LoFi

I have always put the problem I'll explain below down to over aggressive ABS on the MY01 but now I'm not at all sure.

When braking hard on a bumpy surface braking force suddenly dissappears, the pedal feels a bit like ABS throb but the car ceases to slow. The only way to get back brake force is to take foot off the pedal and re-apply.

On a peice of road today there was a drop in surface level running at right angles to the road. The change in level was about the same as when they are resurfacing a road (ramp) but graded into the surface. I started to brake hard just before it but as the fronts moved over the bump most braking force was lost and was only regained by foot off and reapply. Now I can understand the ABS cutting is as load on the tyres lightened but surely braking force should remain constant and should return without having to take your foot off the brake? I'm wondering if something funny is happening to the calipers over bumps. What I mean by funny I don't know!

I have read that others have experienced this. Anyone know what it is and a cure?

Piers LoFi

roadtrip

get the same on my '02 over bumps and grates etc but DONT lift off the brakes, press harder instead and you will find they stop you.

unfortunately most people dont realise how to stop an ABS equipped car quickly. in an emergency stamp on the brakes as hard as possible and DONT lift off the pedal. the ABS stops your wheels from locking.

but I have to agree that Subaru ABS is a little over sensitive over bumpy ground. I put this down to the brakes being very good and capable of locking the wheels easily. so if the ABS didnt kick in when braking over rough/bumpy road surfaces then the wheels would momentarily lock up and skid.

well Ive convinced myself all this!

RoadyT

hades

I had heard about things like this, and the other day whilst enjoying my MY02 on a twisty "A" road, encountered something that might have been similar. I came over a brow at perhaps a slightly illegal speed, cows were in the road, not too close but not that far away. The road was bumpy and liberally sprinkled with cow ****. I hit the brakes moderately, for a split second thought "is that the ABS thing I've heard about", pushed a bit harder and the car stopped as well as I've ever known it. Whether that helps, I don't know.

Personally, I lost confidence in my brakes for half a second, and then got it all back.

LoFi

I'll have to try that peice of road again as suggested as I'm sure the effect is repeatable. When I over shoot the junction and get clobbered I'll send you guys the bill

Piers LoFi

[Edited by LoFi - 9/16/2002 6:12:19 PM]

hades

I look forward to hearing the results. If I'm to be held financially accountable, I suggest you try the test at no more than 0.2mph, and only when no-one else is about.

jpidding

The ABS on Scooby's IS pants! It does cut it too early and removes brake force in doing so....I have experienced this repeatedly when going over level changes as you described above. I concur that the solution is to push harder. On track days I have considered removing the ABS fuse to leave me in better control, but not tried it yet.

BTW my car is a 2000MY.

James

rapiddescent

yes, have experienced this in a MY01 wrx. The brakes just let go for a fraction of a second - rumble strips (usually used for road safety to make you slow down) are the worst for the subaru ABS and could actually help cause an accident.

anyway. the same goes if you are cornering sharply and press the brakes. On the track, I just steer straight towards the outside of the corner and head for the cones with full brakes - usually it means the car will stop in a much shorter distance than steering+ABS. I'd rather smack a cone than hit a spun exige.

rd

jpidding

You have the luxury of cones on your track days! Around the Nurburgring you generally get 1-2m of grass then metal barrier for 95% of the circuit.....makes you drive within your limits and really focusses the attention!

James

LoFi

I'm glad it's not just me being cr*p, which is usual. I must say it has put my heart in my throat on a number of occasions. Gonna try the press harder method. I still find it odd that this is the only car I've had were braking force descreases as the ABS comes in. But then I've never had a car where the ABS comes in so early.

Piers LoFi

Yorkie

I have also encountered this on a fast bumpy B road approaching a corner (MY02). I now carry a clean pair of underpants in the boot. My MY99 never did it as I found the ABS kicked in pleasingly late in the braking process, in fact on occasions the wheels would squeel locked for a fraction of a second before the ABS kicked in.

Yorkie

MarkWRX

I had exactly the same problem on my MY01 UK300 and learned to live with it even though it is frustrating bordering on potentially dangerous.

I posted on here at the time about it, and a large number of people had experienced the same.

I dont get it at all on my STi now though, even on the same roads where the UK300 had a problem.

I presume the ABS is the same on the WRX and STi but the brakes are different.

rich101

MY01 I used to get this sort of behaviour on gravel/undulating roads, but since I got some 6pot AP's I have not noticed it.

Rich