R6n350GT

Im installing the VB&P Grand Touring+ Package.
It comes with a 1.125" front sway bar and .750" (3/4") rear sway bar.

Also new front and rear KYB shocks, springs and the rear 330 lb/in Composite Monospring.

Upon looking for how to install it i read the 3/4" may cause some bad overstear... Is this true even with the 1.125" front ?

Should i use the stock 7/16" rear sway bar? Im replacing all the bushes with Energy Suspension so the 7/16 will have new bushes if i decide to use it over the included thicker 3/4"

Thoughts? Im doing it in the morning (australia) time... Thanks everyone !

Big2Bird

I've run that set up for 10 years and am okay with it.

ronarndt

I have the larger rear bar on my 68 and have no problems with it.

jb78L-82

This topic has been beaten to death with varying opinions so here is mine.

I have the stock 1 1/8 inch gymkhana suspension front bar with poly mounting and endlink bushings (which will make the bar act like a bigger bar..more like your 1.25 inch aftermarket bar). I ran the stock 7/16 inch GM style rear bar with this setup for years and switched in the early 2000's to the GM style 3/4 inch rear sway bar with GM OEM type endlinks (not like the aftermarket rear bars with the horizontal endlink holes like the front bar) since most C3's will understeer at the limit from the factory unless you do something really dumb. The car is very neutral at the limit now (550 front springs and 360 composite in the rear/ Bilstein HD in front/Bilstein Sports in the rear). I intentionally wanted the GM style OEM type rear 3/4 inch bar since I suspect the the aftermarket rear bars can hinder the trailing arm movement, inducing snap oversteer. GM used a totally different endlink design on the rear swaybar of C3's for a very good,specific reason......

I would try the OEM 7/16 inch bar first before doing anything and assess the cars handling. If you do use the aftermarket 3/4 inch bar, I would definitely use an adjustable spring loaded endlink rather than the solid endlink used on the front bar which will allow more trailing arm movement....

cagotzmann

The only consideration with the rear sway bar is the VB&P solution has a very limited travel design. If you look at your OEM rear setup it allows for a much freer movement.

I added a hemi joint to the VB&P Bar so it will mount to the factory mounting.





I use my car for track days, this setup has less binding in hard cornering (better trailing arm movement) and produces less over steer vs the vb&P mounting.

But for basic street driving even if the bar was completely removed you would never notice a difference in feel. Your mind would think there is a difference but if you did a blind test I would bet you couldn't tell when it was removed. Driving on a race track would be a different story. I would leave the rear as is since the OEM is a better design.

jb78L-82

Another option is the BB C3 GM style OEM rear sway bar of 9/16 inch which also incorporates the GM designed endlink...........

zwede

My experience with a 454 BBC that is about 150lbs lighter than stock:

1 1/8" front and 3/4" rear bar was very oversteered. Maybe it would have been ok with an all iron BBC.

Switched to 5/8" rear bar and it was ok but I didn't like the aftermarket end links that would bind when I jacked the car up and bend the links.

Settled on an OEM 9/16 rear bar (kept the front 1 1/8") with the OEM end links.

jb78L-82

What ever setup you settled on, if the car oversteers, you can also add solid poly front endlinks and mounting bushings that will make your front 1.25 inch bar act like a bigger bar (dialing out the oversteer) and more like a 1 3/8 inch front bar...lots of ways to approach this issue....

Sayfoo

It appears to me that every car (springs, tires, shocks, etc.) and driver is a little different. I bought the same parts as you, except for Bilstein shocks, for my '69 BB and I got extreme over steer. I went back to the original 9/16"? bar and still had over steer. I now run without a rear bar and have fairly neutral steering.
I don't think anyone can say for certain what will work for you.
I go along with the theory (not mine) to install a large front bar and use different size rear bars to get what you want.
The heavy springs are great for the mountains, but a little stiff for around town.

ddawson

I also have the Addco 1.25" from and stock rear 9/16" bar.

My BBC also has aluminum heads, water pump, headers and intake. Also a Rack and Pinion and front upper arms and Semi Coilovers to lighten the front.

I don't race it but tight turns feel neutral to oversteer depending on how fast the transition is. I may try removing the rear bar to see what effect it has.

R6n350GT

Thanks everyone for their replies !!
Great to see those whos threads i have been reading chime in also.

Cagotzmann, do you have more pics of the hemi joint setup and where to get one?

TheSkunkWorks

I always advise taking small steps when increasing rear anti-roll relative to front, and to make certain that doing so is actually needed rather than simply being assumed.

For those who have yet to experience what understeer and oversteer really mean when it all goes wrong; understeer (or push) is when you hit the barrier with the nose of the car, and oversteer (or loose) is when you back into it. And, if you're lucky enough to spin without incident, it's just a crash without any of the pain or expensive noises. Take too big of a step towards the oversteer end of the setup scale, or mistakenly assume how a car seems to handle at less than 10/10ths necessarily translates into what it will do at its limits only to find otherwise, and none of this long-standing track humor will seem very funny.

