Gator's 818R

[Santiago]

Must have been late Jim.

You wrote:

A wing has low pressure on top and high pressure underneath...

This is true - when mounted conventionally on aircraft. For those new to aero (who might read this), remember that in motorsports we invert the airfoil because we want the opposite of what the fly-boys want. They would say we run our wings "upside down", because they want to generate lift (or bad things tend to happen). We want downforce (to make good things happen): low static pressure on bottom, high pressure on top.

Best,
-j

[J R Jones]

Santiago, absolutely correct.
You caused me to realize I regard auto-wings as downforce (through drag) rather than upside down lift devices. Given the auto-wing cross section, I wonder how much negative pressure they develop?
I watched F1 Portugal at my son's apartment and was impressed with Hamilton's charge through traffic and the articulated wing going flat for high speed passing. Dynamic drag/downforce control. I do not know what that wing cross section is or it it goes to lift in the flat orientation; not likely.
jim

[Sgt.Gator]

Factory Five 818R, ICSCC NWMECS Mini Enduro at Portland International Raceway. No Chicane. Gator driving. Subaru 2.5L, 5 Speed Trans.
Tuned for NWMECS P1, 226HP, 200TW Toyo R1R tires.

[Sgt.Gator]

Interested in that! Do keep us informed. I love these types of posts. Great information for the 818R crowd. Kept it coming.

Green outline is with the rear wing, blue outline is without a rear wing, same spot, just as I start braking for the blue one brake zone. I had to start braking a lot earlier with the blue one because the braking was not as stable and I don't have the guts to find out just how much more unstable! The green lap was faster despite being slower on the straight.

[Bicyclops]

Must have been late Jim.

You wrote:



This is true - when mounted conventionally on aircraft. For those new to aero (who might read this), remember that in motorsports we invert the airfoil because we want the opposite of what the fly-boys want. They would say we run our wings "upside down", because they want to generate lift (or bad things tend to happen). We want downforce (to make good things happen): low static pressure on bottom, high pressure on top.

Best,
-j

Wings, or airfoils, develop lift in two ways. The one they teach most is Bernoulli's principle - that an accelerated gas has lower pressure. The idea is that when the air splits at the leading edge, the air on the convex side has to go further than the air on the concave side and is accelerated. The other way a wing makes lift is the angle of incidence. When an airfoil is mounted with its chord line not parallel to the fuselage, (or car) the air impacts at an angle to the chord line. We call the difference angle of attack. The impact of the air striking one surface of the wing helps promote the acceleration of the air over the other side and the impact of the air also tends to push the airfoil directly, creating impact lift.

On a conventional airplane, the wing provides lift and the horizontal stabilizer produces down force. A wing on the back of a car is just like the horiz. stab. on a airplane, producing down force. The angle of incidence will be slightly nose down on the wing to do this.

As Gator pointed out, the wing causes drag. There is parasitic drag of having something exposed to the airflow and there is also induced drag - the drag caused by the process of creating lift. Parasitic drag on an airplane is by far the greater of the two, and I would think the same holds true with cars. Most of the drag caused by adding a wing to a car would be of the induced variety except, potentially, the mounts. Round tubing is nearly as draggy as square stock.

Ed Holyoke

[J R Jones]

Ed, Yes your comments are correct. The other aspect Gator touches on is the wing efficiency lost to turbulence from the structure ahead of it, primarily the cage. Two challenges, getting undisturbed air to the downforce device and aft cooling devices.
Indeed aircraft wing turbulence influenced the high tail of F101 and F104 fighter jets. I spent four years with the F106 which had no defined tail as it is a delta wing. That required brute force and lots of pitch angle for take-off and landing. Indeed landing skill was remarkable with the nose high, it was hard to see the tarmac. To your parasitic drag comment, the F106 addressed that with consistent cross section. The fuselage was an hour glass or Coke bottle shape. The reduced fuselage cross section corresponded with the wing cross section. Worked good enough for 1525MPH. Just integrate the wing and body? No easy task. Maybe rising ramp surfaces on the quarter panels, somewhat beyond the width of the cage.
One other point of interest. Flying supersonic the F106 intakes would ingest more air than the engine could handle, and the intakes closed-off with vari-ramp devices.

