70 Chevelle suspensions...

[LSxChevelle]

Have a 70 that I have almost down to the frame. I'm gonna get it blasted here shortly. My plans are to run the AFX spindles up front to have ABS and C6 Z06 brakes behind a set of C6 Z06 wheels. It will be a LSx/T56 drivetrain. This is to be a driver and go on long trips and also go road racing and drag racing. I would be willing to give up drag racing traction to optimize handling in corners. Now the ?'s begin...

I don't have all the $ in the world and will be doing a lot of work myself and w/ connections I have. The AFX spindles seem worth the $ to me because I need spindles (have stock drums) and want to run ABS and Corvette brakes.

1. How much better are tubular arms? Seem to spendy for what I will get out of them. I don't want to use spacers at all and with the wheel offset I will need longer A-arms. Are there any stock lower arms say on another car that could be modified for this? As far as upper I will probably have a set built for me.

2. Should I go w/ airbags?

3. What clearance issues will I have w/ a ~285/18 front tire? Will I have to notch the frame at all?

4. Out rear now...Want a 335/19 tire so obviously gonna need a mini tub. As far as my rear end I will need to have widened to make up for the offset difference. What style of suspension? Better stock style stuff? Airbags? Is 4 link good for corners? can you do air bags for 4 link? Some prices I have seen for 4 link rears don't seem too bad so I am considering.

Any suggestions/links greatly appreciated.

Jason

[PTAddict]

There are two reasons people use tubular A-arms on A-bodies: First, they're shorter to accomodate swapping on a taller B-body spindle, second, they relocate the upper ball joint location further rearward, to give you more positive caster. The B-body spindle swap is considered by some folks to be a bad idea, because it increases bump steer and slows the steering ratio. You can get the same effect of increased camber gain, without as many side effects, by using tall ball joints on stock spindles. See this sponsor's site:

http://www.scandc.com/suspensions.htm

SCandC also sell SPC modular upper control arms, which are a good way to get upper arms of almost any geometry without fabrication.

If you're going with AFX spindles, you'll get the greater height without resort to tall ball joints.

Longer control arms are not a bad idea, in general, but I don't know if you are going to find an off-the-shelf lower arm that will fit. Some of the stock car/circle car suppliers make longer arms for 2nd gen F-body and G-body clips, see:

http://www.howeracing.com

Air bags are cool for the ride height adjustability, but they have no functional advantage from a handling perspective (you notice that competition cars don't use them).

I don't know about late model Chevelles, but I know you'd never get a 335 on a 64-67 Chevelle without narrowing the frame rails and relocating the suspension attachment points. Stock rear suspension on Chevelles is problematic, because the arms are short and undergo such steep angle changes that the suspension will bind up unless the bushings and arms are allowed to deflect. This apparently can be improved with "Jonnie Joints" (sp?) which accomodate rotation of the arms. Do a search on that, or talk to Marcus at the aforementioned SCandC.

If you go beyond stock, most four links are designed for drag racing, and will have binding and geometry issues in a handling car. The best alternative then becomes a three-link, either fabricated yourself or purchased from a company like Lateral Dynamics.

There is a frequent poster on this forum and lateral-g.net, Dennis68, who has done a very thorough job researching the various issues in improving A-body suspension. He's in the process of working through DIY solutions for both front and rear. Do a search for him on these sites, and check out his web site:

http://www.onrails.us/

BTW, I presume you know you can use those wheels without changing the hub-to-hub width by using bolt-on wheel spacers, like those sold by vette brakes:

http://www.vettebrakes.com

But if you engineer it right, it is definitely better to move the hubs out than to use the spacers, IMO.

[LSxChevelle]

Thanks for the great response. I really appreciate when people take the time to sharee knowledge. Like you said I don't want to run spacers. I don't like the idea of going into a high speed turn thinking about spacers. I'm sure they aren't too bad but since I will have a rear end built for me anyways why not take the spacer $ to go to the fab work.

