Rear suspension questions

[Mathius]

Ok, the project: a '76 Chevy Malibu 2-door. It has a bone stock 305 that I hope to upgrade to a 496, or bigger, and I plan to go with a Ford 9". It has a 4-link suspension from the factory, triangular 4-link.



I want to go with a g-machine type build, but it's going to be driven, and will spend a lot more time on the road than a track, if ever.

I have a few questions about how to plan my rear end....

1. I'm aware that airbag suspensions today have been improved to the point where you can set one up as good as any car on the track, but are their any advantages to one? Is the ride more comfortable perhaps or something else I'm missing?

2. Is there some reason I should consider swapping out the factory 4-link? There are upgrade parts available to improve the bushings, and there are adjustable arms for it, etc. but is there a reason to go with a wishbone, or a parallel 4-link with a panhard bar, or some other setup?

Mathius

[derekf]

Can't speak for number 1, but if the 76 Malibus still have the converging 4-link, a search for "4 link" and "bind" should find a lot of useful information (or just search for Dennis68's posts about rear suspension, he's got a lot to say about the C4L's bind issues)

[Mathius]

Can't speak for number 1, but if the 76 Malibus still have the converging 4-link, a search for "4 link" and "bind" should find a lot of useful information (or just search for Dennis68's posts about rear suspension, he's got a lot to say about the C4L's bind issues)

Ok, I found a lot doing that search, basically stating that the factory 4-link is junk and should be scrapped because of the bind issue. But what's the solution? Would a parallel with a panhard be a better setup, or is it just going to cause the same issues.

One of the articles I read stated that some mustang guys ran a factory 4-link, and removed one of the upper bars and ran a panhard, and that was an improvement, but it still wasn't optimal.

Would a wishbone elminate these problems altogether? I can fab, but engineering isn't something I have a lot of experience in...

I've been trying to follow the popular Hotrodding 1G suspension build that the guy did in his driveway (must be nice to have a friend who's an engineer, and another who's a master machinist, etc.) but there isn't a good enough picture of the whole setup for me to get a good idea of how it works.

It looks like he just has a wishbone setup at first glance, but then behind the axle, he has additional rods.

Mathius

[TonyL]

for more info on John parsons car, look in the "cars" section under chevy II. Lots of pics. Or you could just ask him, he's usually around here somewhere.

he also has a web site.

http://www.iimuchfabrication.com/RearSusp/

[Norm Peterson]

One of the articles I read stated that some mustang guys ran a factory 4-link, and removed one of the upper bars and ran a panhard, and that was an improvement, but it still wasn't optimal.

That the GM UCAs are angled more sharply in the lateral direction (45* plan view from vehicle centerline vs about 30* for the Mustang) makes the so-called "poor man's 3-link" approach even more questionable here. You want the 3rd link to handle less of the lateral duty, not more. Ideally none of it (at 0* plan view with respect to centerline). Lateral location is the PHB's job, and the PHB doesn't need to be picking up loads from the control of pinion angle under acceleration/braking as results from a plan-view angled 3rd link.

Would a wishbone elminate these problems altogether? I can fab, but engineering isn't something I have a lot of experience in...

It eliminates some of the disadvantages, but it generally restricts you to running either a relatively high RC (above the pumpkin) or a really low one (beneath it, with the axle ends now located by a pair of uppers). With a bit of work (and engineering), you might be able to get the RC somewhere in between. With a lot more of both you might even be able to get around the issue of the driveshaft itself already taking up much of the best real estate.

Norm

[sinned]

1. I'm aware that airbag suspensions today have been improved to the point where you can set one up as good as any car on the track, but are their any advantages to one? Is the ride more comfortable perhaps or something else I'm missing?

I don't know where you got that information but no, air bag cars cannot be set-up to run as fast as conventional coil sprung cars (everything else being equal). There is a thread floating around about how air bags rates are determined...basically they do not have a specific spring rating as the rate changes as the bag is compressed thus creating a variable spring if you will.



Do bagged cars automatically NOT handle? No, they just do not run as fats as conventionally sprung cars.

[MrQuick]

I don't know, that Goodmark Nova did tear up the track pretty good. Probable not to full potential but way better than stock.