japscrap

hello all.
i'm a newbie to this forum but if my exploits over the last six months of GS300 ownership is anythng to go by, i'm going to be a regular!!

boring background bit - if you have some knowledge, i could really use your opinion
a few thousand miles ago i got all discs and pads changed as a result of warped old discs. got spurious new discs and pads all round and had my brother fit them. the car was ultra smooth and quiet for a few days but slowly it started getting wobbly when driving again. it also pulled to the left under braking and the wobble goes crazy. it also developed a graunching noise from the right hand side (rhd car). the noise can only be compared to the creaking noise you get from the pedals of an old bike and it is definitely cyclical as the noise slows down as the car slows down.

my brother diagnosed the car as having warped new discs. he demonsrated this by removing the wheel, removing the pads and tightening the discs back on with the wheel nuts. as the discs rotated, you could not only see them wobble, you could see that the 'walls' of the disc were actually thicker and thinner in places. rang motor factors and they agreed to take the discs back.

however, he also diagnosed the cause of the graunch as being related to worn brake pad carriers and/ or their bolts. he re-assembled the car but left the carrier bolts loose. only slight wobble in steering, no more graunching and no more pulling to the left/ wobbling. he was happy with his diagnosis so he tightened the carrier bolts and the car returned to 'normal'.

now the question,
chicken and egg- did the carriers cause the discs to warp or did the warped discs wear out the carriers? carriers are a big pile of doh-re-mi and if i don't fit them, will i warp my brand new discs? if the discs were actually at fault and now i have another new set, will worn carriers be ok?

any help gratefully accepted,
regards, Noel

LexFather

Welcome to Clublexus. When you carriers, do you mean calipers?
When you re-installed the new brake pads/discs the first time, did you bed them in?
http://www.pagidusa.com/bedding_in_procedure.htm

What kind of pads are you using? I have never heard of warped rotors two times on a GS.

japscrap

i'm not a mechanic and i'm trying to remember correctly but it's the 'top' of the caliper, not the caliper itself.

isn't it the case that the carrier kinda holds the pads and the caliper pushes against them? there's 2 bolts holding it on. i think there's wear on both bolts and in the carrier itself causing a metallic squeak (like overtightening a bolt) as the bulge on the warped rotor nudges the whole pad assembly slightly as it spins.

have i explained it better?

if so, i need to know;
is the pad carrier somehow to blame for the warps on my new rotors? OR is it fair to assume i bought the new rotors warped because of bad manufacture and by simply fitting the new ones my squeaking and wobble goes away. OR do i automatically need to change these carriers as well (if so, any suggestions with sourcing replacements).

btw, i can't remember what brand they were, i simply went to my local motor factor and ordered standard spurious replacements and i'm not sure if my brother bedded in the brakes properly or not. we have the new ones ready to go into the car and they will be bedded in properly.

thanks by the way

LexFather

No problem, not sure I am helping.
THe caliper is held in by 2 screws. You take those off and the caliper comes off. THe pads come off and there are metal plates (very thin) that go against the caliper and the 2 pistons (you should see the round impressions in the metal).

Did you all use sufficient grease? THere should be no squeaking. I just can't see new rotors warping, unless there was a defect in them from the start.

Do you drive aggresively? Does the steering wheel shake really bad when you apply the brakes at speed?

Maybe tru the rotors?
http://www.trustmymechanic.com/lathe.html

Can you take any pics?

japscrap

my brother reckons they're faulty discs, they were replaced by the supplier on that basis. but i do have a niggle in the back of my mind that the worn carrier and bolts may have somehow caused them to warp through unevenly applying pressure.