posted on October 31, 2010 20:38
Project Nissan Sentra Spec-V Part 6: Modifying the Brake System
By Mike Kojima
When we last left off working on Project Spec-V, we were modding our engine and suspension for maximum power and road holding. Since we now have power and cornering capability, we'll turn our attention to the other important part of the performance trifecta, the brakes.
Follow our project here!
Since we are greatly increasing our engine's horsepower with turbocharging and increasing the stick in the corners with the NT01 race tire, the demands being placed on our braking system have gone up considerably. Although perfectly adequate for street use, the stock brakes were not designed for repeated applications from high speeds for extended amounts of time.
The stock brakes would be woefully inadequate for stopping the Spec-V under racing conditions, which on some tracks would mean slowing from about 150 mph down to about 40 lap after scorching lap.
|We replaced our wimpy stock Sentra brakes with these huge 13" Stoptech Aerorotors with ST40 calipers. These brakes dwarf the later models Brembo brakes as well.
We called upon the experts at Stoptech to cure our brake issues. Stoptech provided us with their racing brake kit with ST40 4 piston calipers and 13” floating rotors. These huge brakes should haul us down from any anticipated speed with ease.
The stock front calipers on the Spec-V are a single piston, sliding design. The caliper is prone to flexing which can make for inconsistent pedal effort. Also, being only single piston, the pressure distribution on the pads between each side and on each pad can be uneven. Lastly, if not maintained well, it’s possible to get a stuck caliper if the slider pins get bent or corroded. This basically results in only one pad doing all the work and one pad getting all the wear. The dragging pad will also run much hotter, possibly damaging the pad, rotor and caliper. The StopTech calipers, having 4 opposed pistons have nothing to ‘stick’ or drag!
|The ST40 caliper has a stiff forged body with this bolt in brake bridge that really stiffens things up.
The StopTech ST-40 caliper is made of very stiff forged aluminum which improves feel and consistency, while the 4-piston design greatly improves the pressure distribution on the pads; more even pressure distribution should improve pad wear and feel consistency. Unlike most other racing brake calipers, the StopTech caliper has dust boots to protect the seals during long term street driving from abrasive pad dust, water and other potentially damaging contaminants.
Tuesday, November 02, 2010 3:59 AM
Great setup, I may have missed it but what did you end up using for pads?
Tuesday, November 02, 2010 4:27 AM
For front brake pads we chose Performance Frictions 01 compound. This brake pad compound has good bite even at very high temperatures. For the rear we used Carbotech XP10 compound, we have found them to work exceedingly well on rear brakes for FWD cars.
Tuesday, November 02, 2010 5:38 AM
Thanks. I've used pretty basic rear pads (OEM usually) on my B13 and not been completely happy with the results. Ferodo 2500's were an improvement with the Wilwoods in front, but they're not the cleanest or longest lasting.
Couldn't agree more on the TE37's. I'd have a set on all 4 of my Nissans if I could, closest thing to it are my NISMO Rays LMGT4's on my G Coupe, light and strong for 21 lbs. My Traklites are light (10 lbs 15") but I have no illusions that over the long haul they're anywhere near as strong as a TE37 and esp in sizes larger than I have, I hear a lot of bent rim stories from somewhat normal usage.
Really nice setup and article, thanks!
Tuesday, November 02, 2010 8:19 AM
Good article, and the front picture is beautiful!
Tuesday, November 02, 2010 9:46 AM
That in the pictures is not a Tilton proportioning valve as the text says
Tuesday, November 02, 2010 9:50 AM
Mike, let me say 2 things:
1) This is THE best looking Sentra I've EVER seen! It made me almost want to go out and get a Spec-V. Keep up the good work and more pictures of the car are always welcome!
2) I didn't see any mention on whether the stop tech rotors are cryogenically treated. I was under the impression that cryo treating increases brake life all around (rotors, pads, decreased warp, etc.). Maybe I did miss it though? Why the deviation from the tried and true Hawk HP+? Was it just a matter of taste, cost/benefit ratio?
Just curious, keep up the great stuff!
Tuesday, November 02, 2010 12:08 PM
Are the Stoptech calipers rebadged Brembos? They look almost identical to the Evo Brembos. Maybe a Porsche spec. Brembo?
Tuesday, November 02, 2010 2:52 PM
If I remember correctly this car was finished last year, right Mike? (and most likely this article was written last year as well, while the car was getting built).
Regardless it's a great car.
Since it was mentioned in the article, I'd like to bring it up.
