As far as I know Craven is the only one I know of that does linear in the front and progressive in the back. I am hoping the progressive will take longer to settle. I really don't want to eat 350 for and install when vendor did not deliver as advertised. My springs had a plastic wrap on the bottom part of the spring. I was told that needs to stay on, but in the picture above no plastic wrap.

I think there is something to putting weight in the back of the car. Braking seems much better.

 

Years ago, when Porsche came out with their 928 (their 1st front engine V8 car), there was much to do in the car magazines I read at the time about how they designed the car to have a high polar moment of inertia. If I remember correctly this was, in part, done by putting the engine up front and the transmission in the rear. This was done to make the car more stable. That is, this make the car harder to rotate or spin. With the weight that you put in the back of your car, you have increased its polar moment of inertia; hence increased the stability of your car. You have also taken some of the weight off the front wheels (I assume you put the weight in the boot). This will make the car less prone to oversteer (or others would say that you added understeer). An interesting solution to your issue...

 

So basically the same as my JCW which is what I would expect.

 

So I am wondering if during hard braking the car's back end gets light and the ABS sees it as slipping and starts to apply, but then the car settles as it slows and the ABS does not really know what to do.

Yes I did put in the boot. I have not had an opportunity to do the hard corner braking lately, but it does "at least to me" feel much better in day day braking. I would notice tail wagging even on hard braking in a straight line.

 

I don’t know on the ABS side of things. But, and I think I noted this before, that with my R56 under really hard braking the back end would get squirrelly and dance around. I never attributed it to ABS. The fix I tried was to increase the braking in the rear by going to a more aggressive pad. The person who suggested doing this raced a E30 BMW. He said that this will hold the backend of the car down. This is the same as what you did by adding weight back their. Another thought as to what it might be is that under hard braking the front goes down and the back goes up. In the rear this will cause a loss of camber and I don’t know what it does to the toe. But it seems more likely that these changes in suspension geometry are causing a directional stability issue, which you are feeling.

 

So.........I had the chance to corner brake today......and guess what, car was rock solid. I think the weight in the boot is working. So that got me thinking. The "challenge" car referenced earlier in the thread, is heavier than the normal JCW. They have stripped lots of weight, no NAV and such, but still weights more. I wonder if some of that weight was added to the boot to help stabilize the back end and get the weight distro adjusted. I have no proof of this but based on my current results makes me wonder..... I would recommend putting couple bags of lead shot in your boot and see if it helps.

 

Roll Cages usually add more weight to the rear than the front...might be a factor

 

+1

 

Well that is true but I was referring to the challenge production car

 

Sorry I loose track of details sometimes.

but I wonder why they would be heavier than the JCW....

it it also depends on where the weight is, as you have questioned.

 

That is the same question the reviewer asked. ?

 

Yes, you brought the springs deeper into the "progressive" state. You essentially stiffened the rear, by going past the soft stage of the spring.

 

Well that might be true, but the back end does not change in height even a little bit.

 

First track day in my '19 JCW HT. (Mods still have not allowed name change.) Five 15 minute sessions on the track with class room sessions in between.

I voiced my braking concern with my instructor. He explained a better technique in my trail braking. Problem solved before I even went out. But now I have another one.

In my second session, using all my instructor's corrections, I'm blasting around the track. 70+ in the big sweeper, 100 on the straight with only a few miscues in the twisties. I must be the fastest man on the planet and breaking all kinds of course records. Finishing the last twisty before the straight, I look in the mirror and there is a traffic jam behind me. How in the world could anyone have caught up to me? I give the pass-left sign. An ex-LeMans car, two high end 911s, and something so modded and totally covered with stickers I couldn't even tell what it was. I could still see the 911s through the next set of turns but they were gone after that. The LeMans car appeared again in a few minutes in my mirror. There was also an old F1 and a couple smaller open wheelers that ran earlier. Tough crowd.

I hope I didn't embarrass any of you JCW guys. I was pedaling as fast as I could.

I thought I needed to report back that there is nothing wrong with my JCW, it was just the driver. My new problem is that I just need to get faster.

 

so what was the better technique in tail braking?

 

Going into a curve, sequence goes threshold, trail, gas. He wanted me to spend more time using trail than I was doing, let it get a little loose, and aim for the back of the apex. He encouraged me to brake later so I could get a feel for the looseness as I went around a curve so I would know how much was too much and too little.

 

Sounds like you had a great instructor.
Keep getting an instructor in the car as much as you can. Most will be really great and helpful. There is so much to learn with respect to driving fast that has nothing to do with the car... Hope it continues to go well for you.

