AP brake pad replacement
Discussion
mfp4073 said:
I decided to do some braking tests today, I used the AP bedding in procedure. When the brakes are cool or have been warmed up everything is fine. However, once the brakes become hot I can hear a rotational grinding noise from the front offside wheel?
When the brakes cool off again the noise goes away.
I've had the wheel off and everything looks OK. This only started when I put in new brake pads.
I'm thinking maybe the central alloy bell expands through high temps, it then just catches the brake pad backing plate causing the noise?
Has anyone on hear had a similar issue?
Might be just worth throwing the 'old' original pads back on John and just confirming that it is the new pads causing the issue? I wonder if there is a tolerance issue with the size of the pads/backing plates etc. compared with the DS2500's?When the brakes cool off again the noise goes away.
I've had the wheel off and everything looks OK. This only started when I put in new brake pads.
I'm thinking maybe the central alloy bell expands through high temps, it then just catches the brake pad backing plate causing the noise?
Has anyone on hear had a similar issue?
Edited by mfp4073 on Saturday 6th July 18:59
Or, and I know not strictly recommended, but swap the pads around, see if the issue disappears.
It might be possible to remove a little material from what ever seems to be catching.
I'm just sorry you seem to be having trouble with what's supposed to be a proven brake solution for these cars and being that the kit is pretty much new.
Lincsls1 said:
Might be just worth throwing the 'old' original pads back on John and just confirming that it is the new pads causing the issue? I wonder if there is a tolerance issue with the size of the pads/backing plates etc. compared with the DS2500's?
Or, and I know not strictly recommended, but swap the pads around, see if the issue disappears.
It might be possible to remove a little material from what ever seems to be catching.
I'm just sorry you seem to be having trouble with what's supposed to be a proven brake solution for these cars and being that the kit is pretty much new.
Yes I was considering swapping the pads back to the DS2500's and maybe even swap the ceramic pads from left to right as well. It does seem odd the problem started with the new pads. I will have ago next week and see what happens. Or, and I know not strictly recommended, but swap the pads around, see if the issue disappears.
It might be possible to remove a little material from what ever seems to be catching.
I'm just sorry you seem to be having trouble with what's supposed to be a proven brake solution for these cars and being that the kit is pretty much new.
It is a bit annoying to be messing around with a new brake kit but I'll get it sorted eventually. "keep calm and carry on" as they say.
Your brakes should be bedded in by now, one thing I did notice is that you can overwhelm the ABS system if you really get carried away and stand on them !!!!!! and that was on a warm dry day.
Anyway as its dry tomorrow I'm off out for a long cruise around Northumbeland, that should clear out all eight cylinders if nothing else.
John
Not sure mine have bedded in fully yet as the car is seriously and deliberately under used! However, I am happy with how they feel at the moment and can already tell that they have immense capability and are far stronger than my old tired stock setup - and they should be!
Just pleased to have a silent braking system now and pulse free pedal more than anything as my originals well past their best.
Just pleased to have a silent braking system now and pulse free pedal more than anything as my originals well past their best.
Just an update on my AP saga. I'll condense the story here to make it easier to follow.
When I had my AP kit fitted last year I carried out the required beding in procedure.
There was one occasion when I heard a strange noise coming from the brakes, I put this down to heat in the pads, as it disappeared fairly quickly once they had cooled off.
I drove the car for a couple of months without any enthusiastic braking and all seemed well. The car was then garaged and spent 8 months off the road.
This month I put the car back on the road and replaced my DS2500's with Pedders ceramic pads all round. ( less dust with ceramics )They were bedded in as per pedders instructions.
I then tried the AP's bedding in procedure for comparison which is more involved and generates more heat. I again noticed that the strange grinding noise was back. Once the brakes had cooled off everything was fine again.
I got back home and examined the calipers I took the driver side brake pads out, and removed the caliper and I then found the reason for the noise.
The actual disc had ground a groove into the underside of the caliper itself and was chewing it up as the disc expanded due to heat.
I'm glad I found the problem but.....how to sort it out?
The saga continues.
When I had my AP kit fitted last year I carried out the required beding in procedure.
