A Body Rear Suspension (Dennis, are you there?)

[ProTouring442]

I have looked into this a little before, but would like to get a few opinions on the subject. Like so many before me, I have already bought into the hype and purchased PST's PollyGraphite products for the rear of my car (1972 442).

So, as I will be removing these, I thought I might look into what is a good idea. I did a bit of searching, and I see that Dennis has already looked into this quite a bit, and maybe a bit more after that! He seems to recommend Edelbrock uppers, A special joint (who makes it?) on the diff side of the upper, and lowers with joints on both ends. Am I right here?

Now, I'm no suspension expert. Hell, I don't even play one on TV (Don't even watch the thing!). Still, what would be better:

1) Going with the Dennis approved set-up.

or

2) Going with the lowers with joints on both ends, a panhard bar, and a torque-arm running under the driveshaft like the add-on one made for Mustangs.

If (2) is the better option, how would/should/could I determine the proper length of the arm?

Any ideas on fabricating the slip joint at the front of the arm?

You are the masters, I am but the learner!

Shiny Side Up!
Bill
'72 442 "Inamorata"

[Derek69SS]

The spherical bearings in the axle housing are from www.wolferacecraft.com

If you hurry, you can get them 20% off (until Jan. 6th )

I ordered mine last week I also ordered the double-adjustable upper and lower arms.

[sinned]

I'm gonna have to say go with the T/A arrangement, you'll be much happier in the long run.

[ProTouring442]

Originally Posted by dennis68

I'm gonna have to say go with the T/A arrangement, you'll be much happier in the long run.

OK... Now for the fun part. I need to learn how to properly set-up a T/A. What length it should be, etc. I believe that (and I could be wrong) if I make it too long, it will cause wheel hop on braking. Is this true? And if so, how extreme? The car is not "hard core" pt, but I am hoping to make it better than stock in any way I can. Can anyone suggest resources I can use to determine the best way to go about this?

Thanks Denny, you rock!

Shiny Side Up!
Bill
'72 442 "Inamorata"

[sinned]

Mark pretty much already covered below but I wanted to add that making the arm length too short is probably not going to an issue. Realistically anything over 40" is plenty long enough and it would make sense that most would use a version of the GNX or "F" body arrangement. Arm locating heights need to be determined as well for accurate assessment. Remember that since the lower links no substantial impact on AS or brake hop issues they can be tuned for neutral/roll under steer.

[Mean 69]

I believe that (and I could be wrong) if I make it too long, it will cause wheel hop on braking.

Actually, it is the reverse. The shorter you make the arm, the higher your anti-squat value will be due to a shorter SVSA (essentially the same as the effective length of the torque arm = front pivot point to rear axle centerline). In this case, the car can show a relatively greater chance of brake hop. Making the torque arm as long as practically possible is best for the brake hop, but then you have two other issues (at least) to consider. One, your A/S value will go down, but that isn't a huge deal in and of itself. The bigger issue is structural rigidity of the arm itself, when it becomes longer, there is a greater tendancy for beaming flex (bending) under an equivalent load compared to a short arm. An A body is a big, heavy car, with a slightly longer wheelbase than a late model Mustang, so use a bit of caution when deriving a setup from the commercially available setups from Maximum Motorsports, or Grigg's. Torque arms are proven winners, but like you stated, the devil is in the design and tuning details.

Mark

[sinned]

Originally Posted by Mean 69

Torque arms are proven winners, but like you stated, the devil is in the design and tuning details.

Mark

And finding the real estate under the car to fit it.

[ProTouring442]

Ok guys, this is good... only I need an education big time! So, what I need now are good resources! As it is unfair to ask anyone to sit and explain all of this to me, I would love it if you could point me to a few books or web sites on the subject. It'll be a little while before I am back under the car, and if I am lucky I can get some of the basics down so I can perform this mod correctly and safely.

Thanks Guys!
Bill
'72 442 "Inamorata"

[Mean 69]

Herb Adam's Chassis Engineering book does a decent job at the Torque Arm basics, though I would personally not go with anything shorter than at LEAST 48", longer being preferred. I toyed with the idea of doing a ~42" setup on an early Mustang years back, but even with that car (lighter, shorter), I'd still go longer if I were to do it again. I think the effective length of a late model F body is of the order of ~60" or so, that would be just about right, no shorter in my humble opinion. Brake hop is the main issue and I'd go to great lengths to minimize/eliminate, I know of a guy that runs a late Camaro on the track and he "still" gets this under certain circumstances. High speed braking zones are not the place where you want to compromise performance.

The three link ideas floating around for the A bodies are also something you should consider, the main issue being gaining clearance for a long upper link past the crossmember on the frame. Here again though, if you want to do it yourself, the devil is in the details, and they are important details. Be safe.

M

[Steve1968LS2]

Originally Posted by Mean 69

I think the effective length of a late model F body is of the order of ~60" or so, that would be just about right, no shorter in my humble opinion.

f-body torque arms are LONG.. very long.. once I switched to a stonger unit I no longer got hop under severe braking (the stocker would flex)..

You can see in this pic just how long a 4th gen f-bod torque-arm is..