A&Q about Lotus
Q:
Thanks guys, good stuff.
I'll try again this weekend and see what can be seen. I'm a little over 700 miles, so I suspect sometime next week I'll send my car in and see what they say.
A:
All,
I experienced this "ice mode" numerous times this past weekend at the track for the first time. The only change made from my previous track outings is a new Ohlin double-adjustable suspension, so I suspect this is some proportional braking issue as described by Nochmal's post in:
as my suspension has yet to be tuned, perhaps I have too much forward weight transfer and I'm close to locking up the rears, thus this mode kick in. I've never felt this before, and have always been very aggressive with the brakes. . It occurred regularly at the end of the front straight. 110MPH, hard on the brakes. Previously they would bite hard. This past weekend, I would say that 80% of the time at the end of the straight, the pedal would be rock hard. There is no pulsating though, so it doesn't appear to be ABS to me. The car would slow, but not to the extent I was used to. Then about half way through the braking zone, the pedal would start to depress and the brakes would really bite (as they used to). I had to back way off my braking distances to accommodate this "two level braking". Talk about threshold braking! Very frustrating.
So what is the current consensus on how to avoid this? I saw Randy's early post about switching the ABS circuit. Since I mount track tires before each event, would it be easiest for me to just pull the LF ABS sensor wire, then restore it after the track event? Thanks!
-RWarden
A:
If the brake pedal is rock hard from the first inch of travel, it could be a vacuum leak, and probably isn't ice mode. If, on the other hand, the pedal goes down a bit, then hits what feels like a block of wood under the pedal, that is what I have.
My brakes are responsive and easy at light pressure, the brake pressure you would normally use around town. When I try braking hard, it feels like I've hit a stop of some kind. If I really stand on the brakes, it will go down a little more, but without any faster deceleration. I haven't tried any hard braking from track speeds on a smooth surface, so I can't say if mine will bite harder longer into the braking event.
I took it to the dealer for the 1k service and they said the brakes feel fine. I still disagree with them and think something is very wrong. My Saab weighs 3500lbs and stops twice as fast as the 2200lb Exige.
A:
Originally Posted by Darkness
If the brake pedal is rock hard from the first inch of travel, it could be a vacuum leak, and probably isn't ice mode. If, on the other hand, the pedal goes down a bit, then hits what feels like a block of wood under the pedal, that is what I have.
My brakes are responsive and easy at light pressure, the brake pressure you would normally use around town. When I try braking hard, it feels like I've hit a stop of some kind. If I really stand on the brakes, it will go down a little more, but without any faster deceleration. I haven't tried any hard braking from track speeds on a smooth surface, so I can't say if mine will bite harder longer into the braking event....
On initial application (stand on the brakes), the pedal goes down a bit and the car will slow, but as you've said "it feels like a block of wood under the pedal" is stopped further depression. After a second or two of that, the pedal will travel the normal amount and the brakes will bite hard as they would normally. This has never occured to me on the street, but I don't stand on the brakes on the street either. This has just started happening, and as I've said the only change has been to the suspension, so I do believe this could be a brake proportioning issue as the suspension is not yet tuned, so I'm likely transferring more weight to the front than I had been previously.
Darkness - have you tried just unplugging the LF ABS sensor, and then retesting this? I plan to do that this coming weekend when I'm at the track again....
-RWarden
A:
By LF ABS sensor, you mean actually unplugging one wheel? Isn't pulling the fuse easier? And wouldn't unplugging a sensor disable traction control as well?
In any event, no, I haven't disabled ABS and tried again. I don't think it's the ABS, the pedal travel and pressure is exactly the same while stopped as while moving. It it was the ABS, then it should be different when braking then when stopped. Still it's an easy thing to try and worth a shot. I'll pull the fuse tonight before I go home, but don't know if I'll get out of traffic enough to actually use the brakes.
A:
I would definately go back to the dealer with this issue. If they insist it is normal, put a lot of emphasis on the fact that it is a huge safety issue.
xtn
A:
Arg, but the car does stop reasonably fast.
Without another Elise/Exige to compare it to, it's hard to make a determination for myself that it is actually broken. If someone else around Palo Alto would let me sit in their running car and push the brake pedal, it would help...
In any event, I would suspect the dealership service dept would have a pretty good idea of what the brakes feel like. Even if they didn't, there were at least four other Elises being worked on when I dropped it off, so it should have been easy to do an A/B comparison. If the brakes really turn out to be broken, then I'm really pissed, because the dealer fed me a line...
They also put 10 miles on the car, which means they extensively road tested it, or they took it to lunch. I have a feeling they took it for a ride, since there was oil on the passenger side footrest. (which I'm also pissed about)
After I pull the ABS fuse, when I get a chance, I'll see if I can get all four wheels to lock up and how hard it is to do that. This will give me a much better idea of what is going on. If I can't lock the wheels......
A:
Mine is going to another dealer this week for the early ABS activation issue.
A:
Removing the ABS fuse was a BAD idea.
First of all, without some wheel speed sensors working, the car doesn't know it's moving, so the speedo doesn't work. 2nd, it screws up the idle control, which results in stalling when coming to a stop.
But the real reason this was bad is that I did this in a parking lot. And, of course, I dropped an access panel screw down into the car, never to be seen again.
A:
I have the abs off and I feel safer because of all the uneven roads
I drive on were setting off the abs.
If you are used to abs systems and drive on smooth surfaces
it might not be worth it.
I find you can lock up the fronts and backs depending on the turn and uphill or downhill can vary which will lock first, but I llike to modulate the brakes
myself in the bumps.
A:
Originally Posted by sndesign
I have the abs off and I feel safer because of all the uneven roads
I drive on were setting off the abs.
