Binding pad on STR?

[AGS]

Hi Folks,

This is my first technical post so be gentle with me

I think my 2002 STR 4.2 has a binding pad on the near side front. I've only had the car a couple of months and not done much mileage in it. Initially I thought it was just the way the brakes were having never owned a car with big Brembo callipers and discs. The noise is actually more of a high frequency vibration which stays for a short distance after the brake pedal has been released. I'm thinking the vibration goes away after the pad has been pushed away from the disc (it goes away quicker when if you are still turning right after braking).

I drove the car quite quickly a week or so ago (coming back from a JEC meeting!) and the vibration has now become a wobble like the disc is warped. Could this be down to too much heat being generated by the binding pad?

Anyway I'm wondering if anyone has an advice/pics (or point me to a URL) on how to strip the calliper to see what's going on in there?

Cheers, Andrew

[J44EAG]

The first thing to do is get the wheel off and strip off the caliper and pads. Until you have eyeballed the brake unit anything we suggest is likely to be pure guess work.

If the car has been standing, it may well be that you have a seized pad or pads or indeed the pistons sticking in the caliper. With an assistant you will be able carefully pump the brake pedal and watch for the pistons moving out of the caliper. You should release the brake master cylinder reservoir cap whilst exercising the caliper. Use a suitable clamp to retract the caliper pistons after ensuring they move easily.

Clean up the caliper to remove rust and dust and carefully copper grease brake pad peripheral running surfaces and the areas where the piston pushes on the back of the brake pad.

I don`t think you should expect the worst yet. I suspect your brake system components possibly just need a good clean up to get things moving again nicely.

Come back to us again once you have things in pieces.

Mike

[AGS]

Thanks Mike. I was told this had been done before I picked it up but maybe they missed this. I'm used to changing pads in our main car (Mitsubishi) which just involves taking one of the calliper bolt/slider pins out and swinging the calliper up. I'm presuming this will be the same, only bigger and shinier!

I'll keep you posted.

Cheers, Andrew

[AGS]

Found a vid on YouTube so I now realise I need to punch the pins out to get at the pads. Will go that far first and see what I find.

Cheers, Andrew

[Martec]

It probably sounds daft, but also try pulling and pushing alternately the top and bottom of the wheel and tyre when fitted as they do at MOT time.

I recently had some horrible brake noises on a car and found the bottom ball joint was knackered, replaced it and the noise went................ I don't understand it either?

Brian

[J44EAG]

Another thing to check. Is the soft ali dust shield just touching the disc? If it is, just gently bend it away.

Mike

[AGS]

Thanks guys. Not driven the car this week but intend to have a look one evening next week. I'm lucky enough to have use of a 2 or 4 post ramp

Cheers, Andrew

[AGS]

A belated update on this one. Finally got around to taking a look at the brakes on Saturday. I made a trip down to Leeds earlier in the week and managed over 28mpg and now know my car is at its most economical at 80mph on the motorway!

So I took out the pads on both front callipers, cleaned off some minor corrosion, applied copper grease and reinstalled. Before we did this we tried applying the brakes with the car on the ramp and the wheels turned freely once the pedal was released so I wasn't holding out much hope that a binding pad was the issue.

The 'droning' noise remains on the near side front under braking. The noise is most noticeable from about 30mph down until the car is almost stopped. There is also quite a violent wobble through the steering wheel when the brakes are applied from high speed which goes away at slower speeds.

I'm beginning to think the droning noise may be a wheel bearing. We couldn't feel any play in the wheels top to bottom whilst on the 2 post ramp.

The other issue we found is that the front tyres, whilst having lots of tread in the centre, are worn on the outer edges. I think the car has been run with the wrong pressures prior to me owning it. I also think the tyres have been on the car for a long time as it hasn't done many miles over the last few years. When you first drive the car the tyres tramline quite badly until they heat up. Their profile is also 'concave' and the offside is badly worn on the inside.

So my plan is as follows:

1. Fit new tyres. I've ordered Dunlop's (ouch!) to replace the Good Year's it's currently running. The Dunlop's have a 'normal' tread pattern rather than the 'V' pattern on the Good Year's.
2. Get the tracking checked.
3. If no better, change wheel bearings and skim discs.

What do you think?

[J44EAG]

The right course of action. BUT POSITIVELY NO SKIMMED DISCS!. Discs that need skimming are likely to be down to their minimum thickness. Skimming will further thin them at which point they will become dangerous due to risk of break up and in any case below minimum thickness discs are an MOT failure item.

Check all ball joints and lever test bushings. These car suspensions wear very badly given a bit of mileage and really throw things out. What mileage has the car?

Wheel bearings are generally finished on the front at 90k miles. They make a "wow-wow-wow" sound when worn. Jacking and removing front wheels, you can turn the hubs. The rotation should be absolutely smooth and no gravelly feel or sound apparent. There is rarely any wobble noted with these hub units.

The procedure for changing wheel bearing cartridges is detailed in my ongoing maintenance post here. There are some detail changes in the general design of MY2002.5> onwards but the needs and actions very similar tp early models. Changing suspension components is also highlighted with again detail changes for later cars. The post is illustrated throughout with many photographs and if read and digested should give you a good insight into what to look for and how to fix these issues. http://www.jec.org.uk/forums/viewtopic.php?f=200&t=8040

At 90k miles, my early V8 came up for major surgery. In addition the opportunity was taken to uprate selected components to suit my own needs and eradicate some of the issues associated with early car foibles. The post is frequently updated as I bite the bullet and attempt to make the car last another ten years before the next tear down!

Mike

[AGS]

Thanks Mike, I'll take a look at your post. The car has only done 41k miles but it's nearly 13 years old I guess. I'll get the bushes etc checked out as that did cross my mind too. We did get the pry bar out on Saturday but ran out of time to do it.

I'm hoping the wobble is the tyres as the offside front is quite badly misshapen where the inside has been scrubbed.

I'll keep you posted!

[Montana5]

Only my opinion but having fitted a new set of Dunlop Sport Maxx Tyres myself last year, and knowing how much they cost on the STR, I think I might have sorted the problem first, before fitting the new Tyres, then have the Alignment done, it is just possible that the problem is the cause of the uneven Tyre wear.

Doug.

[AGS]

I see where you're coming from Doug but I really think the tyres need changed anyway as I think they've been on the car for years whilst it's been sitting around not being used. I'll keep you posted on progress but hope to have it all sorted out for your event in April!

[J44EAG]

At 41k miles, bushes should still have a reasonable life ahead.

Look hard howerver at the lower front bushings. Partivuarly the large one ar the front end of the banana arm adjacent to the radiator. That is the one that gets punished.. If soft and easily moved, it may be split or as indeed I found recently, delaminationg from its outter ali tube mount. If that is the case I can advise on options. Just replacedall that gubbins myself but on an early car.

Before you change the tyres, photograph the tread profile for future reference and keep the pics so you can see any wear patterns which can be used diagnosticaly when future tracking and or bush replacement is needed.

I`ve updated my suspension post several times recently as much work has been done on bushings etc on my own car. Causes, effects and cures are discussed in the post which now rambles on to nine pages of a blow by blow replacement record.

Mike

[AGS]

Thanks for that Mike. I've taken some photos so please let me know what you think. Cheers, Andrew

Offside scrubbing

Offside scrubbing showing 'lip'

Nearside

[AGS]

Here's a couple more

Nearside showing concave profile

Offside