Shims for rear brake pads for Mk3

[Colin M]

I need to replace the rear brake pads soon on my 1996 LS400 and I have a new set of Lexus/Toyota pads I bought some time ago. On reading the section on pad replacement in the manual I have, it says that new shims should be used and the old ones should not be reused. It does not say why and I have always used existing shims on other cars I have owned when replacing pads unless the shims were defective or falling apart. I made a phone call to a Lexus main dealer to find out the price of new shims - an eye-watering £36.95.

I have a couple of questions for those of you who have replaced rear pads. First, have you reused the existing shims and, if so, have you had any problems when doing so? Secondly, have you bought replacement shims from a source other than a Lexus main dealer and, if so, where did you buy them and how much did they cost?

Any help and advice gratefully received.

Thanks.

 

 

 

 

[plexus914]

Replace shims only when broken. If they are not damaged clean the shims properly and put some synthetic brake shim grease on.

(Toyota brake shim grease - black: 08887-80409) or (Toyota brake shim grease - white: 08887-80609 ....it's expensive but this stuff sticks like hell)

 

1997 LEXUS LS400 (RM514U)

 

BR-36 REAR BRAKE CALIPER COMPONENTS.pdf

[Colin M]

Thanks for your reply.

A clean up and a thin skim of grease is what I have done in the past, although I have usually used either Girling brake grease or Copper Ease. Neither of these have given rise to any problems.

[steve2006]

The shims on mine consist of 2 parts, a blue painted one with elongated slots goes on first and then a stainless steel one over that, all original after 22 years on the car. I always coat them fully with copper grease and they are still as new.

[Titch LS]

Colin, you could just as well save yourself £37. Shims are used to stop brake squeal. Rear brakes don't wear as quick as front's anyway and it's highly unlikely you will hear anything after replacing the pads without the shims. I've never had any noise problems when changing pads and leaving the shims off. Done this many times on many cars. I just use copper anti-seize grease instead. 

[Colin M]

Thanks all for your helpful comments.

In the light of what you say I will carry on doing what I have done previously - cleaning up the existing shims and using some copper grease on them. I have not had any brake squeal when doing this in the past and hopefully I won't this time.

[Colin M]

I renewed the pads over the weekend and found all shims to be present and in good condition, although I was surprised to find that the shim next to the brake pad had been stuck to the pad itself with what looked like contact adhesive. For each pad, the shim had to be carefully levered off to break the seal and then the adhesive cleaned off the shim, which took some time to get off.

Three of the sliding pins moved freely but one was seized and took some freeing off. I managed to get it to move sufficiently so that I could get the caliper back over the new (thicker) pads but it doesn't move as freely as it should and I need to go back to have another look at it.

I would like to remove the pin, clean up the pin and the cylinder into which it fits, and then grease the pin before refitting. Can this be done without the risk of damaging anything? Does the rubber boot cover behind the bolt head of the pin just lever off and is there anything behind the rubber boot that needs to be removed to get the pin out?

Any help, as ever, gratefully received.

I am pleased to say that with the shims cleaned up, lightly smeared with copper grease (instead of adhesive ...) and the new pads fitted that there is no brake squeal at all.

[ambermarine]

Colin

The pin comes out and the rubber boot pulls off the body of the caliper be careful you don't tear the boot as they are designed to create a vacuum within the cylinder that moves the pad away from the disc, there is also a rubber o ring on the end of the pin which should be on to create the seal for the vacuum, it sometimes get left in the caliper tube when pulling the pin out.

It is a primitive way of releasing the pad from the disc and will become ineffective when gunged up and rusted.

The system was changed on the later calipers on Mark 4s

 

 

[Verbout]

I've never seen "O" rings on pins on any of the cars I've worked on.

Is it particular to the LS 400?

[Colin M]

Thanks, Ambermarine, that is very helpful.

Just so I know where I am looking for the O ring, is it at the far end of the pin/back of the tube into which the pin goes or is it at the front of the pin near the rubber boot?

Thanks again.

[Rupert Dubreaux]

Colin hi , the O ring Ambermarine mentions is at the end of the slide pin furthest from the boot and fits into a groove in the pin , only one slide pin has an O ring on the rear calipers the other is just a plain pin .

The slide pins have to go back into there respective tubes ,so make sure you make a note of which one go's where .

Good luck 

[Colin M]

Hi Rupert, many thanks - I will make sure I only take one pin out at a time and then replace it. Three of the pins move very freely so I am only planning to take the one stiff one out. When I have done this one I will have a look at the pins on my other car to see what they are like - hopefully all be moving freely but probably unlikely ...

[Colin M]

I have now removed the stiff pin and given it a good clean up, a light coat of grease and it now moves freely.

I initially tried to remove the rubber boot where it was attached to the cylinder but it was reluctant to part company so I left it in place there. Instead I released it at the pin end where it was just pushed over a lip on the pin and it came away here quite easily. I squirted some Plus Gas dismantling fluid down the pin to help release it and get it moving. Working the pin backwards and forwards with a spanner on the nut using one hand and a screwdriver in the other hand pushing the edge of the nut on the pin, I managed to ease the pin out. I cleaned up the inside of the cylinder using a flat blade screwdriver to scrape the debris out that was in there - several scrapes with a dab of grease of the tip of the screwdriver removed most if not all of it.

I have done the other car as well, which was much the same. Three pins moved freely but one was seized. This is now moving freely. It was the pin with a groove in it (bottom pin) but there was no O ring on the pin or left in the cylinder. I tried an ordinary O ring on the pin but it this made it too thick to get the pin back in the cylinder, so I left it as it was. There were no shims fitted to the pads on this car either, so I will try to source some used ones or new aftermarket ones if there are any.

Thanks to all of you for your help and comments.