CV vs. U-Joint rear axle conversion

[Crossle32F]

Hello, I am recommissioning an Elan +2 vintage race car, to be raced at a regional level. The motor (currently being rebuilt) will have about 180 bhp, and the diff. will have 4.1 final drive with limited slip. The car still had the Rotoflex couplings and what appear to be stock diff. output shafts, which need to be upgraded.

Does anyone have any experience or recommendations on CV joint conversions (eg. R.D. Enterprises #50RD0034, Kelvedon #RACEDS04) vs. U-Joint with sliding spline (eg. Tony Thompson #TTR-FD-013, Kelvedon #RACEDS03)?

Any thoughts on 4-bolt vs. 3-bolt diff. output shafts?

Thanks!
Kevin
Vancouver BC Canada

[StressCraxx]

I have the RDent/JAE/Bean axle kit with 4 CV joints. They are all built by John Kouba in Southern CA. He sells only to these three shops. The heavy duty axles and CV joints are supplied with new diff output shafts that are much stronger than the original or even the later upgraded sprint axles. The diff output shafts are 6 bolt using the through holes in the inner CV joints. The great thing about the CV joints are they take up all of the needed axial plunge in the driveshafts. No sliding splines are needed so there is no concern about them binding.

They are reliable and will tolerate full droop of an Elan or +2 rear suspension.
I believe Dan Wardman used them on his +2 for years when he vintage raced it. I believe that car, red with silver stripes and roof is still racing in the PNW.

[Andy8421]

As mentioned above, CVs are a superior solution, unfortunately not accepted in historic racing in the UK as they are not considered a period modification. This has always seemed daft to me, the Austin Mini was using CVs from 1959 onward, and Rzeppa patented the design in 1926.

To be fair, it is possible they weren't used on an Elan in period. 26Rs used Hooke (universal) joints and ball splines to avoid the torque lock-up problems of linear splines.

If you can get away with using CVs, I would.