What is wrong with the C3 front suspension?

vette427sbc

Well-known member
Joined
Sep 25, 2008
Messages
1,034
Location
Jersey Shore
Just a simple question looking for a presumably not so simple answer...
So the C3 IRS has issues with toe steer and a few other things, but what "issues" does the front suspension have? What makes the aftermarket frames with C4 front suspension better? (besides being stiffer and possibly lighter)
 
Well if a 58-64 Impala represents the state of the art in sports car suspension in 1963 then notta thing... :bounce:
 
So do the aftermarket control arms "modernize" the suspension? Vansteel or VandP tubular control arm take car of it? What about a front leaf kit or coil-overs?
 
what "issues" does the front suspension have? What makes the aftermarket frames with C4 front suspension better? (besides being stiffer and possibly lighter)

It's old!
So is the SBC and they can be updated to run quite well

C4 has rack and pinion.

And never underestimate the benefits of getting lighter

A rack can (and has been) added. And believe me, I am fully aware of the benefits of dropping weight

Well if a 58-64 Impala represents the state of the art in sports car suspension in 1963 then notta thing... :bounce:

I was under the impression that it was just the spindles that were shared. Geometry is not the same?


So aside from the obvious, what makes the C4 stuff so much better? roll center? camber gains? Anti-dive? wheel rates?

It seems like some of the undesirable or less than optimal characteristics might be able to be tweaked out of the factory geometry, and Id like to know what they are so I can figure out if its worth it to continue modifying what I have
 
Sarge said it,

I understand that our suspension was penned in 1963 and never went beyond that. Basically a pickup truck under a thick plastic body. My 1990 Range Rover handles better than my 81 Vette

So, can it be fixed? I like the look of the DragVette six link for the rear.

Can the front be fixed?
 
So do the aftermarket control arms "modernize" the suspension? Vansteel or VandP tubular control arm take car of it? What about a front leaf kit or coil-overs?

The only control arms that Im aware of that change the suspension geometry are the SPC tall balljoint arms. All others are just tubular (lighter?) and allow for more caster adjustment.
 
I'm pretty happy with my modified C3 front suspension. I have:
  • SPC tall ball joint aluminum upper a-arms. Improved roll center and allowed me to increase caster some. Can't remember exactly how much I have now because it has been quite a few years ago since I set it, but its a little more than stock.
  • VBP lower a-arms with fiberglass leaf spring
  • VBP anti-bump steer blocks and lowered the car to get the minimum amount of bump steer that I could
  • Aluminum hubs and calipers (dropped 10lbs off each side)
  • Spreader bar between a-arms
  • Still using factory steering. Just shimmed the gearbox for reduced slop and using MOOG joints and idler arm.

A C4 suspension might be better, but I don't see anything really wrong with this setup that is holding me back on performance. It now has an improved roll-center, camber curve, more caster, a lot less bump steer, less mass, and very little slop in the entire suspension.
 
Last edited:
what "issues" does the front suspension have? What makes the aftermarket frames with C4 front suspension better? (besides being stiffer and possibly lighter)

It's old!
So is the SBC and they can be updated to run quite well

C4 has rack and pinion.

And never underestimate the benefits of getting lighter

A rack can (and has been) added. And believe me, I am fully aware of the benefits of dropping weight

Well if a 58-64 Impala represents the state of the art in sports car suspension in 1963 then notta thing... :bounce:

I was under the impression that it was just the spindles that were shared. Geometry is not the same?


So aside from the obvious, what makes the C4 stuff so much better? roll center? camber gains? Anti-dive? wheel rates?

It seems like some of the undesirable or less than optimal characteristics might be able to be tweaked out of the factory geometry, and Id like to know what they are so I can figure out if its worth it to continue modifying what I have

you asked "why" - I really didn't intend to slight you or cause an argument.
 
vette427sbc

Here are some measurements I took years ago. These plots show the changes after adding the anti-bump steer blocks and the 3/4" longer upper ball joint.

