Eaton's 818C Build - Power Window Modifications

[Mark Eaton]

I purchased a left front CV axle for a 2006 Impreza from Rock Auto because that was our donor car. I removed the inner CV joint but the CV joint tripod bearing shown below doesn't fit on the axle in the 818. See photo below, the lower bearing was the damaged one.



Unfortunately, CV axles and joints are vehicle specific. I can't figure out how to order a joint for the axle I have and as far as I know there is no OEM part for a FFR 818C. My kit came with two spare axles without joints.



The 80033 is the "fully assembled" axle from FFR which I am using. FFR tells me those are not currently available for purchase. The 80237 axles came with the kit and do not have joints.

Does anybody have any idea what OEM part I need for my CV joint for either of these axles?

Thanks,

mark

[Hobby Racer]

Unfortunately most aftermarket CV joints are NOT the same and not compatible with the OEM ones. They have the same spline configuration but not the same tri-lobe setup as you have found out. I had to go to my local NAPA store and physically look through ever Subaru Impreza CV joint to find one that was rebuilt using the green OEM CV cup and therefore had the correct tri-lobe.

[Mark Eaton]

Unfortunately most aftermarket CV joints are NOT the same and not compatible with the OEM ones. They have the same spline configuration but not the same tri-lobe setup as you have found out. I had to go to my local NAPA store and physically look through ever Subaru Impreza CV joint to find one that was rebuilt using the green OEM CV cup and therefore had the correct tri-lobe.

Wow, that sounds difficult. It's hard to believe there is not an after market CV axle that fits. They look so similar...

[Mark Eaton]

Unfortunately most aftermarket CV joints are NOT the same and not compatible with the OEM ones. They have the same spline configuration but not the same tri-lobe setup as you have found out. I had to go to my local NAPA store and physically look through ever Subaru Impreza CV joint to find one that was rebuilt using the green OEM CV cup and therefore had the correct tri-lobe.

So, if I get a true Subaru OEM inner CV joint it should fit? Or is that 80033 axle not a Subaru OEM axle? I ask because the 80033 and two spare 80237 axles have obvious different spline sizes.

[J R Jones]

The current business model for auto parts is routine maintenance parts, OEM application catalogues and order your parts. OEM dealers are worse. Specifications and dimensions are hard to find for this kind of shopping.
Creative applications like this are a challenge and without FFR you are on your own. Hobby found an convenient solution with a NAPA dealer stocking inventory and was willing to go out of his routine-way.

In a similar custom driveshaft project I had to match a Dana 44 axle to a Lexus 5 speed manual transmission. My local driveshaft shop was willing to order his best guess yoke for a fitment check...it worked.
I suggest looking for a similar axle/driveshaft shop, take your parts with you. Alternatively a Subaru performance shop may understand what you need.
jim

[lance corsi]

Maybe contact the good folks at the Driveshaft Shop?

[Hobby Racer]

So, if I get a true Subaru OEM inner CV joint it should fit? Or is that 80033 axle not a Subaru OEM axle? I ask because the 80033 and two spare 80237 axles have obvious different spline sizes.

The axle is a custom one ordered by FFR as it mates the Subaru front inner and the rear outer CV's together on a common shaft. The shaft is not important, it's the splines, tri-lobe, and outer CV cup that are. If you have a Subaru tri-lobe, you need a Subaru cup. Conversely aftermarket units sometimes use re-manufactured Subaru parts and sometimes do not, that's why it's hard to mix and match.

The splines on the FFR shaft are sized for OEM Subaru tri-lobes so if you can't find one at a parts store you may need to order one from Subaru. It will be pricey if you get it from the dealer.

[blomb11]

I learned this the hard way too from my donor parts. I went to my local Subaru wrecker to buy front and rear OEM axles to scavenge for parts rather than buying new axles from Subaru. If you have a wrecker nearby check them too.

[J R Jones]

The axle is a custom one ordered by FFR as it mates the Subaru front inner and the rear outer CV's together on a common shaft. The shaft is not important, it's the splines, tri-lobe, and outer CV cup that are. If you have a Subaru tri-lobe, you need a Subaru cup. Conversely aftermarket units sometimes use re-manufactured Subaru parts and sometimes do not, that's why it's hard to mix and match.

