Lock up and ice mode
 

Thought I had this beat by disconnecting the yaw sensor but it’s bad worse than ever. Ultimately it comes down the sudden switch from 100% throttle to 100% brake. I only experienced it once on track at a hairpin when I came in a bit hot. But autocross varies greatly from course to course. This weekends course had a loop where at one end I would get lock up as in no ABS and then ice mode at the opposite end. Considering pulling the ABS fuse but next course might not cause these issues. Anyone else still fighting this? Anyone found a solution?

I had it happen the first time my last track day. Unfortunately this doesn’t seem to be an only 370z issue. My buddy would have it happen a lot in is bmw m3 and no one could disable it without disabling the entire abs system. He looked for years for anyone coding it out etc etc and I think we’re gonna be in the same boat. You’ll either get all the functions or nothing. He’s now on a full race Vette with an aftermarket abs unit for racing and it’s simply amazing according to him. it’s too bad software tuners haven’t looked into cracking the abs modules on vehicles to just code out ice mode because no one likes it on here or the bmw forums or the corvette forums and it’s really a stupid feature that’s potentially more dangerous. How many times are people really taking there 370z, corvette, m3 etc etc. to ice conditions and if anything every ar has an outside temp sensor on them nowadays so bus that data to the abs module and if it’s 85 degrees out it’s highly unlikely I’ll be hitting ice.

There is an upgrade for that, but it is not cheap. Hotrodz is having it done.

Unfortunately the aftermarket solutions aren't legal for the classes I run.

I remember Robert Mitchel said he got ice mode even in a 675LT (or Senna, forgot) on Nurburgring. Hyper cars run into the some of the same issues we do when getting abused on track. I don’t feel so bad about what my Z can’t do anymore haha.

I never had this issue with my 350Z, I can't imagine the abs systems are that different, but maybe they are. It also would be nice if it were either ice mode or full no ABS lockup, the fact that I get two different issues makes it harder to nail down. Thinking this Nismo pro 1.5 way is part of the problem. looking for a good used 3.692 diff to build with a wavetrac.

While I don't agree that 'icemode' is an actual programmed function in the ABS, I have no proof behind the statement.. I just call it a malfunction. After I wrecked my 350Z on track due to this malfunction, I ripped it out and piped in a proportioning valve for the rears. I could never trust the car again with OEM ABS in there.
Been running without it since (7 years now).

Good luck!

Ice mode has been talked about a number of times here over the years. It seems like some Z's get it, and some do not. It's hit or miss with who gets it or don't.

I didn't get at all until I started getting faster and adding aero and other mods. It is not an issue with the rear diff unless your lashing needs adjustment. I got mine with a Wavetrac and Nismo 3.69 gears. The issue is common to street cars that turned into track cars. Street cars are designed to function under track conditions. I have done a lot of research and talking with other Z track day goers and many just remove the system altogether or do a proportional setup as started above.

Most recently it seems that several Z track goers are doing a BMW MK60 ABS system swap. It is not cheap but not hugely expensive compared to a big brake kit. About 3k or so will get you there by competent shop. If you want a full blown race setup you can spend 10 to 12k on a Motorsports ABS system upgrade. My setup will be a hybrid of the two as I am adding the Motorsports controller to my system for better adjustability and tuning. Dang thing has like ten settings that can changed on the fly. According to my installer by adding the Motorsports controller to the MK60 it will bring its functionality to 90% or better of the Motorsports system. The total cost will be around 5 or 6k to me.

Austin Hertel who sometimes frequents the forum just installed the MK60 system in his Z and is racing this weekend at Gingerman Raceway in Gridlife Touring Cup. Find and follow him on Instagram as he will be doing a full review next week. The guy is incredibly fast and knowledgeable about the Z. He does all his own wrenching and has been a great resource to me and others.

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I have seen it happen to people with Zs, but I've never had it happen to me. I still ended up installing a kill switch for the yaw sensor, which helps with braking on turn in. It feels more natural.

To be clear I have two separate issues, likely with different causes.

The ABS failure/full lockup I feel might possibly be due to the diff. The Nismo pro 1.5 is damn near full lock up all the damned time. it's quite obnoxious. I THINK that under hard sudden braking in a straight line the rear is locked so the two rear wheel speed sensors are in sync, the resulting nose dive lightening the rear and the fronts getting the majority of braking force need only lock in sync for a millisecond for the abs to think all for wheels are stopped and not engage their pulses. Pure theory, didn't have this issue before the diff swap, stiffer springs might aid in reduced weight transfer, my suspension woes are another topic all together.

The "ice mode" issue, i did have before the diff swap, though disconnecting the yaw sensor had fixed it, it didn't. The MK60 swap again is not legal for the classes I compete in. Might not be a real performance advantage over a correctly working stock unit but I sleep better knowing I play by the rules.

I don't think anyone is suggesting you cheat but just providing information for all that have similar issues. I don't AX so I have little knowledge of the rules.

I think you should work with someone that knows how to set up the gears and lash if you are having issues with your diff not performing well. Also, what diff fluid and weight are you using, it can make a difference.

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Has anyone looked at the brake booster vacuum to see if it gets low?
(leaking booster line check valve / booster)

Edit:
To prevent thread confusion, I started a different thread investigating the possible role of the brake booster vacuum:
http://www.the370z.com/brakes-suspen...-solution.html

I'm just trying to be explicit as to why and aftermarket option is not a viable solution. To complicate things I also do Time Trials and conflicting rule sets mean I have to give up a one thing to stay legal for the other. True Coil over rears are legal for Time Trials Touring class, but relocating the spring is not legal for Street Touring autocross, not that moving the spring provides any advantage just changes the rate you need to run to have the same wheel rate. I can run 11" wheels and 315 tires for solo but only 10.5 wheel with 285 tire for Time Trials.

There is nothing wrong with my lash in my diff, it's that the engagement is too agressive and when engaged it's full on locked. I'm running the motul esther 140w90. It's as if the ramps are too steep allowing for immediate engagement under the lightest load. I've got the preload set to it's lowest but when activated it's full lockup. It's as if it's for too many plates. I have not opened the carrier to count the plates. I miss the simple clutch type used in the Z31's.

Think you can get different springs for the Nismo Pro diff to change the lock up on them. I've never seen them tho. Think you can change the clutch plates around inside of it too.