Vented or non-vented...your results?

[CarolinaTZ]

I know, I know...VENTED!. But, not necessarily. I just need to know your actual results...good, bad, and regretful

 

I'm beginning the process of the Toyota brake upgrade (I actually bought a set of the huge sw13 calipers...these things are heavy! But, I'm returning them). I understand the benefits of vented rotors but I'm not sure I want to go that route. Can anyone who has kept their non-vented rotors while doing the 4 pot upgrade, tell me if and how easily you reached the limits of the non-vented rotors. I spent extra money on forged wheels and don't want to turn around and add back unneccesary unsprung weight. It's also more expensive and a little more complicated to go with vented rotors so I don't want to use them if I don't need them. Has anyone auto-crossed or done track days with non-vented rotors without issues...at what point, if any, did you realize you should have gone with vented?

 

Thanks in advance for sharing.

Edited November 21, 2010 by CarolinaTZ

[JMortensen]

Those 4x4 calipers, while they seem heavy, are only a couple lbs heavier than the stock 2 piston calipers. Going from memory the weights are something like 7 vs 9 lbs. The weight isn't the problem...

 

I did a 4 piston front brake non-vented setup with early 280ZX in the rear with a ZX master and adjustable prop valve. I went to a HPDE school and one of the things they told us to do was drive through a big puddle and slam on the brakes so we could get the feel of a 4 wheel lockup. I was not locking the rear brakes, even in a puddle. I ended up completely removing the rear proportioning valve and was still not getting enough rear brake. So I switched back to the stock front calipers. This enabled me to get the bias right and the brakes worked pretty good like this for a couple of laps. I've heard others with similar bias problems with other rear disk setups and front 4 piston calipers. I think the answer is larger rear calipers, but then in most cases you're losing your e-brake, which is important for a street car.

 

Autox with either setup wasn't a problem, but at a big track with the slicks I was running I could put enough heat into the system to cause trouble in just a few laps. I ended up punching a hole through a brake pad with the stock front calipers (pics of this in my album, search for "R4S"). At this point I switched back to the 4 piston calipers, just because the brake pads and calipers were larger. I had a serious overheating problem and not only had trouble with pads, but I also boiled the brake fluid a bunch of times even with the 4x4 calipers. When this happens the non-compressible brake fluid becomes steam which is compressible so you wind up at the end of a straight, you hit the brakes and the pedal goes straight to the floor. Not fun.

 

So here's my take on brakes: Stock is adequate for autox. You wont' put enough heat in to cause problems even with multiple drivers and sticky tires. I used to run 3 drivers a lot and never had trouble with brakes, even with street pads. The stock brakes also work for track days if you aren't using sticky tires. The stickier the tires the more heat you will put in the brakes. If you're forced to use the stock brakes, there are things that can be done to mitigate the problem even with sticky tires (venting, bleeding between sessions, etc). If you are driving your street car to the track venting isn't the best idea because your vents can pretty easily get ripped off on the road. Good race pads also help A LOT. The problem with race pads is that they don't work when cold, so they are very dangerous to use on the street. You can switch pads when you get to the event. This is what I was doing at the end there.

 

The better solution for a street/track car that is overrunning the stock brakes and doesn't have class limitations is a big brake upgrade. Most guys can upgrade to the point where they can run streetable pads without vents and still not have issues at the track. If you're getting real serious and have big sticky tires and lots of power and have the big brake setups, even the big brake upgrades can be overrun at some point, in which case you're back into venting and race pads, etc. It's not like you solve this problem once and for all, but as you step up in performance you need to address it again, continually. The bigger your brakes are the heavier they are. The heavier they are the more they'll slow you down, just like a heavy wheel will, as it is more unsprung weight and more rotating mass. Ideally (just like everything else on a race car) you want the brakes heavy enough to take the punishment without breaking down but not heavier than necessary and slowing the car down.

[bjhines]

I tried the stock setup for autoX and had a ball with them. Stock works great for short runs and low power cars. Most people with stock Zcars are only getting 90-130 HP to the rear wheels.

 

Even with low HP cars, Track sessions are a whole different ball game. Stock will work for this kind of duty with low HP, as long as you are willing to do a little bleeding in the pits. The system is run beyond critical limits so you are going to have some issues with consistency and reliability.

