Help With Rear Caliper

[shaunrav4]

Hi

When changing the rear pads on my 4.2 Rav4 I had to remove the caliper to knock the pins out as they were seized up.

Now having reassembled the the caliper and mounted it back on the disk it seems awfully wobbly. Im not sure ive tightened the bolts up far enough but am a little scared I break them as the bottom one is hell of a stiff for a bolt thats not right in. What torque should the rear bolts that attach the caliper be on the rav 4.2?

Will there be play on the mounted caliper before depressing the brake to push the pads up against the discs??

The lower bolt (which is the longer of the two i hope!) is allready protruding from the other side of the mounting plate and if i tighten more it will approach the disc which cant be good?

Any help would be appreciated?.

[anchorman]

I can't just see what is going on there but is that a bolt just below the end of the brake pipe? If so I think you have them mixed up.

[IanXT4]

Here is a diagram, note that they changed the design of the anti rattle spring on our calipers but everything else should be correct including the torques. Just looked at the bolt specs they are listed

BOLTS (FOR REAR DISC BRAKE CYLINDER MOUTING)

10-1.25PX56-15, UPPER

10-1.25PX71.5-15, LOWER

So lower bolt is longer, torque is shown at 44NM

Components.pdf

[gjnorthall]

The bolts pass through guides so when the bolts are tightened - the guides are firm against the calliper mounting. The guides are a loose fit in the calliper so the calliper has a fair amount of movement. This allows for expansion of the calliper and allows the pads to "self-centre". When replacing pads - check that the guides move freely and clean / lubricate if necessary. Theres no point in over-tightening the guide bolts and you can use a drop of stud lock on the threads if you wish. The pic shows the hose disconnected from the calliper - this might be for another reason, but theres no need to disconnect the hose to replace pads. The guide bolts are probably the wrong way around.

[shaunrav4]

Thanks , thats great :)

I did the other side this morning to check I had it all assembled correctly and the bolts were in the right places (looking at the design I wouldn't have got it on at all the other way round). There was no problem with tightening up the other side and it all went back on fine and solid. I torqued it to about 50 NM.

So I took the first side I did apart again to see why it wouldnt tighten up right , gave the threads a good clean and reassembled it. The bottom bolt was still very stiff and required more than 50NM to tighten right in to the guide which it runs through but was a lot better than yesterday. Seems alot more solid now.

I took the hose off as I had to remove the caliper to get the pins out on the bench as they were all rusted and seized up.

Also I freed, cleaned and lubed the guides as they were stuck. Used brake grease in them but I notice the pdf says use lithium soap based glycol grease. Does this matter???

Thanks again for all your help:)

[gjnorthall]

As long as the grease is synthetic - it's OK. Using ordinary petroleum based grease will cause the protective rubber boots to swell and disintegrate - leads to corrosion and seizure of the guides. A £3 tube of Carlube Silicon Multi Purpose water repellent grease will lubricate a few dozen guide pins!

[shaunrav4]

TRW Brake grease PFG110

it looks like silicon grease to me but says contains N-alkylated benzotriazole

Doh - Just read the label on it !!

says "Warning - Only use where specified. Do not use as a general purpose grease on hydraulic components"

aarrrg - how soon is this likely to rot the rubber!?.

[shaunrav4]

Having googled a bit

http://www.apdimages.co.uk/extranet/Documents/Coshh/Ferraris/TRW/TRW_Brake_Fluid_Technical_Info.pdf

says it can be used on all hydraulic rubber parts that are in contact with brake fluid

and

http://www.bowersautomotive.co.uk/Safety-Data-Sheet_PFG110.pdf

suggests its a lithium complex soap based grease

so maybee its ok??

Geez - I used to think grease was grease!

[gjnorthall]

It's fine with rubber and is actually intended for use on calliper guides etc. It shouldn't be used for assembling hydraulic components - red rubber grease would normally be used in these applications.

[shaunrav4]

Thanks.

So I put the same stuff on both sides of the inner anti squeal shims too (did it this morning before I saw the pdf). Should it be ok on there?

Sorry about all the questions...

S.

[gjnorthall]

Copper grease or the modern equivalent - Cera Tec is the stuff to use on the back of pads and external sliding surfaces. Things won't come to much harm if other greases are used sparingly - but such greases may not be long lasting in this sort of environment. Maybe apply Coppaslip or Cera Tec when the brakes are checked at a future service.

[shaunrav4]

Ok, probably gonna replace the calipers when I can afford to anyway so they wont be on there that long.

Annoyingly I had copper slip but thought I'd get brake grease to do a better job as I think I read somewhere it was better. Didn't realize though there was different types of brake grease, assumed brake grease was brake grease.

Thanks for all the help :)

[anchorman]

I'm not a big lover of copaslip although I do use it in the absense of anything else. It is good for exhaust manifolds etc or other vary high temperature applications but it does tend to congeal with time.

I use only Ceratec these days. I have mates at Mintex and Pagid who keep me topped up.