If you are used to abs systems and drive on smooth surfaces
it might not be worth it.
I find you can lock up the fronts and backs depending on the turn and uphill or downhill can vary which will lock first, but I llike to modulate the brakes
myself in the bumps.
sndesign - how did you disable the ABS? Fuse or pull the sensor wire from one (or more) of the wheels?
-RWarden
A:
This past weekend, I disabled my ABS (pulled LF ABS sensor at wheel) at the track. See the description of the problem in my earlier posts above. Whereas previously I would experience ice mode at least once per lap (two heavy braking zones per lap), I didn't experience it once in two days. I did manage to lock up the rear brakes pretty hard on the 3rd or 4th lap and the back end got pretty squirmy, but that is what I would expect under such heavy braking. As with the other Elise controls, it's very easy to modulate the brakes and avoid lockup once you've practiced enough to know what it feels like.
This is definitely the solution I'm going to use for now until Lotus does something about this. Once I tune my suspension and mount Hoosiers, I might enable ABS again to see if it still exists. Perhaps my car is not yet balanced and has too much weight on the front, which could cause early rear lockup under heavy braking? Either way, it's good to know I can avoid the problem. Previously I was having to add 30% or more to my braking distances in these two spots just to be safe.
-RWarden
A:
In my experience so far (15,000 miles) I’ve most noticeably felt the ABS come on when breaking really hard and cornering. I have had ABS come on in straight breaking but it was only barely perceptible. The ABS system seems to be top-notch when it’s working properly. The car is light and the suspension doesn’t dip as much as I think it should when breaking heavily like that. But it certainly stops quickly when commanded to do so.
I find that in daily driving I don’t really need to use the breaks as much in comparison to any other car I’ve driven. The Elise is very good at slowing when the accelerator is lifted. Some would say I should have my alignment checked or the car is designed with too much drag ... but I think it’s working as expected and there’s no uneven tire wear (yet).
A:
Originally Posted by rwarden
This past weekend, I disabled my ABS (pulled LF ABS sensor at wheel) at the track. See the description of the problem in my earlier posts above. Whereas previously I would experience ice mode at least once per lap (two heavy braking zones per lap), I didn't experience it once in two days. I did manage to lock up the rear brakes pretty hard on the 3rd or 4th lap and the back end got pretty squirmy, but that is what I would expect under such heavy braking. As with the other Elise controls, it's very easy to modulate the brakes and avoid lockup once you've practiced enough to know what it feels like.
This is definitely the solution I'm going to use for now until Lotus does something about this. Once I tune my suspension and mount Hoosiers, I might enable ABS again to see if it still exists. Perhaps my car is not yet balanced and has too much weight on the front, which could cause early rear lockup under heavy braking? Either way, it's good to know I can avoid the problem. Previously I was having to add 30% or more to my braking distances in these two spots just to be safe.
-RWarden
\
You're looking for trouble driving the car on the track with the rears locking up first.
A:
Originally Posted by rwarden
I did manage to lock up the rear brakes pretty hard on the 3rd or 4th lap and the back end got pretty squirmy, but that is what I would expect under such heavy braking.
Just checking, but... You're not pressing the clutch pedal while braking hard, are you?
The Elise is set up to be used under hard braking without the clutch pedal depressed, so the 'drive' to the rear wheels stops them locking and stabilises the car.
Bye, Arno.
A:
Originally Posted by Arno
Just checking, but... You're not pressing the clutch pedal while braking hard, are you?
The Elise is set up to be used under hard braking without the clutch pedal depressed, so the 'drive' to the rear wheels stops them locking and stabilises the car.
Bye, Arno.
Arno-
Can you clarify what you mean ? It sounds like you're on the right track (surprise!)... but I'm not sure I understand completely..
Thanks
A:
The Elise is set up in such a way that the brake balance is right and maximum retardation is reached when only the brake pedal is used and the engine is providing some of the braking to the rear.
But this engine braking effect actually reduces and actually turns around as the rears slow down too much and try to lock. Then engine resists and tries to keep the rear wheels turning and effectively stops them locking suddenly. Only the fronts will lock, which is normal, and can be controlled by threshold braking (backing off the pedal pressure a little until it 'unlocks' again and keep it there)
Of course.. This was especially important for the pre-Toyota Elises, as they do not have ABS, but if you disconnect an ABS sensor on the toyota versions you'll need to go back to this method of braking.
Try to train in only using the clutch when shifting or right before you come to a full stop and it would stall (or if you end up in a complete spin ). At all other times, try to keep your foot away from the clutch and only operate the throttle and brake.
Bye, Arno.
A:
I just finished the preventative maintenance on my Fed Elise for the fast approaching LOG. Tested the abs and it works fine, you can feel it in maximum brake input stops from speed. Arno is correct that it is much more detectable if you keep your d***ed foot off the clutch. One oddity that I notice was that I have 90% pad thickness (at 18,000 miles) on all pad sets except the right REAR which has only 60%(!!!) I find this most strange as I have never had any car wear the rears faster than the fronts. I wonder if this might be do th the abs or did I just have a sticking pad. Rotors were fine...Dave
A:
Originally Posted by Arno
Just checking, but... You're not pressing the clutch pedal while braking hard, are you?
The Elise is set up to be used under hard braking without the clutch pedal depressed, so the 'drive' to the rear wheels stops them locking and stabilises the car.
Bye, Arno.
I'm definitely not pressing the clutch pedal while braking. I've been keeping up on this subject, and I agree this is a weight transfer problem interacting with the ABS system. Once I get my Ohlins sorted and the car corner weighted, I'll try ABS on the track again and see if ice mode has gone away.
-Rwarden