Poor braking performance

DanSkelts · Aug 19, 2024

Hi all, apologies for a bit of a long story but anyway hopefully you can help.

I have just rebuilt my 182s front brake calipers after an MOT advisory, but now the brake pedal feels longer than it used to and brakes dont seem to bite very well at all.

After the MOT i took the car for a ~30min drive as the tester didnt make a massive deal out of the seizing brakes, but by the time i got to the destination i noticed they were smoking a little, which prompted the rebuild.

Pads seemed ok possibly a little glazed, but i sanded them down a bit with 120grit to get the shine off, would this sort out glazed pads or should they be replaced?

Dont think there is air in the system, i had the brake pedal chocked in the depressed position while undertaking the work and no fluid dripped out.

Bled the system with a pressure bleeder and no bubbles. But the pedal seems to travel further before going hard now compared to before. Although it does go hard before reaching the floor. But brakes dont feel like they stop as well as they used to.

I did manage to get abs to fire when stamping on it but still doesnt feel as sharp as it should in an emergency stop scenario.

Thanks in advance.

chazza114 · Aug 19, 2024

There's likely an air bubble trapped in the ABS pump, it seems to happen a lot with Clios. If you've access to the Renault Clip system, I'm fairly sure you can plug that in and it'll run a process to move the air out of the system. If you don't, you can do what I and most others do, which is to brake hard a few times on some wet grass or gravel. This should cause the ABS to fire off properly and shift the air. Then just re-bleed your brakes and go from there.

Mr Underhill · Aug 19, 2024

It could be any number of things but here’s some suggestions:

Replace the Pads, it’ll rule out pad glazing as a contributing factor.
Try re-bleeding the brake system to ensure all air is removed. Sometimes, bleeding with the engine running (ABS active) can help.
Are the calipers functioning smoothly, with the pistons retracting and extending as they should? After a rebuild, the calipers and pads need time to re-seat properly.
How old is the brake fluid? It might have absorbed moisture, which can lead to a spongy pedal feel.

DanSkelts · Aug 19, 2024

Mr Underhill said:
It could be any number of things but here’s some suggestions:

Replace the Pads, it’ll rule out pad glazing as a contributing factor.

Try re-bleeding the brake system to ensure all air is removed. Sometimes, bleeding with the engine running (ABS active) can help.

Are the calipers functioning smoothly, with the pistons retracting and extending as they should? After a rebuild, the calipers and pads need time to re-seat properly.

How old is the brake fluid? It might have absorbed moisture, which can lead to a spongy pedal feel.

Hi, calipers are all running as new after the rebuild, brake fluid was unopened from a few months back. Think i will try and get the abs to fire a few times and then bleed a load of cheap stuff through it.

Im not sure if the long pedal is in my head or not, could just be the pads arent good anymore i suppose.

It seems like maximum braking was achieved with less brake pedal travel before if that makes sense?

Thanks for the suggestions!

JamesBryan · Aug 19, 2024

How much pad material is left?

Mr Underhill · Aug 19, 2024

I’ve had some awful pads over the years, namely Brembo and Motrio. Even HP2000 (Brembo Sport) didn’t help. I’m running DS2500 now and the pedal feel is really good.

SharpyClio · Aug 19, 2024

Make sure the pads are located square in the callipers, after 4 litres of brake fluid I realised one of my rears was just not quite straight and it gave a really terrible long and soft feel.

DanSkelts · Aug 19, 2024

JamesBryan said:
How much pad material is left?

Between 5-10mm plenty of material left, the are mintex 1144 i think.

JamesBryan · Aug 19, 2024

DanSkelts said:
Between 5-10mm plenty of material left, the are mintex 1144 i think.

Won't be that then.

I was thinking of the extra travel you get with low pads.

Do you have a solid pedal with the engine off?

DanSkelts · Aug 19, 2024

JamesBryan said:
Won't be that then.

I was thinking of the extra travel you get with low pads.

Do you have a solid pedal with the engine off?

Yes goes solid with engine off and when its on, just feels longer than normal when on.

I can get it to move a little when its off but thats with a considerable amount of force

R3k1355 · Aug 19, 2024

Deffo sounds like air in the ABS pump

Brigsy · Aug 19, 2024

Needs bleeding again, air in the system is causing a longer pedal. Activate abs pump with diagnostics when bleeding.

DanSkelts · Aug 23, 2024

Right, so i've activated the abs a few times on a drive, then ive gone through about 3L of brake fluid bleeding each corner twice.

When i have the eezibleed set up i press the brake pedal 5-10 times as i have seen suggested in another post. This then causes loads of air bubbles to eventually come out the nipple.

Brake pedal then does go hard, but as soon as i turn the car on the pedal goes straight to the floor, even worse than before which i dont understand as no more air has got in the system.

Issue with master cylinder or servo?

MLB · Aug 23, 2024

100% sure the calipers are OK, even after the rebuild?

It sounds like what I had on a previous 182, rebuilt one caliper, put in new fluid and ds2500 pads, ran about 4l of brake fluid through it to get rid of air in the abs system and still had a soft pedal.

