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Group Sc Brake Problems


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#1 260DET

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Posted 03 May 2015 - 04:00 PM

So specifically, what are these problems and what has been done to improve the stock S30 brakes for racing?  And what rules are relevant as to what can and can't be done regarding the stock brakes, I guess that F1 style carbon fibre rotors would not be allowed for a start.

#2 dat2kman

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Posted 03 May 2015 - 04:35 PM

What happens to them in severe use?
The rotors develop fine hairline radial cracking, rotors wear unevenly, pads need replacing after each meeting, brake fade/boiling s a common ccurance,  to extent that brakes need bleeding out f boiled fluid between races, at each meeting, and rotors need replacing at less than 0.2 mm wear.

Rear shoes become ineffective very quickly, some adjust between each race, others pull handbrake on by first click on ratchet, to "lift" pedal.

We are permitted to fit adjustable line pressure reducer, but must not be able to be adjusted by driver while seated.

If you wish to inspect race use pads and rotors, mst welcome, have a fe sets here, from a number f the Gp S Datsun regular racers.

I saw Switzer taking it nce and easy for his Group S debut, well done!


#3 260DET

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Posted 03 May 2015 - 05:31 PM

OK, so they overheat, what then has been done to counter that, front and rear.

Had a brief chat with Switzer yesterday, apparently the Zed's head gasket was leaking but he was going to push on. Don't know what happned to Mike, he was gone early arvo today. Adler in his Porker two bloody seconds clear of everyone, WTF were the rest of them doing  ::)

#4 hmd

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Posted 03 May 2015 - 06:26 PM

Took my car out for a test session on Friday at Winton and after 4 laps the fluid was boiling and my pedal go to the floor.
Flush out whatever fluid was in the system and put in Motul RBF 660 (325 dry boiling point). Today I did a regularity 4 hours relay at Sandown.
At the end of the day my front discs are warped as the wheels shook badly when I apply brake.

I think I need to get more brake cooling and may be a bigger master cylinder?

#5 dat2kman

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Posted 03 May 2015 - 06:35 PM

I'm sually either kissing Adler's rear bumper, or we are touching mirrors into corners. It has mch better corner exit capability.
Flett will be up here in July,,, stay tuned.

HMD, just keep throwing rotors and pads at ot, and yes good fluid, and bleed/dump out each caliper after each race.

260det, as Prpduction rules regs go, we have to use what was fitted, at a Nissan factory, to new cars.
See thread re the CAMS period mds etc, as we know, there were a number f new cars built at "a" nissan factory, new , that are better than the stock cheese-cutters and two puck grabbers.

#6 1600dave

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Posted 03 May 2015 - 06:57 PM

OK, so they overheat, what then has been done to counter that, front and rear.


The drivers have to drive around the problem, basically. It is, after all, "production" sports car racing. There will always be "discussions" (arguments ??) around eligibility of this part or that I guess, but at the end of the day the idea is to race fairly standard cars from the era. In the case of zeds, that means standard brakes (albeit with the usual freedoms of better lining material, adjustable bias, that's about it). And the zeds are reasonably well represented in Group S and (as evidenced by some of Jason's performances) can be relatively competitive in Group S trim.

General blurb from CAMS re Group S :

Groups Sa, Sb and Sc are designed to provide a forum for competitors to race production sports cars from
the ’50s and ’60s (sometimes known as “Classic Sports Cars”), in a form similar to period club racing.
Limited modifications as detailed in the following regulations and defined in the Specification Sheet are
allowed to these vehicles. Where performance-improving modifications are made, these should be of a period
nature and not out of character with the vehicle or group period. To this extent, the modifications permitted
are not intended to radically alter the individual vehicle’s character or appearance and will be of an improved
performance road car nature, as opposed to making the vehicle totally dedicated to outright competition.


240Z spec sheet : http://docs.cams.com...n 240Z - Sc.pdf

Have a read, I reckon you will be surprised at how few modifications are allowed.

#7 260DET

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Posted 03 May 2015 - 08:16 PM

There are quite a few tricks that can be used to cool brakes down if that is the main problem, I understand that only stock spec parts can be used except for lining materials so I was wondering what cooling tricks were allowed and used eg drilling holes in backing plates, using slotted rotors and so on. Saw something different the other day, basically a extended shim which sits behind the disc pads and is shaped to offer some surface area to the airflow. Every bit helps.

I suspect that Adler and co don't just rely on bare factory parts, some of those euro blokes put a lot of work and thinking into their cars. It's not all about money which I think can be used as an excuse by others some times.



#8 hmd

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Posted 03 May 2015 - 08:29 PM

no slotted rotors, rotor must be solid as from stock, you can drill hole or remove backing plate all together.
need to duct some air in to the area as best we can.

#9 dat2kman

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Posted 03 May 2015 - 09:23 PM

Porsche run vented rotors bgger caliper/pad area, cars are about same weight.
And the Elegibility inspectors are on the lookout for illegal spec rotors and calipers, the nabbed the Alfa boys at EC a few years backdef no drilling or slotting f rotors, are able to remve backing plates at front.
Are able to drill holes in rear drum backing amd rear drums.
They just get hot, very hpt!

