Brake pads not fully contacting new front discs IS300H F spo

[Colinb623]

Evening all

I recently treated my F Sport IS300H to a new set of front discs . I re used my old pads as there is only 1000kms wear on them . I know the way to go Is to always replace new discs with new pads but in this case I kept the old ones. I did a thorough job , cleaning all and re greasing caliper slider pins with the correct grease . I've driven about 150km on the new discs and noted the pads aren't fully contacting/wearing on the new discs . Any ideas ?

Note the pic attached is not my car but very similar to what is happening on mine . Only contacting outer edge of disc

[IS300FSPORT]

Classic sign of either a sticking caliper or carrier brackets not allowing pad to move freely.

If you didnt replace the pads you wouldnt have noticed a seized caliper, because you didnt need to push the caliper piston back.

Caliper carrier brackets disturbed at all during your clean? When you refitted the pads did they move freely in the carrier or did you notice them being a tight fit if they are not moving freely you need to remove & file the caliper carrier down sligthly or the pad ears (v slightly) ,& reinsert.

To check for a seized caliper:

jack up the car put it in 'N' , chok the wheels so it doesnt roll, & try spinning the wheel does it spin freely? If there is obvious resistance or wheel refuses to move its likely a seizing caliper.

Personally I'd rule out if its the caliper carrier 'brackets' before spending money on a caliper.

 

 

 

[Colinb623]

8 hours ago, IS300FSPORT said:

Classic sign of either a sticking caliper or carrier brackets not allowing pad to move freely.

If you didnt replace the pads you wouldnt have noticed a seized caliper, because you didnt need to push the caliper piston back.

Caliper carrier brackets disturbed at all during your clean? When you refitted the pads did they move freely in the carrier or did you notice them being a tight fit if they are not moving freely you need to remove & file the caliper carrier down sligthly or the pad ears (v slightly) ,& reinsert.

To check for a seized caliper:

Jack up the car put it in 'N' , chok the wheels so it doesnt roll, & try spinning the wheel does it spin freely? If there is obvious resistance or wheel refuses to move its likely a seizing caliper.

Personally I'd rule out if its the caliper carrier 'brackets' before spending money on a caliper.

 

 

 

Thanks for your in depth reply 👍 much appreciated. 

 

Whats strange is that its happening on both new front discs? I'm wondering could it be anything to do with the old pads and the wear shape on them from my original discs ?

I did note that the pads were a tight fit .I did take the caliper carrier brackets off and give them a clean with a wire brush .I'm going to investigate later today and I'm praying it's not a seized caliper piston . Hopefully not , as like i said its happening on both sides

[Colinb623]

[IS300FSPORT]

4 hours ago, Colinb623 said:

Whats strange is that its happening on both new front discs? I'm wondering could it be anything to do with the old pads and the wear shape on them from my original discs ?

Providing the pads are evenly worn across the entire surface/fitted flat against the the disc it shouldnt be a problem. To be fair you would notice if they were uneven when you took them off. 

I'd be tempted to give it a few miles it may well settle in providing your braking performance is fine, Hybrids are known to have light use on the brakes. Try doing a few brake cycles when the car is in 'N' ,so it doesnt use the regenerative braking just to see if it makes a difference?

Did you Spray brake cleaner on the surface of the disc removing the storage chemicals? 

Worst case remove the old pads & reassemble with new pads & maybe with new metal clips as shown in the image above. They have a few different names (caliper shims) they should ideally provide hardware with new pads.

Providing your MOT is not around the corner give it time to settle, the tester may pick on it visually but on the brake rollers test if if it passes the braking force test nothing to worry about.

Keep us posted pls

[Colinb623]

MOT(nct) was done and passed only a few months ago .thank god.

 

Just to update I took all apart and re done all . I sanded the old pads flat .re greased all clips and brackets and re fitted . And all seems fine .I tested the caliper pistons and both of them extend and retract fine . 

It's clearing the rust on both discs it's seems bit slowly .I will keep this thread updated👍

[IS300FSPORT]

Brilliant the joys of DIY never give up.

[Colinb623]

To update this thread again ,  3 weeks after my last post . The issue never Really resolved itself fully .

So yesterday I took all apart again . And fitted new pads , re greased slide pins, very lightly .it seems I had too much silicone grease on the pins and they were almost locked in with suction .

Anyways the new pads seem to be contacting the disc alot better now and the car is in fact braking better .

Tip of the day ,, don't over grease caliper slide pins :(

[IS300FSPORT]

6 hours ago, Colinb623 said:

Tip of the day ,, don't over grease caliper slide pins :(

This is great tip will be doing mine in the future.

Thanks!