Severe Brake Shudder Immediately After Change

[Foeux]

I changed the discs and pads in my ls400 this weekend. I
was really pleased to see that the calipers had been rebuilt when
pushing the pistons back. They all moved back smoothly with thumb
pressure only and look to have been rebuilt at some stage.

The disc retention screws were made of soft metal and
rounded instantly, despite plenty of penetrating fluid and waiting, they
were removed with a punch and hammer which took ages.

The new discs were cleaned off and put on. The new pads
were copper slipped to stop squeaks (hopefully). Everything was
tightened and checked again. A pal and I service and maintain a modest
fleet of cars between us and have plenty of experience and can see
nothing else wrong (pads not contaminated, all pins and clips secure,
all bolts and nuts done up).

Sadly, the discs are already 'warped', vibrating really
strongly when brakes are applied, the higher the speed the brakes are
applied at, the worse the wobble. Also seems worse once brakes are warm.

It took 3h for this fault to surface and it was not there
before on the old pads and discs; just squeaked a lot and we're running
low. Having looked around the Internet, warped discs seem common but I
wonder if anyone has experienced them this soon after changing.

The eBay seller has agreed to exchange the discs and cover
return costs which I think is great. The discs were 'blueprint' ones.

Any similar experience?

[plexus914]

In regards to aftermarket pads sometimes the sides of the back plate need to be grinded down a little bit. Pads might seize up because of heat. I would not recommend using 'Copper Slip' for aluminium brake calipers. Furthermore 'Copper Slip' dries out and disappears in high temperature. By the way OEM pads are ceramic ones.

Next time get:

Toyota high temp brake shim grease: 08887-80409 (due to ls400/UCF20 repair manual)

or

for EXTREME temperature get stuff like 'PERMATEX 24125 Ceramic Extreme' brake parts lubricant (-46°C to 1649°C )

or

or GRANVILLE Ceramic Brake Grease ..............................................................................................(-40°C to +1200°C)

PS: I am wondering if anyone tried ATE Plastilube yet? (Not sure if -45°C bis 180°C is enough but should be good for the rear brake)

'ATE Plastilube' is a clear, high temperature grease designed for braking components. Also works great for window regulators,

sunroof mechanisms,plastic gears and rubber bushings.

[ROYT]

Did you check the hub was super clean before fitting the discs?

Any dirt causing the disc to 'run out' [of true] will cause/aggravate this problem.

Had Blueprint on the front of mine for a few thousand miles no problem

[cruisermark]

i agree with roy - bluprint parts are very good unless they were fakes which could be the case

[keybasher2]

I used Pagid discs and pads,still performing fine after 4k ish . As others have said the face of the hub where it meets the disc has to be very clean and bolts tourqued up correctly.

Maybe it could just be a bad set of discs?? Not sure why you changed the discs in first place if there was no vibration/pulsing/scoring?

[Foeux]

I used Pagid discs and pads,still performing fine after 4k ish . As others have said the face of the hub where it meets the disc has to be very clean and bolts tourqued up correctly.

Maybe it could just be a bad set of discs?? Not sure why you changed the discs in first place if there was no vibration/pulsing/scoring?

Hub face very clean, used a wire brush followed by a load of brake cleaner and rags. Discs changed due to a large lip and ferocious squeaking. Thought it would be 'like new' if I chaged the lot. It seems I have just created more hassle.

i agree with roy - bluprint parts are very good unless they were fakes which could be the case

Not fakes. 100% feedback ebayer with long history to track back through.

Did you check the hub was super clean before fitting the discs?

Any dirt causing the disc to 'run out' [of true] will cause/aggravate this problem.

Had Blueprint on the front of mine for a few thousand miles no problem

As above, hub was super clean. Did not replace the 'hold the disc still' screws as the others had to be removed with a chisel, half a turn at a time. Could this be a problem?

In regards to aftermarket pads sometimes the sides of the back plate need to be grinded down a little bit. Pads might seize up because of heat. I would not recommend using 'Copper Slip' for aluminium brake calipers. Furthermore 'Copper Slip' dries out and disappears in high temperature. By the way OEM pads are ceramic ones.

Next time get:

Toyota high temp brake shim grease: 08887-80409 (due to ls400/UCF20 repair manual)

or

for EXTREME temperature get stuff like 'PERMATEX 24125 Ceramic Extreme' brake parts lubricant (-46°C to 1649°C )

or

or GRANVILLE Ceramic Brake Grease ..............................................................................................(-40°C to +1200°C)

PS: I am wondering if anyone tried ATE Plastilube yet? (Not sure if -45°C bis 180°C is enough but should be good for the rear brake)

'ATE Plastilube' is a clear, high temperature grease designed for braking components. Also works great for window regulators,

sunroof mechanisms,plastic gears and rubber bushings.

I will look into the lubes you recommend but the shake is so sever I doubt it is that alone. That said it is useful to know about copper slip's properties for future work.

I am going to replace the discs re-supplied by the eBay seller and re-re-check all nuts, bolts and clips. At motorway speeds, when brakes are applied, especially with any steering input, the judder is alarming!

[ROYT]

Doubt the single missing locating screws would make any difference as the wheel bolts it all up tight.

Check you didn't loose any balancing weights off the wheels when doing the job!

[Ruud]

I would also check the caliper bolts. If they are not really tight it can cause similar issues.

And grease up the slider pins. If they are sticky you get a bad judder as well.

[Titch LS]

Fred, I use an impact screwdriver to undo those disc retaining screws. Works every time, even if they are on really tight. As regards to discs/pads, I've had a nasty (high speed) judder on my LS400 too in the past, it seems a very common problem on these motors. IIRC I replaced mine with Blueprint discs and Mintex pads. Everything was great for quite a long time but now after 35K the high speed judder is coming back, but not so bad as before. At slower speeds the brakes are really good with no judder. There is still loads of 'meat' left on the pads. Not a cure, but I have found that braking really hard quite a few times (when safe to do so) does mitigate the judder somewhat. I read about that tip on a brake specialist's site. Might be worth a try, it could free off your calipers a bit if there is something sticking in them, such as the pin sliders and causing the juddering.

[lex - eleven]

I don't know if this has any relevance but I've been told by a mechanic at work who had a gs430 that overtightening the wheelnuts can cause the discs to warp and should be tightened to the correct torque at all times.

[GrahamG]

Does anyone know the correct torque for LS430 wheel nuts?

I have a torque wrench but never dreamed of using it on wheels.

[GrahamG]

To answer my own question a Continental chart gives 76ftlbs / 103Nm for all Lexus models both steel and alloy.

Same value given elsewhere on this site.

[runsgrateasanut]

My understanding is that you have to bed in new discs and brakes gradually. Were you tempted to try extreme stopping as soon as you had fitted them just to test the impact of your hard work? 200 miles before rigorous testing may be adviseable.

I'm no expert.