View Full Version : Cooked Disk Rotor
jimnielsen
24-09-11, 08:22
Finally had a chance to remove the disks from the front of my car after Sandown last weekend. Looks like its been to a BBQ! The other side is cracked too - although not as badly as this one. The pads are Ferrodo DS2500's but I've clearly had them out of their heat range...
Steve Webb
24-09-11, 08:33
Yep they have well and truly been cooked. Did you have trouble with the brake fluid during the day? What fluid are you using?
Hi, Jim!
Have you dropped out the bolts solution for clamping the wheels? It seems to me you're using nuts, isn't it? Thank you.
Cheers,
Cristian.
jimnielsen
24-09-11, 09:48
Steve,
i am using the best fluid that money can buy - AP 600 - but I still boiled it - I need brake ducting and I don't have any....
Cristian - yes, I am using thread in studs - with normal wheel nuts - so much easier to get the wheels on and off because the wheel sits on the studs..
jim
Jim, could you please give me (us) some more details about thread in studs that you have on your Q4? Maybe some pics if you have.
At a local wheel shop here they have managed to "fix" 2 holes on the hub (because I am using wobble bolts for 4x100). I would really like to go for thread in studs solution and get 4x98 rims.
Steve Webb
24-09-11, 13:50
Just watching the F1 build-up for quali at Singapore, and they have just had a closeup of the Mclaren front brakes. Vented, but not grooved at all. I know they are carbon ceramic but surely some of the brake disc tech is transfereable.
So are all these grooved and drilled discs really any better in terms of outright performance or are the grooves etc there to over come something else (glazing of pads)
Grooves were invented when the Honda CB750 with a stainless front brake disc had trouble in the rain. Cars have dry internally vented discs and don't need grooves at all. It's just something that people figured would be better, because it once made sense on a motorcycle 40 years ago.
do not buy the ferodo's it's crap, just like the ds3000
Steve Webb
25-09-11, 07:59
From what I'd read, modern pads, which contain a resin to hold them together, give off gas when the pads are hot and the brakes applied, (the resin holding the braking material together vaporises) If this gas doesn't have a route to get away from between the pad and disc it forms a layer and you get a similar effect to Aquaplaning where the pads float over the surface of the disc.
This is the reason for the grooves, to allow the gas produced to vent away from the pad.
How true all of the above is, or how much of a problem it causes is up for debate. Although it can't be that much of a problem, otherwise F1 cars, the extreme end of the performance envelope, wouldn't be using standard non-grooved discs.
Yes, I've read about the gasses to, also that the grooves are to prevent hot pads from glazing by scraping off the overheated layer.
In the pictures above it's clear the grooves are creating hot spots, which isn't good...bigger brakes or better cooling seems the way forward.
All I know is that they're damn noisy and I won't be fitting them to a road car in future :lol:
wrinx
Had to look them up, but here are a couple of mine cooked discs.
http://i115.photobucket.com/albums/n288/BrulTM/Alfa%20155%20Q4%20repair/Overheated%20brake%20discs/Overheatedfrontdiscs.jpg
http://i115.photobucket.com/albums/n288/BrulTM/Alfa%20155%20Q4%20repair/Overheated%20brake%20discs/Overheatedandcrackedfrontdisc.jpg
http://i115.photobucket.com/albums/n288/BrulTM/Alfa%20155%20Q4%20repair/Overheated%20brake%20discs/Overheatedandcrackedfrontdiscoppositeside.jpg
It was all the way through, except for the centre heart of the disc.
Close up
http://i115.photobucket.com/albums/n288/BrulTM/Alfa%20155%20Q4%20repair/Overheated%20brake%20discs/IMG_5735.jpg
jimnielsen
25-09-11, 10:53
looks a lot like mine - mine also has a fair bit of hairline surface cracking. Looks like they are only good for one season - at least the way I use em...
jim ~
Too many groves and too deep. They only need to be 0.9mm.
