26 replies to this topic

[arwatts1]

Hi I've just bought a March 03 VXT and am curious about the ABS setup. It does seem very easy to trigger the ABS in the dry even, and it's a bit of a shock coming from my old ABSless TVR. I would hate it on a track I think. How easy is it to disable the ABS? Would removing the ABS fuse do the trick, or is it necessary to do anything more invasive? Reading this months EVO magazine, one of the letters talks about a PalmerTrack day where they demonstrated ABS on a VX Turbo by enabling and disabling it. Any ideas? cheers Andy Watts

[GerryM]

Hi Andy, it must be possible to disable the ABS because, as you say, they have done that at Palmersport. I went on my Advanced driving day at PS a couple of weeks ago and we had to drive with and without ABS. I am only a novice I know, but I certainly would not want to drive this car without ABS after seeing the difference for myself! Gerry

[Steve Crisp]

Hi, I believe the better way to do it, is to disconnect one of the wheel sensors. That way, the speedo, etc still works? Can someone confirm this? Steve

[JimH]

Rockstar was the chap who knew about this. IIRC if the fuse is pulled from the ABS then the engine looses its signal which told it if the car was moving which messed the idle up. I think he suggested disconnecting the front offside wheel sensor. That staopped the ABS working without cocking up the engine management system. However, I may have remembered that wrong.

[TheRockstar]

If you do a hunt on the site, I posted a huge amount of info on this previously. Basically if you pull the fuse, you lose all speed signals which means a) you have no speedo, the engine will not run properly, and c) you have no dynamic proportioning in the brake circuite - knock on effect of this means you can lock the rear wheels before the fronts - very dangerous.... The best way to do it is to unplug one of the front wheel speed sensors (connector behinf the wheel). this keeps the speed signal from the other wheels alive hence teh engine will run ok, but flags a fault in the ABS and effectively disables it... Nick

[Mutt & Jeff]

It does seem very easy to trigger the ABS in the dry even

I had a bad scare when this happened to me after I'd been going for it. Seems to be a problem with the sensors reacting badly to heat. You can up-grade the ABS which makes it come on later.......I think that unless you want your car purely for track use this may be a better option than removing a sensor.
Oh, it's a known problem with the VX and your dealer will/should do it under warrenty.
I hope that helps.
cheers

Edited by Mutt & Jeff, 15 July 2003 - 09:52 AM.

[garyk220]

M&J, all VXTs have the upgrade fitted as standard. It is better than the original, but is still prone to activating early on bumpy, broken or loose surfaces. This, I think, is just a characteristic of ABS on a light car with stiff suspension and very little weight on the front tyres. Once you've experienced, you have to adapt your driving style to suit on these type of surfaces IMO. I've done about 250 track miles in mine, and the ABS system has behaved itself. Although I'm fitting better pads and brake fluid soon, so it'll be interesting to see if that causes the ABS to trigger early.

[Ricky2772]

I used to disconnect the abs before, now with the OZ+yokos combo there is no need anymore, and when I still manage to have the the abs kicks in, usually it is much welcomed... (like..."too late" braking at the end of a 200km/h straight... )

[CarlB]

eh?????! Don't be daft! disconnecting the ABS is a rather silly idea. Try checking your tyre pressures - mine were 15psi up on the book level, and since dropping them to the correct pressure the ride hase been made comfy, and the ABS hardly ever comes in unless I brake on gravel. Go on, try the pressures first. C

[R1 nur]

This is becoming my pet subject. 1. Rockstar knows his stuff but he did not mention that the fix he mentioned results in the ABS light being on. IMO unacceptable. 2. I totally agree about adapting your driving style when the road is bumpy. 3. Ditch ABS? Yes do it it is crap! (Unless you 'switch off' when driving and then it is a useful tool.) 4. The ABS demo at the Autodrome was unimpressive IMO. 5. Do a 1st Lotus day and then you will know how well the VX can really brake. 6. If you have the first version of the ABS (I know not applicable to you) you can disable the ABS by driving with the brakes on and full throttle for a few secs.

[TheRockstar]

Dont want to dwell on it too much, but I will just add this. We developed the ABS for the VX because opel held a big stick over our heads... i.e. 'do the ABS on the Speedster or we wont give you any other business' type stick... The system was 'tuned' very quickly with minimal budget, but was initially signed off by Opel as being acceptable. Once the cars were released, Opel got hundreds of complaints over crap ABS... so they came and beat us up with a big stick again. we retuned it at our cost, and this is the 'upgrade' you get if you complain...(or as standard on the Turbo I believe).... Everyone knows the initial ABS tune was too aggresive for this type of car, but this was accepted by Opel in the early days. At the end of the day, a decent driver will always brake better than ABS. and please bare in mind that ABS actually EXTENDS your stopping distance, as contrary to popular public belief, all it is there for is to allow you steer while your braking hard....