No extra ducting permitted. Unless as built, have seen a few cars get lgbooked for running ducting to rear discs, in combination with additional cooling to the rear mounted emgines,,,,,

#10 260DET

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Posted 03 May 2015 - 11:02 PM

Bend/cut the stock shields/backing plates to form air scoops/extractors? Heat should really not be a unsurmountable problem as far as brake fluid and pads/linings go, rotors will crack/craze if not warmed up before hard use. Pads are really important in that some are better than others in removing heat from rotors, use poor heat conducting hydraulic pistons and special shims to reduce the amount of heat being transferred to the brake fluid, aluminium pistons are bad like that And so on..................

#11 dat2kman

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Posted 04 May 2015 - 12:42 AM

When you can get the likes of James Flett, Peter Lang, Chris Grey, Wayne Potts, Russell Stanforth, Mike Jones,
Hung Do, myself, and no soubt a few others that have actually been there and done that, together, and belive me, we have all tried lots of various things, we are, at present, limited to a solid rotor, that retains a hogh degree of latent heat, between each application, that then transfers that as further built up/latent heat into a cast iron caliper, there is only so much these can handle.

I have seen Lang and Potts, sail off the track at T4 and T5, with no brakes whatsoever, I have sailed ff at T1 Morgan Park, alonside an equally braking bereft Shelby Mustang., at the 8 lap point in a 10 Lapper.

We have just about every brand of pad here, crumbled and turned white, ( the QFM branded ones are the worst!)

Australia is the only country where, as Historic Prod Sports category cars, have to run the solid rotor. US, UK, Euro and NZ, in similar type category allow fitment of period correct item.

I'd be quite happy to take pics of failed/destroyed components and post up, ( but this site does not accept my ipad pics)
These very items have been shown to Bruce Richards, he is quite sympathetic to the Z racers, but, as you know, we need to show that Sumi 4 Spots and venteds, were fitted to new cars, at a Nissan factory,
He is the chap that has said he will push this through CAMS, but it comes down to just one  A4 typed letter, from Nissan, stating that they did in fact fit the items to new cars.

#12 HS30-H

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Posted 04 May 2015 - 03:06 AM

Australia is the only country where, as Historic Prod Sports category cars, have to run the solid rotor. US, UK, Euro and NZ, in similar type category allow fitment of period correct item.


As far as the HSCC 'Historic Roadsports' class in the UK is concerned, I believe that's not strictly the case.

They are restricted the stock OEM front caliper and rear drums, but the rotors are free. So they widen the stock calipers with a machined spacer and use a vented rotor. Seems like a reasonable concession in the rules to me.

These very items have been shown to Bruce Richards, he is quite sympathetic to the Z racers, but, as you know, we need to show that Sumi 4 Spots and venteds, were fitted to new cars, at a Nissan factory,
He is the chap that has said he will push this through CAMS, but it comes down to just one  A4 typed letter, from Nissan, stating that they did in fact fit the items to new cars.


The problem being - as far as I understand it - that those "new cars" were not sold to the general public.

#13 260DET

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Posted 04 May 2015 - 08:18 AM

Here we go again :)

Anyway, what actual temps do the rotors/calipers reach Jason? That would be the starting point for selecting pads because there would be proper racing brake pads available that would work. They may have to be specially made to suit but they would be available. Maybe I should have gone the Sc route myself, love these sorts of challenges.

EDIT: A quick search shows that Hawk make a full range of proper racing pads for the S30 including their Blue 90210 and the SCCA favourite the  DTC-70. Have you tried these Jason?

EDIT 2: And here is a gadget that facilitates brake fluid circulation in real time.



#14 hmd

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Posted 04 May 2015 - 11:56 AM

Porsche run vented rotors bgger caliper/pad area, cars are about same weight.


Nope, Porsche pads are smaller than the Datto pads.

Porsche http://www.hawkperfo...ads/hb172f595-0

Datsun http://www.hawkperfo.../pads/hb169f560

Alfa pads are even smaller, most cars in group S have inadequate brake.

The Porsche front discs are much bigger though, Porsche 282x20, Datsun 271x12, Alfa 260x13.
So much better heat dissipation, need to get rid off the heat from the slowing down of the car from speeds.

Plus the 911 have better rear brake and the weight at the back too.


#15 PZG302

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Posted 04 May 2015 - 01:00 PM

Richard,

All the pads have been played with and all come up short in a standard Zed.

As Jason has said it is the heat that can't be dissipated that obviously builds up and then eventually cooks the brakes, or very quickly cooks the brakes depending on the circuit.

The zeds have been battling this in Group S since noah raced the ark. Before the Porsches came in Group S in numbers it wasn't as big a problem, but was still a problem. It is never inspiring to have your foot go to the floor on the track.

Even in the old Division 2 Marque Sports, the precursor to 2F, Zeds would struggle with standard brakes until you took the plunge to run 2B with the associated freedoms.

