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MG MGF Technical - Worrying Braking

MGF Fault 46(b)

Before I take my car to my Rover garage for yet another fleecing, can anyone shed light on this one. When braking hard i.e. on motorways approaching standing traffic rapidly, the steering becomes very shaky with the car feeling as if it's lurching from side to side. The car does not tend towards a particular side and it is still possible to control the direction of the car although it feels very insecure. Braking efficency is not impeded and the effect is not at all noticed under normal braking conditions. Is this a known about problem, or is it because I have become used to ABS on my previous cars.

I too have the same problem, and I think it's a warped disc.
What I want to know is :
1) How to be sure ?
2) how to identify easily (I'm lazy !) the faulty disc ?
(of course, I'll replace both on a axle)

Neil, do you feel aswell vibrations in the brake pedal ?

More likely to be worn wishbone bushes complaining at the stress under braking,change to polyurethane type and enjoy better handling.

Already sounds expensive. Couldn't say for sure whether the pedal vibrates, too busy trying to avoid ploughing into the back of the car in front, although I have always thought of it as a handling problem.

worn disk lets it shake, but not steer (IMO)

So with Mike. Check the rear bushes and rear suspension at first. Than the front.

Dieter Koennecke

Doesnt sound like discs warped unless brake pedal is vibrating - you can check for warped discs witha dial/run out gauge
Warped discs do have a characteristic of only really vibrating under heavy load or when very hot!
Sounds like bushes - or front shock failure?
Suppose it may also be a failed steering component also ?

just a thought. I'm with you on the brake term.
If the car brakes hard, than the front dives and gets strong pressed on the front axis. Each play gets off from this load.
But the rear gets upwards and this results in low load. Each existing play can work and move the car from left to right.
Your opinion also ?
If so, than the rear is 'guilty', is it ? :)

Dieter Koennecke

I only get vibrations in the steering wheel and in the brake pedal. The car doesn't go side to side. And yes, I only get that at high speed when I've got to brake hard.

Rear end feels stable. From whats being said it sounds like front suspension problems. Anyone know who stocks the polyurethane bushes.


I had problems in my last car when braking suddenly on the motorway from high speed, severe vibrations in the steering wheel, although the car did not lurch from side to side, but it did feel dangerous. Problem was front discs, replaced these and all was fine.



simple your finger along the brake disk from edge to centre(when cold). If it feels uneven, this could be cause for shaky steering wheel when braking.


Niel -I would definately get bushes/shocks checked front and REAR - also any steering joints etc!

As Dieter says the rear shocks can affect the front because the car must remain more or less level when braking hard (slight bias to the front)(it may infact be the hydrogas system set up poorly)

For instance if your rear brakes failed - your front wheels will skid - because the car lurches to heavily forward and the wieght distribution is incorrect for maximum effciency

Definately doesnt sound like warped discs!

I would think it is a steering/suspension failure of some kind - have you checked wheel bearings for play ?

i HAVE HAD CARS THAT VIBRATE BADLY when under heavy braking - usually it has been shock problems or steering joint or wheel bearings !

One other place to check - ensure your brake calipers are done up and brake discs are done up and lastly that your roadwheels are done up to correct torque

I came across an escort which drove beautifully until you braked hard - the front central spindal/spline bolts were nearly falling off!!!! should have been 100Nm and split pin secured!!!!!!

It does worry me that it is vibrating and lurching side to side - something is worn/loose so be careful and get it looked at ASAP!


After my experience today with one rear tyre pressure being a little too high (33psi) I would check all tyre pressures as this may be contributing to your problem - frankly the car weaved side to side and felt out of control!

After correction the car was perfect!

If tyre pressure can affect the car that badly - I dread to think what a worn bush could do to it!

Tony, change to the 'tight rear tie bar' by adding 'compliance washers' and set the rear to toe in.

You will be amazed about the behavior under the same test conditions :)
Car beeing less sensitive due different tyre conditions than.

And yes, for some owners a simple tyre pressure check has solved already a lot of silly troubles.
Neil, did you check the pressure ? :)

Dieter Koennecke

Thanks Dieter

This has to be a must for every F Owner!

Sounds like warped discs. I too have the same problem on my EVO VI, this is waht comes from very hard braking and not letting the discs cool properly in my case.

Neil, have you been abusing the car on the road or even a track day?
Jerry Flint

So back to brake disk ideas.

I found the Corrado option data. Similar to B&G conversion done with support from Rog.

The disks from the Corrado are drilled with 4 holes in 100mm, so not original applicable for our MGF, but the inner dia is the same.

I found the Corrado disks at with folowing data.

Volkswagen Corrado 1.8 G60 ABS. 118 Kw.
KBA. No. 0600-756
(This KBA code is the specific German type code for the car. (MGF 1.8i is i.e KBA. No. 2055-402, and VVC is 2055-403) First 4 digits is the manufacturer, second three is the car type.

Availiable front brake disks data is:
ATE PowerDisc, D 280x22 (65 EUR/pcs)
ZIMMERMANN (same price)
BREMSA drilled (180EUR/pcs)

Two of each above required.

2be done:
- enlarge the holes to fit the MGF PCD
- make a bracket to get the caliper to new location.

Thats all

Dieter Koennecke

This thread was discussed between 25/10/2001 and 28/10/2001

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