Strengthening a unibody at the pinch weld

[woody80z28]

I have a 91 Beretta project I'm working on (don't laugh) that will make enough power and is old enough I'd like to strengthen the body. It will be my DD for hopefully years and years to come, so I don't want the creaks and groans you get with an older car.

If I took 1" angle iron or even 1" boxed tubing and welded it to the rocker and pinch weld, would it add a lot of strength? I dont think fabbing "subframe connectors" is possible, since there just isnt the real estate. If it won't add a decent amount of structure, the idea is probably not worthwhile.

If you have a better idea, please let me know.

Here's a picture of the underside of the car, so you can see what I have to work with...

https://static1.pt-content.com/images/pt/2009/02/tn_full_IMG_1941JPG_Thumbnail1-1.jpg

[JRouche]

Now just my uneducated opinion but no, wont do any good. Take a piece of tube or angle of that size and length, support it at its ends above ground. Now step up on it, yeah, step up LOL A lil afraid, might bend? Yes, it will flex, prolly wont bend though, I wouldnt put you in harms way ;) But my point is it just doesnt have enough rigidity to help with any stiffening. For an example, I have 2x4 heavy walled tubes going from front to back on my unibody car, and thats just about good enough without any additional cross bracing.

When you are thinking about steel for framework I like to use tubing, and rectangular tube. For the additional weight of the added cross section you gain alot of strength over square tube.

But for any bracing to do any good it needs to be located right at the suspension pivot points. Those points are going to cause your pan to flex if they are stressed enough. So if you focus on beefing up the area around the forward pivot points on the rear suspension then you can look to carry that additional stiffness forward, supporting the pan in the process.

But I gotta ask, why the concern. Are you seeing stress fractures in the pan or lower body?? If not I wouldnt add a bunch of weight that really wont give you much in return. Now if you were to say you stuffed a V8 in and are concerned then yeah.

But for a DD thats somewhat stock, I dont see the need for a sub frame.

And from a handling standpoint a lil flex in the pan and body isnt terribly bad. As long as you arent cracking windshields, spot welds and suspension pivot points, its strong enough. I imagine a guy that knows his car really well, and how it handles can drive a piece of spaghetti pretty darn fast.

So, if nuthing is breaking, and the car is handling as it should from the factory I wouldnt add steel.

If you want to tighten up the pinch weld area you can TIG weld the seam shut if its not full of sealant. That actually will make it fairly stiff too, compared to the stock welded process, dunno if its just spot welded of not. JR

[qwik1320]

Not laughing - I had a 90 Beretta Pace Car, loved that car. Sounds like a great DD project!

[woody80z28]

Thanks for the reply JRouche. You may have saved me some work!

The stock 3.1L made 140hp and my modded 3.4L is about 220, so I dont think the added power will twist anything up.

The idea was more to stiffen the body up so there are not the creaks and groans you can get with an older car. I have never driven this one (bought it all torn apart) but I assume the chassis is in good working condition.

[caper150]

OT but where did you get the rotiserrie(SP?) I haven't seen one of those since I was in autobody class in the 90's I thought it was a good alternative for quick repairs to the undersides of cars without laying on your back and working overhead.

[woody80z28]

The guys at Nasty seem to think the angle iron probably wouldn't do much, but 1x2" boxed tubing would be worth the effort.

Thoughts?