IS200 (2001) Brake Pedal Juddering

[andykao]

Fairly common issue with the first gen is200/300 - searched though the forum but could not find a decent answer to my problem.

Got the car about a year ago, it was in a bad condition but i nursed it back to almost full health.

Changed the entire front suspension - bushings / ball joints, shocks, etc. Also changed the wheel bearings.

The brake disks were a bit worn out (but still had plenty of meat of them) but the brake pedal was vibrating like crazy when braking (almost like the ABS would kick in). Really strong vibrations in the pedal only, steering was fine.

So i decided to change the front brake disks and pads (rear ones seemed rather new). New disks and pads in, the vibration was reduced by 50-60% but it's still there. I've been trying to diagnose this issue but it drives me crazy :

- pedal judder on braking all the time (the higher the speed, the intense the judder).

- tried changing wheels / rims / tires - same judder

- checked front caliper pins, they were in decent condition (not too much rust) - cleaned and lubed them with high temp grease, put them back in - same judder

- bled all brakes and changed the fluid (brake lines were in great condition) - same judder

What really puzzles me is that with the new disks and pads, the disks get burning hot, and so do the rims (not extremely hot but hot enough). But the calipers are not sticking - if i do some serious braking and get them hot, i can easily push the car forward with very little force - or with the car lifted up, the wheels rotate 3-4 revolutions easily.

The calipers look old (there's some rust over them) but i'm not sure if they're seized or not.

Should i rebuild the calipers (or get new ones)? Should i check the fronts only or can be back ones cause something like this as well?

Or are the hubs warped? Or the new disks warped (brembo disks)?

Any solutions appreciated...

[Mike Carey]

I had the same issue with my 99 plate IS200. It's the calibers causing binding on the disc. (that's why your discs are getting red hot). The pistons are sticking causing the pads to be in contact with the disc at all times even when you're not braking. You need to replace both as soon as possible and that will stop the juddering. I would avoid driving the car too far as the discs will just get hotter and hotter, this may cause a brake failure. I bought a pair of reconditioned on eBay and sent the old ones back to them in order to get a deposit back. Think I paid around £100 and its an easy job too. 

[andykao]

Thanks for the reply Mike, will take the calipers apart next week and get them sorted.

One thing i don't understand, if the calipers are sticking, why can the wheels rotate freely?