Setting up CV joints on a Lotus Europa with a NG3 transaxle.
Though what we, we being the PO, Andy Harwood, and I, have done on this Europa has not been road tested, I thought it still might be of interest.
The NG3 transaxle was sourced from Banks and came with the correct transaxle side hubs. The CV joints were chosen based on that size, which is 100 MM. The CV joints are all VW parts as are the axle and the outer stub axles. Andy had purchased a couple of different sizes (flange Diameter) and a couple different stubs. The difference between the stubs is the length of the shaft and splines.
Another thing is that you need to add a suspension link to the rear suspension as the old universal half shafts are fixed length while the new CV jointed shafts float.
The first thing I did was make dummy shocks. These are nothing but simple adjustable steel bars that you can set the length to match the coil over working lengths. This makes it much easier to deal with the suspension and determine what mods are needed. To make them, simply take ¾ to 1 x 1/8 inch steel bars, slot one end, drill the other to fit the shock bolts and then use a bolt to connect them. I used two bars 11.5 inches long with a 3.25 inch long 5/16 slot for the front and two bars 9 inches long with a 3 inch long 5/16 slot. This gives you the basic suspension travel adjustments to check at full droop and full bump as well as setting your desired ride height. If you wish, you can make them a bit fancier and cut the slot a couple of inches longer so you can use two bolts, tacked in place, which would make it easier to move the suspension through its range.
Now that you have the ability to set the ride height and check suspension movement, you can design and fabricate the added suspension link. You do have to keep checking things like track and keep in mind how the suspension works on the rear. It is best if you can start with the stock suspension in place, move it through the travel and make as many measurements as you can. Then remove the old stuff and use those measurements as your reference. Obviously, you can come up with the needed dimensions in other ways if you get the car in pieces or it already has a difference transaxle installed.
The new link is pretty simple. The current common thinking on it is that is should be parallel and as close to the centerline of the new axle as possible. I take that to mean it needs to track with the axle such that its length and effect on the suspension should match that of the original fixed length axle. Its initial purpose is to keep the rear upright vertical as it naturally has a tendency to twist outboard. So I also think of it as adding an upper bracket to the existing upright. Andy had been following the current norm and had already made brackets that kept the new link pretty close to the axle. The outer brackets The inner bracket makes the mounting look simple but gets complicated due to clearance issues. Still, it works and should prove effective. The link itself should be sized at least .750 inch diameter and have a wall thickness of .156 inches. This gives you the ability to just thread the ID rather than make custom inserts for the threads. The heim ends are then ½ inch bore by ½ x 20NF thread and are heavy enough to do the job. You do have to drill the ends a touch bigger (.453 to .456”). If possible, use both right hand and left hand threads to make the link easily adjustable without removing one end or the other.
In determining which stub axles to use, I just did trial and error between the two. You need to include the new rear hubs as part of this trial fitting and insure that you do not end up with the axle binding and the nut and spacer interfering with the fitting of the wheels. In my case, Andy had purchased and modified a couple of different hubs. The outer spines are different between the stub axles so each has its own style of hub. The ones I believe work best are the ones that started life as drum/ hub units and Andy had turned them down to create a simple hub only. He did express some concern about strength but in reviewing the other hubs, others I have and doing a bit of research, I believe them to be a strong choice. The spacers I used are also VW parts, or at least from EMPI. You may have to turn a couple down to get the right thicknesses you need.
The parts, as far as I can tell are:
NG3 Transaxle CV custom (?) flanges from Banks. Use 100 MM CV joints
VW 100 MM CV joints and boots. Empi PN 87-9917-K ($49.95)
VW Axles: 16.25 inch IRS race axles Empi PN 16-2201 ($279.95)
VW 90 MMCV joints and boots Empi PN 87-9916-K ($48.95)
VW Type 1 and Type 3 stub axle SoCal Imports ($66.95)
VW Type I rear blank IRS brake Drum/ Hub SoCal Imports ($59.95)
No bolt pattern drilled, this is what Andy turned down to make the new hubs.
Empi Spacer/ Shim Kits PN – 16-2400 ($40.95)
VW rear axle Nuts EMPI PN 16-2425 ($8.95)
The brake discs used here are Acura Parts (1990's?) I'm not sure what they are off of.
The rear calipers on this car are Mazda (Miata?) parts with parking brake levers.
I left out the cost of the inner hubs for the NG3 from Banks as I didn't see a listed price and I don't know what Andy paid for them. The rest of the package, less the brake parts as well, looks like about $ 831.35. I used the mentioned sources for pricing but most of these parts are available from multiple sources. I suspect the inner hubs will add between $200.00 and $ 300.00 to that cost. That will also depend upon the choice of transaxle.
I believe you can be creative with the rear disc set up. There are many who have made those conversions. It seems like the only real difference will be the caliper mounting bracket and the size of the pilot turned into the new hub.
The axles have 10 MM + or – 1MM of play throughout the suspension travel. I used more (larger) spacers on the inside of the uprights to insure the stub axle did not interfere with the wheels. You also must insure proper engagement so it is a balance and I just made sure the stock wheels fit over the protruding stub and nut. The stub axles I got also had a splash shield that had to be removed to avoid interference with the upright.
The type 2 shorter stub axle can also be used, but I suspect it would require a different axle as it seems like I was bottoming the axle out when I tried that set up.
I did not provide any details on the new suspension link as this is actually what several others have done and that information seems readily available.
I can't add pictures at the moment but will later.
Please ask any questions you may think of as I'm sure I didn't think of everything here.
