Weaving under heavy braking

[fozluvscars]

I had an 'incident' under heavy braking at speed on the motorway today in my mk1 Mazda 3 mps. The car started to weave quite violently under braking, and frankly i'm gobsmacked that i didn't bin in. Now that i'm home and have changed my pants, has anyone else experience this? The dealer i bought the car from fitted some Federal FD2s to it, which from initial impressions are rubbish, so I'm wondering whether i should fit some new rubber sharpish? Obviously there are other cheaper options such as slowing down, even so, i was extremely shocked at the way the car reacted, especially on a dry day.

[maniac0796]

What size are the wheels? I've found cars with wider wheels tend to weave a lot under heavy braking. It's almost like they find all the little ruts in the road and trying and stick themselves in there.

stty tyres don't help either really

[Badgerboy]

If the rear of the car gets unsettled during heavy braking, you can start snaking worryingly quickly. This can be caused by tyres, suspension (Weight transfer), or even slightly dodgy brakes. I assume you were leaning on the pedal quite hard?

[TheHeretic]

Could be a geometry issue as well? Do you have funny toe-in that could cause the braking to waver one to another?

[durbster]

Tyre pressures ok? I test drove a car once which had one ridiulously low tyre pressure and it was bloody unstable when I hit the brakes.

[fozluvscars]

not sure buddy, but they're pretty wide. reckon you could be right as the car has a mind of its own sometimes. i don't think the eibach springs help as they make the car pretty lively over potholes/bumps. prob a combination of the two. just glad the missus wasn't with me as she would have torn my b*ll*cks off

[jbi]

Uneven road surface disagreeing with your tyres would be my best guess

[fozluvscars]

Badgerboy said:

If the rear of the car gets unsettled during heavy braking, you can start snaking worryingly quickly. This can be caused by tyres, suspension (Weight transfer), or even slightly dodgy brakes. I assume you were leaning on the pedal quite hard?

yeah, was pressing down quite firmly, but had to lift off a couple of times as i thought the car was going to spin - all those years on the playstation finally paid off! have checked the tyre pressures and they're ok. its due a service soon, so i'll ask the dealer to check geometry/tracking etc.

[Mr2Mike]

How many miles has it done? The suspension could be getting a bit tired; slop in balljoints and perished rubber bushes allow things to move around quite a lot under hard braking.

[fozluvscars]

Mr2Mike said:

How many miles has it done? The suspension could be getting a bit tired; slop in balljoints and perished rubber bushes allow things to move around quite a lot under hard braking.

mileage is quite low mate, but all problems i can ask about at the service. a lot of things there i hadn't considered so good to know about

[morgrp]

I'd start with checking the brakes - sounds like a braking imbalance - seized rear calipers are common, where one will be working and the other won't causing the car to becOme unsettled - check the rear brake discs - if one is clean and the other manky then you have prOblems

[Marf]

Personally I'd ditch the tyres for something a bit more premium and as others have said get the geometry and brakes checked immediately.

[veevee]

^^^

Front brakes braking harder than the back, effectively the back of the car is travelling faster than the front and trying to get past. Hard springs don't help either.

[thiscocks]

Did you lock up?

[thiscocks]

veevee said:

^^^

Front brakes braking harder than the back, effectively the back of the car is travelling faster than the front and trying to get past. Hard springs don't help either.

probably because they have bigger brakes on the front? Weaving has nothing to do with front/rear bias.

[PhillipM]

veevee said:

^^^

Front brakes braking harder than the back, effectively the back of the car is travelling faster than the front and trying to get past. Hard springs don't help either.

No, that would make it simply understeer. Other way around for the back to start dancing about.


Could be something as simple as a shot suspension/steering bush on the rear.

[Speed_Demon]

fozluvscars said:

yeah, was pressing down quite firmly, but had to lift off a couple of times as i thought the car was going to spin - all those years on the playstation finally paid off! have checked the tyre pressures and they're ok. its due a service soon, so i'll ask the dealer to check geometry/tracking etc.

Sounds like the kind of thing you'd want seen to immediately really.

[Chicane-UK]

Thinking because the car has been lowered it's messed up the brake balance bias?

[Burrito]

jbi said:

Uneven road surface disagreeing with your tyres would be my best guess

I'd agree with this. My old Clio used to tramline under heavy braking - it could have been the tyres, or the suspension, or the road surface - or it could have been me driving way too fast and having to jump on the brakes.

O.P. Does the above sound familiar?

[fozluvscars]

thiscocks said:

Did you lock up?

yes, briefly which added to the excitement. i know cars can squirm under heavy braking, but i've never experienced anything like this before. i was literally snaking between two lanes whilst attempting not to crash into the car in front. i'm sure going forward she'll start indicating and using her mirrors!