tyl604

First post - On my 2002 GS300 I need front brake pads. On the passenger side everything was fine until I tried to compress the two pistons with a C clamp using the two old brake pads as buffer; done this many times on the Mercedes. Although I was trying both at once, the back piston just would not budge. So I compressed the front one and, doggone it, the back one popped mostly out and showed about 1.5 inches of rubber. Got it back in but now there is a leak. And I was never successful in getting both to push in together.

Are you supposed to open the bleed screw to do this? Of several videos and stickies, only one mentioned the bleed valve. This would certainly have released the pressure on the sticky piston.

Finally I clamped the back piston and pushed the front piston in enough with a screwdriver to clear the brake pads. Then I slid the caliper up to the back piston, pushed it in with the screwdriver and slid it over the brake pads. I put it back together, the pulled the caliper back again just to check. Sure enough it is leaking.

Mechanic wants $75 for a new caliper (says they cannot be rebuilt) and $150 labor.

What did I do wrong? Used a C clamp to push both pistons at the same time. What could have caused the back piston to be such a problem; could it have been malfunctioning all along? Inspecting my pads on that side, I find a pretty good but thin one but the second pad is down to the bone and shows some evidence of metal to metal. Do not see how one sticking piston could have caused this uneven wear but is this possible?

Should I buy a rebuild kit for $5 which I see online at a parts house?

Appreciate your thoughts.

FrankT

You might have gotten some dirt on the piston seal that compromised the seal.
Just buy the kit and reseal the caliper.
And find a new mechanic.

Good luck.

tyl604

Thanks. What would have made the back piston so hard to compress? On my Mercedes I can push the two pistons back with pliers handle pushing against the old brake pads; they are stiff but I can feel the pressure gently release and the pistons will slowly go back. Not so on the back piston on the Lexus.

02Legend

iTrader: (3)

To my understanding both pistons should have went back in at the same time, not independently. I would almost say that the one not sliding very easily is starting to seize. I had this problem with my IS300 front right caliper. Like recommended you can rebuild the caliper with all new parts yourself and it's not to expensive.

tyl604

Guys - I looked at the sticky and just installed the driver's side pads. Piece of cake. This time I took the caliper out and turned the C clamp around and got a good grip on the pistons. Worked fine.

Now I am thinking of rebuilding the right caliper. The only parts I see on a 2004 sticky is a rubber ring/seal, a dust cover, and a retainer clip. Is that all there is on a 2002 GS 300? That sticky also talks about busting loose a 80 ft-lb torqued set of nuts to get the caliper off. Do not think that exists on mine. All I have is two 1.5" long bolts and the caliper comes off - still umbilical with the brake line.

Sounds like I can take the easy way out and pay $70 for a new caliper and just switch it out. Or pay $5 (2004 prices) for a six piece kit.

The sticky says to replace the two copper washers/gaskets (each has three teats) on the brake line. Do the copper washer/gaskets come with the new caliper? if not, can I anneal the old copper washers (used to do it on my motorcycle) and reuse them? Or can I just plain reuse them and not worry.

Thanks for the help.

FrankT

Your call, on replace or reseal the caliper, it just money.
I would anneal those copper crush washers if your reusing them...

Remember to grease those slider pins.
Good luck sounds like your on the right track.

tyl604

Any ideas/tips on getting the pistons out? The sticky said use an air compressor. I do not have anything but a little $20 one which strains to pump my Land Rover tires to 46. Can I use that? Will it clamp on the nipple of the caliper and push in some air?

Would a gas station air hose work - those that charge you $0.75 for five minutes of air? Other ideas?

GS4_Fiend

iTrader: (22)

I got no problems compressing the pistons back when I did mines. Try spraying some wd-40 or pb blaster see if it works. if not, you gonna need to replace it.

02Legend

iTrader: (3)

This is a link for LS400 calipers getting rebuilt. You can use it for info and pictures to help out. The calipers should be very similar to our cars. It should help quite a bit. Hope it helps.

http://www.lexls.com/tutorials/brake/fbcaliper.html

tyl604

Yes, I got a lot of info from the link. Attached is a blow up of the caliper; sent by the dealer. He wants $70 for the rebuild kit which is basically just rubber washers! Am I missing something? The kits on the internet are about $5 and just include a seal, rubber dust boot, and retainer clip. This pretty much jibes with the tutorial link. Do I actually need to replace all the other rings?

FrankT

Looks like the Lexus kit also includes; 2 copper washers, lower slide pin bushings, slide pin boots, bleeder cap, piston seals, piston boot and retainer clip.
If it were mine I would pass on the $70. Lexus kit...

02Legend

iTrader: (3)

I pretty much have the same kit. I bought one from Sewell Lexus when I was going to rebuild the calipers on my old IS300 (totaled). Looking at the kit in front of me, it is all new rubber boots, dust seals and piston grease. I think i paid near $50 when I bought it last year, but I cannot find the part number on Sewell's website anymore. I can't say whether or not you need to replaced the other things, but why not since you already have it torn down and cleaning it out.

tyl604

Went to Pep Boys last night. They ordered a new caliper for $70 and quoted about $150 installation. After reading up on this forum, I decided to purchase the caliper outright and do it myself. Surprisingly they sold it to me for $59 plus a $50 core deposit. So I wonder if the service desk at Pep Boys upcharged the caliper.

Going to install tonight. Will report back.

tyl604

Installed the caliper tonight. Piece of cake. The tutorial showed two three teat copper washers; the new caliper came with a single copper washer. When I removed the brake line it had two washers which were bridged together to fit perfecty above and below the brake line connector. So I just put it back in.

Total time excluding jacking up, removing tire, replacing tire and jacking down - about five minutes.

02Legend

iTrader: (3)

Glad to see you got it all figured out and taken care of.