Only Knocking when braking

[Slobbo]

Hi guys.  Got a Mk3 95 LS400 - I have had a slight irritation for a while now.  When I brake I get a knock from the front end.  I replaced the discs and pads with Mintex stuff and it was fine for a while.  I have also had the upper wish bones and the lower suspension arm ball joints (July last year).  I did have a knock when I wasn't braking as well but this turned out to be a couple of bolts that needed tweaked by 3/4 a turn.  So now I only get knocking when braking.  I don't think the discs are warped.  That feels different (more of a pulse through the pedal).  I've had 2 different places check the suspension and they can't spot any movement or issues.  

Anyone else experienced this?  Ideas.  The car is a joy all other times.

[Malc]

could well be the front drop link arms .....  aftermarket ones are relatively inexpensive ( cf Lexus ) and quite an easy fix ( so I'm told by my indy )

transformed the front end noise level

Malc

[runsgrateasanut]

I've recently had an annoying sound from the front which turns out to be the Brake Back plate. The lower part has corroded away from two of the four bolts and was vibrating against a nearby part.

Ordered a replacement part from amayana for £28 and thought Yippee,  but unfortunately they refunded my money yesterday as the part is "unavailable".

I wired the lower part  (rear of the brake disc) to the Caiiper to a point that does not move. Will have to remove the wire before MOT in August.

 

 

[Malc]

Rob, any update on this ?

Thanks

Malc

[Slobbo]

 I've purchased Blueprint upper arms and drop links.  They are being fitted tomorrow so will update you.  I'll get the garage to keep the old ones and see if they can spot anything else with the suspension apart. 

[Malc]

I had my n/s front UCA replaced with a Blueprint part but sadly it failed after about 43k miles  It cost about £250 if I recall.

The other side was still just about ok on 211k ? miles when I recently replaced it with HAVING TO REPLACE the n/s Blueprint one which was simply failing

I bought all my parts from Amayama Japan at about £250 each ( incl the rear UCAs too ) being Genuine Toyota/Lexus parts   This cost include carriage and HMRC Customs Duty and VAT too

It was then that I replaced the front drop links but they were simply aftermarket ones, the Lexus parts were a horrendously silly price

I would NOT have recommended you buy these UCA Blueprint parts had you asked .......  or read my quite extensive prior posts on this subject

Best wishes whatever

Malc

[Slobbo]

Thanks Malcolm.  Unfortunately didn't see the previous.  I had replaced the uppers about 50k miles ago and they may very well have failed.  I'll put these Blueprint ones on and when they go next time get the Amayama ones.  Not even sure the ones on their have failed.  As I said I've had two different garages try and find the failed part and neither could find movement in any of the joints.  

[Malc]

they would have to take a serious crowbar to the places to see any untoward movement

Malc

[Slobbo]

Well here’s the breakdown

droplinks - slight movement in both  enough to be a problem  

upper control arms. - 1 ball joint shagged and all bushes knackered. 

New stuff on and service has returned to normal.  

[Malc]

excellent 

Malc

[Slobbo]

Well service wasn't returned to normal.  Ended up having to replace every bloody bush on the front end to stop the knock.  I now have to deal with vibratration from the discs.  I put Mintex brake discs on the front a while ago and expected them to be fine as I have used them many times in the past on various cars and always found them to be solid performers.  Is the issue likely coming from sticking calipers or warped disc?  Anybody tried the EBC performance discs?

[steve2006]

Callipers are 4 pot so no sticking slide pins to worry about, did you clean the hub to disc mating surfaces before fitting the new discs?

[Slobbo]

Was a mate that fitted them. I’ll get them off and give them a good clean and see if it helps.