[Sgt.Gator]

If you have the optional 4 pot 12" Wilwood brakes see this post I just made in the Brakes forum:
https://thefactoryfiveforum.com/show...359#post455359

[Rob T]

Thanks for this Gator. I know I have the 16mm pad thickness on my fronts and the 12's on the back. The tech at Porterfield suggested a strategy where I could run 4 or so mm off the front pads and move them to the back...put new ones on the front. I'm not sure what you think of the idea, and I have not done it yet, instead, replacing all pads together.

[Sgt.Gator]

Thanks for this Gator. I know I have the 16mm pad thickness on my fronts and the 12's on the back. The tech at Porterfield suggested a strategy where I could run 4 or so mm off the front pads and move them to the back...put new ones on the front. I'm not sure what you think of the idea, and I have not done it yet, instead, replacing all pads together.

I'm 99% sure the .60" pads will fit the back too. But my rear pads are lasting twice as long as the fronts anyway.

[Sgt.Gator]

I've spent the last week going thru my rear suspension trying to cure a mid corner mid speed tendency to oversteer out of nowhere into a spin. I'll go into more details later on what I've found, but for now I have one quick question:

How much rear droop are the R track cars using? I measured mine, it's only 1/4".

Google was not my friend here, if you Google race car droop you will encounter endless discussions about the pros and cons of droop limiting, and exactly opposite opinions of how much droop and whether to have any droop is better. And much of the info is on dirt cars and late model stock cars which doesn't really apply to my road race car going over a apex curbs and negative camber corners. There are also lots of discussions in open wheel formula car boards but there the arguments for and against are like asking what's the best oil for my engine!

So please, I don't want to set off a long winded theory of suspension droop discussion in this thread, I'd just like to know what the experienced R car builders are running.

Thanks!

[Hobby Racer]

Not sure if this is what your asking. I run +1/4" in the rear so that the car is higher in the rear than the front. This is the amount of rake that Jim @ FFR recommended to me and its what they run on the 818R car that ran 1:59's at VIR for the UTCC.

I have no mid corner oversteer unless I induce it with my right foot

[jforand]

Gator, when you say “droop” are you referring to how much downward travel the wheel has (suspension extension) from the normal ride height? I have not had mine on the track yet, but I have it set right now so that the car settles probably 2 inches once the wheels touch down coming off the jack. With only 1/4” I would think this is going to cause handling issue as the car rolls and weight shifts in corners. I can even envision issues if you had some intense twisting topography in sections of the track like the right hand drop at Laguna Seca for instance. The wheel needs to be able to extend to keep the tire firmly engaged. My Mustang even with Ford Racing’s suspension under it and has 2-3”. I do realize the Mustang is a very different car than the 818, but there still needs to be mechanical conformity and the less flat the track gets the more important it is.

Anyway, I know you didn’t want a long conversation, but that is we’re I plan to start. It might change. I will also be starting without an anti-roll bar.

[DSR-3]

I run +1/4" in the rear so that the car is higher in the rear than the front.

That would be rake. I believe he's referring to extension of the shock/wheel from static ride height.

[Hobby Racer]

That would be rake. I believe he's referring to extension of the shock/wheel from static ride height.

That makes more sense. , I've never actually checked that but to have only 1/4" you must be running some very stiff rear springs!

[Sgt.Gator]

Gator, when you say “droop” are you referring to how much downward travel the wheel has (suspension extension) from the normal ride height? I have not had mine on the track yet, but I have it set right now so that the car settles probably 2 inches once the wheels touch down coming off the jack. With only 1/4” I would think this is going to cause handling issue as the car rolls and weight shifts in corners. I can even envision issues if you had some intense twisting topography in sections of the track like the right hand drop at Laguna Seca for instance. The wheel needs to be able to extend to keep the tire firmly engaged. My Mustang even with Ford Racing’s suspension under it and has 2-3”. I do realize the Mustang is a very different car than the 818, but there still needs to be mechanical conformity and the less flat the track gets the more important it is.

Anyway, I know you didn’t want a long conversation, but that is we’re I plan to start. It might change. I will also be starting without an anti-roll bar.

That would be rake. I believe he's referring to extension of the shock/wheel from static ride height.

Correct!

That makes more sense. , I've never actually checked that but to have only 1/4" you must be running some very stiff rear springs!

I think they are the same rates as yours.

Yes, droop is measured as: First the car sitting level on the ground, the distance from the top shock bolt to the bottom shock bolt. Then raise the car up on jacks and re-measure. Mine only extends down 1/4" to 3/8".

