How much stiffer is the E30 M3 chassis than the standard E30?

[Joey Link]

I'm reading up on the chassis stiffness of E30 325i/is, E30 325iC, E30 M3, and E30 M3 Convertible and how they compare. I'm interested in seeing how they compare. How much stiffer is the M3 than the 325i/is? How much stiffer is the 325i/is than the 325iC? What did they do to make the M3 chassis stiffer?

[backtrail69]

I don't believe that the M3 is any stiffer than the regular e30s because it uses pretty much all the same basic architecture other than the quarters, fenders, bumpers and roof line/trunklid which shouldnt effect things enough to matter.

The cabrio is much looser than the hardtops because there is obviously no roof to reinforce the chassis, the rockers are enlarged to help combat this. There might be a stiffer floor pan, but I am not sure.

If you are only going to buy an M3 because its "stiffer" save your money and just build up a coupe. You will save lots of money and it will handle just as good.

[browntown]

Isn't the windshield a structural member or something on the m3?

[erik325i]

Isn't the windshield a structural member or something on the m3?

Yeah, the front and rear windshields are bonded in to provide some more structural integrity. Besides that though, I don't think there is anything else that would make the chassis stiffer.

-Erik

[LINUS]

As for that rear window thing, I'd be interested in hearing if it added anything to unibody stiffness, as that whole rear window assembly is somehow joined to the unibody. I see th obvious seam on the roof of mine, and I haven't taken the time, but I do need to follow it down the C pillar, as I get a little water dripping into the trunk on the driver-side inner fenderwell.

Anyhow, that window is bonded to a part that isn't directly the unibody, it's not even steel IIRC.

[AdamF 88iS]

The rear window doesn't do anything on M3s. The front glass being bonded makes a difference, though.

[george graves]

So then the question is, can we "upgrade" to bonded glass? Or is it a different windsheild surround and not a different glass part?

[Massive Lee]

Regular e30s can use the thinner M3 bonded windshield and gasket. It is only twice the price. And because the glass is a structural element, it sometimes crack if the shell gets stressed/hit.

[Jean]

Sounds like a great mod ! not lol

[808BMW]

If I had money and wanted more chassis stiffness, I'd get a well built cage.

[LINUS]

Regular e30s can use the thinner M3 bonded windshield and gasket. It is only twice the price. And because the glass is a structural element, it sometimes crack if the shell gets stressed/hit.

And to prove the supidity of some people (not meaning you at all, Lee), a standard e30 windshild & gasket fit an M3 as well.....sadly I know this because this is how my car sits until I can afford a respray. At least I don't have the cowl rust problem.

But yes, some P.O. got someone to shoehorn a standard screen in with a standard gasket. Idiots.

[jmarch]

These cars aren't what I'd call rigid and the difference between an M3 and 325is is negligible. Jack up one end of either and open the door and you'll see what I mean. When I jack up one end of my 993, the whole side of the car rises.

[AdironRider]

Noone ever said a basic e30 is comparable to a porsche.

[ping65810]

HAHA My thoughts exactly. e30 was a mass produced compact semi-luxury sport saloon, not a Porsche. e30s are ridgid compared to lots of stuff. When I would offroad my Ranger, with one front wheel on a rock, u couldnt open either door! Now thats lack of ridgidity

[jmarch]

Hey, they're way better than my old E21. I couldn't even open the door when I jacked one side of the car up.

My point was that these cars are flexible enough that any difference between an E30 M3 and "regular" E30 is unnoticeable.