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So, your first impressions seem to be good, similar to my experience and that of others I have read about who have made this change.
I think mine are currently set at 562mm front and rear, and the fronts are slammed. You have the same wheels I have so I can relate to your measurements. I need to get my fronts up higher and see if that gets rid of the CV joint wobble I have. At least I think that is the issue.
Eddie it is worth noting that when the MoP crew set ride heights for Gollum, we did NOT put the specified 150 lbs in the two front seats.
So after a hundred miles in shitty weather, I can report the following early impressions.
THe JCW Pro setup is good. It's not that I just spent stupid money on it, it actually is.
The ride has gone from STIFF (Sport suspension, B8 Bilstein), to FIRM (JCW Pro).
In Gloucester, on Main Street, certain BANGS have become THUMPS.
So on the daily driver side, this setup is obviously better.
Is is faster? That jury won't come in for months.
I do note that the measurement approach to ride height on the F56 admits of the fact, concealed by the lines of the car, that the crest of the front wheel well is further from the ground than the rear wheel well.
Thus the 578 mm from front lower rim to wheel well arch, and the 563 mm from rear lower rim to wheel arch top, actually yields some rake. The front of the chassis is lower than the back.
I've tried to illustrate this using the Protractor application, but it is being cranky.
I was a bit puzzled at the ride height specifications - as all (OEM, JCW, and our Final) have a greater number at the front axle than at the rear.
So either the car is pitched upwards at the nose (which is not the case), or
The crest of the front wheel well is taller out front, relative to the chassis base.
It's subtle, perhaps a deliberate trompe l'oeil on the part of the designer, but it seems that second option is indeed the case.
These lines are NOT parallel...
Cheers,
Charlie
Last edited by cmt52663; Dec 19, 2019 at 09:11 AM.
When it is cold (Below freezing), I am noticing a bit more “sharpness” in the ride when going over the broken up and repaired, NE frozen and salt damaged roads around me. I am wonder how much the RFTs play into that vs the stiffer springs and shocks. Or maybe I am just feeling what the cold does in general to the tires, shocks, bushing, etc.
OK, the Quaife and the JCW Pro installation are done, and all seems well.
Ride height measured from lower outer rim edge to top center of wheel well.
So, interestingly enough the JCW Pro installation instructions contains some specs for ride height that we ignored.
The rear shocks are near their lowest setting - the spec setting is not attainable ( are the JCW specs BS? ) - which drops the back 11 mm.
The fronts are within center range - which drops the nose 15 mm. Increase to rake from spec is 5 mm. Here again the JCW spec seems quite odd, and was disregarded.
After 20 miles in bad weather, the chassis is planted, quiet, and firm. Too soon to say of course.
But promising.
Cheers,
Charlie
Originally Posted by cmt52663
Eddie it is worth noting that when the MoP crew set ride heights for Gollum, we did NOT put the specified 150 lbs in the two front seats.
Cheers,
Charlie
I am also guessing that the OEM spec of 593/574 mm front and rear is with the weight in the seats as my height with the base suspension was about 10mm above that and the person who posted about the Pro suspension was almost 20mm above that. It also seems like there is some variations in the ride heights of these cars, maybe?
OK, folks here's the tale that has been simmering in the background this year. I believe it can now be told, as all the evidence is finally in.
In January of this year the MoP pit crew installed the K-MAC camber plates, which I sourced through ECS Tuning.
They allowed us to run a lovely alignment for the 2019 competition season, but ultimately became a serious issue.
Here is the timeline for this saga:
It seems that Kevin (Proprietor for K-MAC, out of Sydney AU) produced the camber plates believing that the F56 front shock mainshaft OD was 12 millimeters- which is not the case.
Actually the OEM shock top is 13.3 mm - like this:
OEM shaft OD.
The Bilstein B8 shaft is 13.2 mm, like this:
Bilstein shaft OD.
What lead the crew to finally realize the root cause was that the JCW Pro shaft would not even SEAT in the K-MAC plate as the diameter above the shaft base is greater than 12.5 mm (the base is 12.99 mm) like this:
JCW Pro OD
Other clues observed during this inquiry come from the deformation of the shaft top on the Bilsteins during the past year.
Right front (near failure after about 19k miles):
RF Bilstein - 19 k miles
And the total failure of the LF Bilstein - note the original profile of the shaft base has been hammered by the improper fitment, resulting in the failure:
Snapped LF Bilstein
Joel DeCoff and the Mini Crew, having been very patient, supportive, and reasonable during this ordeal suggested that the center plate of the K-MAC where the shaft seats should be re-bored to properly fit the collar at the base of the JCW Pro shock.
