A brief tutorial on Corvette front suspension please.

C4- C5 -C6 

I'm going to a guy with a yard full of Corvette wrecks and junk with the idea of picking up a set of uprights, brakes, rotors, and up and lower A arms. 
I don't have to have the latest but if a little more gets me better or lighterI probably will spring for it. 

In reply to frenchyd :

Much like Mustang II stuff, the C4 suspension wasn't decent for its time, and leagues above what was available before it, but pales in comparison to anything more modern. In other words it's a good solution for an older vehicle, but I wouldn't use it as a starting point for building a vehicle around. 

It is full of aluminum, transverse leaf springs, IRS, five-links, and awesomeness.  Some of the awesomeness will not be realized without the stock frames, i.e., geometry goes missing without it, but the general design of the stuff is great. 

There were two slightly different (front alignment) versions of the C4, and C5/C6 had some updates and spacial differences, but were not that different, aside from the tranny going to the rear (they also had aluminum front subframes, versus steel in the C4).  Well, yeah, the C5/6 had normal IRS rears with upper and lower arms (with transaxle inbetween), while the C4 had a five-link (with Dana 36 or 44 pumpkin, depending on manual or stick trans), in which the axle shafts are theoretically stressed members of the suspension.

They have only gone to coilovers (instead of leaf springs) on the C8 after all these years.  If one has any fabrication skills, Corvette parts are the easy button for making any car handle excellently with very low unsprung weight (and dollars, so long as pointless coilovers can be avoided).  Many have made businesses of this reality over the past four decades.

Edit:  You only wanted the front.  Sorry, it's way too early for this.  The transverse leaf only weighs about eight pounds.  The bushings are a huge pain to change.  Not a ton of decent shocks are available.  Still, the stuff is awesome.  C4s killed at autox and road course for decades.

While I've done alignments on all of them, I haven't really looked at a Corvette front suspension from a geometry/engineering perspective so I don't have any deep insights.  What I can tell you is that from a driving dynamics perspective Corvettes have gotten better with every generation so get the latest generation you can find. 

Also,  the greatest parts in the world combined in a mismatched fashion without any engineering put into the geometry and how the front suspension interacts with the rear will likely result in terrible handling.

rustomatic said:

It is full of aluminum, transverse leaf springs, IRS, five-links, and awesomeness.  Some of the awesomeness will not be realized without the stock frames, i.e., geometry goes missing without it, but the general design of the stuff is great. 

There were two slightly different (front alignment) versions of the C4, and C5/C6 had some updates and spacial differences, but were not that different, aside from the tranny going to the rear (they also had aluminum front subframes, versus steel in the C4).  Well, yeah, the C5/6 had normal IRS for I rears with upper and lower arms (with transaxle inbetween), while the C4 had a five-link (with Dana 36 or 44 pumpkin, depending on manual or stick trans), in which the axle shafts are theoretically stressed members of the suspension.

They have only gone to coilovers (instead of leaf springs) on the C8 after all these years.  If one has any fabrication skills, Corvette parts are the easy button for making any car handle excellently with very low unsprung weight (and dollars, so long as pointless coilovers can be avoided).  Many have made businesses of this reality over the past four decades.

Edit:  You only wanted the front.  Sorry, it's way too early for this.  The transverse leaf only weighs about eight pounds.  The bushings are a huge pain to change.  Not a ton of decent shocks are available.  Still, the stuff is awesome.  C4s killed at autox and road course for decades.

I won't be using the whole front end assembly, Just  too wide. I love the fact that they are all aluminum.  ( except the spindle)  or is the whole upright a forging?  
 So I'll have to re-engineer suspension pick up points  myself and I know the complexities involved. That's just math and selecting the best compromise. 
 

The rear geometry I'll be using is already wildly adaptable very easily.  Very predictable and remains in use 62 years after the first proposal.  With changes to reflect the various changes in the cars themselves  

What I was asking about is things like Brake calipers. When ( if ever) did they go from sliding calipers to a true 4  piston  caliper?  Brake rotor sizes ( not that's a big deal since top speed and weight will be so dramatically reduced. 
are consumable parts like bearings and pads, rebuild kits, available at local auto parts places or Rock Auto?  
I'm planning on using either torsion bar suspension or (ugh) coil overs. Did any version lend itself to easy changes?  
How interchangeable are wheels?  

APEowner said:

While I've done alignments on all of them, I haven't really looked at a Corvette front suspension from a geometry/engineering perspective so I don't have any deep insights.  What I can tell you is that from a driving dynamics perspective Corvettes have gotten better with every generation so get the latest generation you can find. 

