Tailshafts: 1-piece or 2-piece?
Fact of the day: The mightly Lancer Evolution uses a 3-piece tailshaft from the factory.
There are people out there that say a 1-piece 3" tailshafts is the answer to all your tailshaft needs along with suggesting "cut and shut" re-tubing jobs, china-spec tailshafts, to quality tailshafts using Spicer flanges, yokes, and unijoints.
We've built, balanced and tested a number of different tailshaft designs ourselves so that we can confidently recommend you the right tailshaft to suit your needs and can report we have had a mixed bag of results. "Cut and shut" ruins the lubricant in the staked-in, old and usually worn-out Nissan unijoints (after all, they are on average 10-20 years old), there's only one word for china-spec... "no", SPICER... definitely yes, and the almighty 1-piece 3" tailshaft?
A 1-piece 3" tailshaft at approximately 1200mm length is simply too long for our intended use. The tailshaft will "whip" or do the "skipping rope" causing accelerated wear and tear on all tailshaft components and it will also wear out the gearbox output shaft and seal at a greater rate, not to mention the nose of the diff. Did we mention vibrations and harmonic noises at certain RPM speeds?
So What Can We Do?
For the people that MUST have a 1-piece tailshaft our answer is to build the biggest tailshaft that will physically fit under the floor plan: a 3.25" tailshaft @ 0.065" wall tube thickness, using the highest specification of components: SPICER 1330+rated. We choose SPICER because we believe they are the number 1 manufacturer of tailshaft components.
For the rest of us, Nissan engineers smacked us in the face with the answer even before we picked up a spanner: use a centre-bearing-supported 2-piece tailshaft! A centre bearing supports the tailshaft where it needs it most (around the centre... hence the name) and the 2-piece design allows for maximum "revability".
When we say "revability" we mean that the tailshaft is able to withstand higher RPM's before reaching its critical speed where it will start doing the skipping rope thing - the LONGER the tailshaft the LOWER its critical speed. The closer you get towards the critical speed you faster your wear and tear.
Did you know that a 2-piece tailshaft is favoured, chosen and used in unlimited-budget race cars such as the "V8 Supercars"?
Tailshaft components are all given a rating and there are 3 SPICER ratings that are of interest to us today - 1310, 1330 and 1350. The "V8 Supercar" 1350-rated is literally too big to fit and the 1310-rated is the cheaper "regular series" most people use... but we can do better. ALPHA OMEGA uses 1330-rated components (they are actually rated higher than 1330, which is why we call it 1330+) in all of our tailshafts - the highest rating possible.
Our particular design is rated higher than the rest, uses an internal-circlip design which makes it safer since external circlips can collect road dirt and grime and the circlip can fall out... which we have experienced, and the internal circlip design also makes for a more compact flange, centering the weight optimally. Finally, we can use a thin-wall tube at 0.065" for increased "revability".
So now you know why Nissan and ALPHA OMEGA uses and recommends a 2-piece tailshaft for the Nissan S-Chassis.
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