The last of the Fiat Coupes have drilled rotors from new.
jimnielsen
27-09-11, 07:08
- Yes, I am getting some brake ducting sorted. The car stops pretty well as it is - but at Sandown I was braking from 220 kph 20 times in one session - really way over what the braking setup I have can reasonably expected to do. If I can get the cooling setup correctly I think it will make a big difference..Will try DS3000 pads next time instead of the DS2500's
Already got the new rotors - less than seven days from order till delivery from the UK.
jimnielsen
27-09-11, 07:26
Wheel stud pictures for XTI (Cristian)
There are the studs that I use on my car - I have removed then because I can remove the disk rotor more easily if they are out...They have a 'hex' drive in the front that makes them easy to put in. You have to be careful not to put them in too far or they will foul the front of the hub upright..
cheers, jim..
Very kind of you Jim, thanks a lot!
Do you also use some chemical liquid to prevent unscrewing bolts from the hub? Or it is not necessary because of the constriction force applied by screwing the lug nut?
Cheers,
Cristian.
You have to be careful not to put them in too far or they will foul the front of the hub upright..
Does that mean you leave them loose in the hub?
Steve Webb
28-09-11, 15:15
Technically, studs are stronger than bolts due to the way they clamp whatever they are screwed into, provided they are inserted correctly.
You need to make sure they are tightened up correctly to ensure that whatever they are screwed into is compressed between the treaded part of the stud and the shoulder of the stud.
I'll try to find a pic which will explain it better.
the layer on the disc is pad material and you do need that! because that is making more friction, just like on the track where there is rubber on the track you have more friction, so more grip. the cracking is due too bad disc and pads!
and don't buy the ds3000 it's the same crap or maybe wurse
- Yes, I am getting some brake ducting sorted. The car stops pretty well as it is - but at Sandown I was braking from 220 kph 20 times in one session - really way over what the braking setup I have can reasonably expected to do. If I can get the cooling setup correctly I think it will make a big difference..Will try DS3000 pads next time instead of the DS2500's
Already got the new rotors - less than seven days from order till delivery from the UK.
First, the DS2500 pad is a semi street/race pad, you should use the DS3000 (or switch to Performance Friction) if your car is an only-trackday Q4.
Second, are you really import the discs from the UK while you can buy one of the best disc (http://dba.com.au/4000-series) locally ? :)
jimnielsen
04-10-11, 05:17
Hi jnk - dba cannot supply the fiat coupe vt20 305mm disk in any format. The ones that I was using were the last pair that they had and they did not have another production run. I could certainly purchase the product in the dba 4000/5000 format but they have never made any. The ones from the UK are so cheap that I can replace them once a year (and will probably need to....)
Steve - Yes, the studs are 'loose' but I do put thread locker on so that they don't free rotate. They were quite still to get out because of this....
jim..
So dba has stopped the production of all versions of the 305x28 disc ?
Sh.t , I thought that I'm going to buy the dba discs next year when my brake upgrade is planned.
jimnielsen
06-10-11, 22:24
no, you wont be able to get them from DBA. They only ever made one batch of them. The rotors do not suit ANY car that was ever actually cold in Australia (to the best of my knowledge) - so they are not keen to make others..
jim..
If you use road discs on a modified track car you are always going to have problems - the sight of those discs alone would have me upgrading immediately to something better suited to the job and not going down the same route again.... :doh:
I would suggest moving on ASAP to some separate bells (or top hats if you like) and good quality (AP) 32 x 315 discs
If you carry on and don't learn from what you are seeing you are heading for a big accident, I've got better brakes than you on my Fiat Coupe road/occasional trackday car, I (and others around me) appreciate being able to stop reliably. Good brakes are as important, if not more so than a bigger power output.
http://i103.photobucket.com/albums/m127/Deltona_II/Brakes/BrakesUBBB003.jpg
http://i103.photobucket.com/albums/m127/Deltona_II/Brakes/BrakesUBBB005.jpg
Steve Webb
09-10-11, 12:41
On a slightly different note, how do you find the wilwood calipers?