There was one occasion when I heard a strange noise coming from the brakes, I put this down to heat in the pads, as it disappeared fairly quickly once they had cooled off.
I drove the car for a couple of months without any enthusiastic braking and all seemed well. The car was then garaged and spent 8 months off the road.
This month I put the car back on the road and replaced my DS2500's with Pedders ceramic pads all round. ( less dust with ceramics )They were bedded in as per pedders instructions.
I then tried the AP's bedding in procedure for comparison which is more involved and generates more heat. I again noticed that the strange grinding noise was back. Once the brakes had cooled off everything was fine again.
I got back home and examined the calipers I took the driver side brake pads out, and removed the caliper and I then found the reason for the noise.
The actual disc had ground a groove into the underside of the caliper itself and was chewing it up as the disc expanded due to heat.
I'm glad I found the problem but.....how to sort it out?
The saga continues.
Edited by mfp4073 on Friday 12th July 14:43
Edited by mfp4073 on Wednesday 14th August 08:25
That's a really strange issue you have there.
The only time I've had that exact issue, is when a bent my rear hub on my old ZT260 which made the disc just skim the caliper.
This 'bend' was totally undetectable by eye, even when the new hub was side by side with the old. Talking just a couple of mm here.
Is it possible you have anything similar at all? Or is there any play at all in something that would allow that contact when the expansion of the disc is considered?
Otherwise we're looking at a tolerance issue with the new kit either disc or caliper.
As for a fix, what about a small shim washer? Could that work? I'm just throwing ideas about because without looking properly I'm not sure how the caliper bolts to the hub.
The only time I've had that exact issue, is when a bent my rear hub on my old ZT260 which made the disc just skim the caliper.
This 'bend' was totally undetectable by eye, even when the new hub was side by side with the old. Talking just a couple of mm here.
Is it possible you have anything similar at all? Or is there any play at all in something that would allow that contact when the expansion of the disc is considered?
Otherwise we're looking at a tolerance issue with the new kit either disc or caliper.
As for a fix, what about a small shim washer? Could that work? I'm just throwing ideas about because without looking properly I'm not sure how the caliper bolts to the hub.
Yes this is an odd one!!!! I thought about shims but a left or right movement won't work, I need a to move the caliper forward and away from edge of the disc. I can't really see how to do that.
Hopefully as there is still a few days left on the warranty I might get the job sorted that way?
We shall see.
Hopefully as there is still a few days left on the warranty I might get the job sorted that way?
We shall see.
Edited by mfp4073 on Wednesday 14th August 08:27
Here's another thought John.
Am I right in thinking the CV8 Monaro has to have the caliper mounting holes drilled out to accommodate the bigger bolts used for the AP kit?
The VXR car doesn't. I'm wondering if any slight inaccuracy drilling here would essentially mean the caliper being secured in a fractionally different position forward or backward just reducing the clearance enough not to tolerant the expansion of the disc?
Am I right in thinking the CV8 Monaro has to have the caliper mounting holes drilled out to accommodate the bigger bolts used for the AP kit?
The VXR car doesn't. I'm wondering if any slight inaccuracy drilling here would essentially mean the caliper being secured in a fractionally different position forward or backward just reducing the clearance enough not to tolerant the expansion of the disc?
Yes you are correct, the calipers need to be drilled out to fit the CV8. It is a possibility they were drilled slightly out, but I'm not convinced about that one.
I have a feeling it's a manufacturing issue, I guess AP will want to examine it and make a decision.
I can imagine it's going to be a right pain to sort it all out.
Thanks for your suggestions, but before I do anything I'll see how the warranty pans out just in case.
John
I have a feeling it's a manufacturing issue, I guess AP will want to examine it and make a decision.
I can imagine it's going to be a right pain to sort it all out.
Thanks for your suggestions, but before I do anything I'll see how the warranty pans out just in case.
John
Edited by mfp4073 on Wednesday 14th August 08:28
Yet another update....
AP have examined my problematic brake caliper and have stated that it is within their specification albeit at the edge of the factory tolerance level.
