Rear Brake Pads Too Thick?

[Helno]

I got a 99 RX300 and I tried to change the rear brake pads with the AKebono ACT325 pads. After replacing the pads, I cannot fit the caliper over the pads anymore in order to put the lower bolts through. Seems like the new pads are just a little too thick. Piston is pushed all the way so this is not the problem. Either I got the wrong Akebono thick pads or I am missing something here. Does anyone else have come across similar problem?

Thanks

[tta300]

Will you be able to push in/out the upper caliper slide all the way? There is a rubber plug in the back. If the plug is missing and water gets in, rust can limit the movement and it may be the case.

[carguy07]

If you are using a lug nut to hold the rotor on, take it off. They tend to !Removed! the rotor a little and will not give you enough play to get the caliper/pads back on.

[Helno]

I was able to push the upper bolt all the way in, at least as far as I can see. I am not using lugnuts to hold the rotor back.

The problem seems to be on the outer pads. Actually, I need the caliper to be pushed out towards the center of the vehicle but the outer pads are in the way. If I fit the caliper over the outer pads, then I cannot fit the lower part of the caliper. Seems like I need to do something to push the rotor further into the vehicle to get the clearance.

[carguy07]

Are you adding any or reusing the stock shims?

[carguy07]

Also, make sure that the piston boot is folding in on itself properly. Mine kept bunching up, they can get pinched between the back of the pad and the piston.

[lenore]

I usually take the old brake pad and use a c clamp to pull the piston in flush with the caliper housing. The piston will go in flush. I installed the Akebono pads on both the front and rear of my RX so I know it can be done..

[Grumpa72]

I usually take the old brake pad and use a c clamp to pull the piston in flush with the caliper housing. The piston will go in flush.

I agree with this. The one mistake that I see and hear from folks who replace their own pads is that they fail to do two things:

1. remove the brake reservoir cap and gently lay it back in position on top of the master cylinder. This gives room for the brake fluid when it is displaced by...

2. pushing the caliper piston back in by using the method described in the above post. The reason that the piston needs to be pushed back in is that it is displaced and stays out to make up for the brake pad material as it is used up.

I don't know about Lexus/Toyota calipers but some manufacturers caliper piston cannot be pushed straight in but must be "screwed" in using a large screwdrive. My Nissan was that way. The head of the piston was a large "+" or cross depending on your perspective. You just had to use the screwdriver to rotate the the piston until it was seated all the way in.

One thing to remember is to lay the brake master cylinder cap on top of the reservoir since pushing the piston in will cause the brake fluid to be pushed back into the reservoir. The brake fluid MAY bubble up and spurt out and brake fluid will RUIN what ever paint it touches, even if only a second or two. By laying the cap on top of the reservoir and completely covering it (but not secured into position of course), you preclude any chance that the brake fluid will ruin paint.

[Karl K]

My recommendation is to open the bleed valve before pushing the piston back and close it after the piston hits bottom in order to get the old fluid out of the system and not back into the master cylinder. The fluid that lives in the caliper gets boiling hot and turns nasty and needs to be replaced.

just my way of doing it.

Karl

[lenore]

Karl, thank you never thought of it that way, we old dogs learn something new everyday.

[Grumpa72]

The fluid that lives in the caliper gets boiling hot and turns nasty and needs to be replaced.

That is why most auto manufacturers suggest a two year cycle on replacing brake fluid.

[Helno]

Thank to all for replies. I have remove the brake reservoir cap and pushed the piston in with the c clamp but I don't think it is the piston that is causing the problem. I have attached a picture in case my description is not clear.

I have trouble closing the lower caliper because either the pads are too thick or the rotor is too thick. I need to push the caliper towards the inside of the car it seems like so I don't think the piston are in the way.

Please help.

[tta300]

It seems you've sat the pads well in the carrier and positioned the caliper. Will you be able to push the lower slide in/out? Push it real hard but slowly. The lower slide tends to seize easily. You can push it out to lube the slide and push it back in.

[Helno]

I have tried to push the slide but it does not seem to move so I assumed that it is not supposed to move. I will try to push it again. Thank you for the advice.

[carguy07]

I have tried to push the slide but it does not seem to move so I assumed that it is not supposed to move. I will try to push it again. Thank you for the advice.

That is your problem. Tap the slides with a hammer and they will break loose. They both have to move freely or you will never get it back together and the caliper will not float properly. Mine were seized up on both sides when I did my brakes and the rotors were not making good contact on the outside. One tap with a hammer fixed them and they moved again just like they are supposed to. My guess is yours will do the same. Let us know if this fixes it.

[lenore]

I would take the slides out and lube them, they are probably corroded and need a good cleaning. If you dont the caliper will not float properly...

[Helno]

In regards to the lower caliper "slide", I think I can probably move it a little but it does not slide in/out completely. The 2 ends are flattend, kind of like the heards of the bolts. Just want to confirm that this is the rear caliper lower bolts. Unless the caliper setting is different on my RX for some reason.

[Helno]

I mean the head of the bolts. I think the picture does a better explanation than I do.

[carguy07]

I did not remove mine since they moved freely after smacking them with a hammer. They felt like they were still full of grease and even turned freely. The arrow in your pic points to the slide, it has rubber boots on the ends. It needs to be able move in and out without binding to work properly. Give them a few smacks from both sides and they will break loose. If they do not move freely after you break them loose then you will have to take them apart to grease. If the boots are still in good shape, my guess would be a few pops with a hammer and you will be back in business.

[Helno]

I gomanaged to move the slide pin using a c-clamp. It was seized. Anyway, once I got it to move out a little, I can fit the new pads perfectly. Thank you all for your advice.

[tjmc11]

I have tried to push the slide but it does not seem to move so I assumed that it is not supposed to move. I will try to push it again. Thank you for the advice.

That is your problem. Tap the slides with a hammer and they will break loose. They both have to move freely or you will never get it back together and the caliper will not float properly. Mine were seized up on both sides when I did my brakes and the rotors were not making good contact on the outside. One tap with a hammer fixed them and they moved again just like they are supposed to. My guess is yours will do the same. Let us know if this fixes it.

The slides are designed so as to moved the entire caliper assembly in order to produce even pressure on the rotor. Heat buld up has possibly caused a slight sieze of the slide. Take a clamp or a large pipe wrench and try and squeeze the slide to move it. If that doesn't work, use some penetrating oil to try and loosen the slide. IT WILL SLIDE, but you have to fight it. You may even take the entire assembly off and hammer on it until it moves freely. REMEMBER to re-lube the slide with lithium grease if possible so as to lubricate it. It has obviously lost its lube which has probably caused the sieze. Hope this helps.