Supercharged e92m3 at watkins glen

[Datka]

Originally Posted by SYT_Shadow

Yeah those are really low. Ohlins R&T seems like a nice street suspension but that's about it

I'm running 700/1000 and feel I should run even higher, but MCS says no

Actually Ohlins are pretty good on the track too, but when you start pushing this car hard on sticky tires with aero, its a different ball game.
On the street and for an intermediate driver on the track they are fantastic.

[Datka]

Originally Posted by SYT_Shadow

Yeah those are really low. Ohlins R&T seems like a nice street suspension but that's about it

I'm running 700/1000 and feel I should run even higher, but MCS says no

Shadow, the fact that MCS told you no to higher than 1000 rear spring rate leads me to believe that high rear spring can potentially cause the rear sub-frame failure.
I have heard from different sources that anything more than 800 rear spring can cause rear sub-frame failure on e9x m3.
As far as I know properly built e36 and e46m cars have rear sub-frames reinforced.
This makes me to rethink my plan to go with coilovers that come with higher than 800 rear springs.

[SYT_Shadow]

Originally Posted by Datka

Shadow, the fact that MCS told you no to higher than 1000 rear spring rate leads me to believe that high rear spring can potentially cause the rear sub-frame failure.
I have heard from different sources that anything more than 800 rear spring can cause rear sub-frame failure on e9x m3.
As far as I know properly built e36 and e46m cars have rear sub-frames reinforced.
This makes me to rethink my plan to go with coilovers that come with higher than 800 rear springs.

I don't know. I'm pretty confident in Bimmerworld's recommendations when it comes to tracking this car. Both BW and MCS recommended the 1000 spring rate and when I told them it rides very comfortably and I wouldn't mind going higher they said nothing more is needed, not that it would cause failure.

In any case, the good coilovers don't come with springs so you really decide what you need. You can go with 550/800 (I'm selling some JRZ 2 way like this) or 700/1000

Agreed that the E36 and E46 require reinforcements, but in all fairness those cars are built out of peanut butter and jelly. If you put an E46 and E9X on a lift, the beefiness of the E9X is readily apparent.
I knew I wouldn't buy another E46 when I saw that, it's really a huge difference.

[Datka]

Originally Posted by SYT_Shadow

I don't know. I'm pretty confident in Bimmerworld's recommendations when it comes to tracking this car. Both BW and MCS recommended the 1000 spring rate and when I told them it rides very comfortably and I wouldn't mind going higher they said nothing more is needed, not that it would cause failure.

In any case, the good coilovers don't come with springs so you really decide what you need. You can go with 550/800 (I'm selling some JRZ 2 way like this) or 700/1000

Agreed that the E36 and E46 require reinforcements, but in all fairness those cars are built out of peanut butter and jelly. If you put an E46 and E9X on a lift, the beefiness of the E9X is readily apparent.
I knew I wouldn't buy another E46 when I saw that, it's really a huge difference.

Here is the quote from old 2010 thread-Suspension upgrade options for the M3
"Now, the rear spring is mounted between the rear suspension “Camber link” and the body, and it sits just outboard of half-way between the two ends of the link. It’s a teeter-totter setup that tries to pry the rear subframe DOWN and AWAY from the body when the wheel rises and the spring compresses. What’s worse, the higher the rear spring rate, the more prying force is applied to the subframe when you go over a bump. No wonder E36 and E46 rear suspensions have had problems with body damage – every little ripple in the road is another attempt to pry the subframe off the body.

To prevent damage to the bodywork, it’s necessary to limit the rear spring rate. Later, in discussions of Type Three and Four suspensions, I’ll talk about how this is solved, but for the moment, take it as given that rear spring rates that are significantly higher than stock are a bad thing"

[SYT_Shadow]

Originally Posted by Datka

Here is the quote from old 2010 thread-Suspension upgrade options for the M3
"Now, the rear spring is mounted between the rear suspension “Camber link” and the body, and it sits just outboard of half-way between the two ends of the link. It’s a teeter-totter setup that tries to pry the rear subframe DOWN and AWAY from the body when the wheel rises and the spring compresses. What’s worse, the higher the rear spring rate, the more prying force is applied to the subframe when you go over a bump. No wonder E36 and E46 rear suspensions have had problems with body damage – every little ripple in the road is another attempt to pry the subframe off the body.

To prevent damage to the bodywork, it’s necessary to limit the rear spring rate. Later, in discussions of Type Three and Four suspensions, I’ll talk about how this is solved, but for the moment, take it as given that rear spring rates that are significantly higher than stock are a bad thing"

I recall reading that before, however, the question is not whether the forces are 'bad' but whether the subframe can handle it

Saying that the forces act in a way that tears it apart may be correct, however, a bridge is also subject to forces trying to 'tear it apart' yet lives on happily

I haven't heard of a single failure of subframes with the E9X. I don't think there's an issue here

The E36 and E46 fail all over the place. Front sway bar mounts, front suspension mushrooms, etc etc etc. The E9X is a huge upgrade structurally

[Datka]

I hope you are right. I haven't heard sub-frame failures on these cars either.
If I decide to go with MCS, will call them to discuss this subject further.

[SYT_Shadow]

Originally Posted by Datka

I hope you are right. I haven't heard sub-frame failures on these cars either.
If I decide to go with MCS, will call them to discuss this subject further.

Definitely. Let me know if you need phone numbers. Phil at BW and Wyatt at MCS have been incredibly helpful

PS: get the cooling kit from do88 so you can prove your supercharger works in summer and I can buy one too! Do it!!

[Greg S]

I've never heard of a rear subframe mounting point failure on an E92. But if you're that concerned about it, go to a true coilover rear spring setup, that will remove/reduce the spring acting as a pivot point pulling the rear subframe down.