The Lotus Cars Community banner

1 - 20 of 65 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter #1
I was doing approx 60mph coming up a side turning that I have to make everyday on my commute.

Today I braked perhaps a little bit later that I normally do. It was a nice day and I was looking forward to taking the side turning "enthusiastically" such is the angle of it.

I started braking fairly hard, at least fairly hard for what I consider to be acceptable public road driving.

There is a slight undulation/bump in the road when approaching this turning. I am used to this and normally it causes no problems.

Today however it scared me ****less.

My brakes went completely crazy when I went over this bump. The ABS kicked in. And the pedal went ROCK HARD with approximately only a quarter of the pedal pressure I was originally putting in! I tried to press harder but nothing. The pedal was stiff.

I am absolutely confident there was no gravel or diesel on this bit of road. It was completely clean and clear.

Luckily I only overshot the turning by about 5 meters. Which meant I had to stop completely and select 1st gear and apply quite a big of steering lock to make the turn.

This must have looked extremely odd for the car behind and I'm grateful he wasn't right up my arse like often happens on this particular stretch of road. I was approaching the turning with some gusto and enthusiasm... only to come to complete stop. He must have thought I was an idiot.

At first I thought I had burst a brake hose or something. But I tested my brakes moments later and they were fine...

This incident is very worrying for me and to be honest I have lost a fair amount of confidence in my car now.
 

·
Registered
Joined
·
144 Posts
I'm not sure if what you experienced was "ice mode", as I am not overly familiar with the issue, but I recently read this thread, seems it would be worth your time

Ice Mode - Solved
 

·
Registered
Joined
·
9,786 Posts
Even the best ABS systems have problems while braking hard over uneven pavement... when one wheel gets "light" (i.e. hits a bump, then a void) the ABS thinks you're in lock-up and forces the system to release brake pressure. Your best response is the same as it would be if you experienced lock-up with a non-ABS brake system: release the brakes completely (and quickly) and immediately reapply...
 

·
Registered
Joined
·
292 Posts
This is very interesting as it is one of the things I think is great about my Exige. It is the only car I have ever driven where the ABS doesn't try to kill you. What year/spec are the cars that have experienced this problem? As an example where I live there is a steep downhill hairpin with a big bump in the braking area. My WRX snatches a rear wheel and the ABS fires you across the corner at unabated speed. The Exige handles it brilliantly and the ABS doesnt ruin your day as it picks up the rear wheel.

I use RS14s so the pedal pressure is really low. Does that impact the onset of "ice mode" or is the ABS re-calibrated?
 

·
Registered
Joined
·
2,715 Posts
I tried to press harder but nothing. The pedal was stiff.
This was your problem - it is not a Lotus specific issue it is an ABS meets something confusing issue as somebody stated above, lift, reapply, lift reapply, lift reapply , it can be done in a matter of a few seconds.... Good idea to take a high performance driving class where they let you experience threshold braking with and without ABS enabled - quite a difference ! If you really hate it on the Elise you can remove a fuse but your service engine light will always be on. I think Lotus offers some HPD full and 2 day classes at the factory in Hethel - I went to a half day class , learned a lot and had a blast and it was pretty cheap !

Also hoping you are aware of SELOC your local forum in case you have some non federal issues someday !

SELOC | Lotus Enthusiasts Club
 

·
Registered
Joined
·
1,897 Posts
apk is right.

Ive expierenced this in all sorts abs equipped cars. Not just lotus specific.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #8
I've already posted the same on SELOC, just thought I'd post here to get the yankee view.

It's definately not anything to do with my driving/braking style. I use the brakes smoothly, not abruptly. And I vividly remember in this particular instance I had applied the brakes smoothly.

I was slowing down with quite a bit of force. But then I hit that small undulation/bump in the road and that changed everything. The ABS started pulsing/ticking and the pedal went rock hard. Even when I had gone past this bump, like a further 10 meters I guess, the ABS was *still* going like nuts. Why is this? There was nothing left for the ABS to do be doing.

I can understand it activating perhaps for a brief split second for that bump but why did it remain active for the rest of the braking? And why did the ABS decide to remove 75% of the braking force I had originally before I hit the bump?

The only thing I can think of is that maybe when I went over the bump in the road it inadvertantly and unavoidably jolted the brake pedal at the same time.

But still, this just stinks of a software bug to me really.