Also,  the greatest parts in the world combined in a mismatched fashion without any engineering put into the geometry and how the front suspension interacts with the rear will likely result in terrible handling.

That does seem to be something I've been very successful at. Making The whole compromise between  front and rear,  stiff and compliant. 
Roll and  geometry. Anti dive and anti squat. 
Since the car they are going on will be much shorter, narrower, and lighter than the Corvette  it's really going to be a clean sheet.  
 

I only use sketches early on.  then I start working with wood and plastic. Just like a child's toy and watch for binding and other problem areas as I push it around on chalk covered paper. The best combination seems to be the one that leaves the least dark smudges.  
Different radius corners result in different smudge levels  since it's all a compromise. When you add banking and off camber it really adds complexity. But for cone  racing I doubt that will come into play. 
 

I think I'm going to have to focus on autocourse rather than true race tracks. I just am too compromised aerodynamically to work at high speed .  

I might be an idiot right now, but I think the fronts are two-piston (my reference point is a '92).  They are common PBR (Aussie) parts used on some other vehicles.  All of it is easy to locate, as are track pads that fit right in and dig trenches into your rotors.  All of the stock stuff is pretty easy to get still, either in repop or upgrade.

As for wheels, 17x11 square (5x4.75) fits pretty well with a full turn radius, depending on the body you're using.  It's like they were made that way.  

In the pro-touring world, people have repurposed all manner of Corvette stuff, from C4 to C7, using different frame mounts and whatnot, usually with coilovers.  In my experience, the easiest route to positive effect began with just using the entire subframe (rails included), thereby including all of GM's intended (excellent) geometry.  Width can be dealt with through sheetmetal/body manipulation far more easily than through messing with a frame and pickup points.

The funny thing people don't realize about the C4 is that it is basically the same wheelbase as a Porsche Boxster/Cayman, with a manlier footprint . . .

C4 with C5 rims fits inside stock Corvair front fenders. :-)

I would get the steering assembly too, as much as you can get so you're retaining the system as completely as possible.

No fenders. So won't be an issue. 
Im looking for an aftermarket wheel that has narrow spokes  to reject heat easily.  I raced my Black Jack with solid rotors against newer faster cars with big vented rotors and  while they always had badly faded brakes towards the end of the race.
 Heat radiated past the wire wheels and I could brake just as hard on the last lap as the first lap. 
 

stylngle2003 said:

I would get the steering assembly too, as much as you can get so you're retaining the system as completely as possible.

Too wide. I'm going either with a custom rack or maybe can narrow a MG Midget  steering rack. Don't need or want power steering.  ( another advantage of taller narrow tires) 

In reply to rustomatic :That's a very interesting point about the Porsche and the Corvette.  
No one seems to remember that the XKE and the MGTD had the same track and very nearly identical width. 

But I can't use the whole front frame because it's just too wide  The wider the car the further it has to travel to get around the cones.  Especially on left/right switches.  Since the winning difference is often tiny fractions of a second a few extra feet makes a big difference when you consider how many cones there are  

While rubber on the road predicts speed around the corners people need to remember there are two ways to get more rubber  

Obviously wider but then you need to travel further. But also taller !    Where you don't!  
 

Besides with open wheels you can judge your proximity to the cone without shifting your eyes down to look at the base. 

If you want to swap money for the time to design all of the suspension pickup point the  Dobbertin Cradles are a pretty slick and easy, but somewhat expensive, way to bolt up Corvette suspension onto a custom chassis.

In reply to bgkast (Forum Supporter) :

That would be cool if I could use Corvette design.  It won't work since it's on a car feet narrower and shorter with different roll centers and tires. 

AngryCorvair (Forum Supporter) said:

C4 with C5 rims fits inside stock Corvair front fenders. :-)

Now that's bit of knowledge that few people have and even fewer have a use for...

frenchyd said:

I think I'm going to have to focus on autocourse rather than true race tracks. I just am too compromised aerodynamically to work at high speed .  

Ok I gotta call bullE36 M3 here.  You didn't want to do our Jag vs Chevy race at the Challenge because according to you autocross sucks but turns out you suck at building a race car for "true race tracks" so you're going to autocross?  Whatever.  You should keep the whole Corvette subframe so that it's a simple drop in for the superior Chevy engine.

In reply to Stampie (FS) :

Somebody must have left the gas-light on.

