Jump to content
HybridZ
Sign in to follow this  
Guest 240hybrid

Cross-drilled vs. vented rotors

Recommended Posts

Guest 240hybrid

I was curious before I purchase anything, what are some of your opinions on Crossdrilled and Vented rotors?? Any preferences on either and why? Also what are some of the pros and cons for both?? I'm lookin at some cross drilled, but would like some opinions whats best and whats not.

Share this post


Link to post
Share on other sites

you are talking about two different swaps here.

a cross drilled version of the same solid rotor just uses the s128 toyota brakes, and is bolt on.

vented rotors are thicker and need a spacer and different calipers to work right.

depends on what you are doing. for a lot of stopping hard like auto x you want vented, it costs way more though, but worth.

i ran the toyota brakes on a solid rotor and loved it, also ran metal master pads and never had a fade problem, will do it again once i destroy my bendix pads and cheapo rotors.

Share this post


Link to post
Share on other sites
Guest 240hybrid

When you say toyota calipers you mean the 4 by 4 calipers from 79-84...and is this the standard cab or extended?

Share this post


Link to post
Share on other sites

Use standard rotors, if you use drilled, then have them cryoed ($$$ adds up fast, and they offer no benefit other than looks, and a minute amount of less weight).

 

For racing, or street car durability use a solid rotor, or consider slotted if you need to heat the pads up quickly, however your also reducing brake bite surface area, so again, racers use solid face rotors.

Share this post


Link to post
Share on other sites
Guest 240hybrid

From the sounds of it crossdrilleds only benefit is weight reductions. Are the vented are somewhat effective in deglazing pads? Neither of these setups offer a considerable amount of cooling benefits though, huh? I'm think just the 4 piston calipers on a solid rotor like majority of you recommended. 79-84 calipers off toyota 4by4 pick ups are the calipers needed and bolt right up from my understanding? Do I need them off a extended cab or standard?? Also, how much of a hassle is it to convert rear drums to 300zx rear disc.?

Share this post


Link to post
Share on other sites

Ok, first things first. The front brakes on a 240 are not the weak point. The rear drums, esp. with the aluminum drum is the weak point in the system.

You are throwing around some terms, but they aren't really interchangable, and hopefully this will clear it up a bit.

As it was discussed, don't even consider cross-drilled unless you are going for the bling bling look. There is one reason pads glaze, and it doesn't matter if you have 14 inch rotors or the stock 10 inchers. Pads glaze because they have gone above their operating temperature. If you are glazing pads, it is most likely because you have cheap-o pad. A good quality front pad on the Z will not glaze.

As far as cooling? What you need to be talking about is heat capacity. All rotors are is heat sinks. The bigger they are, the more heat they can take before overheating. Vented rotors help cool the rotor back down by allowing air to flow through the inside of the rotor, transfering heat away. It is inaccurate to say neither one offers more cooling. Cooling is provided by you, i.e. your speed and any ducting you provide to the rotor. The vented rotor will dissapate more heat for a given amount of airflow than a solid rotor. But again, the front brakes of the 240Z are not the weak point and should not be the focus of your first improvement.

Before I give my recommendations, you didn't say at all what the intended purpose is? Track days? All street use? Pure race? All that makes a difference, a rather large difference. A well sorted stock system with 510 drums in the rear will meet all your stopping needs until you get super serious on the track. And if you really want to "upgrade", the absolute best first thing you can do besides swap the front pads for some good ones is to put a disc setup in the rear. The best bet for a rear disc setup is Mike Gibson,(scca), or Ross Corrigan (Ross C). The offer a great rear disc upgrade for a reasonable price. Do a search of this forum and you will find them posting in response to brake questions many times.

If you are going to spend any money, here are my suggestions, in order of priority:

-Good pads up front, something like the Carbotech street line or the Axxis Ultimates.

-Assuming you are staying with the rear drums, swap to a set of 510 iron drums,(have no fins), and a good quality rear shoe, again, Carbotech has the best options for the lowest price. You don't want the run of the mill shoe if you are keeping it and running it hard.