Great looking cars at that event. Some times it is almost worth it the cost of a track day just to see the cars that others bring to an event.

 

Sorry for resurrecting this old thread but man what a great thread - I spent last two hours reading through all the posts. I have the exact same issue like the OP ('19 JCW all stock) and some of you so I'm very interested if any of you with the issue found the definitive cure for this?

Did the Craven Speed springs (linear in the front, progressive in the rear) solve the issue? Did anybody with the issue install JCW Pro coilovers (or any other brand coilovers) and how did they work?

Was it the better/stickier non-rft tires (maybe a tad wider at 215 on stock wheels or 7.5-8 inch wide wheels with 225's) with higher pressure of 38/40 do the trick? More negative camber in the rear maybe?

I also noticed that when I put Ikea bag full of heavy tools and some other crap in my trunk the car did settle a bit better in high speed corner braking - could it be that easy? Should we look into relocating the battery to the rear? There is a thread on here that I found but with only photos and not too many details but I'd be willing to do that if need be - wouldn't it be beneficial to relocate some 45lb from the front of the car to the rear?

Someone mentioned stronger/better gripping rear brake pads - did anyone try that route and did it work?

Thanks everyone for participating in this awesome thread, it's been great reading through all the posts.

 

I managed to fix most of the problems I was experiencing. The springs did help a lot and also stiff sway bar in the back. I have also but ceramic brakes on the car. I don't know if any one of those was a fix. I have had the fish tail once or twice in the last six months but not to the extent that I was getting it before. I drive my car very hard so I would expect to see it more often if the problem had not diminished.

 

I did take my 2019 JCW out on the track (Watkins Glen) for a 3 day event of open track. It has the JCW Pro suspension on it. I ran it with NM 7.5x17, ET40 wheels, wrapped with 215-45-x17 Falken 660, 200 TW, tires. For brakes I ran iSweep IS4000 race pads up front and Hawk DTC30 in the rear. I had little in the way of tail wiggle under really hard braking. I never took the car to the track with the base suspension, so I can’t give you a comparison in that respect. I also never pushed it on the street with the base suspension so I never saw this problem on the street. Sorry.

The car was basically good on the track. There was a bit unevenness in the way it handled under braking and turn-in into corners, part of that was tail wiggle. My feeling was that that the mismatch between the front and rear brake pads played into this feeling. The next time (next year) I go out, I plan to have matched pads front to rear. I hope that helps further.

Overall, the car never felt insecure in the way it handled. It surely handles better than any base Cooper would. On the 3rd day of this event, I was able to match the best time I had with my R56S, which is much better setup to be a track car. So, the JCW has no lack of handling capability, even being basically stock.

Hope that helps.

 

I just switched to non-run flats as I had a damaged tire recently. If I had a chance I'd would have stayed with the run-flats. I prefer the stiffer sidewall feel. The troublesome balance issues up and around the cornering threshold didn't change though. Initial turn-in just seemed a little more positive with the run-flats. Go ahead and boo me everyone, I can take it. Hee hee.

 

I too like the stiffer ride of runflats. We're definitely in the minority on here.

 

I like the stuff sidewall also but I have a wife who rides with me. The run flats create more noise when she is in the car if you get my drift

 

I used both RFs and non RFs on my first Mini MCS and I thought the only major advantage of the non RFs was the slightly softer ride and slightly less noise on the freeway. Now that I have the adjustable dampers there's no reason not to keep the RFs. I didn't change them on the 2014 JCW Coupe either.
I don't know what it is from, but my 2020 JCW Clubman doesn't have any of the understeer I used to notice in my first 2 Minis (corrected by a rear swaybar). Maybe it's the All4?

 

My guess would be the Clubman has a better weight distribution and the longer wheelbase may help too.

Shocks make a big difference with the Run Flats. I had RFTs on my R56S and couldn’t stand them. I changed shocks to Bilsteins and I am back to using the RFTs. I noticed my F56 JCW rode pretty nicely with the RFTs with the base shocks. No issues. However, the Pro Suspension is stiff enough to make the RFTs a bit uncomfortable.

For sidewall stiffness, I found the RFTs to be about as stiff as the Extreme performance tires (200 TW). Similar ride too. In a non-RFT, you need a performance tire to get the same turn-in feel. Of course an advantage with the Extreme Performance tires is the grip RFTs won’t have. Disadvantage is the high tread wear rate and they are only one season...