The splines on the FFR shaft are sized for OEM Subaru tri-lobes so if you can't find one at a parts store you may need to order one from Subaru. It will be pricey if you get it from the dealer.

John, I have re-engineering of rear axles in my future, so I am not asking for a friend.
I assume that the OEM front axle assembly is more robust that the OEM rear axle assembly.
FFR used the inner parts of front axle and the outer parts of the rear axle creating a b-terd and sourcing issues like Mark's.
Is it physically possible (with axle bearing & hub?) to run all front axle components through the upright to the wheel hub?
It leads me to speculate about the choice to not run front uprights in the rear, eliminating this mix-complexity.
jim

[aquillen]

No real reason to expect this info can help you - because you likely will need to do face to face tests at NAPA or the scrap yards - but FWIW below - at least you get some measurements to think about...

https://thefactoryfiveforum.com/show...ighlight=80237

[Bob_n_Cincy]

I assume that the OEM front axle assembly is more robust that the OEM rear axle assembly.

Jim,
The OEM front and rear axle are under the same load in the wrx and use equivalent strength axles and hubs.
The problem with the 818 is now all the torque goes through 2 wheels and not 4.
I believe the STI version 2006 and later had stronger axles and hubs. A few people have upgraded to sti rear hubs.
I had 2 failures as a result of autocross launches. Here are pictures.

axl1.jpg ax2.jpg

[Hobby Racer]

John, I have re-engineering of rear axles in my future, so I am not asking for a friend.
I assume that the OEM front axle assembly is more robust that the OEM rear axle assembly.
FFR used the inner parts of front axle and the outer parts of the rear axle creating a b-terd and sourcing issues like Mark's.
Is it physically possible (with axle bearing & hub?) to run all front axle components through the upright to the wheel hub?
It leads me to speculate about the choice to not run front uprights in the rear, eliminating this mix-complexity.
jim

The front uprights are very different than the rears. The need to accommodate turning being the biggest factor in their differences. It would be quite the challenge to run front uprights and hubs in the rear. Much easier to find the right mating parts for the CV joints. If axle strength is a concern the Drive Shaft Shop makes very stout and expensive axles for the 818.

[J R Jones]

The front uprights are very different than the rears. The need to accommodate turning being the biggest factor in their differences. It would be quite the challenge to run front uprights and hubs in the rear. Much easier to find the right mating parts for the CV joints. If axle strength is a concern the Drive Shaft Shop makes very stout and expensive axles for the 818.

John, Bob,
I was not clear in my (and Mark's) concern for serviceability based on his original post, not finding replacement parts.
Reviewing my 2014 assembly manual it appears the 818 axle is FFR unique because of length?
The outer CV is the donor rear.
The inner CV is the donor front.
Service parts should follow that format, so what is the problem? Mark?

I assume Subaru could, but does not use a common CV for all axle locations (8). (economy of scale?
Some CVs must be cheaper than others, and not as robust, which brings me back to the speculation that the front axle ASSEMBLY is more robust than the rear axle ASSEMBLY.
So then why does FFR not use the most robust parts?
Bob's comment suggests the FFR axle is the weak link.

The front upright could be used in the rear with control arms and a lateral (anti)steer link (and bump steer) but not with drag links. I kinda prefer that.
jim

[Bob_n_Cincy]

Adapting a front knuckle for use in the rear of the 818 would be tricky.
The 818 front has a coil over shock blocking the axle.
Lance used a corvette hub for his rear suspension.

vet.jpg

[Hobby Racer]

John, Bob,
I was not clear in my (and Mark's) concern for serviceability based on his original post, not finding replacement parts.
Reviewing my 2014 assembly manual it appears the 818 axle is FFR unique because of length?
The outer CV is the donor rear.
The inner CV is the donor front.
Service parts should follow that format, so what is the problem? Mark?

Let me see if I can explain this better. The problem is that axle re-manufactures are free to use any shaft having any internal spline count so long as the tri-lobe matches because all they are concerned with is that the overall length of the entire axle assembly (CV joints + shafts) are close to the OEM length and that the external splines on the CV joints match both the transmission and hub. They often times use non OEM shafts, tri-lobes and CV cups when making re-manufactured axle assemblies.

The problem is that we as builders tear them down to get just the parts we need like the CV cup and tri-lobe and then try to mate them up to our custom FFR shafts to make our own custom axle assembly. If we are not starting with complete front and rear axle sets from Subaru, there is no guarantee that the internal bits will fit together.

I assume Subaru could, but does not use a common CV for all axle locations (8). (economy of scale?

Correct, the front outer and rear outer CV's are not the same.

Some CVs must be cheaper than others, and not as robust, which brings me back to the speculation that the front axle ASSEMBLY is more robust than the rear axle ASSEMBLY.
So then why does FFR not use the most robust parts?
Bob's comment suggests the FFR axle is the weak link.

The front upright could be used in the rear with control arms and a lateral (anti)steer link (and bump steer) but not with drag links. I kinda prefer that.
jim

Remember, FFR designed this kit to be built from a single donor car, therefore there are only one set of front hubs to work with. In FFR's defense, it's not always what will work best, but what will work given the product specifications and cost envelope.

[J R Jones]

Adapting a front knuckle for use in the rear of the 818 would be tricky.
The 818 front has a coil over shock blocking the axle.
Lance used a corvette hub for his rear suspension.

vet.jpg

Bob, John, Mark, Thanks for your patience and insight.

Bob, I see that your photos show two distinct failures, the axle and the stub-axle which is clearly a load failure.
Lance mentioned Corvette suspension, in our discussion of front; obviously both. I am familiar with C4 suspension, I am building a Studebaker Avanti on my 102in WB frame with C4 suspensions and an LS/six speed.
Eventually I will find out why the Subaru OEM front axle assembly does not fit in the rear upright. Could it just be the (ball) bearing ID & OD?

John, Mark, I can see the problem servicing this custom axle assembly, it appears individual CVs are not available. I found Axles on the Subaru web page under "Suspensions and Brakes" but no trilobe parts.
I assume FFR made axle splines to fit each donor. Mixing donors adds to potential fitment issues. As you and Art have posted, one has to empirically match splines to the axle.

Mark's experience is influencing my build. With a Honda J series V6 & six speed, I am encouraged to replace the other Subaru bits with Honda. (back to the front upright concept).
jim

[lance corsi]

I used C-4 components for my car. Had to do a little cad work to place the front A-arms, on the rear I stayed with a trailing arm multiple link suspension. Again, I had to change shock mount points, add upper control arm and lower control arm, and a toe link on each side. I’m not running a sway bar due to packaging.

[J R Jones]

I used C-4 components for my car. Had to do a little cad work to place the front A-arms, on the rear I stayed with a trailing arm multiple link suspension. Again, I had to change shock mount points, add upper control arm and lower control arm, and a toe link on each side. I’m not running a sway bar due to packaging.

I built a truss frame at 102 in WB. I use the front crossmember, composite spring and stock shock mount.
I also used the rear stub, with all stock mounts and parts. I do not want serviceability or durability issues.
My engine mounts aft of Corvette proximity to the front. I thought about C5, but this is easier.
jim

dino over 102in Corvette.JPG

[aquillen]

Regarding the axle spline/dia problems - note that when ordering an 818 from FFR they required you specify the donor you were going to use. Because Mark shows axles with FFR part numbers, and from my post of FFR part numbers it is clear that FFR had at least 3 different axles they might supply, depending on the expected donor. And we all know that the aftermarket also provided rebuilt axle/hubs with their own format of splne setups.

Add all this up and we are left with a lot of mix or match possibilities, no fault of any one source. Subaru definitely had multiple versions of axles over time - I had at least three versions end up in my scraps pile here during my project - and some were constructed way beefier than others.

During my waiting period of several months in 2016 for my kit to arrive, I read every build log posted here. There were several run-ins between builders and their axle/hub combinations that did not fit. Guys spent time getting and trying different parts from NAPA, RockAuto, the scrappers and FFR. I was surprised it took me only one try with FFR to get a different axle and it fit my 2008-2009 Legacy hub set which was JDM parts imported off a Japan sourced donor!