On a slightly different note, how do you find the Wilwood calipers?
I found them by using the internet. :thumbsup:
Seriously, I haven't had them fitted long and I know Wilwood are not in the same league as AP or Alcon and the price reflects this, I would say they are more than good enough for road use. I am using Redstuff pads, there is no squeal and they work great.
A trackday will give me more knowledge of them.
jimnielsen
09-10-11, 20:49
Are the AP disks and top hats standard (unmodified) AP equipment? Can you tell me the part numbers please?
Do they fit under 16" wheels - I THINK that I could use 315mm disks - but certainly not 320..
jim..
Are the AP disks and top hats standard (unmodified) AP equipment? Can you tell me the part numbers please?
Do they fit under 16" wheels - I THINK that I could use 315mm disks - but certainly not 320..
jim..
Only the discs, calipers and pads are off the shelf, the rest is specially made:
http://i103.photobucket.com/albums/m127/Deltona_II/Brakes/BrakesUBBB001.jpg
They are a 310 x 32 disc and fit under a standard 16" wheel easy, I have some AP on my other car which are 315, but because the AP caliper is more performance biased item (less bulky) I could run a 320 disc with those in a Motorsport 16" wheel.
If tempted to go the floating disc route be sure they are designed correctly :thinking-011: they shouldn't be clamped up tight on capscrews and any expansion slots should not be a square ended cut. If they are they are made like this ^^^^ there is a high probability they will fail in a bad way, trying to clamp steel and aluminium together and putting it through multiple heat cycles just doesn't work without correct provision for expansion. This is without considering the grade of alloy used to make the bells, there is a reason quality brake setups cost lots of money.
Steve Webb
11-10-11, 07:35
I found them by using the internet. :thumbsup:
Congratulations on giving that joke an airing on its 100th Birthday :thumbsup:
Just curious about Wilwood as I seem to be seeing their calipers more and more on cars that are more about the go and less about the show.
Steve Webb
11-10-11, 07:45
trying to clamp steel and aluminium together and putting it through multiple heat cycles just doesn't work without correct provision for expansion.
I wouldn't have thought the bells in this were made of Aluminium, surely its just not strong enough for the job?
Oh and play nice guys, don't want to have to take your handbags away. :thumb:
Congratulations on giving that joke an airing on its 100th Birthday :thumbsup:
Just curious about Wilwood as I seem to be seeing their calipers more and more on cars that are more about the go and less about the show.
I'll collect my prize later.:nahnahna:
I suppose the ones in the pic are a pretty good example of the durability, as they are of an earlier design which is now NLA, they came from a track car so have seen some abuse and are working fine. Time will tell as to what I think of them.
I wouldn't have thought the bells in this were made of Aluminium, surely its just not strong enough for the job?
Oh and play nice guys, don't want to have to take your handbags away. :thumb:
That's an aluminium bell, no harm in that if done right. No place for sharp steps, edges, slots or rock solid mountings.
Steve Webb
12-10-11, 08:10
Well everyday is a school day as they say.
I guess I'm just used to the Aluminium casings etc on the mowers I use, which tend to have the consistency of cheese.
It's another classic case of the armchair experts making assumptions on something which they have no knowledge or experience of.
To suggest that something is X Y or Z, without actually knowing, testing or being able to see detail is quite idiotic beyond compare. :hyper:
Steve Webb
13-10-11, 08:13
http://www.berlinasportivo.com/forumpics/handbags.jpg
:wink:
Just basic engineering practice I think you'll find.
Spend some time on google and see how proper brake bells are attached to rotors, nothing difficult about it other than potentailly likely to eat into profit margins when hawking low budget products :thinking-011: or being blinded by "monkey see, monkey do"
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