Hindsight's build thread

[07FIREBLADE]

Ask him about his wing mount if you get a chance and the specs on the wing.

[Frank818]

Did everyone tell you your new exhaust exit is better?

Why is everyone installing something between the hood hinges' brackets and hood, are the 2 surfaces that much incompatible?

[Hindsight]

Thanks Frank - Everyone seems to like it and the exhaust smell issues are basically gone. I can still whiff exhaust from time to time but I no longer feel like it is being piped straight into the cockpit. As for the hinges, you don't need to stand them out like that. I did it to gain some extra room for error (I didn't want to run out of hinge travel).

Sorry guys, I wasn't able to connect with Ron (the other 818 owner at the track) today to get specs on the wheels, tires, or wing, but I'm pretty sure the wing is an APR and the mount he either custom made himself (he is a great fabricator) or had made for him.

I'm home now, very sunburned, and very tired. Video is encoding.

Some more info on the experience:

1. I did experience overheating. Both coolant and oil. I don't have a coolant temp gauge (other than in the OEM gauge cluster) but by lap 4 or 5, I would hit 240 degree oil temps and the coolant temp needle would be right under the red so I'd back out of it. I do have an external oil cooler but the only way air gets to it is through a SPAL fan, which does pull a lot of air but maybe not enough. I'm going to change it to be fed with air from the side scoop. Also, I have NO ducting for the radiator yet. Just haven't gotten to it. I know that will make a big difference. Lastly, it was 93 degrees all weekend, and probably much hotter right over the track.

2. Still not happy with the brakes. With the new Ferodo DS2500 pads, it does stop well, and I can confirm that the ABS I installed works flawlessly, but I have to push on the brakes so hard that I am unable to modulate. Brakes are firm, just require too much pressure. I am going to try a smaller master cylinder. I don't think I can drill the hole in the brake pedal arm any higher for more leverage because the pushrod would be at too much of an angle I think. I could be braking much deeper if I had more confidence in the brakes.

3. This should really be item #1 but, it's been 18 years since I have been on a track. Hard to believe. I have a lot to learn.

4. My 818 felt unsettled when the suspension loaded and unloaded. Basically when transitioning from going straight to turning, or when rapidly changing turn directions. It didn't feel like it handled bumps in the track very well either. It was a bit of a handful. Some of that could be bump steer... I didn't get time to check and correct it before going to the track so I will check that out, but I think stiffer springs and better struts are in my future.

5. I'm too scared to drive it over about 115. At that speed it becomes very unstable. The slightest irregularity in the track sends the car drifting right or left. So at the top of fourth gear in the straights, I put it into fifth and just hold the speed to around 110-115. Could be bump steer, lack of a front splitter, or some other alignment issue.

6. I used an app to log my runs and am still figuring out how to read the data, but just scrolling through some of the runs, I see a couple turns where I hit 1.2g (I have no idea how accurate that is though). My best lap time was 1:49. The best lap time for my first session was 1:59 so I dropped 10 seconds over the course of the weekend.

7. In spite of my ~3 degrees of caster, the steering wheel stays wherever I put it, at any speed. It is very easy to turn the steering wheel, but it just doesn't want to return to center on its own. So strange. I need to figure this out. I de-powered the rack the "full" way, but removing the rack from the housing and cutting off the seals from the inside, then welding the pressure fittings closed and greasing the rack with grease before re-installing, so I'm really not sure what could be causing this.

8. I was really surprised by how fast on the straights a number of cars were compared to the 818. I have 268hp to the wheels and a guy in an 07 STI with 300hp to the wheels and full interior pulled me on the back straight. Really surprised me. Part of it could be aerodynamics because you enter the back straight at around 60, and of course, the 818S (or any roadster) is not going to have the best aerodynamics for high speeds, but still... there is an enormous power to weight difference between us if you factor that STI was probably 11:1 and I am at 7:1, so I'm still scratching my head on that one.

9. I saw intake temps in the high 120's, post AWIC. I need to do what Tamra and Andrew did and make a box for my air filter at the scoop. If that still isn't enough, I'll put probes on the AWIC water temps to see if it's the front or rear heat exchanger that needs upgrading.

10. The cut-out issue in the corners: I am 99% positive it was fuel starvation. If I overfilled the tank, the cut-out in the corners didn't happen once. By overfill, I mean having some gas in the filler neck higher than the top of the tank. The first time I did that, fuel got into my charcoal can and began dripping out onto the lower side sail lip and onto the ground. I siphoned 4 gallons off and hit the track where I then encountered terrible cut-out in the corners. So this tells me that a tank filled, minus just 4 gallons, is enough to cause the issue. It will take me a some time to figure out how to resolve the issue, but I need to change the breather so I don't have a reservoir for fuel to collect and slowly drip out of right in front of the right rear tire. Need to plumb in back behind the tire.

