Tom's '07 Monty

I just took on another C3 rebuild/upgrade challenge. My buddy has the yellow 1977 C3 that we just did brake overhaul (& front wheel bearings) and end link bushing replacement.

He wants me to get a solution to his need/want to improve handling of his L82, AT, gymkhana suspension Vette. My impression is that steering feels very light. He has radial tires on the car now with 32 PSI in all four tires. Car is not tracked/raced. Ocasionaly pushed to 100 MPH on short bursts.

Suspension bushings are old but not overly worn/cracking.

My solution is to:

1. upgrade to largest wheel and tires w/o mods
2. replace all suspension bushings (including control arms)
3. Bildstein HD shocks
4. Shorten front springs
5. replace leaf spring with monospring

Your thoughts, advice please

cagotzmann

Is it light steering or loose /sloppy steering ?

Light steering can be made heavier by adding additional caster to the alignment, factory is 1.5-2.75 degrees, get to some where in the 5-6 degrees will increase a heavy feeling to the steering and also increase steering centering ability. This will require after market upper arms or adjustable upper arms.

Improve handling could mean a lot of things ? Any more on what he means by "better handling"

But going from 15" wheels to better 18" wheels will make a difference because you can select much stickier street tires. You will add additional harshness because of less side wall (lower profile).

The13Bats

Rebuild the steering box to spec, if you cant hire it done,
Replace all wear items, helps that craptasic floaty feeling vettes have

The c3 wiil then handle as good or better on the street as any usa car and many imports in its same class and era,

I never saw gym as all that much better handling, just harsher ride,

Herb addams proved a harse ride doesnt always equal better handling and you can have a pretty nice ride and still handle great...

jb78L-82

From another post on suspension and Wheels that I posted a while back:

I have a 78 L-82 4 speed car with the gymkhana sport suspension (67,000 miles) that I have owned for 34 years and I have tinkered with the suspension one part at a time over all those years to achieve the perfect balance of superb handling, steering response and a firm but not harsh ride. Not knowing if you have a base suspension (most likely since most did not have the sport suspension from the factory) or the sport suspension, below is what you need for truly sportscar handling with a great ride for your 78:

Front:

550 lbs front coil springs/1 inch lower than stock-$100
1 1/8 inch solid front sway bar (OEM Bar size)-$200
poly upper and lower control arm bushings-$50
Bilstein HD shocks-$150
Front Spreader Bar-$100
Custom blueprinted/rebuilt OEM steering box- GTR 1999-Gary Ramadei-$300
This modification will make your OEM box about as good as it gets with the OEM steering and very close to a borgeson.....not quite but close

Rear:

360 monospring-$300
Bilstein Sport shocks-$150
OEM Style Rear Sway bar (not the aftermarket type bars. I highly discourage NON OEM/GM style rear sway bars)-7/16 or 9/16 or 3/4 inch (I have this one replacing the stock 7/16 inch bar)-$200
Competition adjustable strut rods with heim joint ends-$200

Total Cost $1750

This suspension will get you a FAR SUPERIOR suspension than what came on the car when it was new, X3 if the car had a base suspension from the factory. You will need to add 17/18 inch rims and tires (ZR rated only W/Y sub rating) later to maximize the superior suspension setup. I have ultra high performance summer only tires Front-255/45/17 ZR and rears 255/50/17 ZR's.







This is ^^^the basic C3 suspension design pretty much unmodified from its original design but maximized for handling, steering, response and grip....I will say this again, the ride is far superior to the OEM gymkhana suspension that came on the car with 255/60/15 crap tires and is very compliant. A neighbor who has lexus LsS460/430 sedans recently rode in my 78 and he commented more than once about the power is great BUT he could not believe how well and tight the ride was....kept saying it.

BTW-the SLP rims and tires above weigh LESS than the OEM aluminum 15 inch rims and 255/60/15 tires..I weighted them both.......................just saying

I said this way back in the beginning of this thread...This ^^^^ will get you a fantastic ride, superb handling, all with basically a stock designed suspension with 17 inch ultra high performance summer only tires.............

I will also add that Karol on this forum with his base stock suspension,L-82 4 speed, and 15 inch aluminum OEM rims with 255/60/15 Radial T/A's, just this past weekend rode in my 78 ^^^^ and then in a back to back comparison we rode in his 78 unmodified base suspension L-82 and he could not believe how much BETTER my car rode than his car (not to mention handle). He loved the rebuilt/upgraded 355 L-82 but raved about the ride....This example is an immediate comparison of real world results, no theory here, with a direct comparison of the 2 suspension types...Not sure what else to say here about this subject.

jb78L-82

The main difference between a gymkhana suspension C3 versus a base suspension C3 is the swaybars and spring rates.