As Walkinshaw had to drill out the mounting bracket they viewed this as a none approved modification and therefore the factory warranty is now void.
Walkinshaw stand by their modification and in their opinion the mounting holes were drilled correctly and they are of the opinion the caliper had a fault.
Thankfully I received a new AP caliper today and it fits perfectly. The join were the two halfs of the caliper match together is also perfectly in line.
I fitted it all back together and brakes feel a lot better than before. I carried out the bedding in procedure a couple of times just to really heat everything up, and thankfully there was no grinding of the disc into the underside of the caliper.
Tomorrow I'll bleed the system again as there are still a few air bubbles to get rid off.
So a big thankyou to Dave Elston at Walkinshaw performance for helping me out it was more than appreciated.
As for AP, I can see their point of view, but when you looked at the caliper it was clearly not right.
AP have examined my problematic brake caliper and have stated that it is within their specification albeit at the edge of the factory tolerance level.
As Walkinshaw had to drill out the mounting bracket they viewed this as a none approved modification and therefore the factory warranty is now void.
Walkinshaw stand by their modification and in their opinion the mounting holes were drilled correctly and they are of the opinion the caliper had a fault.
Thankfully I received a new AP caliper today and it fits perfectly. The join were the two halfs of the caliper match together is also perfectly in line.
I fitted it all back together and brakes feel a lot better than before. I carried out the bedding in procedure a couple of times just to really heat everything up, and thankfully there was no grinding of the disc into the underside of the caliper.
Tomorrow I'll bleed the system again as there are still a few air bubbles to get rid off.
So a big thankyou to Dave Elston at Walkinshaw performance for helping me out it was more than appreciated.
As for AP, I can see their point of view, but when you looked at the caliper it was clearly not right.
Edited by mfp4073 on Thursday 1st August 18:35
Edited by mfp4073 on Wednesday 14th August 08:30
Nice one John.
And thanks for keeping us all updated as this is useful stuff. You've been unlucky then it would seem having a defective caliper.
Glad you've sorted it now.
Have to say very happy with my kit, and very much recommend it. Massive improvement, much more confidence inspiring.
Well worth the money, definitely the brakes the car should have had as standard.
And thanks for keeping us all updated as this is useful stuff. You've been unlucky then it would seem having a defective caliper.
Glad you've sorted it now.
Have to say very happy with my kit, and very much recommend it. Massive improvement, much more confidence inspiring.
Well worth the money, definitely the brakes the car should have had as standard.
It seems people are confusing the feeling they get from brake boosters vs what a big brake kit does.
The APs will help avoid fade and will scrub off speed better but under normal application you’ll be pushed to notice. Also any carbon pad will give even less feel at low speeds and give s
te response unless warm.
Ds2500 are good, yellow stuff are good, ap brakes are good. The amount of servo assist means you get good pedal feed back.
If you want the binary brakes of a car 20 years newer then buy a newer car or learn to use these brakes and the benefit of feel they give. Most people don’t even know how to emergency stop.
The APs will help avoid fade and will scrub off speed better but under normal application you’ll be pushed to notice. Also any carbon pad will give even less feel at low speeds and give s
te response unless warm. Ds2500 are good, yellow stuff are good, ap brakes are good. The amount of servo assist means you get good pedal feed back.
If you want the binary brakes of a car 20 years newer then buy a newer car or learn to use these brakes and the benefit of feel they give. Most people don’t even know how to emergency stop.
I'm not confusing anything regarding these brakes thank you.
I completely understand the physics behind the braking system.
I could immediately tell a difference under normal operation because for the same pedal travel and effort, I now have bigger pads and calipers clamping bigger discs so they feel a lot stronger all of the time. So for any given pedal travel the braking force is now more than it was. And yes of course they will take a lot more fast road punishment then the stock brakes.
However under one good emergency stop condition, the limiting factor is actually the tyres and assuming the stock system can lock the brakes or at least trigger the ABS then a bigger kit won't be any better in this instance apart from perhaps being able to trigger the ABS fractionally quicker.
I completely understand the physics behind the braking system.