I used the ABS quite a bit (playfully I might add) this winter as there quite a snowy/icey winter this year. And never did it make the pedal go rock hard. Ever. I remember playing with the ABS in one situation where I decided to press harder whilst the ABS was pulsing/ticking away. All that happened in this instance was that the pulsing got stronger and the ticking got louder... the pedal still let me push it with no problems.
 

·
Registered
Joined
·
455 Posts
Very easy fix.
Disconnect wheel speed sensor on right front.
Will also need to disable TC is you have that option.
This will disable ABS; ABS light will be on continously; speedo will work;
no check engine light. Reconnect the wheel speed sensor if it rains,
as ABS is helpful in the rain.

Don't pull the fuse for the ABS, because that will disable speedo.
Don't pull any other wheel speed sensor - will either cause speedo to not work
or for ABS to go into hard fault.

When you first disable, you'll likely get lock-up because ABS steps in more than you think. But after you get used to it and (re)learn to threshold brake, lap times will actually decrease because the car turns in better.

I've been running without ABS for about a year and no ice mode, whereas both my current '07 Exige and prior Exige both had "ice-mode" (hard pedal, reduced stopping,
in bumpy braking zones). I have other mods to my braking system, but I think disabling ABS is the main fix. Would appreciate testing by others. A few folks have tried and seem to agree that braking is improved. I regularly work with various instructors and all agree that brakes are improved by disabling ABS.

Other solutions might be hacking the Lotus ABS system - some work in process in this area. Another solution might be Bosch racing ABS system.
Bosch Motorsport - ABS M4 Kit
Anyone tried?

My background is in formula cars that don't have ABS.
ABS in Lotus sucks! TURN IT OFF!!!
Real racers threshold brake without any sissy ABS.

I'm thinking we may require Lotus Challenge Series w2w racers to practice with ABS on and off and then choice which ever seems safer on their car on a particular track. Ice mode seems very dangerous in racing.
 

·
Registered
Joined
·
1,897 Posts
I've already posted the same on SELOC, just thought I'd post here to get the yankee view.

It's definately not anything to do with my driving/braking style. I use the brakes smoothly, not abruptly. And I vividly remember in this particular instance I had applied the brakes smoothly.

I was slowing down with quite a bit of force. But then I hit that small undulation/bump in the road and that changed everything. The ABS started pulsing/ticking and the pedal went rock hard. Even when I had gone past this bump, like a further 10 meters I guess, the ABS was *still* going like nuts. Why is this? There was nothing left for the ABS to do be doing.

I can understand it activating perhaps for a brief split second for that bump but why did it remain active for the rest of the braking? And why did the ABS decide to remove 75% of the braking force I had originally before I hit the bump?

The only thing I can think of is that maybe when I went over the bump in the road it inadvertantly and unavoidably jolted the brake pedal at the same time.

But still, this just stinks of a software bug to me really.

I used the ABS quite a bit (playfully I might add) this winter as there quite a snowy/icey winter this year. And never did it make the pedal go rock hard. Ever. I remember playing with the ABS in one situation where I decided to press harder whilst the ABS was pulsing/ticking away. All that happened in this instance was that the pulsing got stronger and the ticking got louder... the pedal still let me push it with no problems.

Its normal. And not only happens on lotus or sports cars.

Ive had it happen to me in pick up trucks and mini vans, going over train tracks near my house.
 

·
Registered
Joined
·
388 Posts
Very easy fix.
Disconnect wheel speed sensor on right front.
I wanna try this for ****s & giggles. I occasionally run into ice mode and if I'm not anticipating a bumpy section in the road it can get pretty hairy. Fortunately I haven't got into any real trouble but I'd wanna try going without ABS on a strip of road I always drive on that gets bumpy and see how it feels.

Long story short, do you or does anyone have a diagram or picture on how to do this?
 

·
Premium Member
Joined
·
252 Posts
I've read all (or nearly all) the posts here and on other sites.
Braking anomalies aka "ice mode" seems to relate to:
sudden hard braking,
hard braking after WOT,
hard pedal,
a bump in the road,
a spin,
a turn,
going backwards,
depletion of vacuum,
a faulty vacuum valve,
bad programming,
track use,
street use,
year of the car,
sudden impending rear wheel lockup,
............
or none of the above!!-eek-
It seems to be ABS related? But I don't want to give up ABS.
To be fair I've read about "ice mode" on other mfg forums, so it's not unique to Lotus.
Short of disabling ABS, which I'm not willing to do, (feedback on vacuum fixes is inconclusive) is there a cure???TADTS
 

·
Premium Member
Joined
·
4,709 Posts
Short of disabling ABS, which I'm not willing to do, (feedback on vacuum fixes is inconclusive) is there a cure???TADTS
No ... and your 2010 suffers from the same abs related issue. It's not a vacuum issue.
 