RAYS now makes the TE37SL (SL=Super Light) which is roughly 400 grams lighter than the older-classic TE37, yet it retains the same strenght/ weight ratio.
The CE28N is still the lightest monoblock wheel RAYS sells though, and for the money, it would have gone with the CE's.
Also (if money wasn't an issue); now StopTech makes carbon rotors for the ST40 and the ST60 calipers. (hey, everyone can dream right?).
How about Titanium-drilled pistons to dissipate heat even more efficently?
Anyway here is an article I found about those carbon rotors, (worth the read):
Tuesday, November 02, 2010 2:55 PM
Are you using the stock brake master cylinder with the proportioning valve in line? or is there a dual MC setup hiding somewhere? I've thought about possibly gutting the Z32 BMC I have and running a prop valve in line to adjust rear bias. It feels fine now, but I think with some tweaking the car would be more reliable under trail braking.
Tuesday, November 02, 2010 2:59 PM
I know this is a touchy subject, I'd prefer to not be flamed, however..
Do you think you guys could have a comparison of the brake brands you often post about? I have no doubt that DBA, Stoptech, and Performance Friction all make great products, but an apples to apples comparison would be very telling. For example, in the Performance Friction article you spoke of how they machined every surface to ensure it was true and balanced, even the inside of the vanes. This leaves sharp turbulent edge, which according to Stoptech is detrimental to cooling. As such they have the AeroRotor, which has, as you posted here, vanes that are shaped and cast to improve airflow. DBA has the whole Kangaroo Paw thing going on. All very different approaches to venting a rotor, and I would like to see a direct comparison as to the actual performance of each rotor. I'm sure these aren't the only differences between their products. Somewhere along the line, one of these companies is wrong.
Tuesday, November 02, 2010 3:19 PM
Mike wrote in the article that because stoptech has such a large selection of caliper pistons available te can make a specific caliper to work with stock master cylinder and also compinsating for uneven pad wear. Ever see pictures of endless calipers the pistons kinda look like this o O small one being the leading believe.
Wrecked I am pretty sure all stoptech's stuff is made and engineered by them for them.
Wednesday, November 03, 2010 4:10 PM
Endo, Stoptech does indeed account for the stock MC in their setups. However, I think Def is asking about the inclusion of the proportioning valve on a line that already gets regulated within the OEM MC. Generally the Nissan MCs will have a preset pressure at which they reduce fluid pressure on the rear line/s. Example. when rear line pressure hits 500psi it will from then on only increase in pressure at a ratio of .4:1 from that point forward when compared to the front lines. With an aftermarket proportioning valve you can find yourself fighting the oem valve when trying to adjust balance, so often removing the OEM and just using the adjustable can be of great benefit.
Saturday, November 06, 2010 4:28 PM
The prop valve is a Tilton, Its a swing lever type, not a knob because to me, its too hard to tell how its adjusted while driving. I ordered it and was around when it went in.
Der, we did not use HP+ pads because those are street pads and not race pads. They would not hold up for long on a car like this.
JDM, I wish I could afford carbon carbon brakes!
Def, we are not using the factory prop valve, just the Tilton one. A dual M/C system is more flexible but I don't like the way they feel. I know it sounds lame but I prefer how factory brakes feel. I don't like pushing hard with no assist, it makes threshold braking hard and if the pedal ratio and piston sizes are done for more gain, then the pedal feels long to me.
Option, I wish we could do instrumented testing but the cost of such a test would be two days of exclusive track and garage rental, some instruments and data logging some of which we have and around 30 man hours of technician time, a race car, two track days of wear and tear on the race car and probably two sets of tires.
This would end up costing around $8-10,000 in other words about the same editorial budget we have for 3-4 months of operation. Its not easy or cheap to do this sort of stuff.
Monday, November 08, 2010 4:51 AM
That is not a Tilton proportioning valve. Maybe you ordered a Tilton but they sent you something else :P
This one looks like those cast ones made in China which are at 1/3 of the Tilton price :)
Tiltons are machined and black anodized. The handle is nicer too.
Or maybe you ordered a Tilton later and forgot to take pictures of it.
Monday, November 08, 2010 1:05 PM
The one in the photo looks like a Wilwood:
Monday, November 08, 2010 10:03 PM
I wonder if I just used a Willwood part that was in inventory at Techosquare and ended up using the Tilton one in some other car? I know I ordered a Tilton one for that car. That stage of the car was done 3.5 years ago so my memory might be going. I also haven't even laid eyes on the car for over a year. Don't ask its a long story.