Jay M

I tired of screwing around. I don't like incremental upgrades. I want to do it right the first time. It costs WAY too much to do things twice. I love driving the car. It runs great looks good is is quite comfortable. But It doesn't handle anything like a new car. I want to completely redo the suspension. The IRS was designed in 1953! It is a very old design. The Guldstrand 5-bar is very similar to the C4 IRS. That design is only a little over 20 years old ;)


I have searched the archives and there is only one person on the forum who has one of theses setups. Does anyone eles have any experience with this?
The advantages to the 5-Bar are better geometry, less un-sprung weight, less squat.

I'm trying to figure out if it will be worth the expence. $2100 for the kit and $1500 for Guldstrand to install it.

Will it make the car as easy to drive as a C4? Dick said he can make it handle better than a C5 on a race track, but it still won't feel as nice as a C5 because the chassis flexes so much. He said I need a roll cage to stiffin it up, then it will feel like a modern car.

In the grand scheme of things do you think this is worth the expence?

The front end will cost about $1500 for new springs, bushings, shocks, and labor.

The rear would be $600 for a new spring, shocks and labor. But I want wider tires so I would need offset trailing arms. I currently have the Vette Brakes camber rods, but would prefer the more solid Guldstrand rods.
I don't know about labor, but those things would bring the cost of a stock style rear up to:
$300 spring
$170 shocks
$400 offset trailing arms
$275 camber rods
$800 labor?? just a wild guess
$1945 total

Guldstrand 5-Bar:
$2100 5-Bar kit
$300 spring
$170 shocks
$1500 labor
$4070 total

New wheels and tires for the rear $500 for wheels $400 for tires = $900

Total bill for front and rear with new wheels and tires:
Including 5-Bar: $6470
Stock w/offset trailing arms$4345

So in the grand scheme of things adding the 5-Bar would add $2125, or about 50% to the total cost.

So here's what I want to know, would there be a 50% improovement in street handling?

Thanks for helping me think this through.
~Jay

SmokedTires

Looks like a great design, but too rich for me :sad:

Solid LT1

Guldstrand actually helped Chevy design the C4 rear suspension! I have always viewed the 5 bar set-up as a race only modification. I think you would want to investigate going to a new frame with C4 suspension mounts even though it will run even more money than the 5 bar conversion. You may just want to sell your C3 and buy a nice 96LT4 Vette for about double the money of that conversion. The stock suspension with "blueprinted" compoents including the differential assembly will perform well but, will ot work as well as contemporary stuff. I would think long and hard before getting the 5 bar conversion done, ask some hard questions about components like the life expectency of the Heim ends of the links and locating bars, the racers threw them out on a yearly bassis when we ran these set-ups. The life cycle of even the best quality rod ends is limited at best, think long and hard about shelling out the money for a "race" conversion for your street car, it may not be what you wanted in the end and it will cost money to get it back to stock.

Kevin Mason

In the Chevy Power guide, didn't they recommend stiffening the C3 frame by pulling the body and continuous-welding the frame? Also by adding gussets?

Jay M

That would be a very wise and inexpensive thing to do! That is not what Corvette ownership is about! ;)

Seriously, I love the car. I don't plan to ever sell it. The only car I would ever consider trading it for would be BB C2. But I don't want to start all over again. I think the bumper C3's get more desireable every year. I like it so much I drive it 6 days a week in the summer, spring, and fall, and maybe 4 days a week in the winter. That is why I want it to handle more like a modern car.

I suppose I could save money for many years and put a C4 chassis under it, but I think those conversions are VERY expensive! I don't have the time, skill, or space to do it my self.

What is your experience with the 5-bar kit? Do you think racers replaced it every year becasue it was weak, or because racing is so abusive?

Have you ever driven a car with this setup? If so how did it drive? Was there a noticable difference?

I will really pick Dick's brain on this before I make a decision!

Thanks,
~Jay

redvetracr

I believe the original designer of the 5-bar link and the C-4 rear suspension was Bob Riley, in the beginning the 5-link was built by a company in Michigan called RPF inc, which stood for Bob Riley, Protofab and George Foltz...I still have the install instructions for the one I had (sold it to a C/F member) this one came out of an old SCCA/GT-1 racer (still have the old racer too)...You should also know while it might be streetable it was originally designed to be legal in SCCA competition. ...redvetracr

PS: there is NO date on this RPF paperwork but the original price was $1380. withOUT "rod ends" so you can add about $400. for 16 QUALITY rod ends..

flynhi

I went thru this same analysis a couple of years back. I also visited Guldstrand and had a great visit with Dick (What a gentleman!).

I came to the conclusion that the OE rear suspension, when upgraded with poly bushings, Smart Struts, composite spring, proper sway bar and good shocks, was all I needed for aggresive street use. I don't intend on racing the car and I'm not that good a suspension tuner.

So I spent the money that would have gone for the Guldstrand rear on the power plant and 17" wheels.......

Jay M

I found this intersting system on a Greenwood page:
http://www.greenwoodcorvettes.com/StreetGTO.html

It doesn't say much about it, but I thought it was interesting.

Here's another one:

http://www.greenwoodcorvettes.com/StreetDaytona.html

~Jay


[Modified by Jay M, 3:08 PM 4/30/2004]

71coupe

The guldstrand kit looks nice, but it doesn't look as strong as the stock setup. They use aluminum rods/bars in the kit. If you were to hit a hole in the road it may pull the rod ends out. I think it looks like a pretty straight-forward install though. The hard part will be pulling off all of the old stuff

Jasonty

I remember reading somewhere that the drawback of the Guldstrand 5 link setup is that it still uses the half shafts as a part of the suspension. If I'm paying that much cash, I'd want my half shafts supporting none of the suspension. Get a 6 link setup for about $600 and you'll be far better off. If yuo need to know where to buy the 6 link setup, e-mail me, and I'll hook you up with the info.