·
Premium Member
Joined
·
3,738 Posts
I've read all (or nearly all) the posts here and on other sites.
Braking anomalies aka "ice mode" seems to relate to:
sudden hard braking,
hard braking after WOT,
hard pedal,
a bump in the road,
a spin,
a turn,
going backwards,
depletion of vacuum,
a faulty vacuum valve,
bad programming,
track use,
street use,
year of the car,
sudden impending rear wheel lockup,
............
or none of the above!!-eek-
It seems to be ABS related? But I don't want to give up ABS.
To be fair I've read about "ice mode" on other mfg forums, so it's not unique to Lotus.
Short of disabling ABS, which I'm not willing to do, (feedback on vacuum fixes is inconclusive) is there a cure???TADTS
No it's not unique, last year a friend was doing a track day at Infineon in his Vette (modified) on slicks ... he got a screw in his right side tire and it deflated as he was entering T6, the ABS kicked in and basically disable all braking input ... this gave him NO opportunity to deal with the problem and sent him into the wall.

I used to have the problem in my Lotus, I removed the ABS completely and I no longer have the problem. Since I'm using the same servo/boost (aka vacuum) setup, I'm certain it's an ABS programming issue.

I do miss my ABS, it clearly does a good job in a straight line, but it just too danagerous to retain for race duty ... entering "ice mode" in a race situation is not a liability I want to assume.

Rob
 

·
Inactive
Joined
·
831 Posts
On my lotus I would get the ABS coming on prematurely when I hit small bumps in the road while braking heavily. The problem when away through a combination of machining new front upper shock mounts to give more front wheel travel and tuning the front shock bump / rebound. It also seems sensitive to front type sidewall / grip / pressure.
 

·
Registered
Joined
·
6,226 Posts
I have same issue at same spot: downhill, quick turn, not hard brake, the road surface is a little rough but not bumpy.

So is not vacuum.
 

·
Registered
Joined
·
1,837 Posts
IMO the brakes in the Lotus are total crap. As soon as you really really slam on the brakes the abs goes crazy, and you get a slow thud-thud-thud-thud-thud sound from the abs clamping, and releasing the brake, and the car doesnt slow down at all. I think the car would stop 10x better without ABS.

I wonder if replacing the calipers with APR or something would fix the problem, or if it is really the ABS unit that causes the problem.
 

·
Registered
Joined
·
1,269 Posts
I've had the same problem of hard brake pedal and premature (overly aggressive) ABS activation. I pulled the ABS fuse (next time I'll remove the wheel speed sensor) and flat-spotted the tires since I was accustomed to exerting a lot of brake pressure.

Glad to hear it is not unique to my car, but very disappointed to that our cars have this issue. I only realized this problem in the last few months after having the car for 5 years and autoxing for 3 years.

shock setup, brake pads, and tires can all make the problem worse.

I'm been frustrated that my Mazdaspeed 3 brakes better than my elise. Pulling the wheel speed sensor tonight and testing it out.
 

·
Registered
Joined
·
1,317 Posts
Try reducing your rebound damping by a fair bit to see if that helps... stiff rebound should really make the problem worse becuase it'll hang the tire.

Not denying that they probably could have engineered the system to "reset" sooner and allow for full brake pressure without such delay. It seems like the ABS stays on too conservatively long, and the traction control is too late to the game and will allow you to break the rear end completely loose if you have an LSD on throttle in a turn on smooth ground.

I've had it happen lightly once or twice on my car, but i've had it happen on my mercedes a fair bit worse so i instinctively expect that i'm not going to be able to brake very hard over bumps (not to mention it's really rough on the car anyway) so i plan my driving style to roll over bumps and then get on the brakes afterward.

Forutnately On the mercedes i have a factory ABS kill switch becuase off road ABS can be really dangerous... it's like driving with ice mode on all the time if you need to stop more quickly at all.
 
1 - 20 of 65 Posts
Top