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260DET

Historic/Vintage Race Standard Brakes

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Friend of mine has to use standard brakes on his historic race S30 and of course they are inadequate. Putting this up in case some old school racer has some tricks on how to make them work longer, we know the usual stuff but perhaps there is something that is ........ trick :)

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What to do about Z brakes?

 

"The stock Z brakes are adequate for street driving, autox, and drag racing.

The stock Z brakes are adequate for street driving, autox, and drag racing.

This is not a joke. Even with a V8 or turbo pushing lots of hp;

The stock Z brakes are adequate for street driving, autox, and drag racing."

 

- JMortenson

 

 

 

Experiment with pad and shoe materials.  After experimenting with all of the popular brake pads such as Hawk, Porterfield etc.

I prefer Carbotech AX6 material. Excellent cold bite that grabs hard the hotter the pads get.

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13 hours ago, 260DET said:

of course they are inadequate.

 

Is this an assumption or is there something behind the statement?  Serious question, I just hate to see people waste time, money and effort if they don't have to.

 

If they have been shown to be "inadequate" the proper next step is to define in what way they are inadequate.  Heat buildup, stopping power, wear rate.. etc.  Even if a person decides to go ahead on just the assumption that they're inadequate, these things need to be defined.  You can't improve something unless you know where you started. You could actually end up with worse brakes than when you started.  And not even know it.

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Hey Miles, have you had any noise, chatter or squeal issues with those Carbotechs?  I'm currently running the Porterfield R-4S and am reasonably happy with them, but always willing to try something new.  Mostly auto-x and track use, but the R4's were driving me nuts when cold.

Thx.

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I think all you can do is a more aggressive pad, up until you can’t keep them cool. Then focus on heat control.

 

i don’t know about the longevity of the aluminum drums, but they must dissipate the heat quite a bit more then an aftermarket steel unit.

Edited by HuD 91gt

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Phil Robles swears by Carbotech.  He had the same comment about dust, but he loves the friction material. His little Civic is amazing and he's quite a driver as well.  I'm currently on Porterfield friction and like it - once it's hot...

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The problem with  Hawk and Porterfield "street pads" is that  they lack cold bite for daily driving.   Both brands were like blocks of wood when cold driving in stop and go traffic.  Freeway driving was out of the question. I switched back to stock pads and shoes from my local Nissan dealership for several years. 

 

In 2009 I experimented with several of the popular brake swaps and  ended up with Toyota solid front calipers, 79 280ZX MC, 280Z booster (nice) 240SX rear calipers  with Axxis ULT pads all around. This set up worked fine for a daily driver and some mountain driving. But I kept looking for a better street pad. In 2017 I replaced the Axxis ULT pads with Carbotech AX6 pads. Very noticeable improvement.  No more tweaking pad material.

 

https://ctbrakes.com/

 

 

carbotech_compound.jpg

Edited by Miles

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Have used the Carbotech XP10 compound on my race car and have recommended them. But yes, the racing class my friend runs in requires the use of standard OE brakes, he is improving the usual stuff like cooling and compounds but there are also more subtle possibilities like shims  made of ? to reduce pad/bucket heat transfer,  modifications to the OE parts, heat/freeze treated rotors, heat extracting wheels and so on. He has to use 14x6 period style wheels. It's all about attention to detail with his car class.

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XP20 Carbotech compound placed on the stock backing plates. Make sure to use that thin metal shim on the back of the pad since it acts as a heat shield. Better yet get some thin titanium and make shields from that. Cutting it will be interesting but doable.

 

Speed kills - pads, shoes, rotors and drums. If you use race shoes remember they generate more heat and that can  warp those aluminum drums. Add fans to the front brake duct to get more air circulating into the rotor and direct some at the caliper.

 

I'm not judging, but get track data to verify just how often and how hard you are braking to compare with other drivers.

 

You could get cross-drilled brake lines that are suppose to keep the brake fluid cool. You would need a large tank of fluid however.

Edited by gnosez

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I think it's a matter of running the right compound that still functions at high temps. Back in the day katman had a thread where he was talking about running 2 3" ducts to the front brakes to keep them cool. I looked for it and couldn't find it. Joe Demers was making a heat sink that fit between the piston and brake pad, might be a tight fit on a 14" wheel. Found it: http://www.coolshims.com/coolshims-technology.php. John Coffey talked about adjusting drums in between sessions. Heard from several people that ditching the AL rear drums and running the cast iron ones off of a 510 is an upgrade because they can take more heat. If brake recirculators are allowed that would be a biggee, as this would protect against boiling fluid: http://www.colemanracing.com/Brake-Recirculator-P3775.aspx

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Dang I can't find the link from a couple years ago. I think I saw something on Kameari's website about reproducing new castings of the mk63 calipers. They had pics of the rough castings pre machining. I had to translate the japanese obviously. I can't find it on their site now. It was awhile ago though maybe it wasn't Kameari. 