Couple pics:

[Wayne Presley]

4: have you check the rear roll steer?
5: you need the splitter, really plants the front
8: HP is more important to speed than power to weight
9: feeding the motor with cool air is very important to keeping the air inlet temps under control.
10: you need a surge tank, you need a surge tank and finally you need a surge tank...

[Hindsight]

Hahah, thanks for the input as always Wayne!

I have checked the rear roll steer with the following method: I put a piece of angle aluminum across the two lower lateral links (the toe links) at the inboard side (as far inboard as I could until the frame mounting ears were in the way). I then set a digital angle gauge on the angle aluminum and zeroed it out. I then moved the gauge and angle aluminum to the outboard end of the two links. I then adjusted the upper forward link until the angle gauge read zero, then re-checked inner again. Is this an acceptable method? I have a shiny new bump steer gauge.... I believe I could use it to check the roll steer in the rear. I will say that I checked the roll steer before I mounted the body, and before the suspension settled a half inch. Probably should check it again!

Thanks again!

[redfogo]

Try a hydramat before you go surge tank crazy. Cheaper option and they work great!

[Hindsight]

Sorry for the rattle - it was the mount. It is much better in subsequent vids.

[Hindsight]

[Bob_n_Cincy]

Great job Hindsight.
I 'm glad to see you didn't hurt anything.
1. ducting to force all the nose air to go through the radiator is critical.
2. Brakes, been there, done that. What is you PV and caliper set up?
3. right there with you.
7. My steering self centering has improver when I went to 4.5 deg caster
8. power to weight ratio gives you acieration out of turns. Power to aero drag ratio gives you high speed.
10. See Wayne's response.
Bob

[STiPWRD]

Congrats on the successful weekend and coming back with a running motor!

I know you've got the external oil cooler but are you also running the OEM oil cooler/heat exchanger? If so, is it after the external cooler? The high coolant temps may have heated up the oil. Once you get the radiator ducting installed, it may solve both problems.

[Hindsight]

Thanks Slava, I am not running the factory oil heat exchanger. I removed it and put a mocal thermostat controlled sandwich plate in it's place. -10 or -12AN lines (I always forget which) then go to the oil cooler.

I think, it is certainly possible that even without the factory heat exchanger, the high coolant temps may have contributed to high oil temps. My plan of action is going to be to leave my current remote oil cooler setup alone, and instead focus on ducting the radiator. I'll see where that gets me and go from there. Once coolant temps are under control, I will see if oil temps are still a problem.

[Mechie3]

Did everyone tell you your new exhaust exit is better?

Why is everyone installing something between the hood hinges' brackets and hood, are the 2 surfaces that much incompatible?

The hinge mount surface is flat while the hood is curved. Adding something there puts less stress on the hood long term. Alternatively, you could just stack high density foam or a softer rubber to take up the gap and relieve stress. Making a permanent pad just looks better.

[Frank818]

8: HP is more important to speed than power to weight

Without torque, there ain't any HP.

10: you need a surge tank, you need a surge tank and finally you need a surge tank...

Hydramat would not work?

[Frank818]

Jeff, are you getting any good news from the licensing process?
The track sessions will give you opportunity to fix your 10 issues before you push it on the roads.

[Hindsight]

Hey Frank. I have some sort of good news from the state on the licensing process. After eight long weeks, I got a letter in the mail saying they had my application (so I guess that's good right?!), and that in order to continue processing it, they need two appraisals on the value of the vehicle. Wayne was nice enough to help me out and send me one, as were a couple of other forum vendors. So I sent the appraisals back in to the state a week or two ago and am now back to waiting. I would guess it will be another two months until I hear back from them, at best. I thought for sure I'd have a license plate by summer.

Bob, thanks for the input! I will try to get as much camber as I can by cutting the a-arms. I may also slot the upper spindle brackets so I can gain some camber there without affecting the caster so much. Jim Schenk actually suggested that. My only concern doing that is that I worry about the camber changing when hitting bug bumps or going over curbs at the track. I am not sure that two bolts will hold it tight enough.....

[Wayne Presley]

If you still have the stock upper bolts, drill the upper hole out and rotate the bolt 180° to gain more negative camber and still have zero slop.

[Hindsight]

Thanks Wayne! Do you happen to know what size drill bit I should use for optimal adjustability, yet no slop?

[Wayne Presley]

I can measure the bolt tomorrow

[Zach34]

Thanks for posting all of your lessons leaned. That's a huge help to me and I'm sure many others.

I experienced the same kind of handling issues with my Roadster. There was not much on-center feel and the car was very darty and hard to control at 3 degrees caster. I simultaneously went to 6-7 degrees of caster and power steering. It was night and day. The car literally felt smaller, lighter, and ten times easier to control. I depowered my rack in the 818 just like you did. I'm hoping to be able to run 5-6 degrees of caster without the power steering, but if it doesn't feel as good as my Roadster did, I'm adding power.

