d230

Hi all: soon I will be taking the rear seats out of my 911 in effort to lighten up the overall car. It was suggested to me to also put in a rear roll bar - I have one available to me fairly cheap. This rollbar is just the rear - not a full cage. My question is will the rear rollbar stiffen up the chassis and/or body, thus becoming a benefit aside from safety, or is it simply a matter of taking out weight and replacing it with other weight?

TIA

Jeff Curtis

It will add PROTECTION, as well as weight.

IMHO, a rollbar will not add much chassis stiffness...a cage will considerably stiffen up the chasses, especially if it is welded in. <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

I'm going through a conversion to a cage as I type this. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

...what a pain in the A$$!

Bill Gregory

The rollbar should significantly outweigh the rear seats - no comparison there! If welded in, it "might" contribute some slight stiffness, but you shouldn't put it in for that reason. As Jeff points out, a roll cage does make a stiffness difference you can feel. If the rollbar is one where the rear supports attach to the flat portion of the wheel wells, I'd pass on it - that's not the strongest point to attach too. Ditto if the feet just sit on the floor behind the seats. However, if you have to have one with those attaching points, weld a reinforcing larger plate on the floor that also goes up the side sill (an "L" shape) and is welded there also. You could also weld a plate on the wheel well.

Lightening your 911 is a great way to pick up some extra performance, and in many cases can be done without new parts. Of course your intended purpose has a great deal to do with how far you go. If you will be racing, then show no mercy on the interior and undercarriage, for example. If a daily driver that you just want some better performance out of, then you may not pull as much out as a racer would. Removing the a/c is one way to pick up a significant 50-60 lb reduction. Interior sound insulation is pretty heavy stuff, too. And don't think that anything is too small, it all adds up after awhile. Even the key in Porsche's racing 917's had holes drilled in it!

d230

Thanks Bill and Jeff.

9sixty4

Speeking of roll bars. I'm planning on purchasing a roll bar for DE. Before I go to retail, does anyone have a DAS bolt-in roll bar that will fit a 94 C4 sunroof coupe they would like to sell.
Thanks, Jim
64 356 SC Coupe Black
94 964 C4 Coupe Black

Bill Gregory

Jim,

You might also ask on the 964 and 993 forums, as the same DAS bar fits both models.

Jeff Curtis

Jim, if you get anyone that has a DAS for sale, buy that one, as there's NOT many used ones to be had out there. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

If you have TWO offers, please send one my way!