[Biginboca]

Installed Helical LSD a few days ago. Since then I’ve had my rear passenger brake get blazing hot and start dragging twice.

Both times while driving on interstate right after driving somewhat aggressively on some backroads playing around with LSD .

Like the passenger rear brake was dragging really bad I could feel the car was working harder to maintain speed in a high gear and see feel heat waves coming off the passenger rear brake when I pulled over.

Sounds like a stuck caliper, but seems like a big coincidence that a caliper would stick twice in 4 days right after LSD install. (First Time was same day right after install on the LSD test drive.)

Are there any software conflicts with the E LSD and the mechanical LSD that might be going on? LSD maker says no and never heard of this happening from LSD before.

I checked all the brake lines and could find nothing apparently wrong. Was thinking maybe I pinched a line during the install, but can’t see that anywhere. After the car cooled 30 minutes both times this happened everything seemed normal again no dragging brake no heat.

So I ordered a new caliper and will install this weekend but just wanted to see if anyone had seen this before?

[SnapCoupe]

Originally Posted by Biginboca

Installed Helical LSD a few days ago. Since then I’ve had my rear passenger brake get blazing hot and start dragging twice.

Both times while driving on interstate right after driving somewhat aggressively on some backroads playing around with LSD .

Like the passenger rear brake was dragging really bad I could feel the car was working harder to maintain speed in a high gear and see feel heat waves coming off the passenger rear brake when I pulled over.

Sounds like a stuck caliper, but seems like a big coincidence that a caliper would stick twice in 4 days right after LSD install. (First Time was same day right after install on the LSD test drive.)

Are there any software conflicts with the E LSD and the mechanical LSD that might be going on? LSD maker says no and never heard of this happening from LSD before.

I checked all the brake lines and could find nothing apparently wrong. Was thinking maybe I pinched a line during the install, but can’t see that anywhere. After the car cooled 30 minutes both times this happened everything seemed normal again no dragging brake no heat.

So I ordered a new caliper and will install this weekend but just wanted to see if anyone had seen this before?

What DSC mode were you driving in? All on, DTC, or all off? I personally don't have a LSD in my car but I have heard that the E Diff/DSC can fight LSDs in low grip situations if the DSC system isn't fully turned off. I believe there are some custom coding options specifically for those with LSDs.

[Biginboca]

Originally Posted by SnapCoupe

What DSC mode were you driving in? All on, DTC, or all off? I personally don't have a LSD in my car but I have heard that the E Diff/DSC can fight LSDs in low grip situations if the DSC system isn't fully turned off. I believe there are some custom coding options specifically for those with LSDs.

Thanks for responding... I know for sure the second time I was in normal driving mode. Can’t remember the first time.

But you’ve got me thinking... between those 2 times the brake cooked I had also done some very aggressive driving (different day) and also had full traction on to see if it intervened (wanted to see what the new intervention threshold was) and had no issues even though I did get the traction control to activate a few times.

And I’m thinking if it was software wouldn’t both brakes potentially get cooked, not just the same one all the time?

[SnapCoupe]

Originally Posted by Biginboca

Thanks for responding... I know for sure the second time I was in normal driving mode. Can’t remember the first time.

But you’ve got me thinking... between those 2 times the brake cooked I had also done some very aggressive driving (different day) and also had full traction on to see if it intervened (wanted to see what the new intervention threshold was) and had no issues even though I did get the traction control to activate a few times.

And I’m thinking if it was software wouldn’t both brakes potentially get cooked, not just the same one all the time?

When traction control intervenes, it is simply cutting fuel to the engine and preventing further tire spin. When stability control (DSC) intervenes, the car uses each brake corner independently to save the car in the event of a slide. The "E-diff" uses the stability control system to independently control the rear two brakes, so when the computer senses one side spinning faster than the other, it will apply the brakes to that side, allowing the other to catch up.

With a LSD both tires are spinning at the same time (depending on the ratios and style) so the computer will more than likely get very confused if the car is losing traction, yet both rear tires are spinning at the same speed.

[bbnks2]

Sounds like a lot of outlandish theory.

It's more likely you have a sticky caliper and it's just a coincidence. Ediff doesn't fight a mechanical lsd... They both do the same thing. Statability control doesn't get confused. It's a program. It can still brake wheels to keep you within a tolerable yaw rate regardless of wether or not the wheels are experiencing slip... Two different things.

[Biginboca]

Originally Posted by bbnks2

Sounds like a lot of outlandish theory.

It's more likely you have a sticky caliper and it's just a coincidence. Ediff doesn't fight a mechanical lsd... They both do the same thing. Statability control doesn't get confused. It's a program. It can still brake wheels to keep you within a tolerable yaw rate regardless of wether or not the wheels are experiencing slip... Two different things.

Ok thanks for weighing in, I’m just gonna replace the caliper and hopefully that will be the end of it.

[SnapCoupe]

Originally Posted by bbnks2

Sounds like a lot of outlandish theory.

It's more likely you have a sticky caliper and it's just a coincidence. Ediff doesn't fight a mechanical lsd... They both do the same thing. Statability control doesn't get confused. It's a program. It can still brake wheels to keep you within a tolerable yaw rate regardless of wether or not the wheels are experiencing slip... Two different things.

While the Ediff and the stability control system both use the same hardware for corrections, they are separate entities in the way the software works. From a stop, if you press the DTC button once (turning off the traction control where it cuts fuel if the car senses a slip), if you dump the clutch to get the tires spinning the Ediff software will intervene and engage one brake caliper if one rear wheel starts spinning faster than the other. This is to send the torque to the rear wheel that is spinning slower, therefore "simulating" a LSD. This system does not use the yaw sensors, but the wheel speed sensors instead.

If you install a LSD (depending on the ratio) the tires will spin at different rates than the OEM open diff. This will most definitely confuse the system in *certain* situations.

There is a chance it could be a seized caliper, but I just wanted to clarify as I have seen this issue with LSD installations on E9Xs before.

[Chris1337]

Selling an e92 m3 rear end swap, comes with everything you need for the swap. Pm me if interested!