On the coolant/oil heat, I'll offer my experience in the Roadster again. I know it's an entirely different engine, so grain of salt, obviously... I had an enormously oversized aluminum radiator on my Roadster with the 14" fan that came with the kit and a custom shroud. Coolant temps never got over 180 (thermostat temp) on the track. Temps would rise very quickly when idling at a stop, but flipping the fan on or moving even at a slow speed cooled it right down. I have a 3" core custom Griffin aluminum radiator in the 818. Knock on wood I get the same performance.

That huge radiator on the Roadster offered no benefit to the oil temps. While the coolant temps would not get over 180, after 3 laps I pegged my oil temp gauge at 240-ish in 70-80 degree ambient temps. Granted, again, it's a different engine, but unless you have a oil/coolant heat exchanger (and I see you don't), there's really nowhere in the engine casting where the oil and coolant come in close enough proximity to each other to transfer a lot of heat. I don't think upgrading your radiator will do much to the oil temps. Your oil cooler's location could the the culprit. Maybe try some experiemental, non-permanent locations to rule that out?

[Hindsight]

Thanks for the input Zach.

I will first try adding more caster and if that fails to correct the steering issue, I'll look at adding power steering. I wanted to keep the 818 light and simple as a design goal, but not having any return to center causes the serious issue of reducing or eliminating feedback through the steering wheel. When I am in a corner, it is incredibly difficult to feel what the tires are doing. I can't use steering wheel push-back as an input. That needs to be fixed if I'm going to drive the car fast.

For the brakes: I did some searching last night and I do see that the power brake booster will in fact fit in the 818, though I might have to notch out the windshield tray. I have the 1" master cylinder from the 07 WRX and what I might do is add the power booster, swap the master out for the 1 1/16" master, and drill a hole for the master pushrod even lower on the brake pedal than stock, to try offsetting the touchiness of the brakes with the power booster installed. The only concern I have with this is that the pushrod may be at too much of an angle if I move it down. I think the Wilwood setup would be the most ideal but I'm going to try avoiding forking out that kind of money right now.

As for the radiator - good point. I'm running the stock 07 radiator. I should probably upgrade to a thicker aluminum one, but before I do, at the very least I need to add ducting to what I have now. I think it's getting a serious lack of flow.

I'm going to use alumalite to make a front splitter that will flat-bottom the front part of the car, and will then make my own custom radiator shroud based off that. The FFR provided shrouds didn't fit for me at all. Speaking of - sheet aluminum (even thin stuff like .040) is crazy expensive around here

[Hindsight]

I can measure the bolt tomorrow

Thanks Wayne. If all I need to do is drill out the spindle bracket on both sides to the largest OD of the bolt, leaving the spindle hole itself alone, I can cover that without bothering you.

What I don't understand is how it works..... I see the bolt has a lobe on it, but the large part of the lobe is round and it appears to be perfectly centered in the bolt. Only the small side of the bolt is offset. So on one side of the bolt, both the spindle bracket and the spindle itself won't be impacted by the orientation of the bolt, it would seem. So I'm not understanding how it works...... Unless I am supposed to leave one side of the spindle bracket smaller - to the small diameter of the bolt, and the other side of the bracket is drilled out to the larger dia? That would make sense I guess.... Do I need to use any special washer?

[Wayne Presley]

No special washer needed and you can drill both sides the same diameter as the larger side.

[Hindsight]

Thanks Wayne. I'm confused as to how it works. I would think in order for it to work, the spindle bracket would need to have one hole that is the same diameter as the smallest diameter of the bolt (the side with threads on it), and the other side of the spindle bracket would need to have a hole that is actually larger than the thickest part of the bolt (nearest the shoulder).

[Frank818]

The FFR provided shrouds didn't fit for me at all.

They provided you shrouds?

Sorry on the plating. That really sucks and really is super long (will be same here), but like I said, looks like you got some stuff to improve which will make it more safe to drive on roads. No wasted time here.

[wleehendrick]

Thanks Wayne. I'm confused as to how it works. I would think in order for it to work, the spindle bracket would need to have one hole that is the same diameter as the smallest diameter of the bolt (the side with threads on it), and the other side of the spindle bracket would need to have a hole that is actually larger than the thickest part of the bolt (nearest the shoulder).

The axis of the threaded portion of the bolt is off center from the larger shoulder. Therefore, as the bolt is rotated in it's seat, the angular position, determined by the larger shoulder, laterally offsets the axis of the threaded portion.

[Hindsight]

The axis of the threaded portion of the bolt is off center from the larger shoulder. Therefore, as the bolt is rotated in it's seat, the angular position, determined by the larger shoulder, laterally offsets the axis of the threaded portion.