We did that, and subsequently the JCW Pro installation went well.
K-MAC listened, looked at the evidence, and finally the last email I received was this:
I note that Tirerack was interested in this research (thanks Kathy - acting as liaison with Bilstein) and I appreciate that support.
Regrettably I must also report that ECS tuning was NOT interested in this inquiry, and immediately referred me to K-MAC.
Mini of Peabody consistently went above and beyond the call of duty, which is typical of my experience with them over the last 15 years.
So all's well that ends well, and iin my next post I shall return to the JCW Pro setup, final dimensions, and initial impressions.
Cheers,
Charlie
Hello,
Just saw this thread.
We are interested in the technical details, sorry about that. They might have thought you have a problem and since Kevin knows his products in/out they maybe thought best to talk to him. I talked to him personally and he is very knowledgeable.
If you ever want to talk I am always here a PM away.
The author. God help me! ;-). The poster behind me was made by a class of schoolchildren to commemorate the crew and families of the Andrea Gail. It hangs at the Crow's Nest in Gloucester, which I have been known to frequent.
We've all enjoyed, or at least survived, another Christmas.
And at least around here, we enjoy a welcome break from the early onset of winter.
The quarries in Rockport can be truly lovely - looking north from Halibut Point.
And there is a SCCA Runoffs Marathon on CBSSN to distract me from the off season. Oh vicarious thrills!
And while I am being unusually gregarious, I am moved to be grateful for Maryanne Shatford (proprietress of the aforementioned Crows Nest) who gave me the best Christmas Present this year - a BRG Cooper S!
After a bit more than 1,000 miles, I'm delighted with the JCW Pro Coilover setup as we deal with the winter roads around Cape Anne.
But will it be faster on course, when racing resumes?
I've been considering that, and doing my homework on the effects of lowering on MacPherson Strut suspensions.
I do not intend to tackle the process of creating all measurements needed for a WinGeo model, but cannot accept hearsay or aesthetics as the entire basis for setting ride height.
One of the bogymen of excessive lowering is the effect of jacking forces at the chassis, arising from the lower control arm angle. Here's an example - with a bit over 5 degrees of angle on the lower control arm.
So how much lift or drop is actually being conveyed to this chassis, depending on that lower control arm angle? Is it significant?
I dusted off my high-school trigonometry, and made a few assumptions to see if I could work that out.
Assumptions:
the lower control arm is 12" (304 mm) - arbitrarily!
the stroke of the suspension at the outer ball joint will be up or down from center a maximum of 2" (50.8 mm)
1,000 pounds of lateral force exists at the outer joint of the LCA (hub side)
That conveniently means that the angle of the LCA to the chassis will vary +/- 10 degrees, so that is the range of the following calculations:
I was a bit surprised at this, as it seems to me that if the jacking force acting on the chassis in this case is +/- 174 pounds then that is a significant force indeed.
So the next time Gollum is on the scales or the alignment rack I'll have a serious try at measuring that LCA angle!
Cheers,
Charlie
Last edited by cmt52663; Jan 12, 2020 at 03:29 AM.
Oh, wow! This gets really complicated when you get into mucking with suspensions...
Which has forced me into looking into the definition of roll center and effects of lowering ones car. The conventional wisdom is that lowing the car, which lowers the CG, is considered a good thing. Then, more is better, yes? I guess the real answer is that “it depends”.
And then I found that in setting the ride height, the relationship of the front to rear roll center heights will factor into oversteer or understeer...(http://www.formula1-dictionary.net/roll_center.html) Higher in the back is in the direction of oversteer and vice versa; higher in the front is in the direction of understeer. Could this play into the reason that MINI has the ride height measurements about 0.5” higher in the front, which actually keeps the car level as you pointed out, and is in the direction of understeer? This also helps to explain why, when a friend arbitrarily raised the rear of his MINI to give more tire clearance, his car oversteered in a corner and he crashed it on the inside wall of the track he was at... Ugh! Before that he and his car were doing well.
Charlie - Thanks for posting. This info has given me a bigger reason for setting up on my suspension the way I (and MINI) wanted it. The dealer has the ride height the same front and rear (for aesthetics, I would guess). I didn’t particularly want it set this way, but now I know why I don’t want it that way. This means that the rear is actually higher than the front. For me, that is in the wrong (oversteer) direction. I am glad I found this out now and not on the tracks around here, which are very unforgiving when something goes wrong.
Here's a body of knowledge - including a feasible method of locating CG.
Fortunately winter drives me to research - which erodes my ignorance.
Cheers,
Charlie
Wow, I have learned more in the past hour about car roll center setup than I have in the past ten years of listening to “experts”. And so clearly written. An excellent article. Thanks for posting.
