GP Talk (2006) Discussion of the limited edition, MINI Cooper S (R53)-based, John Cooper Works GP.

Suspension Changes. Am I crazy?

Old Aug 7, 2008 | 11:43 AM
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Suspension Changes. Am I crazy?

I would like to improve the GP suspension, but some have said it is already about as good as it gets for a Mini. What I have planned is:
H&R Springs (have from previous MCS)
Hotchkis Adj Front Camber Plates (have from previous MCS)
19mm Rear Adj Sway Bar (need to purchase)
Lower Rear Adj Control Arms (if required to get back to -1 deg camber)

My goals are:
Lower the GP about 1/2".
Improve the handling.
Keep stock wheels (already changed to non-runflat 215/40x18 tires).
Spend as little money as possible at this time (2 kids in college).
Plan for future upgrade to Koni Yellow Adj. Shocks (when stock shocks die).

I will also be adding 15mm wheel spacers for a wider stance and to clear BBK.

Does my plan make sense or will I just be degrading the handling of the GP?

I am not worried about the resale value due to the mods.
 
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Old Aug 7, 2008 | 11:57 AM
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The setup you mention, due to already having the parts, sounds good and you should notice a pretty big difference in handling and a firmer ride.
 
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Old Aug 7, 2008 | 10:16 PM
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Plus 1 on H-Sport Camber plates to set agressive camber and prevent shroomage, Rear sway bar to induce rotation in mid-corner and keep flat. Not sure on springs I initially wanted to do but wanted red springs, when I still lived in Santa Cruz county area, but in sheety Philly I bottom out every where. I am looking to get the JCW convertible springs (harder spring rates) Front sway will reduce rotation tendency, if ya get might want H-Sport rear Comp bar (25.5mm) to nuetralize front. I thought GP/R56 control arms you were able to adjust? Not sure? Sticky tires will help alot ie: Hankook RZ12 or Falken RT-615, Dunlop Star Specs. Also. since ya got GP might want these new Brembo JCW brakes
 
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Old Aug 8, 2008 | 12:56 PM
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save money down the road and get full coilovers.
 
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Old Aug 11, 2008 | 07:49 PM
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Hi everybody...I'm new to this community and this is my first post...and hopefully I'm not out of line......need help!!


I'm looking for a low milage GP in the Las Vegas,Southern California or Phoenix area...I've done my home work and hopefully I will have my first MINI....thank you
 
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Old Aug 11, 2008 | 10:01 PM
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There are a few postings in this NAM GP Forum such as:
https://www.northamericanmotoring.co...d.php?t=145271
https://www.northamericanmotoring.co...d.php?t=148529

Look in the marketplace section of the NAM forum at:
https://www.northamericanmotoring.co...cat.php/cat/12

You can also try the GPMINI forum at:
https://www.northamericanmotoring.co...cat.php/cat/12
 
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Old Aug 20, 2008 | 07:15 AM
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Well, I was crazy.

I installed the H&R Springs and Hotchkis Adj Front Camber Plates. Then I removed the H&R springs and reinstalled the JCW springs with the camber plates. I am happy with the camber plates but not the springs. Here is why:

I measured the JCW springs when I took them off and compared them to the H&R springs. The spring wire diameter is thicker on the front and rear JCW springs than the H&R springs. The front springs have the same outside coil diameter and same coil count. This would indicate that the front JCW springs are stiffer than the H&R springs. The rear springs are the same outside coil diameter but very different coil count. The H&R rear springs have four closer coils at the top than the coils are spaced about the same as the JCW springs. Based on a spring rate calculator, the rear JCW are stiffer than the H&R springs. I was hoping for a 1/2" drop all around with the H&R springs but I got about 1/8-3/16" drop in the front and about 1/4-3/8" drop in the rear. The small amount of lowering was not worth the spring rate change so I went back the the JCW springs.

I know that there are various spring rates for JCW springs and Mini does not seem to went to disclose the spring rates so I am not exactly sure which springs Mini installed on the GP. All four springs are red with one yellow stripe. The front springs have the number 415 stamped near the end. I could not find an numerical marking on the rear springs.

I am still trying to get the front camber adjusted to where I want it at -2.0 degrees but I am having a difficult time getting that much camber at the left front due to the spring hitting the inner wheel well. I will be taking it off again and doing more pounding but I am not sure there is much more I can do. I will get the left front as far as it will go (I suspect around -1.7) and then adjust the right to match. I am at about -1.5 right now and can feel a big improvement in the front end grip. I might not even need a 19mm rear sway bar but we will see after I get the camber all set and get some driving time.

Looks like I can sell the H&R springs (now painted red).
 
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Old Aug 20, 2008 | 07:23 AM
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I was able to get -2.1 by flattening out that seam (and coilovers, which might be the diff).

from my experience, do the 19mm. I ran it at full stiff and the car rotated beautifully and was completely controllable, yet safe on the street too.
 
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Old Aug 20, 2008 | 07:47 AM
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Yea, the coilovers have a smaller diameter coil so there is a little more room. I have flattened the seam/rib and then some. I plan to get the hammer out again but I think I have reached the limit.

