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Unread 08-10-2016, 07:10 PM
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Fair! Fair! is offline
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Default Re: Ford Focus RS Development Thread

continued from above



There is also an OEM front brake cooling solution on the RS, shown above and below. In the image above you can see the smooth plastic duct that takes air from a front scoop/opening and points it into the front fender liner.



Here you can see the fender liner exhaust for the brake cooling air (at left), and from here the higher pressure cooling air stream is thrown at a flap on the control arm. This flap, in theory, guides the air towards the inside of the rotor. We call this a "scoop and flap" brake cooling solution. No, its not as effective as a properly hosed/ducted brake cooling system like you see us build for race cars, but its better than nothing. I think it was Porsche who came up with this scoop and flap technique on factory 911s back in the 1980s? Ford has done something similar on some of the S550 Mustangs also.



The rear brakes seem disproportionately small, and originally I suspected they were the same units fitted to the "rental car fleet" Focus, but I was wrong. When we sent the brake pad scans to our friends at G-LOC Brakes they assured us these were new pad shapes, so the small diameter, non-vented rotor and single piston sliding caliper might be unique to the RS. It is not impressive in size or style - but it should be cheap to replace when parts wear.



Here we see the weights on the somewhat heavy 19" x 8" factory wheels and 235/35/19 Michelin Pilot Super Sport (PSS) tires. There is supposedly another optional tire for these cars, but this RS was ordered with the base standard set knowing they would be quickly replaced. This 235 Michelin PSS shows to be 23 pounds on the TireRack website, so that means this 19x8" wheel should weigh about 28.5 pounds (amazingly heavy) if you do the math. There are definitely some pounds to drop going to a wider 17" or 18" aftermarket wheel - and we plan to measure for new rims after the coilovers and camber plates are installed. We will talk more about that in a future post.



These are pictures of the front strut tower and strut/spring assembly. There is nowhere for the strut with the large diameter OEM spring to go - no room inboard - so there will be no OEM spring style camber plates. I explain this in more detail in the video below, "Suspension Challenges".



Just getting to the top of the strut towers involved removing about 19 layers of stuff under the hood. This is one of the most restrictive engine brace / cover systems we have ever seen.



The wiring for the adjustable twin tube shocks has a connector above the strut tower brace, shown above left. The wiring passes through the top of the brace as shown above right.



After 90 minutes of careful removal, we could finally see the tops of the strut towers and the strut top mounts. The factory RS engine and strut tower brace is crucial and must be retained. It is 7.5 pounds of stamped / welded / fabricated steel. This elaborate brace ties into a number of items, like the strut towers, wiper motors, and lots of plastic covers (aka: Tupperware) that hide the back of the engine bay and strut towers. The OEM strut mount is unusual in that it is bolted into the tower via bolts from above. This is backwards from nearly every McPherson strut car we have ever seen, which usually have studs that protrude through the the tower from below.



After you can access the top of the towers, actually removing the front strut assemblies takes more time. Support the bottom of the control arm, remove the front swaybar end link, disconnect several wiring connectors, then unbolt the strut to spindle clamping bolt. Spread the split in the spindle clamp as shown (above right) with a short extension square drive end. Then pull the lower control arm down. Now you should be able to pull the bottom of the strut out of the top of the spindle clamp. Once that is uncorked, you can unbolt the three bolts at the top of strut mount, freeing it from the engine bay.



This unusual, raised reinforcement lip on the underside of the strut tower (above left) is another thing preventing a camber plate that could work with the OEM springs. Making a spacer to sit below that lip (so the plate could slide inboard) would eat up too much much stack-up height, so it would be nearly impossible to keep an adjustable top mount from raising the front ride height. Switching to an adjustable height coilover strut makes all of this moot - the smaller diameter springs allow inboard travel, and the adjustable spring perch height counter acts the slightly higher stack-up height needed to clear the raised lip under the strut tower. The OEM strut + spring + top mount weights nearly 17 pounds, as shown above right. Coilovers always seem to weigh less, which is a bonus.



After we finally had the strut off the car and the spring compressed, we were ready to remove the strut top mount. We wanted to remove the coil spring so we could digitally rate it, but we stopped short. Why? The wiring for the adjustable shocks could have been ripped when removing the top mount. Yea yea yea, "it looks so easy". Trust us, it wasn't.

To remove the strut top nut would require an impact to spin the nut loose. Even if we custom made a "windowed" socket to allow the wire to pass through, we would have still probably ripped the wiring, ruining the OEM struts. With the chances of making an OEM spring compatible camber plate at zero, we cut our losses and decided no not rate the springs until we had replacement struts. The space constraints made it obvious we had to move to a coilover anyway. This also means there is not an easy path to installing lowering springs (which almost never have enough spring rate anyway).

We had the rear shocks off but neglected to get a picture of these. Will make a point to weigh and photograph these when we install the coilovers next week.

SUSPENSION CHALLENGES

This is a quick video we made over a couple of days as we disassembled the Focus suspension, looking for a way to make a camber plate, improve spring rates, measure for better dampers, etc.


YouTube video: https://youtu.be/DIzkQCFfF94

We are trying to point out the problems we see and offer up possible solutions. There are some good and bad things we noted here, but no super trick zero money solutions for improving handling performance. This video has a few thousand views already and lots of thumbs down. Blame the messenger, I guess?

PART TIME AWD SYSTEM

This internal Ford document about the Focus RS AWD system explains a lot. "During normal operation, most of the torque is delivered to the front wheels." is exactly how it felt to me all the time.

https://photos.smugmug.com/Projects/2017-Ford-Focus-RS/i-LWD4B7x/0/M/ford-awd-system-function-M.jpg

Read this and see what you think. Sounds pretty funky.