One thing I can note is that I have seen video of my MINI from the rear on the track in about a 1g turn and the car has little in the way of inside rear wheel lift. It would seem from the article about roll center that with the little bit that I did in the way of modifying the suspension did what I intended. That is, increase the roll stiffness without affecting the original MINI handling characteristics. And I also suspect that the MINI suspension designers know all of this stuff and had the roll centers nicely located to give a “conservative” handling characteristic, which, for me on the track, is a good thing; maybe not so good for autocross... Now I need to not screw that up with ride heights. Definitely more for me to look at.
All of that said a side comment... I would suggest that, for a relatively inexperienced person taking their MINI to the track, the suggested roll center heights for a front wheel drive car are too extreme (15% front, 30% rear; percent of the CG height). That setup along with a really stiff rear roll bar that people generally (and IMHO wrongly*) throw into a MINI, are in the direction of having oversteer that will be hard for an inexperienced person to handle. Around here that can result in no longer having a car...
*I would put autocross in a different category than running on the track... and this is just my opinion.
Wow, I have learned more in the past hour about car roll center setup than I have in the past ten years of listening to “experts”. And so clearly written. An excellent article. Thanks for posting.
One thing I can note is that I have seen video of my MINI from the rear on the track in about a 1g turn and the car has little in the way of inside rear wheel lift. It would seem from the article about roll center that with the little bit that I did in the way of modifying the suspension did what I intended. That is, increase the roll stiffness without affecting the original MINI handling characteristics. And I also suspect that the MINI suspension designers know all of this stuff and had the roll centers nicely located to give a “conservative” handling characteristic, which, for me on the track, is a good thing; maybe not so good for autocross... Now I need to not screw that up with ride heights. Definitely more for me to look at.
All of that said a side comment... I would suggest that, for a relatively inexperienced person taking their MINI to the track, the suggested roll center heights for a front wheel drive car are too extreme (15% front, 30% rear; percent of the CG height). That setup along with a really stiff rear roll bar that people generally (and IMHO wrongly*) throw into a MINI, are in the direction of having oversteer that will be hard for an inexperienced person to handle. Around here that can result in no longer having a car...
*I would put autocross in a different category than running on the track... and this is just my opinion.
It is for damned sure that what I like in the middle of a 45 mph slalom is VERY different from what I'd care for entering a 100 mph sweeper!
I have often wondered why MINI only lowered the car by 10mm with the optional JCW sports suspension (red springs) on the Gen I and II MINIs. Why so little? Maybe the answer is that it is the sweet spot or the upper end of the sweet spot. I really do think the suspension engineers at MINI know what they are doing, and deviating from that and to get it right will take some really study with a clear target/objective in mind, as you are doing. For me, I will be following MINI’s lead with the front to rear height differences. Not sure how much I can do in the way of actual dimensions and angles of pieces and parts in there. Lime Rock park has a skid pad and an autocross track that I can test the car on before I head out onto the actual track. Late March is my target date for that.
Looking forward to what you come up with for height settings.
I am discovering that making a full and accurate computational model of my car is complicated, and difficult. There are some pieces of data which are apparently hard to obtain.
One example is the spring rates for the front progressive coils used in the JCW Pro Coil-over - Part # 33502361197.
Since my goal is to be able to plot the weight on each corner - starting from rest, and extending over the entire friction circle @ 1g - that's a worry.
Apparently there are three computations which are needed to solve this puzzle:: geometric unsprung, geometric sprung, and elastic sprung.. The dominant factor is the last one, and that is where the need for spring rate data arises.
The static weight distribution on my car (from scale data) is.
In my study of instantaneous centers, roll axes, and lateral and longitudinal load transfer I have found that a weight transfer of more than 65% is not at all unusual, which theoretically could generate the following loads at corner entry for a slow left hander (30% forward, 30% right).
Is this real? From the data I have been studying it seems well within the realm of possibility for Gollum, and it damned sure explains this.
As Eddie observes, and as this data suggests, in a case where weight transfer is severe, and acts on both the lateral and longitudinal axes, the resulting weights at the contact patch can indeed go negative.
This also suggests to me that the point where the minimum load at the back axle falls to zero and wheel lift occurs, it will produce a knee in the overall roll resistance of the chassis. That will affect the oversteer/understeer balance of the car.
It also occurs to me that with the load changing at the right front corner from about 800 pounds to almost a ton on corner entry, the contact patch @ 35 psi more than DOUBLES.
Cheers,
Charlie
Last edited by cmt52663; Jan 16, 2020 at 02:56 PM.
