Rear strut brace - options...

[_Nathan_]

Exactly, it'll stop the cracks as it triangulates the diff pick up points, also acts as a harness bar.

As for the AC shitzer one, why would you need BMW to fit it - 6 bolts!

[The Gorilla]

Hi,

Rear strut brace will be as much use as
a Hand brake on a canoe if your still
running a spring /shock rear end.

Bracing a damper to another damper and
the chassis does zero.

If your running coilovers but no cage etc
then it may make laetral rear end sway
a little stiffer in the dry, when your about
a wisker away from the rear end limit.

As regards a rear end brace that bolts from
rear strut tower to rear strut tower while being
bolted to to the boot floor, that will make sure
that the distance between the strut towers
stays the same at about 1.2 / 1.5 lateral G,
but I expect you would only be able to see
that if running full slicks with a suspension
set up that would be undriveable on the road.

As regards picking up the rear diff, well if the
diff is solid mounted then fine, but if not
then somebody please explain to me how it
works ?

Regards,

The Gorilla.

[glendog74]

I love The Gorilla

[AlexGTT]

Originally Posted by The Gorilla

Hi,

Rear strut brace will be as much use as
a Hand brake on a canoe if your still
running a spring /shock rear end.

Bracing a damper to another damper and
the chassis does zero.

If your running coilovers but no cage etc
then it may make laetral rear end sway
a little stiffer in the dry, when your about
a wisker away from the rear end limit.

As regards a rear end brace that bolts from
rear strut tower to rear strut tower while being
bolted to to the boot floor, that will make sure
that the distance between the strut towers
stays the same at about 1.2 / 1.5 lateral G,
but I expect you would only be able to see
that if running full slicks with a suspension
set up that would be undriveable on the road.

As regards picking up the rear diff, well if the
diff is solid mounted then fine, but if not
then somebody please explain to me how it
works ?

Regards,

The Gorilla.

Agree with you Gorilla but my own personal reason for running a Safety Devices type rear strutt with floor pick-up is to, as Shimmy mentions, help prevent rear sub-frame cracking and brace the shock towers when running Intrax coilovers. Not that bothered with absolute on limit G's with slicks, etc.

If running slicks a full cage would be essential, for me.

[AlexGTT]

Originally Posted by glendog74

I love The Gorilla

You love everyone.

[The Gorilla]

Hi,

AlexGTT- The rear strut brace will do nothing to
prevent the rear subframe ripping out the boot
floor, if anything it will accelerate it.

The rear subframe seeks to leave the E46
shell due to the ''torque twist' of the diff under
extreme load.

That is why the rips in the boot floor in most
cases follow the same pattern.

By stiffening up the rear end of the shell the
loads when transmitted from the torque of the
diff into the boot floor via the diff mounts will
be greater as that area has been made more 'rigid'
and the laods which can be partially disspearsed by 'flex'
now have nowere to go.

This will accelerate the point load, which is the sub
frame mounts to the boot floor.

Hence your 'ripping' dynamics increase not reduce.

Regards,

The Gorilla.

[funtime]

Originally Posted by The Gorilla

Hi,

AlexGTT- The rear strut brace will do nothing to
prevent the rear subframe ripping out the boot
floor, if anything it will accelerate it.

The rear subframe seeks to leave the E46
shell due to the ''torque twist' of the diff under
extreme load.

That is why the rips in the boot floor in most
cases follow the same pattern.

By stiffening up the rear end of the shell the
loads when transmitted from the torque of the
diff into the boot floor via the diff mounts will
be greater as that area has been made more 'rigid'
and the laods which can be partially disspearsed by 'flex'
now have nowere to go.

This will accelerate the point load, which is the sub
frame mounts to the boot floor.

Hence your 'ripping' dynamics increase not reduce.

Regards,

The Gorilla.

hmmm doesn't sound good, was going to order one, nowI'm not sure. When I spoke to John though he said it was designed to prevent subframe cracking. What your saying does make sense but i'd like to hear what John has to say.

After all, every race car they have runs one

John?

[The Gorilla]

Hi,

Unless the 'cause' of the ripping dynamics
is addressed, ie] the subframe mounts via the
boot floor, then no amount of 'stiffening'
to secondary panels is going to prevent it.

The rummour mill suggests that this issue
was addressed on later shells, but it is
an inherent design flaw.

The point being the harder the car is pushed,
reason for thinking about Thomas Fangdangle Strut Brace
in the first instance, then the more likely
the problem will be.

Unfortunatley these things sound so matter of fact
because they generally are.

Regards,

The Gorilla.

[Thorney]

There are three seperate areas here:

1. Sub frame generated cracks in the boot floor
2. Running rear coil over suspension
3. Lateral stiffness running slicks
4. Running harness's

The harness bar/boot/suspension stiffener was designed for numbers 2,3 and 4 not specifically for no.1. As Gorilla says, the cause of this is a pulling motion and a strut brace etc wont really affect that. However, No.1 is covered by BMW's warranty (unless you run coil overs on the back) so our advice is to check yours is fine before fitting a strut brace or other upgrade (we do it as a matter of course on all suspension fitments). As the sub frame issue is well known and unrelated to anything other than diff movement on the floor BMW wont DK any warranty unless you have parts that will make this stress worse (slicks, coil overs).

In short, if you are worried about the cracking issue get your car checked, if its ok then mod away, if not then BMW will fix it under warranty. After this is you want to run slicks/coil overs/harness's then fit the bar.

[7.77]

was about to buy one, but with a asking price of postage @195 £, will do a different way