86527863d47d823.jpg

86527863d498d8a.jpg
 
what "issues" does the front suspension have? What makes the aftermarket frames with C4 front suspension better? (besides being stiffer and possibly lighter)

It's old!

Tell that to Brian Hobaugh. I just watched him win the 2013 Optima Challenge with a basically stock suspended, SBC 65 Corvette -- bet that irritated the high dollar LS powered, C6 suspended pro touring cars, not to mention the Lambo, Mercedes, and a host of GTRs.

Pappy
 
what "issues" does the front suspension have? What makes the aftermarket frames with C4 front suspension better? (besides being stiffer and possibly lighter)

It's old!

Tell that to Brian Hobaugh. I just watched him win the 2013 Optima Challenge with a basically stock suspended, SBC 65 Corvette -- bet that irritated the high dollar LS powered, C6 suspended pro touring cars, not to mention the Lambo, Mercedes, and a host of GTRs.

Pappy
Great for him, must of pissed off a lot of high dollar participant.
they must feel that they spent a lot of bucks for nothing after getting their asses whipped.
it's just an opinion,
It's old, sorry
LOL
 
Not exactly a Bone Stock Suspension.
Buried underneath a few nice additions - over 500RWHP, Adjustable Shocks, Wilwood was a sponsor - so, probably a set of good grabbers too, and some really, very nice footwear:
1269527f7e138fbcc.jpg

It has a stance you've gotta just love.

Cheers - Jim
 
That '65 is a sweet ride, 315's on the front is quiet insane LOL..... They say it's got stock control arms so the suspension might be "close to stock"... I definitely see why many C5/C6 owners are frustrated :thumbs:
 
315's -- that's way up from what I saw he was running earlier. I recall (from notes) Nittos - 275/30/16 Front and 345/30/19 rears. Makes me reconsider using 18s. Can't seem to find "shoes" that big. Definitely out of Size 15s now.
 
Bumping an old thread--

So what is it about "tall ball joints" (like the SPC A-arms) that improves the handling characteristics of the front suspension/steering? My plans for this year are handling improvements to make it better on the street.

I understand the geometry of my stock control arms is off from factory design by having lowered the car, but haven't studied it much.

I am looking at the VBP tubular upper control arms mainly to get more caster, but they don't have a tall ball joint.

I'm lowered with 550lb springs, 1 1/8" sway bar, VBP bump steer blocks, a spreader bar and 255/50 x 17" Nitto tires. It still likes to wander a bit and things sometimes get exiting in a not good way when 'exercising' it on our crappy roads. I have a good alignment set to basically street specs with about 3 1/2* caster.

The rear end is lowered a like amount and has a dual mount spring. (I also have a rear wheel bearing going bad which will be taken care of soon.) 10 year old Bilstein shocks.

Not going to go the front monospring or coilover route.

I hope to put a Giovanni rear end under it later this year too.

'Splain it to me, Lucy!
 
Last edited:
John - here are a couple of thoughts for you to take a look at:

Here is a link that takes a slow review of the BallJoint and front suspension:

http://www.musclecardiy.com/performance/muscle-car-handling-upgrades-front-suspension-system/

here is a quick Tips :

126956e68bfc7ea29.jpg

I also recall the C3 front A-Arms are from the Chevelle of the same period. There is a lot of FRS discussion on the Chevelle forums that might be helpful. Also - Mark Savitske is really helpful on the phone. I also recall he sometimes hangs out at either Pro-Touring - or Lateral-G. BTW - He likes to talk!

Also, you might check out Coleman Racing for some alternative Ball joint prices and A-Arm options.

BTW - I haven't forgotten to look for that Carroll Smith pub.

Cheers - Jim
 
Its in the approval que. When/if approved it will be in the Chassis Suspension section. Three page pdf of ideas to check for "Instability."

Cheers - Jim
 
Top