I'm used to production car suspensions where droop is often 2+ ". Dirt track cars run way more than that! But formula cars often run zero or tiny amounts of droop like I measured. The only way I can see to increase droop (if I want to, that is yet to be determined) is to change the top shock to the S height and then lower the coilover spring perch down back to the normal ride height. But then I lose that much bump travel.

I was watching the Monaco Grand Prix yesterday and now that I'm tuned into droop I noticed how often an inside front tire would be completely off the ground when they were cornering. They were running zero droop on their front suspensions.

Hobby if you get a chance I'm really curious what your droop is.

[jforand]

Agreed that Formula cars will run way less and dirt cars will run way more. I believe that you will find this function is largely governed by the amount of chassis role that is allowed to manifest. If there were zero chassis role allowed then an inside tire picking up would point to zero droop. Formula cars actually do roll a decent amount more than you would initially think. The best way to see it is watching the in car view when they are ripping through some successive esses and looking at the upper front control arms. It actually is much more visible if you watch with the TV in a small amount of fast forward, it enhances the rate of change for the motion. Very much like watching the front wing elements bend down under the aero loading at high speed.

There is also another HUGE component to mechanical compliance and grip when you get into Formula 1 and that is the tire. They run 13" wheels and very tall sidewall tires. The tire itself is a HUGE part of the suspension. They rely on the tire to handle a lot to smooth things out and this allows for stiffer spring rates. In running the new lower profile tires they skate all over the place without making serious tunes to the suspension as the sidewall does not conform nearly as much. The lower profile tires we all run in comparison put us in a different boat.

So total chassis role is going to be the summation of the suspension deflection and the tire deformation/conformity. I believe that you will find this is significantly more than a 1/4" even on a Formula car. An anti-roll bar works to subtract out some of outer suspension compression as it attempts to lift the inside tire resulting in more of a squat than a role. SO if you start to see daylight under a tire my bet would be that you have already burned likely an inch of extension droop at the tire (not between the shock mounting bolts as you described.

If you are measuring at the shock mounting bolts then the physical setup and geometry really need to be know. In the 818 the geometry is as simple as it gets and the shock travel is still shorter, but a lot closer than the travel out at the tire. If you move the shocks inboard and use push rods to move cams and such to redirect the forces there are all kinds of other ratios that can come into play. I don't know the ration of shock shaft movement to tire movement on an F1 car (and I'm sure they are all likely a bit different), but I am pretty sure it is a lot greater ratio than we would have.

To increase droop you simply need to have more of the shock compresses at ride height. I did not do any exact measurements, but I would say something close to 1/3 of my available shaft travel is down in the shock tube at static ride height and available to extend up when the loading of that particular corner goes down.

One final note/trick. In an effort to understand how much shock deflection I will be getting on the track I installed a small zip tie around the shock shaft. You just pull it tight so it will hold its position and push it all the way up against the shock tube at static ride height. It will get pushed up the shaft with deflection and will come back showing the largest deflection achieved.

IMG_6643.jpg IMG_6644.jpg

[Sgt.Gator]

To increase droop you simply need to have more of the shock compresses at ride height. I did not do any exact measurements, but I would say something close to 1/3 of my available shaft travel is down in the shock tube at static ride height and available to extend up when the loading of that particular corner goes down.

One final note/trick. In an effort to understand how much shock deflection I will be getting on the track I installed a small zip tie around the shock shaft. You just pull it tight so it will hold its position and push it all the way up against the shock tube at static ride height. It will get pushed up the shaft with deflection and will come back showing the largest deflection achieved.

IMG_6643.jpg IMG_6644.jpg

To increase droop you simply need to have more of the shock compresses at ride height. Doesn't that require softer springs? How do you compress the spring and keep the same ride height?

Thanks on the zip tie tip. I'm familiar with that trick, it's the same one for checking effects of aero downforce changes. A poor man's Linear Travel Sensor.

When you get a chance please post your measurements. Thanks.

[Bob_n_Cincy]

Gator,
I increased the length of my top hats by 1" to keep the shocks at the middle of travel when at ride height.
2d shock cad.jpg

Since the picture above I have changed by springs to 500 in the rear.
I am also running helper springs in the rear so my springs don't unseat.
Bob

rear assembly

shock.jpg

[jforand]

To increase droop you simply need to have more of the shock compresses at ride height. Doesn't that require softer springs? How do you compress the spring and keep the same ride height?