Thanks again,
Jason

[PTAddict]

Here's another site to look at for '70 Chevelle ideas:

http://www.zefhix.com

[PTAddict]

And here's a thread on those spherical bushed rear control arms I mentioned above:

http://www.lateral-g.net/forums/showthread.php4?t=3478

[sinned]

285's are not going to fit on the front without completely removing the inner fenders and then you will have to limit how low you go. On the rear, anything over a 315 is going to require moving the rear frame rails.



Before doing any work (it sounds like your ready to a whole bunch) be honest about your intentions with the car. If it is to handle really well and see some track time then there really isn’t any reason for that much tire. If you want it for aesthetic reasons jump right it with the sawzall. You also need to decide which suspension design you intend to go with, I saw on another post you are considering a 3-link or T/A arrangement, if so you may be able to incorporate some of the frame rail narrowing into the design of the suspension and save some headaches.

[LSxChevelle]

Thanks for the input. Like you said about the rear area I want to figure out my best route before touching anything. I'm no susp expert but the idea of a T/A and notching the frame rails seems like the best bang for the buck for me. It should be a descent setup for drag and corners. Now about the front, what will fit up there with the inner fenders in place and obviously rolling the lip of the fender? It will be an 18" wheel for sure and I do want air bags to adj ride heigth so I wont be making tite turns while slammed down.

Thanks again,
Jason

[USAZR1]

Now about the front, what will fit up there with the inner fenders in place and obviously rolling the lip of the fender? It will be an 18" wheel for sure and I do want air bags to adj ride height so I wont be making tite turns while slammed down.
Thanks again,
Jason

275/35/18's will fit and work fine.

[nekkidhillbilly]

www.westcentralauto.com/SRW.htm

cheaper tube a arms

[darren@ridetech]

A properly set up air spring system will handle just as good (if not better) than a performace coil spring setup. Not to mention that the ride quality will be a ton better.

[sinned]

A properly set up air spring system will handle just as good (if not better) than a performace coil spring setup. Not to mention that the ride quality will be a ton better.

Yeah, OK. Didn't we have this discussion not too long ago? Air springs (which are progressive) cannot ever be tuned to handle BETTER than a conventional coil spring.

[darren@ridetech]

In certain applications it can be. For instance, on the drag strip you can add a couple extra psi in the right rear to help it launch.

As long as you have the correct coil spring rate for a given vehicle weight they will be equal. But one of the advantage that an air spring has is you can alter the spring rate through air pressure for various vehicle weights, driver preferences, and driving conditions. It will also ride a lot bettter on the way home from the track.

[kennyd]

In certain applications it can be. For instance, on the drag strip you can add a couple extra psi in the right rear to help it launch.

As long as you have the correct coil spring rate for a given vehicle weight they will be equal. But one of the advantage that an air spring has is you can alter the spring rate through air pressure for various vehicle weights, driver preferences, and driving conditions. It will also ride a lot bettter on the way home from the track.

and look bada$$ at the same time !

[DonQuehotey]

Yeah, OK. Didn't we have this discussion not too long ago? Air springs (which are progressive) cannot ever be tuned to handle BETTER than a conventional coil spring.

yeah umm ok...... wouldnt that also be completely dependent on the application and the duty. I wont jump on the Darren bandwagon but when you are referring to linear spring rates versus progressive rates, it is going to completely boil down to application. Correct me if I am wrong but I also dont think you will get a bag to handle better than a properly set up coil spring but I dont see any reason why you can not get one to handle just as good.

[LSxChevelle]

I'm looking to go to the drags every so often, road track maybe twice a year, and some auto x every so often. Basically a street driven car that can do all 3 tracks. Air will give me easy adjustment for launching. If it were drags only I would go 4-link and if it was for road track days only I would do some insane coilover set up. Air bags seem like they will be a perfect balance between ride comfort, price, and launch set up.

So here are my plans and if anything seems like a bad idea let me know.

