Cold braking performance

[Patrick Bateman]

Does anyone else have issues with braking performance when cold?

Don't get me wrong, I know cold braking is never going to be peak performance but this always happens to me a while after getting the discs and pads changed and is at the sort of level where an emergency stop would look absolutely pathetic. They feel ok until you go to press the pedal reasonably hard then you realise they've got nothing else to give, I'd struggle to get the ABS to trigger in the wet.

They're fine for a while after getting changed, but being a second car it can sit for a few days between drives (although it's not a garage queen, will do 5000 miles a year) and then eventually the brakes become genuinley crap until, in road driving terms, you put a lot of heat into them.

For instance, my discs and pads were only changed last summer yet tonight on the drive back from work (quiet enough roads I might add...), I was having to do a lot of heavy braking from ~70 to 30 numerous times before they would even become reasonable. If I don't drive the car for a few days now they'll end up the exact same, it's not like they're all crusty and just needing cleaned up.

I thought I had resolved this when switching to TRW front pads but that no longer seems to be the case. Given these are rarely daily drivers, I'd assume some of you may have had the same issue.

 

[MarcB]

Has the pads became glazed ?

My pads had only been changed around 3 months ago and had to get them stripped and cleaned and all rubbed down with emery paper to rough them up.

 

[photo_ed]

I've never had a significant problem with the Trophy brakes from cold, however, my 200 Cup sometimes suffers from the symptoms you describe, especially if it's not been used for a while. A good drive out usually sorts it though.

When I had Ferodo DS2500 pads fitted to the Trophy last year I was half expecting, after chatting to a few folks about pad choice, to have a small drop in initial cold performance, but this certainly hasn't been the case, the pedal feel and bite has actually improved all round. Which makes me think that the Brembo's which were fitted before, despite having plenty of material on them had 'gone off' a bit, which I also suspect is the case with my Cup now.

Edit: Just had a thought, when did you last have the brake fluid changed, this could be the root of your problem if it's past it's best?

 

[sj2112]

Are your calipers all good and if original maybe could benefit from a refurb?

 

[Paul Morris]

As above, get the fluid changed. I had similar issues recently. I’m no expert but I think the garage said the fluid had 2% water content (no idea how bad that is). I also had to change the seal and lid to the brake fluid reservoir as it had perished. Bought three litres of fluid but only needed one. The original stuff was a different colour so it was easy for the garage to see when it was flushed. Might need two litres to be sure.

Since the fluid change the discs and pads are fine.


Sent from my iPhone using Tapatalk

 

[RsMax]

Just three questions:

1. Which pads and discs do you use? Are they worn?
2. When was the last time you changed your brake fluid?
3. Any road salt on the car? Any dirt on the pads / discs?
4. Have you checked if the calipers work?

I would check brake fluid as said before.

 

[Patrick Bateman]

Just three questions:

1. Which pads and discs do you use? Are they worn?
2. When was the last time you changed your brake fluid?
3. Any road salt on the car? Any dirt on the pads / discs?
4. Have you checked if the calipers work?

I would check brake fluid as said before.

Three eh? /

Thank you all for the input. Brake fluid was actually changed at the same time as all discs and pads last summer. Everything bar the front pads is OE Renault, front pads are TRW which I've liked in the past compared with OE Renault. I'd fully overhauled the calipers in 2017 (see photo). The driver side one needed replaced when the discs and pads were last done due to one of the bleed nipples shearing unfortunately.

The discs still look in good condition to me. One point of note would be that the car does a noticeable pull to the left when braking hard- it had also done this for a while before I refurbished the calipers.

Regardless of that, the braking performance does get good again after putting a lot of heat into them, albeit it takes far too much effort to get to this. Why would brake fluid have an influence on this from cold?

Would this also make sense if the pads were glazed? It seems to me it's inaction that causes them to become crap over time. I'd have guessed if the pads were glazed the brakes would be crap regardless of being hot or cold...correct me if I'm wrong.

 

[Big Dave]

Something else to throw into the mix.
IF,, youve overheated the pads, ie had a bit of brake fade, ive found they dont work aswell afterwards...
I had this after a trackday i did in another car, the pads never were the same again...And i swapped them out pretty soon afterwards.

 

[Patrick Bateman]

What conditions would cause the pads to glaze?

I haven't been near brake fade.

 

[Oracle]

. One point of note would be that the car does a noticeable pull to the left when braking hard- it had also done this for a while before I refurbished the calipers.

Rear caliper imbalance can cause rear wheel steering.

 

[Patrick Bateman]

Hmm the rear have just been cleaned up as one was sticking so I'd hope that wasn't contributing. Maybe the fronts need a proper clean as well.

Regarding pads I'm tempted to stick some Pagid ones in, haven't tried them before and they're not expensive.

 

[Oracle]

Hmm the rear have just been cleaned up as one was sticking so I'd hope that wasn't contributing. Maybe the fronts need a proper clean as well.

Regarding pads I'm tempted to stick some Pagid ones in, haven't tried them before and they're not expensive.

Does it pull to the Left or Right?

And only initially when making an emergency stop, but not under spirited but progressive hard braking?