996 c4 break rumble

[geno melici]

any help will be appreciated

i have a 1999 c4 coupe tip

when i break at low speeds less than 10 mph

i get a rumble from the break pedal as if the abs is kicking in anyone have any ideas whot wrong and how to fix it?

thanks in advance

[Loren]

Air in the lines?

When was the brake fluid last changed and bleed?

[wross996TT]

Inspect the brake assembly...any debris? Are the rotors wearing evenly or are they warped?

[geno melici]

Inspect the brake assembly...any debris? Are the rotors wearing evenly or are they warped?

pads and discs are new so cant see these being the problem.

loren i dont know when the fluid was changed last i think i will do it is it a big job? hard ? should i get it done or attempt it myself is there any diy article?

could the problem be the abs sensor ? where is it located

cheers

[Loren]

I doubt it is your ABS - does the ABS light come on when this happens? If not, then it is highly doubtful.

Brake/Clutch Fluid Change and Bleeding Instructions

[geno melici]

I doubt it is your ABS - does the ABS light come on when this happens? If not, then it is highly doubtful.

Brake/Clutch Fluid Change and Bleeding Instructions

cheers loren

no the abs light dosnt come on.

another question please will a rear suspension damper and spring from a c2 coupe fit a c4 coupe

[Loren]

I doubt it is your ABS - does the ABS light come on when this happens? If not, then it is highly doubtful.

Brake/Clutch Fluid Change and Bleeding Instructions

cheers loren

no the abs light dosnt come on.

another question please will a rear suspension damper and spring from a c2 coupe fit a c4 coupe

No C2 and C4 have different weight balances (4WD in C4) so the spring rates and damper rates are different for the weight differences.

Similarly the weight difference between a 6 speed and Tiptronic also require different suspension components.

[wvicary]

It could very well be the ABS at fault and there will not be any codes or light. If the ABS sees a wheel speed difference it will activate. This often happens from a damaged sensor,incorrect air gap or damaged sensor ring. The odd time metal filings will accumulate on the sensor due to it having a permanent magnet and change the sensors A/C output signal confusing the ABS unit in thinking the wheel is measuring a different speed. Only a few KPH difference in wheel speed will trigger this effect and not set a code because there is nothing electrically wrong as far as the ABS controller is concerned.

[RFM]

Some simple points to look at, are the calipers, pads and tension springs, rotors and wheels properly fastened? have the tyres on the same axle, the same dimensions allowed by Porsche? are they or some of them worn?

[geno melici]

Some simple points to look at, are the calipers, pads and tension springs, rotors and wheels properly fastened? have the tyres on the same axle, the same dimensions allowed by Porsche? are they or some of them worn?

where will i find the abs sensors

[RFM]

You can find them in the front and rear, left and right wheel hub carriers.