91CamaroRS305

iTrader: (2)

Ok, before anyone asks.....YES I will get a stronger rear end in the car by next season, and altho it is street driven I will go with a strip car over a street car, now on to my dilema.

I got a Comp. Eng. ladder bar/subframe setup off ebay for $95....couldn't pass that up. This is going to be a fall/winter/early spring project so time isn't an issure here.

Now my questions are, am I able to tub the rear end for bigger tires with a ladder bar setup?? Or will I need to install some rear frame rails??

Also can I just cut the whole rear floor of the car because I will not need or have back seats, or will the floor need to be in there for structural reasons?

I understand that I will need to still retain the PHR to keep the rear end centered, but is there an alternative to the PHR to go with bigger tires and still keep it centered??

AlkyIROC

My car isn't tubbed out (yet) and I have ladder bars. I had to section my rear floor so the ladder bars could clear through it. The third gen has a very low floor line compared to the axle height. The upper tube of the ladder bar goes right through the floor line. With the taller rear tires, I'd like to raise the axle height even more that that would just about put the ladder bars inside the car. My tire height is currently 29.5" and I want to go to 32". Tubbed out with some 32 x 14's would be nice. Once I get the rims with the backspacing I want, I can start working on plans/dimensions for a narrowed diff.

I use an aftermarket panhard bar which works fine however under a hard launch if the back end sqauts or lifts, the panhard rod allows the diff to move sideways if there's too much compression or seperation in the suspension.

The better way to do it is to install a diagonal link in the ladder bars. It's a simple link that attaches to the front mount bolt on one ladder bar and the rerar lower bolt on the other ladder bar. This will keep the diff centered even if the suspension extends and compresses.

If you're going to tub the car, you need rear frame rails since the factory "frame rails", which are nothing but sheet metal, will be cut out. Once you cut them out, the back of the car still needs some sort of support. Rear frame rails will allow you a place to mount a crossmember for a coil over kit.

Doing a back half means a lot of work. The fuel tank will have to go plus a lot of factory sheet metal. This isn't a job for the typical back yard mechanic. There's a lot of fabrication and alignment to do to get it right.

91CamaroRS305

iTrader: (2)

So with the ladder bars the setup would for a "N" of sorts if I was looking down on the ladder bars correct? I looked at your pics on your website (2nd time it has helped, first brakes now this) and they are really informative for just being pictures, so thanks on that.

But the support bar would take the place of the PHR and I could essentially remove that correct?

As for the tubbing, I think I will only fiddle with that until I reach the stock frame rails and then stop there, cause I don't have the money for all the other mods that must go along with it. However if I don't tub the car can I still install a coil-over bar up top to support a coil-over setup in the car?

AlkyIROC

With ladders bar, straight 4-link (not triangulated), or our 3 link suspension with a torque arm, something needs to locate the diff under the car.

GM uses a panhard bar. Some custon hotrod applications also use a panhard bar but have it attached to the top of the diff to the frame. It's about half the length of a third gen panhard bar. Normally a ladder bar or 4-link system uses a diagonal link since this is the most effective way to locate the diff. There's also a device called a wishbone link. It has 3 mounting points. 2 points mount to the bottom mounts of the ladder bar/4-link at the diff and the third mount is attached at the front mount crossmember under the driveshaft. This type of system also locates the diff and prevents it from moving side to side.

On cars like G-body of Mustangs, they use a factory triangulated 4-link system. The top mounts are angled inwards at the front. This also keeps the diff centered.

Using any of these devices will all work fine. Normally it's a matter of what fits the best. Like I said, I still use a factory style panhard bar (aftermarket with rod ends) but if I ever get around to tubbing my car, the narrowed diff won't allow the long panhard bar. I have a diagonal link already to put between the ladder bars but haven't installed it yet because I may change the distance between the ladder bars with a narrowed diff.

Shagwell

we run ladder bars with the daigonal link on my dad's blown 68 camaro- had a front caliper lock up about a month ago - went through the traps backwards @ 117mph....not a fun experience(even for me just watching), but the diff never moved, on the other hand the 33.5/15's weren't happy.....
- As Stephen stated, you'll have to cut part of the floor out of a 3rd gen to clear ladder bars. Until you switch to coil-overs or relocate the springs, you can't tub the back. The "inner fenderwell" is the sping pocket. You can do some modification to this area and clear a larger tire though. The rear floor sections can be cut in some areas, but not in others, as they are part of what carries the car(note: I hate unibody......). You can ladder bar what you have, but there's close to as much work in bracing and re-using spring mounts and such as to just go ahead and back-half the car.
If you're going to go through the work of ladder bar installation and intend on one day tubing it for larger tires, you might as well go ahead and back-half the car. Then you have something sloid to tie everything too, instead of rigging and re-rigging everytime you change soemthing. A couple bent rear frame rails and two short pieces of 2x3 to tie into the front "subframe" and you'll be set for anything you intend on doing.

91CamaroRS305

iTrader: (2)

Shagwell, need a tad bit of clarification.

Since I am thinking about tubbing it out, where would I attach the new rear frame rails? Would I need to find a solid part of the unibody to attach it too and go from there, or is there more to be done on our cars?

And I take it the easiest way to go with tubbing would be to use coil overs right??

Thanks for the info!

AlkyIROC

My SFC are custom made. I have my front ladder bar crossmember welded between the SFC. When I eventually tub my car, the frame rails will simply get welded to the crossmember.

If you tub it, you'll need some sort of suspension since removing the factory sheet metal frame rails, removes the factory spring mounts. The only way to support the rear of the car is with some coil over shocks. An upper crossmember is welded between the frame rails above the diff for the coil overs to mount to.

The easiest way to back half a third gen is to buy a kit.

http://www.swracecars.com/pdf/CATpg13.pdf

Competition Engineering : Product : WELDED REAR FRAME KITS

Shagwell

- you need some sort of frame rails. Mine are 2x2 box tubing slid into the front "subframe" and slide into the rear, fully welded, plus a couple extra braces. - For the back-half itself, the easiest route is to buy a pair of formed rear frame rails and fit them to the car. Then a cross tube for coil-overs and a fuel cell. - From there it's all about tin work(flooring).....

here's a link to my exhaust post. - the pics show my frame-rails fairly well....
https://www.thirdgen.org/forums/exha...rue-duals.html