[R1 nur]

No offence meant mate. I did not know you were actually involved in the development. Would have toned down my comments if I knew!

[VEX]

At the end of the day, a decent driver will always brake better than ABS. and please bare in mind that ABS actually EXTENDS your stopping distance, as contrary to popular public belief, all it is there for is to allow you steer while your braking hard....

Agree with Rockstar on this, stats prove that cars with ABS actually have a high impact speed in accidents.

This is for two reasons:

1) ABS does actually extend your braking distance but allows you to try and steer out of it.

2) ABS in any car, at full force, make such a racket that people tend to back off a little.

First thing I do in any car I get into is to trigger the ABS so I know what and how it feels and sounds like.


Since I have had the upgrade the brakes are great and far more controlable. Won't be discounnecting anything on my track days.

[Thorney]

Interestingly enough at Oulton Park this week I didn't have any problems with ABS at all. It kicked in on a few occasions when I'd out braked myself but actually helped me get round the corner in one piece as I didn't do the panic lock up type reaction. Only problem I had was the actual bite of the pads themselves so I think an upgrade is due there

[R1 nur]

Interestingly enough at Oulton Park this week I didn't have any problems with ABS at all. It kicked in on a few occasions when I'd out braked myself but actually helped me get round the corner in one piece as I didn't do the panic lock up type reaction.

I reckon on smooth roads it is fine. Just when it gets a bit bumpy.

[Purebob]

I thought the ABS demo atpalmersport was very effective. why did you think it poor r1? I had full control at full pelt WITH ABS, a teeny bit but lost teh rear under cascade braking and instant death with no ABS. Was your experience different? I must agree though that the ABS triggers too soon if there is any 'lightening' of the car over crests or bumps. Heres a refernce I use re: ABS and stopping distances: "Do cars with ABS stop more quickly than cars without? Perhaps, but that’s not the main purpose of ABS. It is a system designed to help you maintain control of the vehicle during emergency braking situations, not necessarily make the car stop more quickly. ABS may shorten stopping distances on wet or slippery roads and most systems may shorten stopping distances on dry roads. On very soft surfaces, such as gravel or unpacked snow, ABS may actually lengthen stopping distances. In wet or icy conditions, you should still make sure you drive carefully, always keep a safe distance behind the vehicle in front of you, and maintain a speed consistent with the road conditions." So it should help you stop quicker than a locked wheel.

[Dave T-S]

lost teh rear under cascade braking

Bob
I think you meant cadence braking....

[TheRockstar]

Tis true. When testing cars in Sweden, the ABS does improve your stopping distance on packed snow, as it can sense the point of wheel lock much faster than a human. without ABS, you find yourself continually locking the wheels, then releasing, then locking - net result = a very long stopping distance. However as soon as you drive the car on ICE, its a different story. The ABS just continually releases the brakes and you dont slow down.... in this situation its better to have a locked wheel where the friction slows you down...... ABS doesnt deal well with loose surfaces either... what tends to happen here is the surface moves under the wheels or wedges in front of it, this causes the wheel to slow, and fools the ABS into thinking the wheel is slipping... therefore the ABS releases the brakes in the same way it does on ICE, net result = long stopping distance. Under NORMAL driving conditions 'like what we all experience' ABS is of little benefit (unless your a muppet driver). Cadence braking is much more effective, as the driver is better positioned to make judgements over wheel lock or steering. Few people however actually know how to cadence brake properly, or realize that with a locked wheel you cannot steer....this is where ABS is of benefit. Few people also realise that for ABS to work effectively you MUST stamp on the pedal with full force, otherwise the ABS thinks your not trying to brake as hard as you actually desire, and releases the brakes more. Anyway, the point is. On THIS type of car with enthusiast drivers like us, ABS is of little use. For the weight it adds to the car, i'd rather have a space saver tyre - much more useful.

[TheRockstar]

No offence meant mate. I did not know you were actually involved in the development. Would have toned down my comments if I knew!

Lol... no offence taken, I personally didnt work on it, some of my colleagues in Germany did.... but my guys are working on advanced systems integrating ABS / VSC with Electric Steering......




Nick

[Jim_Cross]

Nick, You say that ABS systems increase stopping distances. What about systems which control each wheel independently, allowing each wheel to be held around the point of lock up? Obviously this isn't something a driver can do, but must improve the stopping power over standard ABS systems?