It is interesting to me that the left side was about -0.3 stock and the right side about -1.4. I was surprised at the different between the two sides. If only the left side could have been the one with the large negative camber when stock. Just my luck.
 
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Old Aug 20, 2008 | 01:59 PM
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"I know that there are various spring rates for JCW springs and Mini does not seem to went to disclose the spring rates so I am not exactly sure which springs Mini installed on the GP. All four springs are red with one yellow stripe. The front springs have the number 415 stamped near the end. I could not find an numerical marking on the rear springs."

Yeah, I don't have the spring rates, but I do have the part numbersfor all 3 rears and 3 fronts. They are described as soft, medium, and hardest. I will post them in a couple of weeks when I get back home.

"I was able to get -2.1 by flattening out that seam (and coilovers, which might be the diff).
from my experience, do the 19mm. I ran it at full stiff and the car rotated beautifully and was completely controllable, yet safe on the street too."

+1 on the rear sway bar, less roll-over feeling too. And yes bang out fender to get the -2 camber, I had 2.5 on ex-MCS. You spent the mulah on the H-Sport camber plates might as well get them some serious camber.
 
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Old Aug 21, 2008 | 11:35 AM
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howsoonisnow & pgt,

Which brand 19mm bar are you using or what are the adjustment rates on your bars? I would normally go with Hotchkis but I see their rates are very different (lower) than the Alta.

Hotchkis: 54%, 88%, 128%
Alta: 115%, 140%, 177%

From howsoonisnow's signature, it looks like a Hotchkis 25.5 mm bar. What setting are you using on the street? On my old 2003 MCS, I thought the 25.5mm bar (softest setting) with camber plates induced a little too much oversteer but that car was quite a bit different than my GP.
 
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Old Aug 21, 2008 | 11:43 AM
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From: DC Metro
I was running the HSport but moved up to an Rspeed 22mm bar (same as Webb sells)
 
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Old Aug 21, 2008 | 01:16 PM
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I had the H-Sport 'Comp" bar on the MCS BRG, just FLAT around corners, it was sweet, but I also had the front bar to "compensate for the overcompensation"

On the GP I have H-Sport "Sport" on highest setting, I was considering Comp bar but put the 19mm to test out. It seems that the GP stiffer JCW springs coupled with the lighter rear end facilitate rotation with just drop throttle (no brakes needed) So, I am keeping the Sport bar.

BTW: I run 34psi on fronts and 35.5 psi on rears, if I drop rears to 34 psi, the rear sticks better and takes a more "aggressive" drop throttle to induce rotation maybe even a gentle tap of brakes at slower speeds. Play with your air valves see what is good for you, what psi works for me, may not work for you, (many variables: wheel size, tire size, tire, weight, etc) but my point is that it does make a difference in handling characteristics.
 

Last edited by howsoonisnow1985; Aug 21, 2008 at 01:28 PM.
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Old Aug 21, 2008 | 01:40 PM
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yeah....I'm running 33 up front and 29 in the rear on rcomps for autox. the rear likes that based on wear patterns (not quite to rollover on the sidewall which means you're using all the tread)
 
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Old Aug 21, 2008 | 02:10 PM
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Guys,
Thanks for the 19mm input and tire air pressures. I was concerned that the H-Sport 19mm would not be enough since it's stiffest setting is in between the Alta softest and middle setting. I would prefer the H-Sport and it sounds like it will be enough on the stiffest setting.
 
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Old Aug 21, 2008 | 02:16 PM
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well, there are some tweaks you need to do to fit a bigger bar (like getting more camber). the 19mm on full stiff was fine for me...I only went larger and set it in the middle so that I could tweak if needed.
 
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Old Aug 21, 2008 | 06:27 PM
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AUTO-X

Originally Posted by PGT
yeah....I'm running 33 up front and 29 in the rear on rcomps for autox. the rear likes that based on wear patterns (not quite to rollover on the sidewall which means you're using all the tread)
Are you running 15 or 16 tires?

My psi listed was off the 17s, not the GP wheels, but its similar (33 in front 34 in back) ughh! 18s! Do you know if I could run oem 16 x-lites for scca, or stuck with 18s?

QUICKMINI, did you figure out how to get at least -2 camber in front?
GrassRoots Motorsports has great article on MINIs camber adjustments and comparos both on track and auto-x maybe called "Make it Stick". And GPs do have an adjustable bolt on rear control arms. (to straighten out camber a bit)
 

Last edited by howsoonisnow1985; Aug 21, 2008 at 06:35 PM.
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Old Aug 21, 2008 | 07:00 PM
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I was referring to my 15" set but I'm on a new 16" set with wider rubber. I'll have to play around a bit with pressures in eight days...next event.
 
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Old Aug 21, 2008 | 08:54 PM
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Target parking lot at midnight
 
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Old Aug 21, 2008 | 09:03 PM
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seriously! I've been pushing as hard as I dare do on the street....a hard corner near my house at speed. I've cornered so hard, I get the four wheel drift going, so I know I'm at the limit. Still not getting wear across the whole width which means -1.4R camber is more than enough.
 
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