Chassis Reinforcement for E30

[JiB 2]

I've got a Ground Control trackday coilover kit for my E30.

It's running 600lb+ springs, I'm worried about the chassis handling it as I don't have a cage yet.

Is this recipe for cracked struts and a mushed chassis? It does a banana impersonation as is

Strut braces will set me back $300+ for front and rear, a $300 I'm probably not all that will to pay if I don't have to.

Car has done 320,000kms...so it's not a particularly fresh chassis.

[CamB 48]

The rear won't do much of anything since the springs don't locate off the strut tower. I'm not sure the front brace will protect the towers much, but it might stop the flex. The front springs are more like 400lb yes?

By the way, JiB's not kidding - the car really does flex (eg front to rear when you jack it up), and its not obviously rusty anywhere I have seen.

[hank_bukowski 0]

www.turnermotorsport.com

Buy every E30 chassis reinforcement kit they have.

[CamB 48]

Front engine mounts part of subframe looked fine (we replaced the engine mounts a short time ago), and it has standard sway bars so I'm not sure the sway bar reinforcements will do much.

It'll be worthwhile inspecting all that though.

Edited August 25, 2008 by CamB

[JiB 2]

www.turnermotorsport.com

Buy every E30 chassis reinforcement kit they have.

I'd rather not spend money on stuff that won't help all that much, as I need the money elsewhere in the car. Also, the items on the Turner site don't really have anything to reinforce the strut tops apart from overpriced (imho) front strut bars. And as CamB has explained I most the stuff isn't too applicable to my car, and neither have I seen much of that stuff on NZ E30's.

I plan to have a cage by the end of the year, but this won't extend to the rear struts/diff - which is all tied together with big bits of subframe. But the caged E30 race cars I've seen still run strut braces front and rear regardless of whether the cage extends to the front or not.

So is strut integrity a problem? I'm thinking strut braces for both ends will stop things flexing/breaking somewhat? Perhaps I have been hanging around Japanese cars for too long, but strut braces for E30's seem prohibitively expensive...

[3series 0]

It does no harm to use the search feature at the top of the page.

http://www.drivenperformance.co.nz/scripts...?idproduct=1286 I believe someone got a price around $180 for one.

http://www.bimmersport.co.nz/forums/index....;hl=strut+brace

http://www.bimmersport.co.nz/forums/index....;hl=strut+brace

Edited September 22, 2008 by bmw3

[Silver Fox 43]

A lot of the E30 series cars have no cage to the towers, our 2 cars have all the cage inside the cabin, and to date, after 2 years, show no signs of any chassis problems. I get them on the alignment machine every couple of meets, and I'm sure it would show there if something was happening.

As you will have a bit more power and weight I guess, you may want to look at taking the back bars thru the firewall to the top of the spring platform rather than the tower, and the fronts to the tower top. I wouldn't think you will need much more than that.

We don't run strut braces, don't see the need for the extra cost myself.

Edited September 22, 2008 by Silver Fox

[E30-323ti 66]

I'd rather not spend money on stuff that won't help all that much, as I need the money elsewhere in the car. Also, the items on the Turner site don't really have anything to reinforce the strut tops apart from overpriced (imho) front strut bars. And as CamB has explained I most the stuff isn't too applicable to my car, and neither have I seen much of that stuff on NZ E30's.

I plan to have a cage by the end of the year, but this won't extend to the rear struts/diff - which is all tied together with big bits of subframe. But the caged E30 race cars I've seen still run strut braces front and rear regardless of whether the cage extends to the front or not.

So is strut integrity a problem? I'm thinking strut braces for both ends will stop things flexing/breaking somewhat? Perhaps I have been hanging around Japanese cars for too long, but strut braces for E30's seem prohibitively expensive...

A rear 'strut' brace won't do anything other than adding a bit of reinforcement where it bolts on.

But Z3 reinforcement plates will do the same.

For the front of the cage, you aren't providing much additional rigidity unless you are triangulating the towers, both vertically (down to the base of the A-pillar) & laterally (to the mid of the dash bar or better to the windscreen bend in the A-pillar). And strut top to the opposite A-Pillar base a-la E30 M3 DTM cars, but that is pretty extreme.

The single bar to the strut top, as described in the motorsport manual, provides mainly frontal impact protection.

E30's to tend to 'banana' as you say, typically at the firewall, the more attention to this area will see the greatest improvements to chassis stiffness.

E30 DTM car:

Triangulated Towers & subframe:

From in the car:

For the rear of the cage, if you are not planning to go to the shock towers, are you going to the boot floor? Directly above the springs?

E90 cage for reference:

[E30-323ti 66]

A lot of the E30 series cars have no cage to the towers, our 2 cars have all the cage inside the cabin, and to date, after 2 years, show no signs of any chassis problems. I get them on the alignment machine every couple of meets, and I'm sure it would show there if something was happening.

As you will have a bit more power and weight I guess, you may want to look at taking the back bars thru the firewall to the top of the spring platform rather than the tower, and the fronts to the tower top. I wouldn't think you will need much more than that.

We don't run strut braces, don't see the need for the extra cost myself.

What rate are the E30 series springs (progressive of course)?? IIRC the are Kings 'Super Lows' aren't they??

[Silver Fox 43]

yes, the rears are sl's, the fronts are specials, 350lb from memory for the 318's, but Stocks could tell you.