Bottom line: Press hard enough on any car and you're sure to uncover something it isn't doing satisfactorily. Better that is a matter of mild understeer, particularly on the street and/or for those who aren't intent on pushing the limits in the first place. My $.02

R6n350GT

I was hoping you would chime in !

I read many of your posts against the 3/4" bar with non OEM mounting.

Quick bit of more info
Front has the KYB shocks, heavier springs, and instead of using the rubber that came with the front sway bar kit i used the Energy suspension front sway bar kit poly bushes.

I also replaced lower and upper control arm bushes with energy suspension and new ball joints.

The steering cylinder was replaced with the borgeson steering box

So the front end should be solid. New rotors, pads, rebuilt brakes and braided lines with new master cylinder and motul rbf 600 fluid.

Now to the rear...
The Composite monoleaf spring im putting in, it comes with its own rubber spring bushes. I have the energy suspension spring bush kit, which ones should i use ?


Option 1: Use the 7/16" rear sway bar but with energy suspension bush kit i have, will that make it act like a thicker bar like the front?

Option 2: Use the 3/4" bar but
a) swap the solid brass tube to a spring setup like this
https://www.vbandp.com/instructions/...inks/file.html
If so where can i get the spring ??
b) Shim the bracket that holds the sway bar + bush to the frame with a 1" plate (a suggestion i read about on here to help stop the with bindind the non oem setup
c) just try the 3/4" and see how i go

The rear has KYB shocks about to be put in
trailing arms will have new energy suspension bushes
the large rear suspension diff cradle im pulling out and putting energy suspension bushes in will have energy suspension bushes
and the diff itself will have them too...

Trailing arm i have new bushes and shim kit, plus new bearings for the wheel bearing but that will not be anytime soon, that job is big !

Thanks for the support and guidance.

R6n350GT

Oh and the kit came with U-bolt and plates and another bush holder, is this for years with no stock sway bar???

Im still using factory wheel sizes, which are terrible for grip even with new tyres, they car just slides with pushing hard on the brakes.. Thats another upgrade, to find a good set of wheels with the right offset to make them flush and accept new technology rubber.

Any suggestions ?

R6n350GT

So if this car is just for street and some mountains where im not pushing to the limits your saying stick with the 7/16?

R6n350GT

Now pics



Leaf spring being replaced



Need to clean all the old sound deadening



Will paint this with new sound deadening



Old vs new



Old vs new



years of dirt



trailing arm bushes but shot.. i forgot to mark the camper adjustment so will need new alignment. New energy bushings going in





this diff cradle bush needs to be replaced



yet to be removed. not looking forward to this

jb78L-82

I use the poly bushings on my composite 360 VBP monospring and have since 1986.

Using poly bushings will make any bar act like a slightly bigger bar with rubber bushings. I would try the stock 7/16 inch bar with the rubber bushings first before making any changes. Like Skunkworks says, take baby steps, access, and decide.

You can buy the spring loaded endlinks for the aftermarket bar from a number of sources...I believe MidAmerica has what you need.

I have found by far the best shocks to use with a composite spring are bilsteins..I have Bilstein sports in the rear with my 360 spring. Bilstein HD's are probably adequate for the 330 spring.

Hope that helps!

jb78L-82

You may want to try poly mounting and endlink bushings on that front 1.25 inch bar to dial in some understeer to counter the slight tendency for oversteer with the 9/16 inch rear bar or just go to a 7/16 rear GM rear bar.

jb78L-82

As some have stated all ready, everyone's car, driving style, and setup are different. A few other items on my car that may be different than yours:

1. Front Spreader bar
2. Poly bushings on the Bilstein HD's in front with the 550 springs 1 inch shorter than stock.
3. Poly upper and lower control arm bushings
4. A big one....Ultra high performance summer only VERY sticky 255/45/17 ZR tires in front and 255/50/17 ZR tires in the rear. Most of the 15 inch tires like goodyears, coopers, BFG, etc are frankly low traction passenger car tires and will offer minimal performance at best. I always chuckle when I read about so and so with a high horsepower SBC or BB that can spin the tires at will in any gear rolling...junk tires will enable you to do that and think about the traction at 8/10th driving? Not much. My L-82 355 with 425+ gross HP will not spin the tires when rolling...enormous traction from the tires.
5. ANOTHER important mod in the rear: Competition adjustable HEIM jointed strut Rods-NO BUSHNINGS to compress-Greatly reduces unwanted rear wheel camber changes!

R6n350GT

Ok so use the poly bushings from energy suspension not the ones that come with the Composite spring.

Go with the 7/16th bar but ill have to use the energy suspension bushes. I dont have easy access like you guys to parts. Anything i buy comes with a huge price tag here and shipping from usa is $40 min for a small package let alone sway bars and shocks. KYB will have to do for now.

Thanks for the help