In the near future I am going to be getting new shocks then sway bars then springs in that order. I think I have decided to go with a 1 1/4" front. What size rear would be appropriate. My car now has the stock front bar and no rear.

 

I had similar question a while back and found majority of folks seemed to think leave as is, so I did. I have 3/4 front, no rear.

 

I went through this a few months back and everyone seemed to recommend no bigger than 1 1/8" front and 5/8" or less rear for my aluminum head/intake SB 69'. I have only heard of big block cars needing the 1 1/4" front bar. The 1 1/4" may be too much especially with that all aluminum LS-1.
I'm just relaying what I have heard from the forum, VB&P, and VanSteel.

 

What are the negatives of using a sway bar that is too large. These are going to have to work with my stock springs until I upgrade them.

 

Sway bars with poly mounts X-mit higher amounts of pounds to the other side in a compression turn.

The larger the sway bar the less spring per side is required to level the car in a high "G" turn.

 

I have had the factory F41 bars in my car for years.
They are:
1 1/8" front and 9/16" rear.
They are both mounted in urethane bushings. The car drives really well with those bars. It corners nice and flat. I autocrossed it with these bars and the car did really well. It has a nice handling balance and feel. I also have urethane in the rear strut rods and Bilstein shocks all around.
Hope this helps...

Jim :steering:

 

I´m just installing to my all iron -73 BB front 1 1/8 and rear 3/4.
I also believe you shouldn´t go for 1 1/4 the 1 1/8 should work better. If your overall balance is lost due to too heavy front bar the car will understeer. :auto:

Also if you are later planning to put in stiffer springs that points to direction not to go over 1 1/8. Reason is that the stiffer springs means that you do not need that much bar in order to eliminate body roll...

Corvettefaq.com has also many interesting articles on this.

 

Do the springs and shocks first but do the front first and then the rear (except for the shocks. Put good shocks on the rear too). You may find that you don't need a larger front bar or any rear bar at all.

When you tighten up your suspension you are affecting dynamic weight transfer. This can be done with spring or bars or both. There are two handling schools of thought on how you effect suspension control. One, the Guldstrand school, works the process with stiffer springs and lighter bars. The other, the Herb Adams (of Pontiac Trans Am fame) school, is lighter springs and stiffer bars. Ordinarily, not both, at least not to their extreems (heavy springs and big bars).

Essentially, the tighter you make one end of the car, the more dynamic weight gets transferred to the looser end. So if you have a tight front you will raise the ability of the front to grip by moving the weight to the rear which means you could generate an oversteer condition which is where the rear wants to come around on you. But it could also bring the car into a better balance. You just have to work the suspension piece-by-piece until the car behaves the way you intend it to.

This takes time but it will save you money since you'll buy only the parts you need to get the result you want. If, after working the front springs you find the rear wants to come around on you, consider a stiffer rear spring or adding a rear bar. How heavy a bar depends on how much the car is oversteering. A C3 Corvette suspension expert could probably get you almost exactly where you want to be with a recommended package but then they'd have to know a lot about your car, how you drive it, and what you want the end result to be in specifics.

 

Springs, shocks and sway bars work with each other.

If the front bar is too big then the car will plow in a corner, this is called understeer.

If the rear bar is too big then the back end will come around too fast, this is called oversteer.

 

This is definitely a case where bigger isn't better. The descriptions above are accurate by my experience. Tire size and design should also be considered.

My experience with my SB 71 with 1 1/8" and 3/4" on OE sized BFG T/As was severe oversteer. Dropping back to 5/8" rear bar resolved this.

I think you can run heavier bars if you step to 17" wheels and high quality tires since the increased adhesion will mask imbalance. Even so, I'm currently running 17" Bridgestone Potenzas with 1" front, 5/8" rear, poly bushings, front and rear composite springs and KYB GR-2 shocks. This setup is comfortable to drive and corners very, very well.

Do a search on this. A couple of months ago, I posted the calculated roll resistance of a variety of front and rear bar sizes. This will give you an idea of the dramatic difference in roll resistance a relatively small difference in bar diameter will yield. For example, the resistance of a 3/4" rear bar is TWICE the resistance of a 5/8" rear bar.

Also see the ADDCO web site for a table that compares roll resistance of various sizes of bars in percentage terms.

 

I run an 11/4" on the front only, see my sig fro the rest. The guys are right though you cannot change one thing on your suspension without considering the others. In particular with sway bars they work in balance with your springs and the bump and rebound of your shocks. Poly bushing will also significantly change character of your suspension.

For what its worth. My set up works well with positive turn-in, neutral handling with progressive oversteer at the upper end.

Graeme :cheers:

 

Just noticed my sig does not say that I also fitted gas filled adjustable shocks.


G :cheers: :rolleyes:

 

:iagree:

 

Sorry, that's backwards. When you stiffen an end of the car, it will put more load on THOSE tires. e.g. stiff front swaybar creates understeer (front sliding)

:cheers: ,
Chris

 

Factory front 1 1/8 and rear 7/16 will do it for a 68-77. You might want to see my website- FE-7 handling on 77Facts.

 

Yes, I know. I do that frequently. I think in one direction and write in another. It's not the first and it won't be the last time I do that. But thanks for bringing it to my attention. D'oh!

 

I am starting to see there is lot more involved than I had thought.

If I can only afford to do one thing at a time which would be the best order?

Shocks, springs then sway bars? OR
Shocks, sway bars then springs?

For what it is worth, I have 17" fronts and 18" rears with sticky Kumho Ecsta MX's. Would that make me want to go with larger or smaller bars?

 

Here's the order I would suggest:
1. Replace ball joints, tie rod ends, idler arm, steering rag joint, Control arm bushings (consider poly).
2. Overhaul steering box or install Steeroids RP.
3. Consider installing Smart Struts, HD strut rods with poly
4. Springs
5. Shocks
6. sway bar(s) with well lubed poly bushings. Spring end links offer further adjustment for fine tuning.
Alignment by a knowledgeable shop. C3s are not hard to align but you will need someone who really knows C3s to deal with the changes you have made. Check with local Corvette club members for recommendations.

With this set up, I would start with 1 1/8 front and 5/8 rear. Your wheels and tires may allow you to go larger but I would be careful. If you choose to go larger, start at the front and only change one component at a time.

You will be adding stress to frame members and OE welds that are 25+ years old. Strip to bare metal at connection points of crossmembers and sway bar connections and reweld as required and paint with POR. Numerous folks including myself have experienced failed welds and tears in the crossmembers.

BTW, How ya comin on those C5 brakes on your 70?


[Modified by flynhi, 6:53 PM 3/26/2004]

 

-------quote
My experience with my SB 71 with 1 1/8" and 3/4" on OE sized BFG T/As was severe oversteer. Dropping back to 5/8" rear bar resolved this.
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Flynhi, so in my case, 1973 all iron BB (more weight on front), you might agree that 1 1/8 front and 3/4 rear might work? :auto:

 

The spring rates and bump and rebound of your shocks are the critical factors with the weight. Once this is sorted then, and only then can you address the sway bars. Only change one thing at a time so that you can guage the effect of that change. Get your spring rates sorted then adjust the shocks to suit and only then do the sway bars. Even then I would suggest fitting the 11/4 front first, check the effect then try fitting the rear (and 3/4 sounds right). I have heard a lot of people fit a rear bar then take it off because the handling was better with a stiffer front only. :cheers: