Donor parts list, first draft thoughts

[PhyrraM]

Here is the list of parts that are being used currently on the prototype:
• Front spindles with full brakes and front lower control arms

WRXs come on two widths. Sedan and wagon. Will there be accomodations for both lower control arm widths?

• Rear spindles with brakes and parking brake
• Steering rack, tie rod ends, and upper steering column assembly

The steering rack mounts changed about 2005. Will there be accomodations for both?

• Pedal box and throttle

'02-'05 WRXs have a traditional cable throttle. '06-'07 WRXs have a drive-by-wire throttle. Again, will both be accounted for?

• Master cylinder and brake booster, and clutch master cylinder
• Engine with turbo and intercooler (if WRX model)
• Transmission

'06-'07 WRX had an upgraded transmission and *may* take a unique AWD>2WD conversion kit.

• Rear lower control arms, toe links, and CV joints

Same question about the Sedan and wagon widths.

• Seats and gauge pod
• Fuel pump
• Radiator
• Wheels and tires

I will add that it's very likely to use the OEM wiring harness as a base to work from.

Other thoughts...

*IF* FFR will confirm that wagon width components and cable throttles will work, then it's almost certain that you can use MANY other cars as donors with very minor issues. The biggest issue likely to be a cable clutch on some models.

The "secondary donor" list would be:
'90-'94 Legacy
'95-'99 Legacy
'95-'99 Outback
'93-'01 Impreza
'97-'01 Outback Sport
'97-'02 Forester

[Dominator]

Good questions Phyrra. I'm hoping a lot of the "secondary donor" cars will work for this 818 car.
I have probably 2 sets of everything needed for this build from my 1st Gen Turbo Legacy parts cars.

[riptide motorsport]

Me too.

[StatGSR]

The biggest issue likely to be a cable clutch on some models.

IIRC, cable transmissions can easily be converted to run hydraulically, if need be, but i would still think that a cable could be used, just wouldn't be the stock cable..

[skullandbones]

PHyrram,
You mentioned donor harness. Would it be better to incorporate all aspects of the harness or will that be something that can be trimmed down. I've heard on the roadster that an EFI harness was put on a diet by a wiring harbess service and went from 75 to 35 lbs. On this project that could be very important. It's a little pricy though. Also, did you notice if a kit harness was mentioned? I didn't see one but I could have missed that. Even if it was, it would not include the EFI portion, I bet. WEK.

[StatGSR]

^ yes the harness would likely need to be trimmed down/merged, would not be much different from swapping a wrx engine into an older subaru.

[Dominator]

I would hope that the body with the new signals and lights would have their own chassis harness, and the donor harness is just for the engine management. Some of these older "donor" cars wiring is in rough shape, cracked shielding and whatnot.

[mn_vette]

I'm curious about the gauge cluster. Are we stuck with the digital odometer at its current setting? Or is there a way to reset it? I'm sure the dealer has a way, but that may cost an arm and a leg.

[PhyrraM]

My personal guess is that FFR will use the complete donor harness as a base for the complete 818.

My reasoning is that the complete column is apparently being used. This means that almost all essential controls are going to be OEM. Turn signals, ignition, parking lights, wiper controls, etc will all need to utilize the stock connectors to plug into the switchgear. Also, there is a perfectly usable fuse/relay box under the hood of every donor car. It would be ashame to throw it away. The non-used functions (power windows, etc) can be stripped out to save weight when the harness is opened up to relocate a few components for mid engined mounting - if desired. It's fairly simple matter to lop off the connectors for the Subaru lights and replace them with connector for Hella or Toyota (or whatever) lights. The basic circuits are the same regardless of light manufacture.

I'm guessing that FFR will include fairly detailed instructions on how to modify the harness for the mid engined location and changes for non-Subaru lighting.

[skullandbones]

It makes sense that FFR would use the chassis and engine harness since they will marry up well and I think you're right that the use of the complete rack and column of the donor points toward a plug and play with the existing harness. It is such a pain in the a** to take a harness apart but I guess that will be necessary for the relocation of the engine sensors and such (engine location). Thanks, WEK.

[Bacon]

And using stock brakes all around with the stock master cylinder, wouldn't that make the brake bias way too much toward the front?

[Xusia]

A front brake bias is bad?!? That's where 70% of your stopping power comes from. On motorcycles, the rear brake inherently has a lot less stopping power than the front brakes (1 smaller disc with a single 2-pot caliper in back, vs. 2 huge discs with dual 4-pot or 6-pot calipers up front). This is by design, because the rear brake doesn't have to provide much stopping power to deliver the benefits of combined braking.

[StatGSR]

And using stock brakes all around with the stock master cylinder, wouldn't that make the brake bias way too much toward the front?

bias is easily adjusted/corrected with brake pad selection and or an adjustable proportioning valve...

[Bacon]

The donor wrx has more weight on the front and with a higher center of gravity will also have more weight transfer. With the 818 having more weight on the rear and less weight transfer, the rear brakes will probably need to do close to as much braking as the front. If you keep the same bias, whenever you are doing threshold braking on the front, the rear tires will only use a fraction of the available grip. If you want to have effective braking, you need to move the bias closer to 50-50.

Sport bikes can lift the rear tire under braking rendering the rear brake useless, I have yet to see a car do that.

[skullandbones]

It wouldn't surprise me if FFR included the proportioning valve with the kit. They could supply one for 8 bucks, I bet. Since everyone would suffer from that big change in four corner weight, it would be logical to include it (easy fix).

Also, I think it is great that the donor seats might be used. That means some issues with seat height, etc. have been addressed. It will make the install very slick and simple. If you had luxury options on your donor, you could use them. Cool. WEK.

[Xusia]

The donor wrx has more weight on the front and with a higher center of gravity will also have more weight transfer. With the 818 having more weight on the rear and less weight transfer, the rear brakes will probably need to do close to as much braking as the front. If you keep the same bias, whenever you are doing threshold braking on the front, the rear tires will only use a fraction of the available grip. If you want to have effective braking, you need to move the bias closer to 50-50.

Sport bikes can lift the rear tire under braking rendering the rear brake useless, I have yet to see a car do that.

Of course. My point wasn't that the rear brake is useless (far from it actually). My point is that it doesn't take much rear brake force to achieve good braking effect.

For the record, most sport bikes are pretty close to 50-50 weight bias (the worst I've personally seen was around 46-54), and like I said, they still achieve good braking with minimal rear brake force.

[Oppenheimer]

Of course. My point wasn't that the rear brake is useless (far from it actually). My point is that it doesn't take much rear brake force to achieve good braking effect.

For the record, most sport bikes are pretty close to 50-50 weight bias (the worst I've personally seen was around 46-54), and like I said, they still achieve good braking with minimal rear brake force.

Though larger, longer, heavier bikes, like cruisers, the rear brake ends up being a significant part of the stopping effort. You can (and should) use a lot more rear brake with them.

I know this is an issue with the FFR Roadster, how to achieve brake balance, when the donor parts were designed around a different chassis. A proportioning valve is more band-aid than a real fix for a car with such lofty performance goals. OK for your average hot-rod, for a car that we're trying to compare to Elise, Cayman, and Ferrari, not so much.

I'm imagining someone will come up with some clever way to reuse rotors and/or calipers from some older, oddball Subie or something, that will end up with a pretty decent overall balance, some mix n' match solution that which will become the go-to fix for this. Guys with deeper pockets will find a solution that involves new Brembo (or whatever) stuff specifically sized for the application (betting FFR will offer that as one fo the options, which has been hinted at already).

[StatGSR]

^ new web site states there will be a wilwood kit available... either way, what I said already will work just fine.

[riptide motorsport]

Small issue, easily addressed with a biass adjuster.........non-issue really.

[willboss]

I'm curious for the Subie experts. I know the Saab 9-2X is essentially an Impreza/WRX, but is it close enough to be used as a donor based on the information we now have?

*IF* FFR will confirm that wagon width components and cable throttles will work, then it's almost certain that you can use MANY other cars as donors with very minor issues. The biggest issue likely to be a cable clutch on some models.

The "secondary donor" list would be:
'90-'94 Legacy
'95-'99 Legacy
'95-'99 Outback
'93-'01 Impreza
'97-'01 Outback Sport
'97-'02 Forester

[fateo66]

I'm curious for the Subie experts. I know the Saab 9-2X is essentially an Impreza/WRX, but is it close enough to be used as a donor based on the information we now have?

It should, all the mechanical parts are the same as the wrx wagon year to year. With the exception of the saab having a tighter ratio steering rack (which I really have to question the merit of this because 05+ wrx's have a different/ tighter steering rack) and not having the 4pot/ 2pot brakes in 06

[PhyrraM]

The Saabs are wagon width. Saab also did some work on the suspension bushings to make it feel a bit smoother. The revised bushings *should* still be compatable with anything FFR does.

[el_jefe]

Also, I think it is great that the donor seats might be used. That means some issues with seat height, etc. have been addressed. It will make the install very slick and simple. If you had luxury options on your donor, you could use them. Cool. WEK.

Which also means that ultra wookies should easily fit with race bucket seats.

[skullandbones]

So true. It would be a shame for those big guys to have to install a "Gurney bubble" in the roof like on the GT40 (ha). Space issues are pretty serious even in the roadster (same wheel base) that's where you see many of the mods. I think I have spent most of my time trying to stretch it one way or another. It would be nice just to install the seat, pedals, and column and forget it. WEK.

Note: I think FFR will accomodate both lower control arms. They have in the MKIV so it would be consistent for them to do it.

[scartaan]

I have not seen donor ABS brakes or air bags addressed. Any thoughts?

[spaceywilly]

And using stock brakes all around with the stock master cylinder, wouldn't that make the brake bias way too much toward the front?

I got 4pot front calipers and the legacy H6 rear bracket for my WRX (some year legacys used the same rear caliper as the WRX, but with 1" larger rotors, so you can buy the bracket as a cheap rear brake upgrade). The calipers were $400 and the bracket was $100 and it moves the bias quite a bit towards the rear (the 4 pot calipers actually have less clamping force than the sliding calipers, and the 1" larger rotors gives you more braking force in the rear). I think this would be a good option for people building the 818.

https://www.subarugenuineparts.com/p...roducts_id=914

https://www.subarugenuineparts.com/p...roducts_id=958

[StatGSR]

I have not seen donor ABS brakes or air bags addressed. Any thoughts?

why would one need either of those? not to mention properly retrofitting either of those would likely be impossible, and if you just put them in, they would likely kill you...

