different front brakes, for shucks and grins... [Archive] - The Acura Legend & Acura RL Forum

: different front brakes, for shucks and grins...


3g Legend
12-28-05, 01:49 PM
Okay, so I just wanted to share...JUST BECUASE I CAN.

I have an extra set of front brakes from an RSX type S (300mm rotor) that I am making fit my RL. Why? Honestly, its because I need to put my stock wheels back on the good ol '96 to save money for tires for the Volks. Now, since the stock wheels wont clear my 14" STOPTECH Big Brake Kit, I have to go back to stock brakes. The only problem is that I dont have pads for the stock calipers! Yes, I am being really frugal right now. I have two sets of used OEM pads for the Type S calipers, so might as well use them up right?

Now that you got the point, all I had to do was machine the center bore of the rotor from 64mm to 70mm and the rotor and caliper will bolt right up. (Machining is free when you do it yourself) The piston size in the caliper will go from stock 57mm to 54mm (Type S caliper). The rotor size goes from stock 282mm to 300mm. The end result is a shorter pedal and a 4% shift of brake bias to the rear of the car giving it a better balance and a little bit more heat capacity of the larger rotor. (Lowering the car has reduced weight transfer to the front under braking so I am able to add more rear brake to stop in a shorter distance-based on the fact that the more brake work you do at each wheel, the shorter stopping distances you will have)

Anyway, this is still a smaller brake setup than the '99-04 RL's, but I dont care because I had the stuff laying around anyways! And yes, the RSX brakes fit in the stock 16" RL wheels :)


FYI:
'96-98 RL front rotor is 282x23mm rotor (same as Integra Type R)
'99-04 RL front rotor is 300x28mm rotor
'02-05 RSX Type S rotor is 300x25mm rotor

Kenso
12-28-05, 03:21 PM
Pretty cool that you discovered that. Might come in handy for someone sometime down the road. On a side note, regarding one of your other discoveries, how does the RL handle with the TSX coilovers? Do you think the TSX spring rates work ok with the RL? I've considered trying it myself and that was my only concern. Sorry for taking the thread off topic.

3g Legend
12-29-05, 01:47 PM
No problem, actually I found a problem when installing the rotor onto the hub last night... the RL hub diameter is too big to fit into the hat section of the RSX rotor. I guess I'll have to search for another rotor.


As for the TSX coilovers. I look at it in two ways, 1, it's too soft because I have the car super dumped, and when its that low, the spring and dampening rates need to be increased. 2, Its the Basic kit that is basically the softest settings TEIN offers. If I would have gone for the next stage up, I would have had adjustable dampening, which is what I probably wanted.

Its definitely better than stock shocks on lowering springs thats for sure, but never gave up a thing for the plush ride the RL was designed with.

Gride_Cruiser
02-05-06, 05:56 PM
Hey 3g Legend,
Despite issues in fitting the Type S rotors on to the RL hub. Would the Type S caliper just bolt on directly? Also, would you happen to know if 99-04 RL front brake set up is a bolt on for the 96-98 RL's? And therefore compatible with the KA7's and the KA8's as well? Finally, how did you figure out brake bias if you were to go with the Type S brakes?
Thanks!

3g Legend
02-06-06, 11:37 PM
Hey 3g Legend,
Despite issues in fitting the Type S rotors on to the RL hub. Would the Type S caliper just bolt on directly? Also, would you happen to know if 99-04 RL front brake set up is a bolt on for the 96-98 RL's? And therefore compatible with the KA7's and the KA8's as well? Finally, how did you figure out brake bias if you were to go with the Type S brakes?
Thanks!

Yes, 99-04 RL brakes will probably be a direct bolt on to a 7 and 8 chassis. The caliper does bolt right up.

When I talk about bias, I am referring to the relationship of torque output at the front brakes vs the rear. You can do some simple calculations comparing rotor size and piston sizes to get the change in torque assuming friction is constant.

Gride_Cruiser
02-07-06, 12:59 AM
Thanks to 3g Legend.

kotetu
05-13-07, 05:59 PM
I always tell ppl NOT to mess with the brake bias. I am a firm believer in the engineering capability of honda brake designers, and a DISbeliever in DIYers who are not trained to design brakes. You're skirting a dangerous path messing with bias - in your case you are not messing with it much, though. Your calculations are off slightly, but it works in your favor.

You reduced the front brakes by 4.5%, yes, but you did not shift anything to the rear. So the rear stays the same. The overall effect is that you have changed your bias by about 1% to the rear, not 4%. It probably doesn't feel any different.

piston D piston R R^2 Pi piston Area
RSX 54 27 729 3.14 2290
RL 57 28.5 812.25 3.14 2552

rotor D front effective TQ area rear effective TQ area
RSX 300 687,066.31 239,865.31
RL 282 719,595.93 239,865.31
95.5%

bias front bias rear
RSX 0.74 0.26
RL 0.75 0.25


EDIT: I just noticed how old this thread is. :lol:

Oh and BTW, I plugged in 75 25 in there but I don't know the stock setup of the RL. If you plug in 8020 or 7030 you will find that again it shifts by about 1%.