 

I think that rear disks are an important improvement, but they must work well with the front disks to make any real improvements. Pad material choices are usually enough to get the balance right. The issues with solid vs vented rotors is that they reach different temps at different times under different circumstances. You cannot balance your brake set up on street or autoX courses. It takes punnishing track time to find the weak points and adjust for them. Of course, Track duty is nothing like street duty, so what works with one does not work with the other uses.

[ashintar]

I have the 4x4s on non vented rotors with a sr20 setup. With carbotech pads I can run 2-3 hot laps on a 1.4 mile course before any noticeable fade starts to show. They should hold up just fine in some auto-x

Edited November 28, 2010 by ashintar

[johnc]

There is no measurable performance benefit from installing the Toyota 4 piston calipers with non-vented rotors. IMHO, it actually hurts performance. The real benefit comes from the vented rotors.

[JMortensen]

There is no measurable performance benefit from installing the Toyota 4 piston calipers with non-vented rotors. IMHO, it actually hurts performance. The real benefit comes from the vented rotors.

Disagree. You will get a measurably longer amount of run time before fluid boils or pads disintegrate IME.I thought I had put that in my first post, guess I missed it. Other than the slightly larger heat sink, I agree. By screwing up the brake bias the stopping performance is worse.

Edited November 29, 2010 by JMortensen

[z-ya]

Yes, the vented make a big difference. I'm running the typical vented/4x4 V6 caliper on my 180WHP track car, and I never have any issues with overheating (stock drums in rear). Car is very fast in the turns though. The problem with the setup is a lack of pad options. There are many pad options out there for the 240Z calipers. Not so many for the 4x4 V6 calipers (if you've got some sources, please let me know). What I use is Porterfield R4 compound, but they are made to order for those calipers. They are not cheap.

 

Many ITS racers have to use the stock brakes, so it is possible to find the right fluid and pad (lots of options) combination to turn fast lap times. You may need to flush the fluid after each session, but if you are not doing a lot of track days, it's not really a big deal. For autox, the brakes never get hot enough to matter.

 

So it really depends on how serious you are about doing track days. For street and autocross, the stock brakes are great. The only upgrade I recommend is upgrading the booster on early 240Zs to the larger 280Z style. It requires drilling, but is worth it INO.

 

Pete

[h4nsm0l3m4n]

Yes, the vented make a big difference. I'm running the typical vented/4x4 V6 caliper on my 180WHP track car, and I never have any issues with overheating (stock drums in rear). Car is very fast in the turns though. The problem with the setup is a lack of pad options. There are many pad options out there for the 240Z calipers. Not so many for the 4x4 V6 calipers (if you've got some sources, please let me know). What I use is Porterfield R4 compound, but they are made to order for those calipers. They are not cheap.

 

Pete, I used Z32 brake pads with my 4x4 vented brake setup. Pad selection is pretty extensive and they mounted to the caliper just fine. There were some interference issues between the pad backing plate and rotors though. I clearanced them a little bit with a grinder and got them to fit well. Maybe that's a cheaper option for you.

[CarolinaTZ]

First let me say "thanks" for a no-nonsense board like this...there's lots of fluff on the internet and it's good to find a "most of poser talk weeded out" website.

 

Anyway, based on what I'm reading here, I'm leaning toward vented. I did some weighing and there's not as much difference between the 2 rotors (stock vs vented) as I suspected...around 3-4 pounds. There was a 5 pound difference between loaded stock calipers and loaded '92 4Runner calipers. I was leaning toward the big-small-piston calipers but, it looks like there's more pad (with some grinding) choices with the fatter calipers.

 

I searched and could not find a full explaination but, why will the 85-88 Maxima front rotors not work with my '72 hubs? I could only find a reference to using a ZX hub w/ the Maxima front rotors...is it possible to use these rotors with my '72 hubs? Seems like this would be an easier solution over the 300zx rotors that require spacers.

[z-ya]

Pete, I used Z32 brake pads with my 4x4 vented brake setup. Pad selection is pretty extensive and they mounted to the caliper just fine. There were some interference issues between the pad backing plate and rotors though. I clearanced them a little bit with a grinder and got them to fit well. Maybe that's a cheaper option for you.

 

Maybe that is what Porterfield sent us this year. They were close, but they didn't fit right without a lot of hacking. Porterfield sent a replacement set with the correct backing plates. I'll give a set another try.

 

Thanks,

 

Pete