My old Blue 260, ex Steve Cox, car would suffer badly around the Sydney tracks in the longer races even with using Hawk DT70 pads. Once I got the green Zed with the discs all round and vented rotors up front with 4 spot Wilwoods, and pad size wasn't much bigger, I had the best brakes I had seen in a Zed in the mid 90's and no fade or heat problems what so ever.

The quickest way to sort the brakes in my Zed was to go up to Group 2B and create an orphan that wasn't competitive after the late 90's and too modified to play in Sc and built too late to play in Group T.

The only way to resolve the issue is to look at running a vented rotor at least, which Jason and the others from down south have pursued to no avail, let alone run the 4 spot calipers and bigger rotors.

#16 260DET

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Posted 04 May 2015 - 04:25 PM

Seems to me that everyone in Sc would have to battle brake heat problems, not only S30's, and of course bigger brakes would be better. But you have what you have  so optimising them is the go, which could involve several minor tweaks that add up to a significant improvement.

What temps were your brakes getting up to Matt? As I mentioned before, a good way to sort out pad problems is to go to a specialist knowing what temps are involved. Pagid for one have heaps of data available on the relative strengths and weaknesses of their various compounds, a informed choice could be made just using that info. I don't accept that it's not possible to get a pad to handle the heat, it may rip the hell out of the rotors but hey, that's part of racing old cars isn't it?

#17 PZG302

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Posted 04 May 2015 - 07:40 PM

The blue car would cook anything up to the hawks, including black flash and the pads i used to get made for it.

The green car would cook anything less than hawk dt70 pads on the front and the rear pads would last one season before being replaced due to overheating. I ran a good high performance road pad on the rear to get the brake balance that worked for me.

And I used standard solid rotors on the rear and tp magna rotors on the front. The rear rotors lasted over 10 seasons. The front rotors were replaced every second set of pads as they would be worn down like an hourglass and starting to get heat cracks, but they were cheap and did the job.

I only used slotted rotors once and they lasted one race, the pads were that aggressive. Standard vented rotors lasted much better.

Also driving style does come into what pads will work best for someone. I have tried pads that others raved about and thought that a dunlop volley on a stick was better, yet others have usednthe hawks which i reckon are great and will say they are terrible pads.


#18 260DET

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Posted 05 May 2015 - 08:01 AM

While the figures are to hand, Project Mu make an off the shelf brake pad with an operating temp up to 980*c. Cast iron has a melting point of ~1150*c. And what about ceramic coated rotors? Anyone tried them?

EDIT: And if you want to nearly melt the rotors how about Carbotech XP20 compound which is effective up to 1093*c.

#19 260DET

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Posted 06 May 2015 - 08:37 AM

Over 600 views but little conversation, just about finished anyway :)

Wheels. Obviously are relevant to brake cooling so throw those awful Performance Heavyweight's into the bin and get serious. It may well be that some wheels would act as a fan for the brakes but that's beyond my knowledge so let's just look at the design of the usual Watanabe style and start with the proposition that the more open the design the better. Those less well known come from Enkei and Konig, Enkei always make a good light wheel while the Konig Rewind is a very open design, pic below.

And finally onto the touchy subject of driving. I'll just leave the quote below from a driver who raced a standard braked S30 and say nothing.

"You just have to drive while being easy on the brakes. On hard and then off for short intervals Don't drag the brakes, no trail braking, left foot brake, and learn how to carry more speed through the corners. Move roll stiffness to the back of the car so it rotates more and gives better control with the throttle. Install the front brake backng plates from a early car or run no front backing plates. Hawk blues have worked well for me.

Most important, take weight out of the car and make sure the rear drums are adjusted tight."

Another quote.  "You will need to balance your braking agressivness with trying to get about 2 hours of life out of pads. You would be surprised what lap times you can get by rolling on and rolling off the pedal. Solid, consistent, threshold braking will only gain a .1 or .2 seconds on most turns and is usually the last thing a pro driver tries to squeeze out. From turn in to apex is where the magic happens."

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#20 dat2kman

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Posted 06 May 2015 - 09:19 AM

Jolly shame you never got into actually racing,your car, let alone racing in Group S, with your first 260Z that you had way back 15 or 20 years ago. So easily could have, still could today!
You'd have nailed it.
You'd be right out in front of every Porsche and DeTomaso!
And best of all, your brakes would never ever give you an ounce of trouble, and your confidence level will be at 110%!

Talk is one thing, very easy to do, the actual doing of it is totally another, and the number of curve balls that get thrown at you during a race, keeps you on your toes.

We have tried pretty much everything as you recommend, even a few things that you havent come up with, but it comes down to the effective management of the heat buildup, and inability to dissisipate the heat, from the components that the category requires us to work with, and within the rules we are required to follow.

The Group N cars have pretty well got it sorted, under their rules.

Some of the Group S Datsun racers are discussing this now in relation to " safe workplaces/OH&S " this is a different tack, in that we are "working" within rules, as set by an Authourity, that a number of us now, have physically proven are "unsafe" and could cause personal injury.
More a pro-active, than a re-active, stance.

Get involved, go and do it, instead of telling us theories and second hand gathering of research.
Come and work with what we have to work with.






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