Okay, so I just wanted to share...JUST BECUASE I CAN.

I have an extra set of front brakes from an RSX type S (300mm rotor) that I am making fit my RL. Why? Honestly, its because I need to put my stock wheels back on the good ol '96 to save money for tires for the Volks. Now, since the stock wheels wont clear my 14" STOPTECH Big Brake Kit, I have to go back to stock brakes. The only problem is that I dont have pads for the stock calipers! Yes, I am being really frugal right now. I have two sets of used OEM pads for the Type S calipers, so might as well use them up right?

Now that you got the point, all I had to do was machine the center bore of the rotor from 64mm to 70mm and the rotor and caliper will bolt right up. (Machining is free when you do it yourself) The piston size in the caliper will go from stock 57mm to 54mm (Type S caliper). The rotor size goes from stock 282mm to 300mm. The end result is a shorter pedal and a 4% shift of brake bias to the rear of the car giving it a better balance and a little bit more heat capacity of the larger rotor. (Lowering the car has reduced weight transfer to the front under braking so I am able to add more rear brake to stop in a shorter distance-based on the fact that the more brake work you do at each wheel, the shorter stopping distances you will have)

Anyway, this is still a smaller brake setup than the '99-04 RL's, but I dont care because I had the stuff laying around anyways! And yes, the RSX brakes fit in the stock 16" RL wheels :)


FYI:
'96-98 RL front rotor is 282x23mm rotor (same as Integra Type R)
'99-04 RL front rotor is 300x28mm rotor
'02-05 RSX Type S rotor is 300x25mm rotor

3g Legend
05-14-07, 12:09 AM
I always tell ppl NOT to mess with the brake bias. I am a firm believer in the engineering capability of honda brake designers, and a DISbeliever in DIYers who are not trained to design brakes. You're skirting a dangerous path messing with bias

I am an automotive brake engineer and have been in the industry for 8 years now.

kotetu
05-14-07, 12:24 AM
Well there ya go! You're walking a dangerous path, but you're trained to walk it! :giggle: I hope you didn't take offense. Most of the ppl on the forum who talk about upgrading there brakes don't know what they are doing - I always advise them to change the brakes uniformly in the front and rear to preserve the bias.

Anyway - from what I have read, 70-80% front is fairly common for FF applications. I don't know what the Legend is stock. What would you say a safe range of bias adjustment is, and why?

This is a really good opportunity to get the advice of a pro. :D

What is your opinion on how much flexibility there is in brake bias? And I'd like your opinion on the stock Legend/RL setup, strengths and weaknesses. Why choose a BBK over upgraded pads, or vise versa? etc.

3g Legend
05-14-07, 01:09 PM
Well there ya go! You're walking a dangerous path, but you're trained to walk it! :giggle: I hope you didn't take offense. Most of the ppl on the forum who talk about upgrading there brakes don't know what they are doing - I always advise them to change the brakes uniformly in the front and rear to preserve the bias.

No offense taken. You have the right idea, if you don't know what you are doing, don't bother trying. Chances are you will make it worse than better. Education is key to upgrading brakes.


Anyway - from what I have read, 70-80% front is fairly common for FF applications. I don't know what the Legend is stock. What would you say a safe range of bias adjustment is, and why?

Most all normal production cars have a roughly 80/20 % split front bias. Understand that when you decel, you have a lot of weight transfer to the front of the car, so most of the braking will be done up front. To stop a car in the shortest distance, you want to maximize the efficiency of all 4 corners. This means getting the most rear braking done as possible without making the rear unstable. Most production cars stay away from having the rear unstable because if something were to fail, the manufacturer wants the car to remain controlable. This is where there is room to modify you brakes to gain performance.


This is a really good opportunity to get the advice of a pro. :D

;) Glad to help

What is your opinion on how much flexibility there is in brake bias? And I'd like your opinion on the stock Legend/RL setup, strengths and weaknesses. Why choose a BBK over upgraded pads, or vise versa? etc.

When you lower your car, and change damping and spring rates, tire compound, geometry etc, you are changing the balance of your car. This may make your optimum brake balance different from stock. On a street car, you will probably be able to push the bias to the rear up to 5 or 6%, maybe more depending on the platform and how efficient stock is.

My opinion is that early RL and Legend brakes are minute, but for street cruising, you don't need much. If you are an aggressive driver, you may find that you are overheating your brakes. This would be because the stock rotors don't do a whole lot of good dissipating the heat you are putting into the system. The later model RL up to 2004 has larger front and rear rotors that can soak up a lot more heat. The performance benefits of a big brake kit are that you will have a firm shorter pedal, and plenty of heat capacity for whatever type of driving you may want to engage in. Other benefits include longer pad/rotor life.

It is important to educate yourself on a brake company before buying an upgrade. Just because it is an aftermarket company, does no necessarily make their product better than your stock components. I have seen too many times where an perceived upgrade is actually a downgrade in performance and manufacturing. OEMs do a lot of testing and have high tolerances for their product that most aftermarket manufacturers cannot afford to follow. Stoptech fortunately is your friend here. They pride themselves in their engineering to give you the best products on the market. But don't take my word for it, do the research yourself :)