Maximum axleshaft swing in degrees?

[ezzzzzzz]

My rear suspension is out for powder coating and new bushes. While I'm there I will complete the Porsche CV axleshaft conversion. BlueOvalZ used the 930 CV joints which are overkill for the application (killing a mosquito with a 5lb hammer as he stated). I LIKE that though. Anyway, These allow 23 degrees of movement (strength diminishes quickly past the 15 degree mark). This is achieved by a 40mm thickness where smaller joints are on in the 32mm range. I have every intention of using these for strength alone but I now wonder what the actual range of motion for the axleshaft is in a 240Z. Smaller CV joints are good up to 200+hp (maybe more) and allow only about 17 degrees before the cage moves out far enough the allow a ball to dislodge causing detonation. All that said, could one of you (with an assembled rearend) measure the total movement of the axleshaft from extension to compression using an angle finder? I'd like to know the maximum swing in degrees. If no one get around to it I'll do so myself when everything gets reassemblied in a few weeks.

[blueovalz]

Some of this will depend on your spring rate, and sway bar set-up. On my Z, if I jack up the entire rear (level, but both tires are off the ground), I get about 5" of droop. The Axle length will be about 13" as measured from the CV to CV centerline spacing (just a close approximation here based upon my set-up). This equates to a 21º angle. In practice though, I will rarely see anything over 5º with the car on the ground (although, I have had the rear off the ground while driving). Again, it depends upon set-up, and what you're doing with the car.

[ezzzzzzz]

Thanks for the feedback, BlueOvalZ. I was considering how many are still running U-joints (including me) which operate at a much more restricted angle than a CV. My Z is street driven only but I hope to get some track time in the future.

[blueovalz]

One last thing to consider is the ever present squat the Z has. Any launches (or when exiting a turn) on an already lowered rear suspension will increase the angle (on the outside wheel) at a point in time when maximum torque is being applied to the joints.

[ezzzzzzz]

I'm having no success in finding a part number for the 100mm x 40mm CV joint. Every supplier says they don't stock much of their so-called inventory. As such, they can't measure anything...I'll need a specific application. It looks like I'll be using the 930 joints. Much looking seems to price these out around $75-80 for a cv joint/boot kit. I have 4 - 4.5" diameter cold-rolled steel disc's to create the adapters. Got them cut to 1.5" and 1.25" per pair for my design and spent $43 on them. I wish I had a lathe of my own so I could get these further along. Check out my gallery to see the original adapters I had made. The CV shown is a Type 4 (100mm x 34mm) with a limit of 17 degrees. The 100mm x 40mm allows 22 degrees and the 930 has 25 degrees. The R180 bolt-in side flanges are from a 720 front diff. They work perfect in my NISMO R180 LSD.

[blueovalz]

I'll measure mine, but the original set of CVs I was going to use were 944 (Type 4). They were almost a perfect fit in the 280ZXT compantion flange. This adaption would require a light turning on the lathe of the ZXT companion flange, and then drilling new bolt holes. Unfortunately I tossed them as I never thought I'd have a need for them. Attached is a link for some Porsche CV info I collected when making my decision on CVs.

 

http://www.blindchickenracing.com/How_to/CVJoints_Axles/cv_joints_101.htm

[ezzzzzzz]

The thought of machining the companion flanges occured to me. The problem with those I have is a lack of depth to accomodate the hub and cage through full articulation. There isn't enough clearance there. That link is useful but it fails to mention the elusive cv joint I'm looking for. The list of BMW's is grey-market in the US and unsupported by parts dealers here. There may be the identical part in many of our models here. The problem is locating these cars or parts to physically check. The difference of 108mm vs 100mm is not worth the trouble really. I just thought I could keep things tighter and lighter. If I can find the time, I'll head over to a local Porsche dealer and see if they have something on the shelf. The 930 cv joint looks like the only viable path. One quick question, The 930 uses 10mm bolts vs the 8mm in the smaller cv joints so is the bolt pattern identical aside from the bolt size?