Well, yes. To get more compression/settling of the spring you either need softer springs or to reduce the preload on the spring. It will certainly lower the car. I have about 3" of ground clearance at the lowest point. I screwed the adjuster up with no load on the suspension just until the spring assembly had the slop removed. I also have the 500's in the front and the 300s in the rear as I believe the R supplemental instructed (to my surprise I might add). This way at full droop/extension I do not have to worry about the springs unseating as Bob discussed. I know I do not want to go lower. If I were to crank up on the spring more attempting to preload it would simply raise the ride height by stealing my available droop, which is also something I do not want to do much. If these settings aren't in the ballpark then a spring change really needs to be the answer. Cranking them 'stiffer' only raises the ride height by stealing the droop without preloading the spring until the shaft is at full extension and only then do you start preloading the spring. I am certain this later scenario will result in handling issues. You really want the shock to always be somewhere in the operating window and not bumping up against either extent under normal operation.

Thanks on the zip tie tip. I'm familiar with that trick, it's the same one for checking effects of aero downforce changes. A poor man's Linear Travel Sensor.

No problem, going to be monitoring these to gather data as to the suspension settings and spring rates.

When you get a chance please post your measurements. Thanks.

I'll try to work on getting measurements probably on Wednesday. I broke the car recently and have been very involved in trying to resurrect it. I actually succeeded tonight which is nice as I need to head out of town tomorrow.

[Hobby Racer]

Hobby if you get a chance I'm really curious what your droop is.

I'm kind of curious myself. As soon as the transmission is back in the car and the suspension is connected I'll take some measurements.

BTW, I'm running the shocks in the "S" mounting hole to give me more ride height adjustment. My springs do come unseated when lifting the car.

[Sgt.Gator]

BTW, I'm running the shocks in the "S" mounting hole to give me more ride height adjustment. My springs do come unseated when lifting the car.

Exactly what I was considering, except adding the Eibach Helper Springs like Bob did to keep them seated.

[jforand]

I guess I misunderstood the original post and did not catch that you were really wanting to not change the ride height.

I actually am a bit worried about the the clearance to the exhaust header and then the oil pan. I think I will consider changing to the S mounting location in the rear as well and buy another inch or so.

[jforand]

I took the car for a couple laps around the neighborhood. I looked at the zip ties on the shock shafts and decided I had too much travel (about 1.5") in the hood without any G's or bumps. I decided to move the rear shocks to the S ride height position as discussed and I put two additional compression turns in on the rear springs over just tensioning the spring assembly when unloaded. I think this will be the initial setting for the VIR trip.

Measurements:

Ground Clearance (measured at the front and rear edge of the driver's cockpit up to the lower side frame rail)

Loaded (static ride height, no driver)

Front - 4.0"
Rear - 4 1/2"

Unloaded (jacked on the centerline of chassis until the tire were just touching the ground)

Front - 5.0"
Rear - 5 5/8"

Shocks

Loaded

Front - 14 1/4" (bolt to bolt)
Rear - 14.0"

Unloaded

Front - 15 1/4" (bolt to bolt)
Rear - 15 1/8"

Since it was challenging to measure bolt to bolt I attempted to put a caliper on the zip ties and get an extension (droop) measurement there as well

Front - 0.75" (shaft zip tie direct measurement)
Rear - 1.15"

The numbers should match, but do not entirely cross check. I would trust the caliper zip tie measurement more than my bolt to bolt.

Ratio of shock shaft to ground clearance change, which should equate to droop at the tire which is really what matters.

Front 1:0.75 (tire/shock)
Rear 1.125:1.125 (There seems to be a bit of an error on this one as the tire should move more than the shock as it is further out, but the rear geometry is about as close to 1:1 as you can get with the shock very vertical and all the way out at the tire.)

[Sgt.Gator]

I've spent a crazy amount of time going thru my rear suspension. This all started when we decided to do an alignment to double check why I was occasionally getting spins at mid apex with no throttle or brake inputs. We discovered that the rear suspension had movement that we could barely feel but hear it clearly. We thought the cheap eBay solid spherical rod ends had worn out. So I bought a set of LCAs from TSS Fab with the intent of a quick swap out. Nothing on this car is ever quick...