In reply to Stampie (FS) :

I'll race you stock* against stock. Jag against any stock 4 seater Chevy ( Camero/Nova/ Monte Carlo etc) I even offered to let you use my XJS to drop your 454 in. So it really could be Chevy engine against Jag engine. But you last said you were dropping out.  If you've changed your mind, let me know, I'll get my Jag XJS ready.  
 

I've always wanted to build my MGuar  so if educating you isn't on the ticket I'm building it next instead of the XJS. 

One of the things I Intend to do on that. MGuar is to use all aluminum. So I can weld up my own aluminum A arms, buy them premade or use The Corvette.   It looks like the C-4's are selling a lot cheaper than buying them premade and I'll be finding out if the C5's are near the same price this weekend. I'll also look at brakes. The 4 piston calipers on Jaguars are iron. If Corvette uses true 4 piston calipers in aluminum and I can get them cheaper than Wilwood will sell be the aluminum upgrades for the Jaguar. Why not use Corvette?  
 

* When I say stock I'm talking about race condition, interior removed racing seat in place roll cage etc. Not a tube frame fiberglass body. 

What autocross class is this going to be in?  Sounds like one of the open-wheel mod classes is what you have in mind.

frenchyd said:

In reply to bgkast (Forum Supporter) :

That would be cool if I could use Corvette design.  It won't work since it's on a car feet narrower and shorter with different roll centers and tires. 

The dobbertin stuff is the (dark grey in bgkast's pic)  mounts for the upper A-Arms and shock that bolts to a stock cradle. You can then narrow the stock cradle (light silver that the lower A-Arms and steering rack bolt to) to your desired width. That does alter the stock corvette roll center but it allows you to chose your preferred width.

Note how GM has made many a one-piston caliper that applies more braking force than some four-piston calipers . . .

That's kind of a bummer regarding your steering needs, as again, the C4 stuff works great.  It's only 2.3 turns lock-to-lock, and if you're lucky, it comes with a free cooler setup . . .

MrJoshua said:

frenchyd said:

In reply to bgkast (Forum Supporter) :

That would be cool if I could use Corvette design.  It won't work since it's on a car feet narrower and shorter with different roll centers and tires. 

The dobbertin stuff is the (dark grey in bgkast's pic)  mounts for the upper A-Arms and shock that bolts to a stock cradle. You can then narrow the stock cradle (light silver that the lower A-Arms and steering rack bolt to) to your desired width. That does alter the stock corvette roll center but it allows you to chose your preferred width.

Roll centers change suspension  geometry requirements. As does track width,  and length. Not to mention weight,  speed, and radius of corners. 
so mounting points will change.  Fred Puhn's book provides you with the means to do the calculations. And since I'm welding up my own frame I can change all that. Plus I'm likely to simply cut off the bushing holes and drill and tap for rod ends. 

Afco and SCP  both used to sell aluminum tubular A arms in a near endless variety of styles and lengths.  They were the easy button because then it was a few calculations away from an order.

 I read both of their catalogs last night and unless some dealer someplace has the odd piece They aren't going to work.   
The Corvette pieces are going to need work and they will be seriously heavier than  Afco or SCP.   
Now I  need to look at the whole package to tell if the Corvette stuff will be a suitable compromise or if it's  time for me to start fabricating jigs. 

rustomatic said:

Note how GM has made many a one-piston caliper that applies more braking force than some four-piston calipers . . .

That's kind of a bummer regarding your steering needs, as again, the C4 stuff works great.  It's only 2.3 turns lock-to-lock, and if you're lucky, it comes with a free cooler setup . . .

Racing brakes are a different demand than for the street or an occasional autocross.  Single piston sliding calipers  will disappear one lap into a track like Elkart Lake.  ( 4 miles, 3 really long straights  and 9 hard braking corners). It might last 2 laps at Brainerd  That's only a 3 mile track with 4 hard braking corners.  I'd use the 4 piston calipers Jaguars come with except they are heavy iron. Not only do they add weight they fail to dissipate it as quickly as aluminum. 
 

TVR Scott (Forum Supporter) said:

What autocross class is this going to be in?  Sounds like one of the open-wheel mod classes is what you have in mind.

I don't know.   Around 1500 pounds, silly amount of horsepower but only 5.3 liters.  I'm torn between a really cool set of knock off Mag ( real magnesium)  wheels with a fantastic history  and A set of Wire wheels.   Defiantly not production anything.  
I mainly want to vintage race it. 

Ok!  I look forward to seeing the progress!