...another FWIW ...
You can also find WEB blab not related to FFR/818 at all, where people muse and guess about the axles and drive train parts in the OEM engineered drive train maybe being less than as strong as WE might want in a rear only drive setup. Translating those opinions suggests to me that with all wheel drive, the donor systems would have shared the torque amongst the axles so no single axle had as much stress as we might put on them in the 1/2 as many parts = twice the torque (sort of) in the 818. But then again, the newer Subarus (not sure where this happens at in model years) have more sophisticated power train management - which suggests to me at least - for such newer systems, a power train computer just might put a lot of torque out on one, two or three rather than all four wheels for some road condition... i.e. newer donors might have beefier parts.

Now in my case, running a '98 manual transaxle on the H6 3.0 motor, which was almost never sold world wide with a manual, (stories exist some Aussies got manuals if I have it right), I consider my car at high risk of snapping an FFR axle the first time I slip my foot sideways off that clutch pedal. I suspect getting axles from FFR is about as likely as ordering a new 818 kit today and getting in a week or two... The WEB blab on the 3.0 also presumes the reason the 3.0 wasn't shipped with a manual during it's early years (at the least) was the transaxle would not hold up to the torque. Why a turbo 4 wouldn't tear up the transaxle leaves one to wonder of course, although I think the 6 could dump more torque from an instantaneous clutch dump than the 4, even if at continuous output ratings the torques were similar.

Figuring out the mindset of any vehicle OEM regarding parts is pretty much impossible today - unless you are an insider on the project in question. We really are relegated to trial and error, at best sharing what we know with each other, and probably going to the aftermarket axle guys mentioned above.

[Mark Eaton]

My donor was a 2006 NA Impreza. Not sure if I order that inner CV joint it will fit the 80033 or 80237 hubs. I think the only thing I need at this point is that Tripod bearing that fits the 80033 axle.

[Mark Eaton]

Regarding our damaged CV axle I just sent my fourth CV axle back because the inner spline size was wrong. Good news is that I am learning a little more each time. I am at the point now of getting them from Salvage yards. Our local yards have plenty of Outbacks but not impreza like our donor.

We have begun fabricating an extra rear fire wall and side panels and powder coating them. Also, I found this sound deadening insulation I really like from Rockville Audio...

[Mark Eaton]

We also made this handy access port over the fuel sender/pump unit. The entire firewall piece will be removable so I don't know how useful this will be but I couldn't help myself.

[FFRWRX]

We also made this handy access port over the fuel sender/pump unit. The entire firewall piece will be removable so I don't know how useful this will be but I couldn't help myself.

Pretty sure you will never have to use that access port. But if you didn't add it in, then you would certainly need it at some point.

Rick

[Ajzride]

I like that powder coat color, do you have a code or link?

[Mark Eaton]

It is this Eastwood HotCoat Flame Red Translucent Powder Coat

https://www.eastwood.com/eastwood-ho...der-59153.html

[Mark Eaton]

Here it is:



Getting to this point has been a real pain in the neck. The above solution involves the 80237 Axle which came with my kit but I wasn't expecting to use, an outer CV joint from a "remanufactured" rear Axle from Rock Auto for my 2006 Impreza donor and front inner CV joint from a company called Febest. I got that part on Amazon, https://www.amazon.com/dp/B00DMA2PWG...roduct_details

All in all I went through 8 CV axles from rock auto, Napa, my local salvage yard. My local Salvage yard has a 2006 Impreza in Eugene so they had to send the axle down. Unfortunately they kept sending the front and I needed the rear. so painful...

I have become really good at taking apart CV Axles and reassembling them. So, got the new axle in and it looks good. We messed with the alignment a bit, feeling positive



and the engine won't start. Ugh,





this gave me heartburn, talked to some gearhead buddies, found two loose grounds, fixed them, and she started!!

Go karted 1.5 miles and she is stalling, acting like over heating. the right side coolant tube is hot, the left is ICE cold. I think I need to replace the thermostat.

that's where we are right now.

