i have an early version of Richard's twin link suspension so I can't comment on his later version. If the upper link is mounted high enough on the upright, you might be able to get a bigger CV joint there but most of the twin links I've seen don't allow it. Replacing a CV joint isn't that big of a deal so if it has a short life, it's less of an inconvenience than say replacing a u-joint.
The EMPI Type 1 stub axles are longer than the stock stub axles by about an inch, maybe less. I would think that most wheels would be able to accommodate that. Using the Type 1 stub axle will require the use of the 94mm (I may have called them 90mm earlier) CV joints.
The problem I'm having to deal with now is a hub. Jmarkusic suggested machining a blank drum (
https://socalautoparts.com/product/brake-drum-rear-blank-pattern/). My machinist was concerned about a cast hub being brittle and didn't want to risk it. I would note that the stock hubs are cast (I don't know if they are iron or steel). Looking at the stock hubs, they are beefier around the splines so I'm a little concerned about the torque they'll handle. I plan on calling SoCal Auto Parts to ask them how they are used. and I'll report back.
Another option is these centers (
https://dansperformanceparts.com/jamar-db-center-6-bolt-splined-long-axle/). They come in 5 and 6 bolt flavors. They are actually centers that are meant to be bolted on a larger, more complicated hub. The idea would be to machine a plate to be bolted onto those centers to accept wheel studs. Because of the OD of the center (about 4.2", they would have to be machined to make room for the wheel studs. If you designed the plate well, I believe this would be bullet proof but it's expensive - not just the price of the centers but also the steel round to machine the plate.
There are other options like rear brake discs but I'm not sure they are any better options than the blank brake drum. Unless you make your own hub (which would require machining your own splines!), there aren't any other options for a hub that I've seen.
Measuring axle length
I asked the guy (a guy?) at Blind Chicken Racing (their website was referenced by Jmarkusic:
http://blindchickenracing.com/How_to/CVJoints_Axles/axles_and_cvs.htm) about that and here is our conversation:
me: First, is the listed length of the axle the distance between the circlip grooves? or the total length of the axle?
Then, how should I measure the length of axle I'll need? I assume I would measure between the outside face of the inner race of the outer joint and the inside face of the inner race of the inner joint. Should I position the inner race in any particular way (eg. each inner race in the center of the joint or one inner race at the outside and on at the inside of the joint)? Since this is for a street car, I won't need to accommodate a lot of plunge.
mark: Axles are measured in total length. Most aftermarket axles have extended splines so they can be trimmed to fit the application.
To measure axle length, assemble your axles with stubs and put your trans in place with flanges installed. With the stub and flange horizontal to each other measure from the bottom of the flange cup to the bottom of the stub cup and subtract 1/4” to 3/8” depending on how much flex you get with your trailing arm. You could go a bit more in your case as travel is not important.
me: From your description, it appears you are saying that the "faces" of the CV housing are the important distances. Because I'm not using a VW transaxle, I have tranny drive flanges that are fabricated and as it turns out, the "cup" of the flange is much shallower than the stub axle flange (I'm using EMPI stub axles). I've attached a pictures. Should I deduct, say 0.2", from the measurement to mimic a deeper cup dimension?
mark: The old school way of checking for axle length is getting a wooden dowel and trimming it until you have ¼” of clearance for the axle.
I sent Mark the photo of my drive flange depth to give him an idea of what I'm dealing with. I've attached other pictures of it in case it would help you fabricate your own (Thank you SwiftDB4). If I were to make a change to them, I would make a taller "lip" around the circumference to better support the CV joint. I'm not sure if I understood Mark's answer so I included the entire conversation.
I also asked him about the capacity of the CV joints. Here's what he said:
With bug CV’s (94mm) you can probably do 100hp as long as you don’t try and pop the clutch. A four cylinder engine is more forgiving as it has less rotating mass. You put a V6 in there you will probably blow the CV’s or axles (or both) if you are on it. If you can stuff 944 CV’s in there it will take a lot more power.