In the end I replaced the caliper I refurbished with an exchange unit and all was well again.

DanSkelts · Aug 23, 2024

MLB said:
100% sure the calipers are OK, even after the rebuild?

It sounds like what I had on a previous 182, rebuilt one caliper, put in new fluid and ds2500 pads, ran about 4l of brake fluid through it to get rid of air in the abs system and still had a soft pedal.

In the end I replaced the caliper I refurbished with an exchange unit and all was well again.

Yes pretty confident in the caliper, was good enough to lock the wheels the other day and no leaks that i can see.

JamesBryan · Aug 23, 2024

Where abouts are you?

Maybe someone local could activate the pump for you using diagnostics.

DanSkelts · Aug 23, 2024

JamesBryan said:
Where abouts are you?

Maybe someone local could activate the pump for you using diagnostics.

Im in Plymouth, wouldnt feel safe driving it now, much worse than before i started bleeding again

Mr Underhill · Aug 23, 2024

DanSkelts said:
Im in Plymouth, wouldnt feel safe driving it now, much worse than before i started bleeding again

I think it's as James has already alluded to. The ABS module can trap air inside it. If the ABS module was not properly bled, air bubbles will still be in the system, leading to a soft brake pedal when the ABS pump activates after starting the engine.

I have got around this in the past by finding a gravel area and trying to activate the ABS, then coming back and rebleeding. It's a proper mess about and you go through lots of brake fluid. Diagnostics is an easier solution.

DanSkelts · Aug 23, 2024

Mr Underhill said:
I think it's as James has already alluded to. The ABS module can trap air inside it. If the ABS module was not properly bled, air bubbles will still be in the system, leading to a soft brake pedal when the ABS pump activates after starting the engine.

I have got around this in the past by finding a gravel area and trying to activate the ABS, then coming back and rebleeding. It's a proper mess about and you go through lots of brake fluid. Diagnostics is an easier solution.

Hmm I did go for a drive activating ABS quite alot prior to the second round of bleeding, perhaps not enough. Does anyone know the symptoms of a bad master cylinder?

Mr Underhill · Aug 23, 2024

DanSkelts said:
Does anyone know the symptoms of a bad master cylinder?

With the engine off, apply steady pressure to the brake pedal. If it slowly sinks to the floor, you might have an issue.

DanSkelts · Aug 23, 2024

Mr Underhill said:
With the engine off, apply steady pressure to the brake pedal. If it slowly sinks to the floor, you might have an issue.

Ah okay thats good to know thanks, i imagine its just more air in the system somehow, will persevere a bit longer.

I changed the rear lines for braided a while back and never had any issues like this its a right pain.

Mr Underhill · Aug 23, 2024

DanSkelts said:
Ah okay thats good to know thanks, i imagine its just more air in the system somehow, will persevere a bit longer.

I changed the rear lines for braided a while back and never had any issues like this its a right pain.

When I restored my first 182, I had every single part off it at one stage. All brake lines removed, subframes, you name it. It took about 3 days of swearing and endless litres of brake fluid, runs up and down the road, to finally get a decent pedal. Lesson learned.

One story I often tell is when I asked the missus to jump in and pump the pedal as I had a slight leak in the top of my eezibleed system.

Noticing there was no fluid coming out of the caliper nozzle, I shouted "pump the fookin pedal", to which she said "I am".

I go around and she's pumping the clutch

I'd completely lost the plot. 🤣

DanSkelts · Aug 23, 2024

Mr Underhill said:
I go around and she's pumping the clutch

🤣🤣

Advikaz · Aug 23, 2024

Mr Underhill said:
It could be any number of things but here’s some suggestions:

Replace the Pads, it’ll rule out pad glazing as a contributing factor.

Try re-bleeding the brake system to ensure all air is removed. Sometimes, bleeding with the engine running (ABS active) can help.

Are the calipers functioning smoothly, with the pistons retracting and extending as they should? After a rebuild, the calipers and pads need time to re-seat properly.

How old is the brake fluid? It might have absorbed moisture, which can lead to a spongy pedal feel.

What he said

DanSkelts · Oct 20, 2024

Right, little bit of a revival as im back on the task after attempting to bed in new caliper seals and see if theres any improvement. There wasnt.

I've now rebuilt the calipers - again, this time with a bigg red kit rather than an ebay one. And this time only using brake fluid as lube rather than the supplied silicone grease. I have also changed the pads.

Now i cant see how air would be in the abs pump as i had zero fluid coming out the lines when rebuilding calipers as brake pedal was chocked, and i could see no fluid leaking from lines. The reservior never ran dry either.

Either way i went and activated the abs pump on a gravel car park (a lot). And no more air has come out.

I must of gone through over 10L of brake fluid, used every brake bleed method known to man, and every combination of bleed order i can. Car on and off.

Now when the car is off the pedal gets firm but there is still some travel when i press hard. Then its very soft when turned on, although it doesnt go right to the floor like if a bleed nipple was open.

Anyone have any other ideas of what could be causing this?

Cheers

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