I started the disassembly and much to my surprise the eBay links were just fine. No play in the rod ends. It turns out the vast majority of the play was in the bolts. The previous builder used standard bolts threaded the entire length. Those thread surfaces were wearing down in every part of the suspension where they went thru the frame tabs. So after finding a thread in the forum about using AN bolts I ordered up a bunch of AN bolts from Aircraft Spruce and went about replacing all my bolts with AN. They are a noticeably tighter and more accurate fit than standard bolts from Lowe's. And bolts in double shear on the body are 50% stronger than on threads:

Double Shear thru Threads vs Body.JPG

Another issue was the spacers used on each side of the rod ends. Some were aluminum and had deformed. Others were steel but didn't seem to be in the right places to align the rod ends correctly.

It wasn't just the 1/2" bolts, there was also the issue of the LCA rod ends and the R height inboard bolt holes. I don't know what FF does in the new frames, but in my old first gen frame the upper R holes inside are not both 5/8" inch, the rear one is 5/8" and the front one is an OEM size metric hole. Since the rear is 5/8" it is not a direct swap with any LCAs designed for WRX/STI LCAs. Bushings are needed to adapt the oem sized rod ends to the 5/8" bolt.

And since I lowered the tranny a long 5/8" bolt would not work, it brought the nut too close to the CV boot. This wasn't an issue with the eBay LCAs using a 1/2" bolt, but to eliminate the play I need to use a 5/8" bolt. After a lot of permutations I ended up using a 5/8" bolt with a 3/4" x 5/8" bushing in the rod end and a nylon locking jam nut to secure it. The bolt is under almost no tensile stress in this application, it is all double shear stress, so I'm confidant a nylon locking jam nut will be strong enough to hold the bolt in place.

So then came the droop issue. To add a bit more droop extension I moved the upper shock mount to the S position (lower). To compensate for the ride height I lowered the adjuster on the coil over but it turns out you can't go very far doing that because the adjuster ring will contact frame and spindle adaptor and cause suspension binding. I also tried inverting the shock to reduce unsprung weight but although the shock can handle being inverted, it won't work in our frame, or at least I couldn't make it fit without frame interference. I ended up with a little less than 1" of extension/droop.

I went thru the initial setup of the LCAs per Wayne's instruction thread. I discovered that the upper trailing arms needed to be very slightly adjusted to eliminate toe in/out under compression. That may also have been part of the issue with mid apex spins under compression/lean.

Other mods in progress:
The engine cover at the humps vibrates quite a lot at high speeds. We temporarily installed bolts to hold it down but now I've swapped them for a quick latch type button release to each hump to secure it.

I need to carry more fuel than the little Boyd tank supplies. We talked with Fuel Safe about designing a fuel cell that would fit in the "stock" location behind the driver, and actually drew one up in CAD. The most we could fit in was 18 gals, but it's unlikely it would actually hold 18 gals by the time the a fuel pump and slosh box are added. In thinking about the actual use of the car I've only carried a passenger on track once. So I ditched the custom tank for a standard size 22 gal Fuel Safe Spectra Lite fuel cell that will mount where the passenger seat is located. The real capacity is probably about 20 gals. I've taken the passenger seat out and am awaiting the fuel cell from Fuel Safe. More on that in a couple of weeks.

Rear Fender flares for larger wheels tires. Permanent mounts for the Garmin Catalyst. LINK ecu (next fall).

[Santiago]

It turns out the vast majority of the play was in the bolts. The previous builder used standard bolts threaded the entire length. Those thread surfaces were wearing down in every part of the suspension where they went thru the frame tabs. So after finding a thread in the forum about using AN bolts I ordered up a bunch of AN bolts from Aircraft Spruce and went about replacing all my bolts with AN.

Yup. I learned this with a front SLA conversion done to my Mustang years ago. When first installed, everything worked great. After a season of use, the threads started to bite into the parent metal just enough to nibble out an oval hole, creating slop. You would go into a hard braking zone and the car shimmied all around as the front suspension shifted back and forth just that tiny amount. I've used AN bolts wherever I can ever since (also per Carroll Smith's advice).

For folks wondering, this is a vibration thing not a lack of proper torque on the bolts. If you mark your bolts (you should) you'll never see the marks move. Torqued bolts are like stretched springs, so they will be subject to vibration. Most threads are harder than the parent material which they are joining (you know, like those Grade 8 bolts everyone thinks are the cat's meow). The threads will win the war.