[J R Jones]

Mark, After the "incident" you mentioned the extraordinary wheel camber and potentially frame damage at the suspension mounts.
Have you identified alignment affiliated damage or is the wheel camber OK?
jim

[Mark Eaton]

Jim,

Nick and I spent a couple hours reworking the alignment last Saturday and it seems to be ok. The engine definitely got knocked to the right side about 1/8" but we have good camber and toe and castor on the front wheels. I figure we'll go kart another 50 miles or so and check everything again.

[J R Jones]

Jim,

Nick and I spent a couple hours reworking the alignment last Saturday and it seems to be ok. The engine definitely got knocked to the right side about 1/8" but we have good camber and toe and castor on the front wheels. I figure we'll go kart another 50 miles or so and check everything again.

Mark, Your speculation on 1/8 in displacement suggests that the vehicle "thrust angle" may be off. Thrust angle evaluates if the rear axle follows the front axle properly through measurement. Your laser experience may help you measure this, or get a professional.

https://www.tirereview.com/alignment...s%20the%20same.

https://www.capitalone.com/cars/lear...ifference/1983

jim

[Mark Eaton]

I have no movement of coolant through the pipes and she overheats at about 2 miles of easy driving. I replaced the thermostat hoping that was the problem but I think the real issue is that I haven't done a modification to purge air from the system. I have been reluctant to do the "mod" for this which many have mentioned and recommend, I guess because its not mentioned in the build manual. I was hoping "tipping" the car up and down to get the bubbles out would to the trick but no luck. So, I could use some help here. I guess I need to drill and tap a 1/8 NPT hole in the coolant outlet as shown? and screw in a brass barb?



A hose should go from the brass barb to the coolant expansion tank which my NA donor didn't have. So, my question is should I buy a OEM coolant expansion tank(for the turbo models) and hook it up? Or can I run that hose to the existing fore expansion tank which is shown here.



Can I just "T" into that hose?

I did install a "fill kit" as recommended in the build manual. Not sure if there's an option to use this to help purge?



Thanks for the help!

[Bicyclops]

What worked for me was a 137 kPa cap on the radiator and a 108 kPa cap on the expansion tank. I capped the tube next to the radiator cap and ran a 5/16" hose all the way back to the expansion tank from the radiator breather pipe that was on the right side top of the rad. At the front of the engine I used something like this:
https://www.amazon.com/Radiator-Atta...s%2C178&sr=8-9

in lieu of the Wayne mod. I ran a hose from that to the expansion tank with a tee in it to pick up the hose coming from the radiator. The plastic overflow tank I put in the engine bay and ran the overflow from the expansion tank to in the top and down to the bottom so it will suck the coolant back into the ex. tank as it cools.

When I filled it all, I put the back of the car up on jackstands so the filler neck of the expansion tank was the highest point after filling the radiator and the side pipes as much as possible level on the floor. I used one of those filler funnels you can also get on Amazon. It all worked out really well. Thanks for ideas MRG Motorsports and others. I did throw a code for coolant sensor voltage high, but that went away after 50 miles or so. I think that was because I also put in a heater under the dash and it took a while to run the bubbles out. It always runs right in the middle of the temp gauge. I got the fan to come on for about 15 seconds after idling for 22 minutes and the front coolant pipes get hot in just a few minutes.

Reading your post again, yeah, I think you're gonna need an expansion tank to make it work right. The key I think is the high pressure cap up front and the lower pressure cap at the rear tank. Make any expansion and bubbles happen back there instead of at the front which is lower.

Ed

[Mark Eaton]

What worked for me was a 137 kPa cap on the radiator and a 108 kPa cap on the expansion tank. I capped the tube next to the radiator cap and ran a 5/16" hose all the way back to the expansion tank from the radiator breather pipe that was on the right side top of the rad. At the front of the engine I used something like this:
https://www.amazon.com/Radiator-Atta...s%2C178&sr=8-9

in lieu of the Wayne mod. I ran a hose from that to the expansion tank with a tee in it to pick up the hose coming from the radiator. The plastic overflow tank I put in the engine bay and ran the overflow from the expansion tank to in the top and down to the bottom so it will suck the coolant back into the ex. tank as it cools.