78 gymkhana suspension:

Front sway bar 1 1/8 inch
REAR SWAY bar (base cars do not have a rear bar)-7/16 inch
Front Coil Springs-550 lbs
Rear 7 leaf steel spring-292lbs

78 Base Suspension:

Front Sway bar-1 inch
NO REAR SWAY BAR
Front Coil Springs-260 lbs
Rear 9 leaf Spring-192lbs

Clearly there is a BIG difference in the suspensions. A C3 does not have much anti roll built into the suspension and will roll a ton with a base suspension, be very floaty with a base suspension and understeer severely at the limit with a base suspension. The gymkhana cars will do all of the former MUCH less but even then will still understeer at the limit, since all C3s came from the factory built to understeer...........

Rescue Rogers

The PO of my car installed a grand Touring package that has everything you listed and it feels great and handles really well. The front springs sit alittle high and I bought some cut springs from a member here to drop it alittle without cutting the touring springs for when I sell alll those pieces.

That was my original solution or QA1 adjustables up front to get the nose lower, but I got a VBP front and rear monospring sytem sitting on the shelf I am going to insstall instead, over the course of the summer

redvetracr

6. more aggressive alignment specs

Tom's '07 Monty

Great advice. Thanks. Basically what I had in mind. I forgot about the steering box and alighment.

roscobbc

Simplest way to 'weight-up' the steering is to replace the stock steering wheel with as small a wheel as you can get. More effort then required and heavier steering ensues.......

Priya

I want a craptastic floaty feeling in my C3. Do I just have to replace the good parts with worn out ones?

LT-1 kid

thats what I did on my 68 BB, made a huge difference for the better

NewbVetteGuy

OP:

Don't miss the subtle but important detail in JB78L-82's suggestion.

Bilstein HD's on front, Bilstein Sport's on the rear because of the 360lb monospring needs the fast rebound rate of the Bilstein Sports or the rear will get "bouncy".

JB78L-82 originally bought HD shocks all the way around, but bought Sports for the rear to get rid of the bounce; learn from the mistakes of others.


Also, don't bother with the other brand mono springs as they are all super curved and make the rear stick up like a 4x4. The VB&P Monospring is the way to go for a more modern, lower rear stance. (And 10" bolts, IMHO.)

-If you're buying the rear spring from VB&P you can ask them to make it 1" shorter on both sides to add extra clearance for wide wheels.

If you relocate the Parking Brake (cut it off and re-weld it to attach on the top or inside of the trailing arm instead of the outside), and are going with 18" wheels, you should be able to fit 275 width rear tires on the rear. (At least one person on here is running 285 width rear tires with stock trailing arms and the e-brake relocated, but I've seen a LOT of people running 275s.)



Tirerack.com is the cheapest place I've found the Bilsteins and occasionally they have some sort of mail-in rebate to get them even cheaper.


You should focus on steering and handling separate, IMHO because there's SOOO many things that could cause sloppy steering that have nothign to do with the suspension or tire alignment.
Adam

mizellbe

Why hasn't anyone brought up rack and pinion steering. I would think it would be a much more effective system. You can lose a lot of front end weight. and have better response.

NewbVetteGuy

There's some very knowledgeable folks on here who will swear that a well maintained stock steering system will perform nearly identically and will have a slightly shorter turning radius. They know 100s times more than me so I kinda have to believe it's possible.

Personally, I can't tolerate sloppy steering; I don't want an old grandma car with 20 degrees of play back and forth to keep the car going straight down the road, even if it WAS built in the 70s, so I went "nuclear" and bought a Steeroids rack and pinion setup... (Having said that I paid $$$$ for a Steeroids rack and then realized that the screws holding on my steering wheel were loose... so maybe it's best to ignore me on this subject...)



Adam

NewbVetteGuy

Put the stock wheels and tractor tires on and run the air pressure freakishly low, buy some 150k AC Delcos, get an old worn out steering box from the For Sale Forum, a really worn out rag joint for the steering column and then loosen all the screws under the horn button 2x, chew up all the rubber bushings you can reach with an angle grinder, remove some of the leafs in the rear spring down to like 2 or 3 leafs. You'll need a good 40 degrees back and forth to keep it going down the road and a neck brace before you go over a set of tracks! ;-)

From Corvette to Grandman's Caddy in no time!




Adam


P.S. That's the most horrifically ugly C3 I've ever seen as your Avatar! What happened to your chrome bumper conversion?

NewbVetteGuy

Roscobbc drivin' with his teeny, tiny steering wheel (it's even right-hand drive for his UK roads):




Adam

midigike

Priya

Cool! I'll get right on that!

That car is my pride and joy, it gets way more compliments than my C3. I wear a disguise when I'm in my C3 so I won't be seen driving it.

Hubby wanted his garage for the winter so my chrome bumper conversion is on hold until he lets me have it back. If he kicks me out every winter its going to be along time until I'm done.

roscobbc

I'm offended - don't drive a RHD car (other than my work daily) and I'd never, ever wear a blue ribbon in my hair (pink, maybe?)