[J R Jones]

Based on my thus-far limited 818 experience, FFR fasteners are a mixed bag (SAE/Metric) and coordination of holes and fasteners is not consistently optimum.
Fabricating cars and parts my rule of thumb is one size larger diameter from the drill index. IE: 5/16 fastener, 21/64 hole for fit, tolerance and serviceability.
Not all fastener grades, torques and clamp loads are the same. A 3/8 or M10 can vary from 6000PSI GR5 to 14,000PSI Gr 12.9.
I gave-up on lock washers, but flanged fasteners where possible are advantageous.
An expensive alternative to bushing fasteners are shoulder bolts. In either case astute clamping is important.

[Bicyclops]

Based on my thus-far limited 818 experience, FFR fasteners are a mixed bag (SAE/Metric) and coordination of holes and fasteners is not consistently optimum.
Fabricating cars and parts my rule of thumb is one size larger diameter from the drill index. IE: 5/16 fastener, 21/64 hole for fit, tolerance and serviceability.
Not all fastener grades, torques and clamp loads are the same. A 3/8 or M10 can vary from 6000PSI GR5 to 14,000PSI Gr 12.9.
I gave-up on lock washers, but flanged fasteners where possible are advantageous.
An expensive alternative to bushing fasteners are shoulder bolts. In either case astute clamping is important.

As an A&P mechanic and aircraft builder, I was appalled at the grade 5 fasteners FFR provided. Threads in the joint! AN bolts with proper shank length were ordered for most everything important and holes reamed to size as necessary. Auto manufacturers are guilty of putting threads in shear joints, too. Too many different bolts to keep in inventory and too many ways for the assemblers to screw up. Old cars rattle for just this reason.

Ed Holyoke

[J R Jones]

Ed, My (incomplete) 818 has has had two previous owners, so no accountability. I have found M12 nuts crammed on 1/2-13 shock mount bolts, and other atrocities. Today I found a mix of SAE and metric on the radiator frame....WT?
Metric used to be an inconvenient curiosity for me, but being observant and critical I have come to love them, especially Yamaha and Honda designs. The number, size and grade is always right with few if any fastening problems.

I recently rebuilt a 1968 300hp 327 SBC and was reminded of unplated fasteners and "two sizes fits all". The engine has 3/8 and 7/16 course fasteners everywhere. That period chassis stuff is somewhat more diverse and fine thread.
In comparison the metric brands I mentioned design more numerous and smaller fasteners. The lengths are discrete; they go together one way only; when they do not balance-out, you have done something wrong, assuming you saved everything.

BTW I bought Victor Reinz/Fel Pro gaskets and head bolt kits for the SBC. The head bolts are M11 - 2.0 and 12.9 grade flange heads. That fits the 7/16 bosses in the block. They come with sealant pre-applied to the threads.
I easily could get a 13mm socket on the hexes. I had to hammer the 5/8 socket on the interfered 7/16 head bolts to get them out. Good work Chevy.

[Bicyclops]

I am SAE and am learning metric. It does make some sense, I'll admit, unlike '60s vintage Triumph motorcycles where I cut my teeth. British standard, Whitworth, and starting in the late '60s/early '70s some metric thrown in for good measure - Oh my gosh. It was so hard to deal with. My first Triumph didn't even come in a basket, it was more of a pile. Complete? Uh uh. Also back then my understanding of torque was tighten it until it strips and back off a bit. :-0 And the Queen's English maintenance maunual - "Use a spanner expeditiously". Actual quote from the manual. How's a teenage American doofus supposed to figure that out?

Sorry, serious thread drift.

Ed Holyoke

[jforand]

Wow, you had a lot going on there. Shows the value of tearing back into things at regular intervals to inspect. Glad you found it all.

I guess a couple years ago now I had the 2016 Mustang up at VIR and had a similar issue. The suspension has been pulled and replaced with the Ford Racing Track setup, all bushings swapped for Delrin or sphericals, I run the GT350 wheels to get an 1.5" extra in the front and another 1" in the rear of rubber and utilize Pirelli racing slicks. I say all this to simply illustrate that the car encounters significantly more force than a stock ride would. As such, regular inspection is much more important. I find things loosen quite often.

