BMW M5 Forum and M6 Forums banner

1 - 20 of 141 Posts

·
Registered
Joined
·
2,182 Posts
I drove 2 stock M5s before buying my current one with Dinan front and rear braces. Only thing I can say is that the front end is especially "tighter" with the brace. My front end is more responsive despite my Steering center link needing replacement.

The rear brace WILL make the car more prone to (off throttle/drop throttle) oversteer.
 

·
Premium Member
Joined
·
13,589 Posts
I drove 2 stock M5s before buying my current one with Dinan front and rear braces. Only thing I can say is that the front end is especially "tighter" with the brace. My front end is more responsive despite my Steering center link needing replacement.

The rear brace WILL make the car more prone to (off throttle/drop throttle) oversteer.
How? It doesnt increase roll stiffness. The front/rear braces are supposed to stop strut tower deflection, nothing more. The rear towers arent budging on the bank vault E39 chassis, and on the front they arent gonna move a lick with the cushy soft stock suspension. I will say this though, they do seem to make a difference in the way the steering feels.
 

·
Registered
Joined
·
2,182 Posts
I will say this though, they do seem to make a difference in the way the steering feels.

Yes and that is what I felt, better/different steering feel.
 

·
Registered
Joined
·
2,182 Posts
I take everything back. They do nothing, dont buy um
 

·
Registered
Joined
·
7,564 Posts
Do some searching...this has been covered many times over the years. The net of it is that the E39 is a very stiff body structure both in torsion and bending stiffness. The natural frequencies in both modes are significantly higher than any prior BMW chassis...enough so that further improving them for the E60 was difficult enough that only a very minor increase was made.

There is no measurable performance benefit that anyone has ever documented. Owners are not able to tell if one is present or not in blind testing. No vendor has ever provided measured data for a strut bar on an E39 either. It would be rather easy to put some strain gauges and capture real time strain data which could then be back-calculated to show what load the bar is carrying in real time conditions.

On older chassis designs, especially something like the E12, E21, E28, etc, these bars are definitely useful as the torsion and bending nat freqs of those chassis is much, much lower than an E39.

Chuck
 
  • Like
Reactions: JDMM5 and MikeyMike

·
Premium Member
Joined
·
13,589 Posts
Do some searching...this has been covered many times over the years. The net of it is that the E39 is a very stiff body structure both in torsion and bending stiffness. The natural frequencies in both modes are significantly higher than any prior BMW chassis...enough so that further improving them for the E60 was difficult enough that only a very minor increase was made.

There is no measurable performance benefit that anyone has ever documented. Owners are not able to tell if one is present or not in blind testing. No vendor has ever provided measured data for a strut bar on an E39 either. It would be rather easy to put some strain gauges and capture real time strain data which could then be back-calculated to show what load the bar is carrying in real time conditions.

On older chassis designs, especially something like the E12, E21, E28, etc, these bars are definitely useful as the torsion and bending nat freqs of those chassis is much, much lower than an E39.

Chuck
The only time I noticed was with sticky R comps and on coilovers with 1000lb springs.
 

·
Registered
Joined
·
1,567 Posts
If you feel something its Probably the placebo effect. :hihi: My 2 cents...

But sersiously... I did feel something. Rather like a cool kid :cool: after standing back and observing the installation of my mod.
 

·
Registered
Joined
·
2,182 Posts
If you feel something its Probably the placebo effect. :hihi: My 2 cents...

My lack of driving experience on a non-Dinan M5 means I can't agree or disagree with you, i will however say that I have added strut braces on other cars and if the difference felt was placebo then I need to be on medication.

On a couple of cars the difference was night and day.

I HAVE heard that each M5 drives different so the "improvement" I felt over the other test drives might have just been difference of feel from the two cars.
 

·
Registered
Joined
·
3,427 Posts
Discussion Starter #12
Do some searching...this has been covered many times over the years. The net of it is that the E39 is a very stiff body structure both in torsion and bending stiffness. The natural frequencies in both modes are significantly higher than any prior BMW chassis...enough so that further improving them for the E60 was difficult enough that only a very minor increase was made.

There is no measurable performance benefit that anyone has ever documented. Owners are not able to tell if one is present or not in blind testing. No vendor has ever provided measured data for a strut bar on an E39 either. It would be rather easy to put some strain gauges and capture real time strain data which could then be back-calculated to show what load the bar is carrying in real time conditions.

