Cutting out solid rear bench back

[slowlysideways]

In my venture for increased weight loss, I understand the solid rear bench backing offers a lot of structural support for the rear of the E30.

Has anyone ever cut this out, and replaced it with a welded in rear strut brace between the two turrets? (not on the shocks themselves)

Or would you suggest using a hole-cutter to remove large bits of metal without getting rid of the metal itself?

The same applies to the solid metal â€Ëaparcel shelf'…

Any thoughts/ ideas would be appreciated.

[Cotty]

In my venture for increased weight loss, .

Would you really save much weight if your replacing what you cut out with a strut brace.

As I have read before on another thread, cutting these panels out isnt a good idea

[Widge]

You can cut it out but you need to weld in a frame around the apature you create to take the loads and forces tha would otherwise have gone through the panell, so you won't save any weight. OR you'll have a floppy car.

[slowlysideways]

i thought a welded rear brace would offer the same support as the rear bench, but at the fraction of the weight.

i removed the ski hatch piece and was very suprised just how heavy that little piece of metal was.

i want to get it under the tonne, i'm currently at 1049kg, with 20litres of fuel in, unladened.

[slowlysideways]

before the "fit fibreglass bumpers, bonnet, boot, carbon fibre doors" crew come on board, this is to be done on a budget, so every little helps.

maybe i'll rid the spare wheel well for a thin sheet of ally

[Cotty]

i want to get it under the tonne, i'm currently at 1049kg, with 20litres of fuel in, unladened.

Go on a diet

[Widge]

IF you do want to loose weight, take the bumpers off and get rid of all the stuff in them, They are really heavy. With a bit of imagination you could then just reattach the outer skins so it looks like the bumpers are still there.Glass is very heavy as well. Get some perspex and cut it to size for the doors and rear window.
The point isn't that a strut barace will take the forces but rather that that panel is designed as a stressed part in the vechile and therefore has quite a few forces acting throuh it. You'll notice it has shapes pressed in to it to carry these forces around the ski hatch, you effectively need to do the same.

[Simon]

It's no problem cutting this section out, but it will have to be caged up to make up for the loss of structure, proper built E30's don't have the section or parcel shelf.

[CaesarBob]

Is that the V8, Jagermeister'd M3??

[Simon]

Is that the V8, Jagermeister'd M3??

Yes, it is indeed.

[e21Jason]

Hi

I forget the proper name in aircraft construction, but take a hoel saw to the panels, then (you can buy the tool but easy to get made on a lath) using a tool you put a return flare on to on edge of the hole so it has a bellmouth apperance.

This give a stronger and lighter panel than orginial.

Jason

[slowlysideways]

that red one is a beast

[Motorhole]

Theres probably LOADS of crap behind the dash you can get rid of too. The E30 gloveboxes weight a tonne as far as gloveboxes go, so you could probably loos quite a bit by ripping out the dash , all the crap behind it and the replacing it.

Or even don't replace it! Get a 2nd hand stack system and mount it on the bulkhead

[Demlotcrew]

It's no problem cutting this section out, but it will have to be caged up to make up for the loss of structure, proper built E30's don't have the section or parcel shelf.

'Proper' built E30 dont have Liquid based 'Heavy' Batteries in the boot.

Andrew

[Simon]

It's no problem cutting this section out, but it will have to be caged up to make up for the loss of structure, proper built E30's don't have the section or parcel shelf.

'Proper' built E30 dont have Liquid based 'Heavy' Batteries in the boot.

Andrew

I used the picture as a guide for the panels being cut out, it's one of the best pics I could find.

Also, this car gets used regular, so it's probably the best set up for what he uses the car for.

[slowlysideways]

any more photos of the red one about - i'm going to be cutting my rear bulkhead out as i'm building my own cage

thanks

[Simon]

Here's the original thread of the build...

http://www.bmwcarclubforum.co.uk/forum_ ... =roll+cage

Orange BTW!

[CaesarBob]

maybe i'll rid the spare wheel well for a thin sheet of ally

Isn't the spare wheel kind of structural as well. Thought it was part of the rear-end impact protection, assuming there was a wheel in the hole.

[slowlysideways]

I think people confuse the word "structural"

The spare wheel well itself isn't structural, yes its a crumple zone if you were to get hit from behind, but as you quite rightly say - this is only the case if you have a wheel in the well, with a tyre on, and air in the tyre.

As I don't drive around with a spare, reason being because I dont drive around with any tools, no point having a spare if i have no means of changing a wheel.

Then I might aswell rid the heavy spare wheel well, for a thin sheet of ally (or similar) and brace it.

Was the orange BMW "professionally" (god i hate that word) put together, and the cage made?

Basically my final result of my own cage will look similar, just not as many bars and tubulars, but i will be removing the rear bulk head

[Simon]

Was the orange BMW "professionally" (god i hate that word) put together, and the cage made?

Have a read of the thread, the cage was made by a reputable cage builder, all the details are in the thread.