[Xusia]

in regards to the airbag I could maybe see your point, but the ABS? How in the world could retrofitting those be an issue? And how could they kill you?? Given the proliferation of ABS, I'd be very surprised if any of the donors had non-ABS brakes, so FFR must have some kind of answer.

[el_jefe]

The weight and suspension changes will make the ABS system interesting at best, and lethal at worse. ABS is programed for specific parameters, when the vehicle strays outside of them bad things happen. Example, certain cars can lift a rear tire on an autocross track. When that happens, the ABS thinks it's on ice and releases the brakes (all of them) until the tire starts spinning again. As a WAG, I would say that the 818 will tend to go into antilock in the front well before the rear. A proportioning valve will help, but it still will be interesting. Keeping the antilock will probably be very frustrating for drivers that push the car hard or track it.

[StatGSR]

^ that

Plus Subaru ABS system is terrible to begin with... pretty much everyone I know pulls the abs fuse in winter just so they have a chance at stopping.

[skullandbones]

I haven't tested mine yet but on my roadster I put in a Wilwood pedal set with bias adjustment (which can be adjusted on the fly from the dash) and running a proportioning valve too. I may need the valve for fine tuning but maybe not. I am not a dedicated track guy but do plan on some track time to get my experience up. It seems to me that although it would push the budget a bit, it would be a good upgrade for a serious track person on the 818. Also, I agree that ABS could be a disaster on such a drastically different platform. WEK.

[el_jefe]

Besides a proportioning valve, playing with different Subaru master cylinders might be an idea for folks that have the time and knowledge to test the system. With any luck, Wilwood will have a decent system, although I don't hold out much hope for it.

[skullandbones]

According to the website: [B]Our development partner companies KONI Shocks and Wilwood Brakes have already designed performance upgrades that will be available through Factory Five.[B] FFR hasn't been making any wild claims so I would expect the pedal set to be available when the kit is available. It sounds like a reasonable timeframe. For Wilwood this would not be a big deal. They probably don't have to design one from scratch anyway. IMO. WEK.

[Evan78]

Depending on how much more the 818 uses the rear brakes than a WRX does, using a proportioning valve and/or pad compounds with stock wrx brakes may not be the best solution as Oppenheimer said.

If you shift the bias too much to the rear, you're going to over work that little rear rotor and get fade way before the front is seeing any fade. If that's the case, increasing the rear brake size is the more appropriate approach, as Spacewilly suggested.

Pad compounds and proportioning valves should be used for fine tuning, and may not be a good solution for such drastic differences as using brake rotors sized for a car with a 60/40 weight distribution on a car with a 50/50 or 40/60 weight distribution. Whatever Willwood kit becomes available will probably be a good indicator of what relative sizes will work well and then people can go about finding cheaper solutions such as mixing and matching existing Subaru parts.

[Nuul]

WRXs come on two widths. Sedan and wagon. Will there be accomodations for both lower control arm widths?

This is very good point. The wagons look to be a cheaper donor from what I can tell. Even the salvage title WRX sedan models are fairly pricey for some reason. I've been wanting to keep the donor under $5K so I can put some money into upgrades/repairs on the engine & trans. For that price about the only thing I'm seeing are models with 200K+ miles on them.

[PhyrraM]

I editted the first post to include the steering rack mount change in 2005. Hopefully both mounts will be accomodated or the donor window gets really small.

I'm sure it's a coincidence, but the 2006 model that FFR built the prototype around was not the most numerous WRX. If too many decsions are made from it's use with prototype, the overall "minimum" build cost of an 818 will rise past the $15K goal for most.

[RossLH]

The steering rack mounts changed about 2006. Will there be accomodations for both?

The mounts changed in 2005, in that 2 mounts were added--the preexisting 4 mounts were not modified. If the design accomodates for the '05-07 STI crossmember, any '02-07 WRX or STI crossmember will work.

[PhyrraM]

The mounts changed in 2005, in that 2 mounts were added--the preexisting 4 mounts were not modified. If the design accomodates for the '05-07 STI crossmember, any '02-07 WRX or STI crossmember will work.

Fixed for the date.

As I currently understand it there is debate if you should be installing the newer rack on the older crossmember. Doing so leaves out the stiffener bracket and puts all the load on the "ears".

[RossLH]

I think you're confusing the parts a little bit here. The '05-07 STI steering rack does not fit in older crossmembers.

[PhyrraM]

I have seen the newer rack installed in the early crossmember. The bolt spacing on the newer racks "ears" is the same as the "cup clamp" on the older rack. What doesn't fit is the 4 bolt reenforcing bracket, leaving questions as to whether it should be done.

In any case, FFR should build the 818 to accomodate either rack....That's the point of the thread.

The 818 will not use the actual crossmember.