-Rear disc swap,(see above)

-last would be to upgrade to the vented rotor setup up front.

The important factor in sizing brakes is heat capacity, not whether the pads glaze or not. If your pads are glazing, you are likely running your local auto parts store brand. Step up to some good pads, they don't cost that much and offer so much more. Also, bleed your entire system,(with a good fluid like Ford Super duty, or ATE super blue), get good shoes for the rear,(and ensure the front brakes are not sticking anywhere). You would be amazed at what a good working stock system can do. Stock front rotors with good pads, 510 rear drums with good shoes will provide everything you need till you are on the track in the advanced groups trying to stop from 130mph over and over again.

-Bob

Share this post


Link to post
Share on other sites

So Bob,

 

Why the switch to steel rear drums?

Wounldn`t a steel drum hold more heat than an aluminum drum? (in racing / hard driving enviroment)

 

Also, what would be your take on companies such as Porterfield (for 1) offering "heat treated crossed drilled vented rotors" ?

They (Porterfield) also state about "cross drilling" - that it helps to vent gases, aids in rapid heat dissipation, helps prevent rotor warpage and improves braking in wet conditions!

 

I am in full agreement adout quality pads/shoes suited to the particular need and the fact that fresh brake fiuld is a must!!!

Share this post


Link to post
Share on other sites

Check out the writeup done by Terry Oxendale (Blueovalz) on his car over at zhome.com where he does the junkyard 300ZX 4 lug vented rotors and 280zx calipers on his car, specifically the steet setup. I have gotten all of the parts to do my swap the same way but lack the time...

Share this post


Link to post
Share on other sites
Originally posted by D Carrow:

So Bob,

 

Why the switch to steel rear drums?

Wounldn`t a steel drum hold more heat than an aluminum drum? (in racing / hard driving enviroment)

 

Well, I'm not Bob, but yes the steel drums will hold more heat than the aluminum ones, and that is why you would want them. Bob already mentined it - the ability to absorb more heat without overheating is the name of the game. The aluminum will dissipate heat more quickly, but they also overheat more easily.

 

Heat dissipation is a long-term effect - it's effect is negligible during a hard stop, or rapid fire series of hard stops. Heat dissipation comes into effect when you are not braking - having better dissipation means that you need less time between stops for the brakes to cool back down.

 

The heat capacity of the rotor/drum is what you are using during a hard stop. The rotor/drum essentially has to completely absorb the energy of the vehicle's motion during the stop. So, higher heat capacity brakes let you stop safely from higher speeds, and allows more repeated brake applies before overheating.

 

Finally, another reason that the iron drums are more desireable is that they are stiffer than the aluminum ones, and should allow a better pedal force to decel ratio.

Share this post


Link to post
Share on other sites
Guest Anonymous

There was a time that I did lot of belt grinding of aluminum and steel. The steel may have got hotter but I can tell you the aluminum after becoming too hot to handle took forever to cool while the steel cooled faster.

Share this post


Link to post
Share on other sites
Guest 240hybrid

I plan on using the car for both street and some autocross. Pads are likely to be the weak point in the braking system, but when I go to use my brakes in competitions, I'd like more stopping power when the time calls. This is why I was considering disc in rear also. As far as that question on glazing pads, I havent had a prob. with them, what I ment to ask is if Slotted, not Vented will help against this(my snafu bonk.gif ). Trying to get to know what each type offers.

Share this post


Link to post
Share on other sites

I mostly agree with Bob H. Stock brakes with good pads went a long way for me. My car was getting pretty fast, and on the track my stock brakes were not cutting the mustard. I first upgraded my pads to KVR carbon fibre/metallic pads. HUGE difference. My brakes were once again more than able to do the job. ie 5 hot laps before fading with stock brakes, to 14 laps before fading with KVR pads.. no other mods.. same track...

 

I don't truly agree with the rear disc swap. I have found so far, that they are not needed till you are talking about very high hp applications/ or full track cars. The rear only brake 30% or less of the car.. (unless you install an adjustable bias)

 

I have the Toyota 4 runner 4 piston caliper swap with the 300zxt vented rotors and Axxis metalic pads, with stock aluminum drums/ with good pads.