Parts Assist M Speed has the new units though. I know I wasn't on their site when I saw the post about the castings from a couple years back.

These were a factory Z, hako, caliper for vented rotor. I'd run these. Not sure what the "stock" rules mean in his class but the mk63's were the road racing caliper back in the day weren't they? (I don't know too much about the old factory race car setups from back in the day) I've always assumed the mk63's were the homologation brake for one of the lower sports car classes.

 

https://www.rhdjapan.com/parts-assist-m-speed-mk63-4pot-caliper-brake-kit-s30-s31-b110-gc10-kpgc10-pgc10-kgc10-kpc10-pc10-gc110-gc111-gc210-gc211.html

 

*I would ignore the rotor diameter callout in the RHD description.

Also, found this on the "other forum" should be some info in here.

https://www.classiczcars.com/forums/topic/56999-looking-for-a-set-of-sumitomo-calipers-mk63/

 

Kameari should have a stock vented disc

http://www.kameariengineworks.co.jp/Catalogue-v3/catalogue-075-20160731.pdf

 

Edited by JavelinZ
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On 2/13/2019 at 7:18 PM, JMortensen said:

I think it's a matter of running the right compound that still functions at high temps. Back in the day katman had a thread where he was talking about running 2 3" ducts to the front brakes to keep them cool. I looked for it and couldn't find it.

katman?  Where the hell has he been for the last 10+ years?  Oh, that's me, back from the dead.  That thread may have been on improvedtouring.com.  Assuming your friend also has to run the stock drum brakes, here's how we made brakes last in an ITS car, which at the end of its development was probably as fast as any CP vintage car.  I don't know what compound Carbotech has today, but back then the HT-9 was the only thing that would hold up to the heat on the front.  The HT-10's that replaced them were not as good, but that was about the time that SCCA pissed me off by outlawing remote reservoir shocks so I quit thinking about Z brakes.  I ran both the Nismo rear shoe, and the relined Carbotech shoe, I think.  We cryo treated rotors and drums.  We ran the parking brake so we could adjust the rears during the course of a race.  That and having an adjustable prop valve so you can make the rears take their share of the load is critical.  If you aren't turning the friction surface of the drums blue, then you ain't there yet.  Scour the junk yards and find every Z drum you can find and have them turned and expect to rotate in a new set every weekend.  Up front, don't fall into the trap of using a pad that maximizes the pad material, in other words instead of this |  | , you want this \ /. The outer radius of the rotor runs hotter because its going faster (linearly) and wears the pad faster.  Nothing worse than having to pump the brakes every corner to take up the slop from tapered front pads, maladjusted rear shoes, and expanded rear drums.  We drilled holes in the backing plate on the rears for some cooling, but not much else you can do back there.  Up front we ran three 3" ducts on each side, one to the hub area of the strut to cool the bearings, one to a custom "can" that blew air on either side of the rotor, and one that blew into the caliper overtop of the pads.  That one was tricky to make as there isn't a lot of clearance between the caliper and a 14" wheel that we had to run.  I also drilled a series of small holes around the periphery of the pistons just behind where they contact the back of the pads so air could circulate behind the pads from the aforementioned duct over the pads.  PM me and I'll send you some pictures.

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Welcome "back", Katman!

 

For many of us, the problem is ostensibly a simple one.... after many years of hibernation or at most sporadic use, the Z finally gets a chance to stretch its legs.  The engine runs, more or less.  Things creak in the suspension, but it suspends, more or less.  Even the headlights work.  And the brakes?  They worked in the driveway.  Finally getting the car up to speed on the local rural road, I press the brakes, and... mush.  I pump them, and yes, they sort-of work... but the car pulls hard to the left.  One can feel a set of brakes (front left? rear right?) lock up and smoke... while another set feels like somebody greased the pad with bacon-fat.

 

Then comes the question: what should I do?  Those pads, remember, haven't been changed since the 1990s.  Maybe even the 1980s.  Do the calipers even work?  The brake fluid is older than some of the members on this forum.  So... should get refurbished stock parts from Autozone, bleed the brakes, and call it good?  Maybe I should.  That would be the economical thing to do.  But for many people, it feels deficient, inadequate, simplistic.  Technology has moved on!  Progress!!  And I should install parts that were already so-so almost 50 years ago???  Thus, the quandary.

 

It's not about racetrack performance.  It's about personal psychology.

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