Buy a 9 inch housing with Chevelle schock and LCA mounts / 4th gen F-body T/A and panhard bar mount / widened to work w/ the C6 Z06 wheel offset. I will run a used pumpkin since it is a 9 inch and they don't break. (often that is) Then add some nice boxed LCA's, LCA relocation bracket to adj LCA's, Airbags, BMR Panhard bar, and a BMR adj T/A.

Housing - $350-$400
Axles - $250
Used pumpkin - $300
Gears - $100
BMR Boxed LCA's -$175
LCA relocation brackets - $70
Rear Air bags - $1000?
BMR Adj T/A - $330
BMR Panhard bar set up - ~$400

So bags in the rear replace the shocks and eliminate the springs??

So say ~ $3000 for the rear susp and drivetrain. That sounds good to me but I am no expert. Sound good?

Jason

[sinned]

I hate to have to go over this all over again since we just did it a month ago but you cannot ever, no matter what, get an air bag to handle as well as a conventional coil spring. When track testing it is imperative that there be no variables such as those progressive springs present. Hell, listen to a pit radio at any major event, they spend the entire race trying to maintain spring pressure within a few pounds or adding 20 lbs here and there in an attempt to balance the car. Does this mean an air bag car won't handle well? No, but it is inaccurate to say they handle just as well as conventional springs. Do a search, we just covered all this.



If they were so great, wouldn’t some race team somewhere be running them?


Jason, LCA relocation brackets are for improving drag strip launch which is not always a bad thing but in this case could lead to a very short SVSA and lead to brake hop since you stated you would be attending some HPDE.

[LSxChevelle]

So with the set up I stated would you say I may handle better than a stock C5 Vette? I ask this b/c I had one for a few months and did some laps and am happy w/ that handling. I'm not competing or shooting for 1.1 lateral g's on street tires. But I do want the ability to lower/raise since I'm around damn speedbumps!

Jason

[sinned]

Ummm, no way in hell.

[PTAddict]

The C5 sets a fairly high standard. I've not driven one on the track, but I've chased them

You will notice that your Chevelle is a bit bigger, higher, and heavier than the C5 This creates challenges when trying to equal or surpass that car's handling.

Seriously, the kind of subjective evaluation you ask for here can't be done from just a parts list. You'll have to learn enough about the basics to make sure your basic geometry is in range for "good handling" cars, then spend more time driving the thing on a track, noticing how it behaves, then asking folks how to improve the things you don't like (which will be partly subjective).

But to answer a slightly different question, with a good front end (like the ones I noted from SCandC) and the rear solution you're contemplating, you have the potential for a very good handling car, and one that will be a gas to drive and learn from. That's why we do this crazy hobby.

[DonQuehotey]

I hate to have to go over this all over again since we just did it a month ago but you cannot ever, no matter what, get an air bag to handle as well as a conventional coil spring. When track testing it is imperative that there be no variables such as those progressive springs present. Hell, listen to a pit radio at any major event, they spend the entire race trying to maintain spring pressure within a few pounds or adding 20 lbs here and there in an attempt to balance the car. Does this mean an air bag car won't handle well? No, but it is inaccurate to say they handle just as well as conventional springs. Do a search, we just covered all this.

well well well......."dennis" ( reminds me of a cartoon that I used to read ) I think you are incorrect! IMO (which all of this argument is really subject to personal preference ANYWAY) A variably progressive spring rate would aid in getting the tires back down to the surface faster which would be preferable to surfaces with a lot of bumps or surface transitions. I also think that for your "average aggressive" driver a progressive spring rate would be better... again my opinion. Now I will agree that with a profesional or extremely smooth driver and a smooth grommed coarse a more linear flat rate is the way to go. But then again, I am neither a professional driver or tuner and I dont pretend to be one either. I am nothing more than a pro tour fan... you know...a car that does everything well from driving down the road, turning a corner or going from the bleech box through the traps. I think it is great that we all have subjective opinions! It definitely adds a little spice dont ya think Dennis?
I will completely agree with Dennis that in no way in Jeruselum is that car going to handle like a C-5. To accomplish that... you would be lucky to still be using the skin of the original car.