems like I never got around to a 4-link suspension fabrication and I find that I am way behind the times on what would be a good application for my present project. Truth of the matter is...I may not want a 4- link or the like on this project either....like I said I have confused myself ..hmmm.

I'm working on a ruff '61 vette that we just about have the frame off body ready to remount on the chassis.. The frame has had the rear section replaced in the past so I'm not concerned about maintaining the integrity of a valuable stock component. (has had some front repair as well).

I have no original engine pieces except for the 4- speed trans...which I will retain just because I feel that that was the spirit of this type car. I will probably build the cheapest big torque small block with good heads I can afford..like the common 383's... and as radical a retro roller cam as possible, for the old solid lifter bad a#% sound, plus the performance. Having the 4- speed makes a rough idling cam easier to manage on the street..so I thought I'd take adventage of it. (may grow weary of it and change my mind but for now...)

Having said all that . My dilema is what would be a practical simple direct approach to suspending this car where it will launch well as possible (400 hp or better likely) while improving the ride on this old chassis (they ride like a buckboard wagon). I'm sure I can spend some time removing a leaf or two, experimenting with shocks, traction bars etc...just thought with todays components there might a reasonably affordable, relatively simple solution that would be superior to the old school ways...? Maybe not too... Increasing tire clearance under this relatively stock body/chassis would of course be very helpful in increasing the off line traction situation...even though I understand there some really sticky street type (cheater slicks) these days... that could be all that is neeeded...but I doubt it. The car is light and I'm confident there will abundant horsepower to light 'em up.

So...what'dya think guys??

Thanks and best regards....Stan

..."take a deep seat and get a far away look in your eye"...

"......launch well, and improve ride..........."

That's a pretty strong wish on one of these Stan.

So many choices, so little time. You're right about the buckboard deal, that was my biggest disappointment as a starry eyed youngster when I got to drive a Vette for the first time. All the clunks, squeaks, and groans were annoying too. (of course nowadays I'M making those noises!! )

You may have to decide which half of your desire list is more important to you, launch or ride. Unless someone has modified your car, it should have radius rods (similar to the old traction masters) mounted above the front half of the rear leaves. As for improving the front suspension, you are probably already aware that the crossmember, and all attached components, are '53 Chev in origin. Not much encouragement there.

Let's see, you could go back and do that '60's thing we used to do. Since the front crossmember is a bolt in just unbolt it, slide in a pair of 3 or 4" I beam sections and raise the front. Then take your rear springs to have a little more arch put in them, and mount the axle on the bottom (that's for the 4" lift, 3" only needs the axle relocate). Then a pair of ladder bars and "bingo", '60's gasser look. Does absolutely nothing to improve your ride, it'll corner worse, lauch could improve a bit depending on how you set up the bars, and you can fit a taller tire in the back (of course for the look you need little guys in the front). While it won't ride any better it'll probably make a bunch of old guys at the cruise in smile, and it'll really piss off the Vette club nuts. No Bloomington points for you!

Your idea of playing with the rear spring rate is a plausible way to keep expenses down and gain marginal improvement. I'm sure in the DFW area there are some savvy spring shops that could make a set of more compliant springs. If the stock radius rods are still there they should control rear axle rotation reasonably well. Or you could go to a longer, adjustable ladder bar arrangement which would help your launch but might impact cornering negatively. You're also going to be limited by the "tunability" of the stock front. Again, maybe a progressive wound spring would help, along with new bushings and a larger anti-sway bar. Avoid urethane bushings as they increase harshness, not really needed in that car. For ride quality and control, gas shocks should make a big improvement.

The four bar, coilover set up will probably make your situation regarding ride quality worse. Lots of people will argue this, but from what I know coilovers aren't well suited for vehicles over 27-2800#. Your's tips in close to 3000 so you're sort of on the high border line. With the right spring rate and a high quality shock, some good adjustable 4 bars, you can dial in whatever launch characteristics you want. Just don't expect great ride and cornering.

Something I haven't seen done would be to fabricate a rear suspension similar to late '60's early '70's GM passenger cars. Two decent size coil springs, two lower locating arms, and one or two upper control arms, and an anti-sway bar. Look at the suspension under a Chev pickup from that period. To this day, Nascar rigs run essentially that suspension design. You'd have to scale it down for your vehicle length, but it's a thought. That would give you both launch and ride, at least for the rear.