On older chassis designs, especially something like the E12, E21, E28, etc, these bars are definitely useful as the torsion and bending nat freqs of those chassis is much, much lower than an E39.

Chuck
dont worry, i already know the truth.

i just wanted a few people to take note that the e39 chassis is still as still and that strut braces are for the most part, "bling" mods.
:hihi:
 

·
Registered
Joined
·
9,355 Posts
dont worry, i already know the truth.

i just wanted a few people to take note that the e39 chassis is still as still and that strut braces are for the most part, "bling" mods.
:hihi:
You trollin?
 

·
Registered
Joined
·
5,919 Posts

·
Registered
Joined
·
3,427 Posts
Discussion Starter #15
Bingo! He's home alone with nothing better to do.
trying to figure out the wiring on these seats. i have nearly all the wires matched up, and figured out, but there's 1 wire i dont know about...well actually 2 i dont know haha...
 

·
Registered
Joined
·
3,337 Posts
trying to figure out the wiring on these seats. i have nearly all the wires matched up, and figured out, but there's 1 wire i dont know about...well actually 2 i dont know haha...
I don't believe you. There is nothing that you don't know about. :rofl:
 

·
Registered
Joined
·
205 Posts
The best explanation I've heard for the front brace is that it controls deflections that result in undesired camber changes...

The theory is the following:
Even a slight bending deflection of the top of the strut tower can translate into a few tenths of a degree of camber change.
The outside front tire camber increases a few tenths to the positive side especially with fast cornering. It's this change in the control of the camber
that improves the way the car steers and corners.
 

·
Registered
Joined
·
3,427 Posts
Discussion Starter #18
I don't believe you. There is nothing that you don't know about. :rofl:
well you see the issue is that the older cars are single stage, while the new cars are dual stage. old cars have round pin connections, new cars have straight pins.

i have most of it right as far as the power for the movement goes. i have 2 empty pins though from my m5 seats with the old harness now. but i cant figure out what those pins are. i had to swap over the old seatbelt mechanisms though to make sure the safety stuff works as it should, i know all the power features work. all that leaves is the heated seats power, which logicall makes sense. ill find out tomorrow when the seats go back in the car.

fml

lol
 

·
Registered
Joined
·
647 Posts
Do some searching...this has been covered many times over the years. The net of it is that the E39 is a very stiff body structure both in torsion and bending stiffness. The natural frequencies in both modes are significantly higher than any prior BMW chassis...enough so that further improving them for the E60 was difficult enough that only a very minor increase was made.

There is no measurable performance benefit that anyone has ever documented. Owners are not able to tell if one is present or not in blind testing. No vendor has ever provided measured data for a strut bar on an E39 either. It would be rather easy to put some strain gauges and capture real time strain data which could then be back-calculated to show what load the bar is carrying in real time conditions.

On older chassis designs, especially something like the E12, E21, E28, etc, these bars are definitely useful as the torsion and bending nat freqs of those chassis is much, much lower than an E39.

Chuck
Ding ding ding!

Source:BMW’s future design and development: Is the new avantgarde conservative?

"The 1996 E39 5 Series was a truly outstanding car. Many journalists claimed that it was the best luxury sedan in the world, blending a rare mix of sporty handling and performance with comfort and elegant design. It raised the standard so high that arch-rival Mercedes-Benz E Class took two generations to surpass it – and just marginally when it finally did in 2002. The man behind the E39 was dr. Wolfgang Reitzle, the highly respected product chief of BMW during 1990s.

But why was the car so good?

First, its chassis was made immensely strong – 80 percent stiffer in torsion than its predecessor, this was by far the stiffest car back then. So stiff that BMW found it unnecessary to raise chassis’ rigidity anymore in the subsequent E60. Also, it was much safer under crash while being just 10 kilograms heavier than the outgoing model. Even more, the whole car actually weighed less than the old generation, thanks to the use of all-alloy engine, aluminum transmission case and aluminum suspensions. The suspensions of E39 was a technical milestone. It employed a new Z-axle multi-link setup, which had superior wheel control and was made almost entirely of aluminum alloy – a first in mass production car."
 

·
Registered
Joined
·
3 Posts
the service "advisor" said that a strut brace will help with the outer wear of the front tires, (not wearing excessively and my alignment is fine)

Because he didn't try to sell me one, I tend to think this might be true.
 
1 - 20 of 141 Posts
Top