Eaton's 818C Build - Power Window Modifications

[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

[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

[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.