 

The rear won't lock up under severe braking, and on the same track, I ran 24 laps with NO fade.. (I was waved off because my lapping session was over)

 

I don't do too much competion anymore, (mostly lapping days with my Z club etc..) The car stops unbelievably well. I don't feel I need the rear disc swap yet..I may still do it, as I want to swap to 5 lug, so I may do it at the same time.

 

But that is just my 02 cents. I am not a brake expert.

 

Vented is the way to go for the front. I have heard many horror stories of drilled rotors.. funny thou..I have never heard about vented rotors. cheers.gif Even though it is a bit more expensive to convert.

 

4 piston with stock rotors are more than enough for a street Z... If you can lock your front wheels during braking, you have enough braking force.. (just an indicator).. doesn't take into account repeated stops...

 

How you intend to use your car is the main factor.

Share this post


Link to post
Share on other sites

Ok, I need to clarify why I think the first major upgrade should be disc brakes.

It is not to add braking capability, but rather to add consistency.

With the stock aluminum drums,(as aluded to before), don't have as much heat capacity,(think of a small vs big rotor), but most important, they expand when they get hot and flex under pressure of the shoes. When all that is added up, that is why your foot goes nearly to the floor after a few hot laps with stock aluminum drums. It is the additive effect of the aluminum expanding, flexing, and any other play in they system. That leads to less consistency where you need it most, on the track.

That is the reason I suggest that be the first upgrade, not because it offers more braking, which it really doesn't. It just allows the braking system to do its job as intended every time.

zr8ed, you ought to try the 510 drums. Sure, they don't look as cool as the Z drums, but they are a lot more effective. I'm sure you are familiar with the pull the parking brake up a click or two as the run session progresses.... smile.gif

Share this post


Link to post
Share on other sites

BTW, for street with some autocross? Stock disc's up front with stock calipers and either Axxis Ultimate, KVR or Carbotech pads.

For the rear, 510 drums with Carbotech shoes.

Good fluid all the way around, I suggest ATE superblue or the Ford Super duty. The ford stuff is ~$4-5 a quart and the ATE is usually $10.

Flush the system,(brake fluid), at least once a year and have fun!

That will be much more than you will need. For the speeds you will see at autocross, the stock system is more than adequate. Until you have enough traction,(read sticky tires like Hoosiers, etc), a big brake setup won't offer any advantage. As it was said before, if you can lock up the tires, the limit is not the brakes, but available traction.

-Bob

Share this post


Link to post
Share on other sites

According to DBA, their slotted rotors improve stopping power over their non-slotted in actual tests. About 5-10% from memory. The downside is that the pads will not last as long.

 

DBA are a reputable company to my knowledge.

Share this post


Link to post
Share on other sites

For God's sake don't put 510 drums on your Z! MAYBE they offer more consistency. I know I had to adjust my rear drums about every other track session or I'd have to do the E-brake a couple of clicks to get the pedal back. But those 510 boat anchors are ugly! Al dissipates heat better as well, holding the heat isn't the name of the game, dissipating it is. Anyway, I can say that overheating the rear shoes/fluid was never an issue for me with the Al drums.

 

I'd rather live with adjusting them all the time than live with the ugliness and weightiness (unsprung mass) of the 510 drums. I went to ZX rear discs instead.

 

I'm half convinced this "mod" was created by the 510 guys in a ploy to get our snazzy Al drums.

Share this post


Link to post
Share on other sites
Guest Anonymous

240hybrid, the bigger calipers and vented rotors are a big step in the right direction. And as the guys said, dont bother with cross drilled or sloted. Ducting some cold air to them would be a good thing also.

 

The front brakes handle 70% of the braking work. Deal with the front first and do the rears when you get some extra cash. IMO they can wait.

 

Jon

Share this post


Link to post
Share on other sites

Damn, the discs on my 240Z was warped and had to order new ones. I ordered the cross-drilled from VB sour.gif

I should have asked you guys before ordering... Payed big $ (the taxes and custom fees cry2.gif ) I hope they are at least a little better than the old ones...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

×