There is a dip in the early part of the back straight coming out of a turn they call Oak Tree (slowest corner on the track). So as hard as you can hit it to optimize the start of the straight and hard on it from 2nd to redline in 5th by the end of the straight. So I was hitting the dip and the car was jumping all over the track. It felt like I was getting blasted by the wind like when passing a semi truck on the highway at times. I came back to the paddock and asked people if they were getting blown all over the place. They all looked at me like I was crazy. "Really? Like on the dip in the back straight? It is like tornado alley". Again, they all looked at me like I was nuts.

So I started jacking up the car to look at things and was watching the rear passenger tire was lifting and pulling in as they do during the extension until they lift off. Standard extension motion as expected until the tire lifted off the ground and the top of the tire tilted out (positive camber direction) by about 1.5" with a clunk!!!! Houston we have a PROBLEM. The outer bolt on the upper control arm (camber) had loosened and was allowing a whole lot of slop. Good news is I did not crash and actually did not damage anything. retorqued everything and the car was back to normal......the wind was gone

I would like to see someone else solve an inclement weather problem with a couple wrenches.

[Sgt.Gator]

jforand, very similar episode in 2019 at the Cascade Enduro at Portland International. 3.5 hours into the race the right rear upper shock bolt that attaches the shock to the knuckle removed itself, causing the wheel to flop out at the top, spinning the car so hard counterclockwise that the left rear CV axle sheared off at the hub. Luckily it was in a rather slow speed corner and we missed hitting the wall. Another "Good Judgement comes from Experience. Experience comes from Bad Judgement" day. Loctite on all suspension bolts. Nut & Bolt check everything under the car before a race.
No doubt I will miss one in the future though...

[J R Jones]

j, I have a buddy with a similar Mustang that had a rear suspension failure on the street, or maybe an autocross. Anyway it broke the rear subframe near the shock mount. He stated it was not an uncommon failure.
I raced a GT350 in Trans Am with a Boss 351 when they went to GT rules.
jim

JRJ 350 1.jpgJRJ 350 `76-2A.jpg

[Sgt.Gator]

Another track day on Sunday with highs and lows.
The highs: The rear suspension is now cooperating and is consistent. The only times I started to lose rear end traction was under too early power application coming out of turns. Each time I was able to catch it before it spun. Mid apex spins with no throttle or brake inputs are gone. And no off track excursions.
Oil temps, oil pressures, and trans temps were great after 2 x 20 minute sessions in 90 degree weather with a hot track. The little Garmin Lady was urging me on to go faster and faster. But I had to temper her with watching the boost gauge.
We were still seeing a boost control problem. I was trying to keep boost at a low setting to stay in my class HP/Weight limit, but the turbo kept going to 18psi at WOT. For the third session we set it to wastegate which should have been a solid limit at 13-14psi. On my 3rd lap there was a pop and decided lack of turbo power. I drove back to the paddock where we noticed a tinkling sound from the turbo. Packed her and came home.
Today we put a bore scope in both sides. The intake side compressor wheel and case is damaged. The exhaust wheel looks ok. Rather than start taking everything apart we decided to go ahead and order a new turbo. This one was a Subaru OEM turbo off a 2016 STI with 25K miles. Since I have no need for 350+ hp we decided to go with an IHI VF48 Hi Flow turbo. They are a slightly higher performing version of the oem VF48 used on late model STIs. And cheaper than a new one from Subaru, only $1,028.00 incld shipping from Flatirons.
Why it failed will have to wait until we can dissect it. That's on hold until the Fuel Safe cell and Link ECU are ready to go to, then we'll do it all at the same time.
It never stops!

[jforand]

Glad you got the chassis sorted out. You found a lot so it had to be much better.

That is a bummer about the turbo. I saw your comments on my turbo and the fragile nature of them. I agree. Actually when I got the core in the mail of looked like they tied it to a leash and dragged it cross country. I go in touch with them saying there was no way it was balanced (or true) anymore and they said they would not do anything unless it mal-performed. I was like it will be a year before this thing spins!!! Anyway, I hope it lives, I think there is not a huge risk of failure being on the hot side. I don’t really have to worry about but shooting through the IC and into the engine.

[Sgt.Gator]

The following is not about the 818R, but about my STI. However we typically will make the same mods to both cars, so what you see below will be coming to the 818R very soon..