TRACK TEST at MSR-CRESSON 1.7 CCW, JULY 15, 2016

Brad and I trailered the Focus out to Motorsport Ranch on Friday morning July 15th, leaving my house at 5:30 am. We arrived at the track at 6:30 am, just after sun up, and started to unload. This was the first time in a long while where we got to run on a "member day" at MSR. There were close to 15-20 cars on track with me during the first 2 sessions of that morning, so there was a bit of traffic to deal with - but this also gave us a good gauge of how well the car was doing. Weather was mild but threatening rain, so we wanted to get a couple of sessions in and head out before we got soaked.



We mounted two video cameras, a microphone (still testing optimum placement - these videos still had too much wind noise), and one of our trusty AiM SOLO predictive lap timer/data loggers. I have used this exact AiM unit dozens of times at this track and it always reads within .1 seconds of the AMB transponder timing loop on a NASA race weekend. It isn't some free phone timing app with a slow GPS transponder - this has 3 accelerometers and a 10 Hz GPS. Sidebar - one of my friends used my other AiM and ran his cheesy phone timer app at this same event, and the phone "lap timer" was consistently 4 seconds a lap off!



Event Photo Gallery: https://vorshlag.smugmug.com/Racing-...st-MSR-071516/

Temps here in North Texas in late July can be oppressively hot, but we got lucky. With the first session on track starting at 7:30 am, ambient temps were only 79F and overcast, so we were encouraged. We had high hopes for the RS and anticipated some good lap times. These are temps we normally don't see until Spring or Fall.

The Track

Below is the course map for the 1.7 mile MSR course, which we made for the use of our NASA Texas Time Trial group, (I do this for every NASA Texas event we attend, and hand them out at the driver's meeting). This is the most common course and direction for Motorsport Ranch's 3 different track configurations. It is also the one I am most familiar with, and it is the easiest to drive.



This course is relatively flat, easy to learn, and has no dangerous "off" sections to worry about. The only thing we caution drivers about on the MSR 1.7 is to avoid the high curbing in a few areas - namely in "Rattle Snake", which are a series of esses in T10 and T11. I've seen people high center their car or worse when getting greedy in that section, so I tell my students to only touch the paint, and always stay off the big curbs.

The Driving

Just so you know a little about my experience in general and at this track, I wanted to preface this post with a little background. I did my first track event in 1988 and have been driving on track, competing at road course events, and instructing for HPDE students for nearly 3 decades. I hold a NASA Time Trial competition license and have raced in several wheel to wheel road races as well. At heart I'm an autocrosser (since 1987), and I use the aggressive car control I learned dodging cones on track to maximize driving on the "Friction Circle". Watch the data logged g-load trace in the video below: a good "friction circle" driver can make the trace follow a circle when transitioning from lateral cornering to braking and into acceleration. I'm by no means perfect, but I try to always keep the tires loaded up to the extent of their limits - you can hear the tires "singing" in every hot lap.

I am also fairly tough on brakes, but I hate coasting. Coasting is death! I am either on the gas or on the brakes at all times, and I Left Foot Brake (when no downshift is needed) so there is no time coasting while moving my feet around. In a manual transmission car I always rev match downshift using the heel-toe method, and do not abuse engines by downshifting early and relying on engine braking. Brake pad replacements are much cheaper than engine rebuilds.

I also try to data log and shoot video of nearly every lap I drive on track or autocross, in the pursuit of both maximizing the car and my own driving. I am no "pro driver" by any means, and acknowledge that there are always someone faster, but I'd say... I'm no slouch. Owning Vorshlag and being at track events constantly for the past 28 years has allowed me to drive upwards of 1000 different cars, and likely 150+ different cars on track.



At MSR-Cresson's CCW 1.7 mile layout I have driven maybe 300-400 laps, and have also run their 1.3 mile CCW track, the 3.1 mile CCW track, and the CW 1.7 mile circuit here many times over the past 10 years. I have set 4 or 5 NASA class track records at this track in various classes and cars.



Reference times: My quickest lap time in a street legal car on the MSR 1.7 CCW course is a 1:17.25, which was set in 2014 in our NASA TT3 classed 2011 Mustang GT. My most recent NASA lap times back in March of 2016 were in my TTC classed 1992 Corvette (nearly bone stock in every way) with a 1:21.9 and a 1:27.6 in our TTD classed BMW E46 330. All of those times were on Hoosier DOT legal R-compound tires. The TTD lap time was a bit disappointing, though, because we still had the bone stock drivetrain (195 whp) and I made my best lap times on heavily corded 245mm Hoosier R7 DOT tires. That 1:27 lap was painfully slow but still good enough for the win.



To keep from damaging a brand new car with 83 miles on it, I decided to stay off all of the high FIA curbs on the apexes of nearly every turn here. To be consistent and sage, I would instead just "kiss the paint" on the apex curbing, to use all of the paved track available. The exit curbing is all standard FIA semi-flat "gator teeth" concrete curbing, which is safe to drive on, which I DID use to maximize corner exit room. I kept engine revs under 6000 RPMs, but vowed to push the car as hard as I could while keeping off the dirt. I didn't want to be accused of "sandbagging" the baseline track times, so that when we do changes there could be a huge improvement.

The Settings

I ran the car in "Street" mode in the first session and "Track" mode in the second session. "Drift" mode did not seem appropriate for getting fast lap times. In both sessions the Traction / Stability control system was turned off completely.... press and hold the button for 5 seconds, while a counter dials down, then it says the system is off. It wouldn't stay off, but I will get to that.

continued below

Last edited by Fair!; 08-10-2016 at 08:19 PM.
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