Right - I believe I'm on the same page as you, but is my statement about the hole sizes in the spindle bracket accurate? If so, I believe I understand fully, if not, I'm still confused

[Loring]

I should have a surge tank alternative fairly soon. I'm still working out the fill pump specs.

[Wayne Presley]

The hole in the spindle is the same size as the shoulder, as you rotate it the spindle moves in relation to the hole giving you the camber gain.

[bbjones121]

I feel that pictures would be extremely valuable here?

[Wayne Presley]

One bit of warning, you have to have your wheel mounted so the wheel/tire doesn't hit the upper ball joint.

[Hindsight]

Thanks Wayne, that makes sense.

[Frank818]

I feel that pictures would be extremely valuable here?

Better, a video. Im sure Wayne has a couple in his pockets.

[Hindsight]

I will take a video when I go to install it. I can only see it working if ONE side of the spindle bracket has a hole that is only large enough for the small threaded diameter of the bolt. I am pretty sure that is how the struts are in the WRX. If the holes on both sides of the bracket are large, then when you rotate the bolt, the bolt can simply shift around in the bracket holes instead of staying put while forcing the spindle inward or outward.

If one of the bracket holes is large, I could always weld a piece of steel over the hole and re-drill it to the smaller size, but would need to ensure I get the alignment just right. Anyway, I will take pics and post video.

[Hindsight]

Had some tire rub - forgot to mention that. Not awful, but there isn't really anything I can do about it aside from modifying the fenders. Based on the rub location, I doubt adding more camber to the front tires will fix it. I can trim it a bit where that bolt is though, but that is the least concerning area.

[Canadian818]

Had some tire rub - forgot to mention that. Not awful, but there isn't really anything I can do about it aside from modifying the fenders. Based on the rub location, I doubt adding more camber to the front tires will fix it. I can trim it a bit where that bolt is though, but that is the least concerning area.

What front springs are you running?

[Hindsight]

Stock S springs all the way around. 275 rear 350 front I believe.

I'm going to get new spring rates all the way around after I figure out what the ideal rates would be. Having a buddy help me out with this.

[Frank818]

I'm going to get new spring rates all the way around after I figure out what the ideal rates would be. Having a buddy help me out with this.

If you come up with formulas and stuff, or no matter the method, I'm interessed, cuz you know with my added weight in the back it may well change my springs-shocks setup, but I have no idea how to determine yet.

[Frank818]

I'm very surprised about your aweful g-forces starvation issues. You are the 1st one I read about with that problem, what have others done to not have the issue? I'm sure many run the old FFR tank and track the car too.

[Hindsight]

Hey Frank, there are well-defined formulas that all the suspension manufacturers use to design a setup for any given car. You take into account the corner weights (which would account for your heavier engine), unsprung weight, motion ratio (motion of the shock vs the wheel), suspension type, and use of the car. You then target your desired suspension frequency and all that gets plugged into a formula and out pops your spring rates and shock valving. http://eibach.com/america/en/motorsp...sion-worksheet

A good set of dual adjustable coilovers from someone like Ohlins or Penske is going to run like $3500 to $4000 but it is worth it in my opinion if you are going to race. Going to the track, I expected to be able to run a bit like a Miata: Super, super fast through the turns and so-so on the straights. I ended up being one of the slower cars through the corners because the suspension was scary and unpredictable, while being fast on the straights.... so it was more like driving a Camaro than a Miata. Watching the in-car video of guys in other cars running good suspension is like night and day. They just power through all the turns with bumps and curbs and it doesn't upset the car at all.... stays perfectly planted. I'm not going to get that with the setup I have now. I am considering just changing spring rates for the short term but I have doubts the koni shocks that come with the S will be valved properly for stiffer springs. The only well to tell would be to put them on a shock dyno. Of course, having the konis re-valved is another option.

[Hindsight]

I'm very surprised about your aweful g-forces starvation issues. You are the 1st one I read about with that problem, what have others done to not have the issue? I'm sure many run the old FFR tank and track the car too.

Others have mentioned it. redfogo couldn't even get up his driveway with 1/2 a tank of gas. But yeah, I'm not sure how many other people are tracking their car and using the FFR tank instead of a fuel cell or the boyd tank. The boyd tank has baffles. Fuel cells typically have them as well. I have the newer FFR tank. No real baffles - just one short wall next to the fuel pickup. All that said, even I am surprised by the fact that I was getting it as bad as I was with a fairly full tank. If I filled the tank to the point where I could see gas in the filler neck through the filler hole, and then I siphoned exactly 4 gallons off from there, I would get starvation. My gas gauge registered about 3/4 to 7/8 full at that point. I don't see how air could even get to the fuel pump pickup at that tank level but it must have been happening because if I over-filled the tank, the issue went away.