I am wondering if anyone knows the specs for JCW's rear sway bar. Is it the same sway bar as MCS?

Would it be worth it to upgrade to a stiffer sway bar to improve understeer?

Thanks !

 

I put my caliper on it and it shows 22mm. Not sure an upgrade is worth it as most are 22mm.

 

The JCW 3-dr hatch's rear sway bar is the same part number as the '14 and '15 Cooper and Cooper S with the Sport Suspension option. What that diameter is exactly I'm not sure.

The NM 22mm rear sway bar should be adequately stiffer to reduce understeer, and it's adjustable so we should be able to balance the car to preference. I'll very likely be putting it on my JCW when it arrives next month.

It's worth mentioning that the diameters are only actually relevant if you have the tube style [hollow w/wall thickness vs. solid] and exact spring steel properties. Add in the lever arm moment too to the equation to get actual sway bar spring rate.

 

knecht:
Thanks so much for your quick reply. These specs are not available anywhere or at least I've not been able to find any info. So first hand knowledge based on actual measurement can't be beat. Thankyou!

 

Ryephile:

Oh so not all sway bars are soild? Any idea if JCW swaybar is hollow or solid?
If its hollow, then I'd agree that NM solid 22mm sway bar would be worth a try.

 

Other than a stiffer sway-bar, what else can be done to reduce understeer?

 

I plan on buying Cravenspeeds Big Pair to see how they perform.

 

It's a mix; some are hollow, some are solid. It depends on who's making them, their weight/stiffness criteria, packaging criteria, etc.

Assuming the steels are the same and the moment arm is the same, the solid NM 22mm would be stiffer than any 22mm diameter hollow.

I would also assume the NM bar's adjustable holes bias on the stiffer side [shorter moment arm], but we'd need to measure that in-person to verify that.


*A stiffer rear spring rate also reduces steady-state cornering understeer, however putting that into effect is usually easier said that done.
*Adding negative front camber will improve front end grip in corners, reducing understeer. The OEM way to do that is to buy the "camber correction" knuckles that add -30 minutes, aka -0.5 degrees of camber. Allegedly LAP Motorsports has a front strut camber plate they use for the IMSA Conti sports car challenge, but that's also very likely tied to extremely expensive bespoke racing dampers.

 

Great point! Not sure if the stock part is solid.

 

IMO - A stiffer rear sway bar is the simplest way to keep understeer in check. Understeer is a problem with most FW drive cars. I have added one to my last 2 MINIs and the results have been outstanding. The back tends to lose traction a little more easily but overall the car will way more predicable and neutral. IMO the #1 bang for your buck!

 

Did not know about these. Price seems reasonable to give them a try.
If you do try them please share your installation experience and if you notice the reduced body flex.

 

Is that a MINI OEM part?

 

Thanks for sharing your experience. I want to give it a try.
Do MINI dealers install NM sway bars or do you have to go to an indy shop?

 

jamgolf. Do it yourself. That's the fun part with these cars. You need a few tools (torque wrench, spanners etc) and proper support stands for the rear of the car. Takes a couple of hours and you will have the satisfaction of knowing you did it!

 

I used to own a Jeep a few years ago and installed/modified several things on that Jeep. But that was just such a rugged vehicle that I did not worry about messing up its handling, it makes me a bit nervous messing with the JCW's suspension myself - since its all about handling - which is easily affected by geometry.

But you are right - the satisfaction of DIY is sweet. I actually watched the 2 part video on youtube on installing the NM swaybar. I might actually do it myself

 

Yes, part numbers 31216860989 and 31216860990

As discovered by cmt52663 in his auto-x Cooper build thread

 

These will stiffen the body, but not reduce understeer. So get the sway bar first.

We had a 15 JCW in last week and it has the same 22mm hollow sway bar as the standard F56.
Going to the NM solid bar is a great improvement as the hollow bar is just not stiff enough. I've installed a few already and it's pretty easy.

To reduce understeer more you can add more neg camber with the powerflex adjustable camber bushings. They replace the stock bushings with polyurethane but are offset so you can adjust the camber.

 

Has any one done this and the poweflex bushings at the same time


Running -1.5 on my r53 with BC coil-overs + swift with thick rear ARB
But as my f56 has adj factory damping I won't be swapping these out anytime soon

 

Great information, thanks for sharing! It looks like an NM sway bar is in my future.

 

All good advice Way.

The one note of caution I would add is depending on exactly how the FCAB is captured by the subframe and how the Powerflex bushing is designed, there is a possibility the offset bushing will rotate over time, changing the alignment. It's very design-specific whether it'll be a problem, as not all offset bushings are designed the same.

Whether the Powerflex offset's retain their positioning or not will be a function of close engineering scrutinizing and putting on lots of miles to prove them out. This is beyond just saying "I installed them so I say they're fine. It means installing, beating on the car senseless for thousands of miles, and then re-checking the alignment.

 

OK so two questions here:

1) Looking at the sway bar picture on your site I see two sets of holes at the end of the sway bar - which set of holes provides the greater effect against understeer the ones closer to the end of the set further from the end?

2) If I install the adjustable bushings, what camber value do I ask my alignment guy to dial in so as to work with the sway bar to reduce understeer?

 

The holes closer to the bar are less understeer. I had Way install a 19mm bar in my MCS in 2008. Middle setting. Bar was $200, labor $100. Took 2 guys about 45 minutes. Made quite a difference, it was just about right for me. I hear if you install too stiff a bar the car is prone to swapping ends if you go too fast into a turn and have to slow down.

 

Once installed the two holes give you the adjustment. The hole closest to the front of the car is the stiffer setting, and the other closer to the rear bumper is the softer. All the ones we've put on the F56 so far have been the soft setting and been great.

For a daily driver street car you could shoot for 1.5 neg camber. That will give you a good improvement and not be too aggressive to eat your tires.

 

Thank You sir. Now I know which Way to go (pun intended).

 

Have Dynamic dampners on 2015 JCW....would adding the NM 22 Solid Sway bar improve handling AND can you add powerflex adjustable camber bushings and negative camber with the dynamic dampners?