Hi All,

I recently installed the JCW Brake Kit on my R53 MCS. I understand that the R53 JCW brake kit is essentially the same as the brakes on stock R56 (rotor size, caliper and pads). However, I could never compare them myself until I got to drove a rental R56 MCS this week.

After driven the R56 with stock brakes, I can instantly feel the difference in pedal response - the R56 has much better pedal response over my R53 with JCW brake kit. The R56 has a much sharper brake feel on the road and the brake pedal travels MUCH shorter than the JCW kit on R53. Even when I am just playing with the brake pedal at idle, the difference is apparent. On my R53 with JCW kit, the pedal can be pushed down 3 times the distance the stock R56 pedal would go, making my R53 pedal feels spongy over the solid feel stock R56.

I was shocked to discover the discrepancy as I expect them to be the same. Am I missing something here? I'd assume my upgraded R53 should have the same pedal response and yield the same brake power with similar pedal travel. Does the stock R56 has upgrade brake line/hoses (not included in R53 JCW brake kit)?

Despite my car has 65k miles, I did my JCW brake kit about 7 weeks ago and the rental R56 has under $1k mile. The installation was done properly with correct fluid bleed and reflush. Can someone enlighten me here? Thanks in advance!

 

The unknown here (at least openly admitting it from me) would be if there are any changes to the piston bore size in the two calipers. Looking at the OD of the rotor that's easy and assuming a modest street pad in use the only relationship you describe would be either a piston size change or a mc bore change. Like you however, I don't think this is the case. If it's not the case then the only other thoughts would be about the bleeding or the pedal ratio being slightly different.

 

Here's a link that might help, https://www.northamericanmotoring.co...d.php?t=112474

You are right that the R56 S oem brake up front is the same as the R53 JCW. A review of www.realoem.com part numbers will show that while some part numbers have changed for the years, many are the same.

You can take a front set of R56 S fronts and bolt right in a R50, R53 or R52 with just a change in the brake line.

Not sure why they feel so different. Might be two very different pads. I'd drive an R56 with more miles and see how it feels. Hope that helps.

 

Thanks for your comments.

I thought the pads were the same, even if they were not similar, would it dramaticly effect the pedal feel? I guess this is open for debate.

and yes, the one thing I want to investigate is the bleed and how well it was done. Perhaps it was a less than perfect job so I am planning to ask the installer to do the bleed again...

Any R53 owners with JCW brake kit here that may share their thoughts on their JCW brake v. R56 brakes?

 

Also have the installer check and make sure the front pads are in the right place, there is an inside and outside pad, but they both fit in the other place too. Then what happens is the piston pushes the pad sideways causing it to wear wrong which could lead to bad pedal. If they also did the rear pads that would be an issue, even if not, the rear inside pad spring clip can come off the piston and cause the same issues above.

 

What about a possible hose issue? Also, could the R56 master cylinder be different? Maybe a higher system operating pressure?

 

Yeah, that's what I am wondering too... perhaps R56 uses better brake lines/hoses or bigger master cylinder?

I am hoping for owners who has driven both R53 with JCW brake kit and stock R56 to share their thoughts...

 

Fireball Tim ran into trouble when upgrading the brakes on the R56 for Street Tuner Challenge. The stock brakes were so good that the brake kit he installed made little improvement. The new factory JCW brakes must kick serious ***.

 

Yes they are different, but how much different, I would bet not much. I'd flush the system, check the hoses and fittings, the Brake res cap and also look for leaks around the master cylinder behind the firewall, it's been known to happen.

 

Mach V has an R56 and I have the R53 with JCW kit. The R56 has a super sensitive tip in....grabby. The R53 is more progressive. Dan has driven mine and we chalked it up to different pads between the two.

I have my JCW kit off the car (and for sale). Would it help if I measured the piston size? Obviously, someone would need to post the R56 info to compare.

 

The part number for the piston o-ring is the same for the R53 JCW and R56S calipers.

 

then it comes down to pad material, master cylinder and the amount of fluid in the system.

 

What about rotor condition? Couldn't 1 car's pads and rotors have been properly bedded in while another not?

 

unlikely. having driven a few R56's now...the brakes are 'grabby'. the ones on my car were solid and predictable and progressive (like good brakes should be). The stock ones I had on my LGT were capable, but gave you no indication of doing anything for the first half of pedal travel *pucker*. A Brembo swap fixed that problem though I never felt the need to do better for my R53 than the JCW.

 

Hi PGT,

So it sounds like you agree and confirm my impression of R56 stock brakes feeling more "grabby" than the JCW brake kit for R53 right? I completely agree that "The R56 has a super sensitive tip in....grabby. The R53 is more progressive." So I guess there is a slight difference on the pedal feel despite the specs are identical.

Not sure what is causing this as I'd expect two brake setup with identical specs to feel the same... maybe I should just ask for another bleed/reflush.

 

Hi Hemiheaded,

I had someone installed the JCW brake kit about 7 weeks ago and the rental R56 has about 800 miles. I think it's safe to assume the rotors on both car are fairly new and the pads have been properly bedded by now.

 

not going to matter. are you saying you want the JCW kit to be 'grabby'? I felt it was superior to the R56 brakes because it wasn't.

 

My feeling is that the r53 brake pedal travel is much better as it is slightly longer and very progressive; perfect for the track and heel and toe. When I drive an R56, it takes me awhile to not launch things through the windshield, as the pedal is more like an on-off switch.

 

PGT and Redbird73,

You guys brought up some valid points. I have no experience in tracking so I didn't consider the benefit of a "progressive" brake/pedal feel in that measure.

I have driven a few BMW and remember their brake to be "grabby" and "on-off switch" like similar to my impression of R56. Without thinking much, I thought the faster response and short pedal travel of R56's brakes are superior than my JCW kit on R53.

IMHO, I prefer the brakes to be more "grabby" for road use...

 

Anyone know if there is a slotted track worthy rotor for the R56''jcw'' front brakes available??

 

Just my $.02 but I like the progressive feel of even the base R50/53 brakes and I do not track driving whatsoever. It allows for good modulation in stop-and-go and low speed driving. Like when traffic is slowing but you don't know how much or how quickly, the feel allows you to ease into it to begin then jam into it when traffic quickly stops.

 

It's called brake modulation and here's a quick review http://www.autoxcooper.com/carbotech..._pads.html#faq

 

check the part numbers for the R56 pads vs. the R53 JCW pads....they should be different. All else being the same, the R56 pads should fit and give you the same feel.

there are aftermarket pads now for both. Hawk HPS for example...they won't have that high initial bite and will be more like the stock JCW pads.

 

The master cylinders look different when comparing the drawings on realoem.com. If they are indeed different, then that is the reason for the difference in brake feel. The R56 probably uses a master with a larger piston bore(s) which would result in a stiffer pedal.

 

It's been awhile but, wouldn't a larger bore have a softer pedal? Larger confined area creates a lower pressure in a closed system compared to a smaller area. IE- 2 holes in 2 different bottles of equal proportions (capacity, fluid, yadayadayada). 1 bottle has a 1/4in hole, the other a 1/2in hole. If equal force from outside is applied, the smaller hole will have a higher pressure from being forced through a smaller hole. I think that's how it goes, anyway.