Update on this: "Saturday at ORP was a downer. The STI was running lean and still has boost control issues despite installing a new downpipe and re-plumbed the Tial EWG. A compression test showed fine, but the leakdown test showed a leak in an intake valve. I have a spare engine ready to swap in, so we called it a day and took it to the shop to start the swap."

1) The Tial EWG was cooked to the point of the EBCS vacuum lines being brittle. They were literally toasted. We've rebuilt the ewg and and are running hard lines for the EBCS and coolant to it, see pics. The EBCS lines are stainless. The coolant lines are temporarily aluminum, we'll swap those out for stainless at the next service after we break in the engine at ORP.

2) We sent the heads and block to Outfront for their evaluation. They found one cam lobe and it's follower/bucket/lifter damaged. Did the bucket damage the cam or did the cam damage the bucket? Hard to tell, it's a chicken and egg thing. BC cams was contacted and they have agreed to replace the cam under warranty. Thanks BC for support!
Outfront is doing the head work including replacing all the buckets.

3) Outfront went thru the block and although no damage we went ahead and replaced the bearings and rings. This block/heads will become the new spare engine. I hope not to need it for a very long time, but history says that's not likely between running the STI and the 818R.

These pics are a work in progress on the engine stand. The lines will have heat protection and will be secured before it goes in the car.

......

[Sgt.Gator]

We swapped the failed turbo for a new IHI VF48 High Flow. We now know the what caused the turbo to fail:



A tiny RTV gasket plug stuck in the oil feed banjo line in the turbo. The oil feed line did not have the oem wire filter, most builders remove them. The plug was a little cone shape small enough to move thru the line from the engine, but large enough to completely plug the line into the turbo. I have no idea how it got into the pressure side of the oil system without being caught in the oil filter first.

We are installing a Vibrant oil feed -04AN filter in the new line.

A new LINK ECU is also going in along with a fuel cell. More on that soon.

Meanwhile testing the new engine in the STI went well. No boost creep/spike. I'm really impressed with how cool the engine is staying. On a 100 degree day we ran 4 sessions for a total of 1.5 hours of track time. The coolant temp, oil temp, tranny temp, diff temp all stayed below 195 degrees! Oil pressures rock solid lap after lap in all corners. And for the first time I can ever remember on a 100 degree day, when I came off track after each session and idled across the grid and up into the paddock, at engine idle the oil pressure still read 25 psi! Normally it drops to 15 or even under 10 psi because the oil is approaching 250 degrees. I'm optimistic we have figured out the right recipe for keeping the engine cool.

[Wayne Presley]

Another track day on Sunday with highs and lows.
The highs: The rear suspension is now cooperating and is consistent. The only times I started to lose rear end traction was under too early power application coming out of turns. Each time I was able to catch it before it spun. Mid apex spins with no throttle or brake inputs are gone. And no off track excursions.

The bump out I'm sure was causing the rear twitchyness.

[Sgt.Gator]

The bump out I'm sure was causing the rear twitchyness.

Hi Wayne. Great to have you active in the 818 forum, we've missed your sage advice! Are you building any 818s now?

[Wayne Presley]

Hi Wayne. Great to have you active in the 818 forum, we've missed your sage advice! Are you building any 818s now?

Currently not right now but I do have an 818R kit that I should sell. I have a LFX swappped miata (GRM endurance car), LS3 swapped 996.2 (swapped and selling), GT40 Mk1 (fix, paint and sell), SC fox body (fix and tune) in the shop and an FIA to build right now.

[Sgt.Gator]

I'm done with the JDM ecu and tuning it with a Cobb AP. And I'm done with the little bitty Boyd tank. Time to get serious!
22 gallon Fuel Safe and Link ECU going in:








We will also move the battery and the fire bottle from under the hood to in front of the Fuel Safe in the passenger compartment.
Rear fender flares to fit much larger rear wheels/tires.
It should be ready for Test & Tuning next week. Arcflash is serious about getting it back in the races too.

We also plan to move the coolant tubes to the center tunnel and possibly a BMW ABS system. That is in the future.

Next Up will be an AIM integrated PDM and Display to replace the factory dash gauge display. Virtually all the wiring will come out and be replaced with motorsports grade wires and connectors. That will be this fall. The AIM will integrate well with the LINK Ecu and give us great datalogging and a bunch of other features.