I could immediately tell a difference under normal operation because for the same pedal travel and effort, I now have bigger pads and calipers clamping bigger discs so they feel a lot stronger all of the time. So for any given pedal travel the braking force is now more than it was. And yes of course they will take a lot more fast road punishment then the stock brakes.
However under one good emergency stop condition, the limiting factor is actually the tyres and assuming the stock system can lock the brakes or at least trigger the ABS then a bigger kit won't be any better in this instance apart from perhaps being able to trigger the ABS fractionally quicker.
George Smiley said:
It seems people are confusing the feeling they get from brake boosters vs what a big brake kit does.
The APs will help avoid fade and will scrub off speed better but under normal application you’ll be pushed to notice. Also any carbon pad will give even less feel at low speeds and give ste response unless warm.
Ds2500 are good, yellow stuff are good, ap brakes are good. The amount of servo assist means you get good pedal feed back.
If you want the binary brakes of a car 20 years newer then buy a newer car or learn to use these brakes and the benefit of feel they give. Most people don’t even know how to emergency stop.
I was out in my car yesterday and only did slow town driving in day to day traffic.The APs will help avoid fade and will scrub off speed better but under normal application you’ll be pushed to notice. Also any carbon pad will give even less feel at low speeds and give s
te response unless warm. Ds2500 are good, yellow stuff are good, ap brakes are good. The amount of servo assist means you get good pedal feed back.
If you want the binary brakes of a car 20 years newer then buy a newer car or learn to use these brakes and the benefit of feel they give. Most people don’t even know how to emergency stop.
Since having just changed my AP caliper I noticed a world of difference in brake feel and stopping ability compared to the faulty one and that was with cold pads.
The new pedders ceramic pads are first rate too even when cold the lack of dust is very impressive and they are completely quiet in operation.
As I've said a few times when I first fitted the AP's I was expecting to just touch the brake pedal and feel their instant stopping power with very little to no brake pedal travel, especially when you take into account how big the set up is.
However, as these brakes are really track focused when you think about it if you had that instant grab everytime you touched the brakes you no doubt would unbalance the car.
So as you say I did confuse the feeling of the brake booster with what a big brake kit does which is to allow a driver to continue to use the brakes without them fading out every two minutes.
So that wrong assumption compounded with a faulty caliper led to this long discussion. Hopefully it will be of interest to some owners, and yes after all the hassle I've had I'm glad I've got AP brakes.
Edited by mfp4073 on Wednesday 14th August 08:22
George Smiley said:
Glad it’s fixed 
You will get more surface rust, this simply means a bit of brake trailing to resolve, the discs don’t warp
Yes I rember reading the avalanche of complaints about AP brake disc warp years ago. If I remember correctly the problem iwas caused by brake pad transfer causing high spots on the disc?You will get more surface rust, this simply means a bit of brake trailing to resolve, the discs don’t warp
As far as rust goes I'll keep the discs nice and clean.
Edited by mfp4073 on Wednesday 14th August 08:43
Edited by mfp4073 on Wednesday 14th August 10:05
RipGMH said:
My mechanic advised that rather than break gently to ‘protect’ the brakes with good brakes you want to brake a bit later and heavier to avoid glazing the disks.
Good advice, I brake as normal for day to day driving, but on a quiet road you can brake harder and deglaze the pads when required.Edited by mfp4073 on Wednesday 14th August 18:12
Your mechanic is talking out of his arse.
Normal braking is good practice, late braking if you are on the track or spanking it. If you get surface spots, which you will, the easiest way to clear it is go up and down one junction of the motorway, trailing on the brakes from 70 gradually slowing down to 50 a few times followed by some stabbing on and off, followed by trailing. Repeat on the return, jobs done.
Alternately pour oil over the disks to keep them rust free but don't cry when you don't stop. disks will be shiney
Normal braking is good practice, late braking if you are on the track or spanking it. If you get surface spots, which you will, the easiest way to clear it is go up and down one junction of the motorway, trailing on the brakes from 70 gradually slowing down to 50 a few times followed by some stabbing on and off, followed by trailing. Repeat on the return, jobs done.
Alternately pour oil over the disks to keep them rust free but don't cry when you don't stop. disks will be shiney
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