When I filled it all, I put the back of the car up on jackstands so the filler neck of the expansion tank was the highest point after filling the radiator and the side pipes as much as possible level on the floor. I used one of those filler funnels you can also get on Amazon. It all worked out really well. Thanks for ideas MRG Motorsports and others. I did throw a code for coolant sensor voltage high, but that went away after 50 miles or so. I think that was because I also put in a heater under the dash and it took a while to run the bubbles out. It always runs right in the middle of the temp gauge. I got the fan to come on for about 15 seconds after idling for 22 minutes and the front coolant pipes get hot in just a few minutes.

Reading your post again, yeah, I think you're gonna need an expansion tank to make it work right. The key I think is the high pressure cap up front and the lower pressure cap at the rear tank. Make any expansion and bubbles happen back there instead of at the front which is lower.

Ed

Thanks Ed, I'm going to have to read this through a few more times. I don't have the radiator breather pipe on the right upper side of the radiator as my donor was NA and not turbo.

[Bicyclops]

Do without it then. If you fill the radiator with the car level or even with the front raised some and keep filling it until the side pipes are as full as you can get them, cap it and then lift the rear, and you shouldn't have any air in the rad. With an expansion tank the highest point, fill it until it bubbles no more and then start it up and keep filling it. With a bleed at the hot water exit from the engine (high point of the hot side), you should be able to get it all. The expansion tank is going to need a drain back to the water pump. The NA water pump might not have a fitting for that and you might have to tee into the "oil cooler" return or the heater loop return.

https://www.subaruparts.com/v-2002-s...and-components
There's the expansion tank. It shows 2 radiator caps, #13. The round one is for the rad and the one with ears is for the expansion tank.

Ed

[Ajzride]

These cars are brutal to bleed the cooling system on. At first I tried lifting the front end (I used an engine hoist and had it 60" off the ground), but that didn't work. Next I bought a vacuum fill system that is supposed to put the entire system under a vacuum and suck the coolant in, but that didn't work either. Finally I took Bob's advice and built a coolant bleeding loop in the car.

https://thefactoryfiveforum.com/show...l=1#post412847

[Mark Eaton]

I ordered an after market coolant expansion tank and some other parts to hopefully fix my coolant-bleeding/burping problem. I think I may have a way to add another 5/16" blowoff hose to the radiator like on the turbo models. I figure now is the time to install my heater and route my heater hoses. Here is my heater. I completely copied TheHelixx's thread on this...



Here are the hose mock-ups



Initially I was going to run the hoses over the engine like this:



But I'm thinking keeping them low to avoid air trapping and overheat problems is advisable. Like this???



If anybody has any nifty ideas for the best way to route these hoses feel free to chime in.

[Ajzride]

Mine are run like the second picture. Running them high will definitely make it harder to bleed the system.

Which heater core are you going to be running? I found that the stock water pump didn't make enough head at idle to push water through my Restomod Air unit to bleed it until I revved it up to about 1500RPM.

[Mark Eaton]

Which heater core are you going to be running? .

Vintage Air Gen-II Heaters 506101

I bought it from Summit

https://www.summitracing.com/parts/VTA-506101

[Mark Eaton]

So, I drilled and tapped for the "de-gas" burp valve on the coolant outlet of the engine. It is a 1/8 -27 NPT hose barb and ran the 5/16" hose up to an aftermarket coolant expansion tank I got on eBay.



I also got the 137kPA OEM radiator cap, and an adaptor to run a second "de-gas" burp hose from the radiator to the coolant expansion tank like the turbo models already have.





On the lower 1/2" outlet on the coolant expansion tank I ran a 1/2" to the return line on the heater hoses (blue)



This set up seems to work after 10 miles. coolant was coming out of the 5/16" outlet next to the cap so I ran a hose from that to the overflow tank I had left over from my mk4 build (lower yellow arrow)



I have not drilled a hole in the thermostat. After another 10 miles I don't seem to have any coolant leaks and no overheating!


I bought an aftermarket

[lance corsi]

Mark, I have a tri-lobed cv joint if you want it. Pay shipping from Cincinnati?

[RPGs818SNA]

Sorry for the late chime in on the heater hose routing, Mark. The forward 35" or so of the side body piece fits tight against the side frame starting about 5 inches above the bottom of the frame. You may want to run the red and black hoses below or beside the coolant pipe. Way to go on getting the cooling working and not leaking!
RPG