Brake pulses

[MTUpower]

w123 84 300TD, genII w126 front rotors/calipers. Newer pads, well worn rotors.

Twice now I've had wheel shake/brake pulsing when braking at higher speeds. Later in the same drive it goes completely away. It only happens when braking. clues as to what this may be a sign of?
Thanks
William

[bluebird]

Have you used a micrometer on your rotors to see if they are still in spec?
My first thought is warpage when warm, so that begs the question how hard were you breaking, were you going down hill, and or, could your calipers be dragging heating up the rotors. I understand that it goes away but exactly what are the circumstances that seem to cause this malfunction. Also are the calipers the same manufacturer on both sides? Just throwing out thoughts.

[sixto]

Those were the symptoms that led a friend of mine to find that Uro brand tie rods had worn to looseness in less than a year. Don't just tug on the tie rods along their length, check for play along the axis of the end pins.

Sixto
87 300D

[MTUpower]

Originally Posted by bluebird

Have you used a micrometer on your rotors to see if they are still in spec?
My first thought is warpage when warm, so that begs the question how hard were you breaking, were you going down hill, and or, could your calipers be dragging heating up the rotors. I understand that it goes away but exactly what are the circumstances that seem to cause this malfunction. Also are the calipers the same manufacturer on both sides? Just throwing out thoughts.

The rotors are worn- but the pulses do not heat up the rims at all, and they can go away in the same trip quickly. I took both caliper off the same car and they were the same make.

[MTUpower]

Originally Posted by sixto

Those were the symptoms that led a friend of mine to find that Uro brand tie rods had worn to looseness in less than a year. Don't just tug on the tie rods along their length, check for play along the axis of the end pins.

Sixto
87 300D

I'll be checking those but they are fairly new both of them. I'll find out what make they are.

[vstech]

I had similar issues when my Guide rod bushings were shot...

[MBeige]

You already know the rotors are worn. How did you confirm?

I had bad shaking/pulsation when braking from high speed also. Replaced rotors with new ATE (solid type) with new pads and bearings and shaking went away.

[MTUpower]

I confirmed the rotors were worn because I pulled them from a yard, and you can see that they were worn. The new pads did not touch in all places for at least a 10 days of driving, and the old pads wore unevenly- the edges of the rotors are higher.

I'll check the guide rod bushings, thanks VSTECH.

This fall I'll be changing the rotors and perhaps the master cylinder and booster. Anyone know if a w126 booster fits the space allocated on w123?