Charlie,
Two cents worth of observation that probably accounts for nothing in this conversation:
I had two great instructors, a couple of years ago, at the MINI Performance School in Thermal, CA. The were (are) professional race drivers. They had some interesting observations of the MINI as they also instruct with BMWs, RWD. One was the suggestion that in the MINI, one should begin to accelerate at a greater distance before the apex of a corner rather than the suggested point of a RWD (or AWD). The DSC was turned on below 50%, as I was told, kept on because of "students" on the track. They explain that the power (torque) pulled the lateral forces towards the center, thus more control and less corner roll. The MINIs used were JCW autos and braking, obviously even with paddles, was different than manuals. Watching Bimmers on the autocross track they drove, and then the MINIs, it was quite obvious.
The other point was illustrated on the skid pad with the rear end breaking loose. Again it was suggested, that uniquely in the MINI from their experiences, they did not turn sharply into the skid, but only slightly and applied a lot more power. They suggested this course of action, to novices should only be used as a "last resort" however an experienced MINI driver would control the action, almost second nature. As they illustrated on the pad.
This points me to theorize that the MINI is an unique animal in the racing world, more ways than one may expect. It appears that the power/torque effects of the FWD MINI is a lot more complicated than the calculations may appear. Just 2 cents worth.
Charlie,
Two cents worth of observation that probably accounts for nothing in this conversation:
I had two great instructors, a couple of years ago, at the MINI Performance School in Thermal, CA. The were (are) professional race drivers. They had some interesting observations of the MINI as they also instruct with BMWs, RWD. One was the suggestion that in the MINI, one should begin to accelerate at a greater distance before the apex of a corner rather than the suggested point of a RWD (or AWD). The DSC was turned on below 50%, as I was told, kept on because of "students" on the track. They explain that the power (torque) pulled the lateral forces towards the center, thus more control and less corner roll. The MINIs used were JCW autos and braking, obviously even with paddles, was different than manuals. Watching Bimmers on the autocross track they drove, and then the MINIs, it was quite obvious.
The other point was illustrated on the skid pad with the rear end breaking loose. Again it was suggested, that uniquely in the MINI from their experiences, they did not turn sharply into the skid, but only slightly and applied a lot more power. They suggested this course of action, to novices should only be used as a "last resort" however an experienced MINI driver would control the action, almost second nature. As they illustrated on the pad.
This points me to theorize that the MINI is an unique animal in the racing world, more ways than one may expect. It appears that the power/torque effects of the FWD MINI is a lot more complicated than the calculations may appear. Just 2 cents worth.
I am not sure why those instructors would suggest to apply throttle before the apex, well enough alone even further before the apex than they would typically apply it. The only reason I can think of as to why to do that is to compensate for a car that is aggressively setup towards oversteering. Application of the throttle in a turn will cause the car to understeer; FWD or RWD, doesn’t matter which. But, RWD has the advantage of being able to induce oversteer with an excess amount of power. Ideally the fastest way through a turn is to be slowing all the way to the apex and accelerating after the apex. There are some great “lap of the track” videos on YouTube that show this. It is particularly visible in the IMSA DPI car videos where the telemetry is shown. They will typically be braking right up to the apex and then accelerating from there.
I have read in road/track tests of the Gen III JCW that there is a tendency for it to oversteer in corners when out on the track. So, maybe, the instructor’s guidance is to compensating for that? It could be. I have not yet had mine out on the track, so I have no experience to speak to. I hope MINI hasn’t been too aggressive at moving the JCW towards the tendency to oversteer. I have worked hard at improving the cornering of my Gen II S without moving the handling too much towards the tendency to oversteer. There are just too many unpredictable circumstances that I have come across where driving a car with the tendency to oversteer would not be fun to deal with. I am hopeful my Gen III JCW performs similarly to my S.
I have great interest in what Charlie comes up with relative to the height settings of his MINI and he is really good at explaining the “why’s”. He and I have different objectives, but this information can be used for either of us. It seems that I have already learned that I can “screw up” the handling with ride heights and that I can change the tendency for oversteer with differences in the front to rear ride heights. Hopefully, I get it right. The guardrails at the tracks I go to are very unforgiving if I get it wrong...
Tarbo lag.
it's also advised to over slow for a corner rather than not slow enough, the former loses tenths the latter loses seconds, partial throttle earlier than Apex to balance the car through the steady state cornering should be common no matter the drivetrain layout.
Edit here's an F1 pole lap from 2018 with telemetry
https://youtu.be/EaV_fueeGKk
Last edited by strat61caster; Jan 17, 2020 at 08:35 AM.
Now I need to not screw that up with ride heights. Definitely more for me to look at.