Then, if you want to chuck the launch part of the wish list there is always the adaptation of C4 Corvette suspension. There are companies making kits to adapt the later suspension to the earlier frame, so the path has been traveled. Do a Google search and you can probably locate at least one of them. See what they've done then duplicate it with your skills and equipment. You'd have a car that would ride nice, and corner well, just wouldn't be a drag race star.

Thank you Bob......

You have reminded me of something that I had completely forgotten...the trailing arm suspension. I just couldn't put my finger on what this car needed for my application.....I believe the trailing arm set up is exactly what I was searching for...I was just plain brain dead....been readin' too many magazines I guess! Great idea!

I'm going to do some measuring right away and see if I spot any potential problems with the shorter trailing arm geometrics... I can't think of anything right off the bat that would cause a major problem. I'm not sure just how a shorter trailing arm will affect the pinion angle...during the more abrupt up and down travel. At first glance I believe you have hit the nail on the head for what I'm trying to accompolish.... It will remove the leaf springs and give me another 3 or 4 inches for tires (a great bonus) as well as addressing the ride and launch situation.... Not super trick and high dollar (unless it was on a Nascar) but practical and just right for this "oldies" street ride and my pocket book. Thanks again, Bob.

Maybe someone out there has seen or tried something similar to this before...I'd be interested in information regarding the do's and dont's anyone has experienced on any trailing arm fabrication... or stock trailing arm modifications that might be applicable. It's always easier after you've done one, and would surely save some trial and error here.....

Many thanks, best regards...Stan

..."take a deep seat and get a far away look in your eye"...

Sounds like you already have the concept, so as you're probably aware, the shorter the trailing arm, the tighter the swing of the axle in it's travel. One way to deal with that is, rather than having the trailing arms fastened rigidly to the axle housing, to look at the triangulated four bar set up that is often used on street rods. Both the lower and upper rods pivot, thus retaining a minimal pinion yoke arc, and eliminating the need for a panhard bar. Normally these setups use a coilover, but there's no reason you couldn't mount correctly sized "conventional" coil springs on a 4-6" pad (depending on coil size). It does limit space for routing exhaust though.

Thanks again Bob...yep the exhaust is a problem with the x-frame on these old vettes. The local spring shop can get about any spring for this fabrication quite reasonable and will work with me if its to weak or strong. I'm looking into the triangulated 4 link set up as we speak... Do you think the triangulated system will act something like the old stock trailing arm system?

I tried the links for the triangulated link system Streets...doesnt come up for me. I'll try it again later..web site might be experiencing some problems. Thanks for the reply......


Stan M.

After rereading my second post I see the need for clarification. There are a couple ways to look at it. If you look at the '67 to '72 Chev pickup arrangement, the trailing arms are solid to the axle, and converge toward one another as they go forward, and pivot in front, then have locating arms to control axle rotation. The other is like what is on my '67 Bel Air. There the upper and lower arms pivot at both ends and point pretty much straight ahead. The springs mount to the top of the lower control arms right in front of the axle housing. Lateral control is from a panhard bar. Lots of brackets on the housing!!!! But it works pretty well. Also, both sets of arms are relatively short, though the lowers are longer than the uppers. You might want to try to find a '65-'68 full size Chev to look at and do some measuring. You could either copy the dimensions or scale them accordingly, depending on space considerations. One note, if the full size car has a 10 bolt rear it will probably only have one upper arm, the 12 bolts use two.

The triangulated four bar will work very similarly to the four link system I described on the Bel Air (pivot both ends of each bar), but because of the triangulation of the upper bars it doesn't require a panhard bar for lateral control. Either way an anti-sway bar will aid cornering................but just in case you're unaware, you must have a front anti-sway bar of equal or greater resistance if you install a rear, otherwise the rear will tend to want to "steer" the car, giving you some weird reactions when you go through dips and such.

Arrrrghh...me hearty's.. scuttle the barge and buy a Glastron....
the link is still uncoperative Streets...thanks again though, maybe its something on this end we've just changed to newly available cable internet . Has a few bugs still....

Maybe a C3 /C4 conversion up is the choice even if it financially delays the project....?? Looks like the chassis is a little tight for what I would really like to do...hmmm.

On my 53 Ford Trk I used a camaro IFS from a car w/the steering box in front of the x-member.(latter style)
For the rear I used Crysler 5th ave sw springs.

The trk was a excellant driver. Don

Sierra Mike - I recently attended 2 national Vette shows & both had a repro frame for the C1 that took the c4/5 suspension. I got to drive one & all I can say is WOW.