Aaron Pfadt

It's fun to be able to post some of the cool things we are working on here at Pfadt. This week we have been conducting final durability testing on our long anticipated carbon fiber driveshaft.

This little video shows the cycle testing we are doing. The torque we are cycling to is 1350 lb-ft. That is past the failure point of the factory aluminum shaft. Remember, that shaft sees engine torque only, not multiplied torque from the gear box. How much torque does your engine make? We have over 10,000 cycles to 1350 lb-ft on this shaft so far. I'm pretty sure the hydraulic ram is going to fail first



One of the interesting things is that the aluminum driveshaft has about 2x as much twist at the same load as our carbon shaft. Not surprising exactly, but interesting to see anyhow.

Here are some photos of a 'beta' unit being installed in a C6Z.

Note the weight of the stock assembly versus the Pfadt assembly

This is 4lb 10 oz lighter. All of the savings is rotating mass also.





This beauty replaces the rubber 'guibo'. Guess which one is stronger





This shows the whole assembly before it is installed in the torque tube.



Coming very soon!

wmckeenster

how soon is "very" soon?

GrantB

Less work for the synchronizers, too.

Any idea on the cost? Will it be available for the older 10mm tubes?

I've always wondered what the purpose of those guibos in a torque-tube application were, and how they affected the natural frequency of the system. I replaced mine with solid couplers, shimmed to less than 0.001" of run-out, and I still get some weird vibrations from time to time.

Aaron Pfadt

The cost will be around $2000 for the kit. We will have C5 and C6 varieties. Only the hardware will be different for the 10mm versions, the shaft and couplers will be the same.

With the guibos removed, the power application is much more snappy. We designed flex into our couplers to deal with misalignment in the torque tube bearings. That is a huge advantage over the solid couplers on the market.

I would look at the carrier bearings in your torque tube. When we pulled the tube from out C6Z with 14,000 miles on it, the rear bearing was making a ton of noise. Your symptoms from the other thread sound like a bearing to me.

-Aaron

Aaron Pfadt

Wayne,

Josh is going to finish up the durability testing while I am in Europe for the 24 Hours of the Nuerburgring. When I get back if the testing goes as expected we will start a production batch. I expect it will take 6 weeks to get a batch complete. We should be shipping in mid-July.

Around the same time as the Featherlights I did get your e-mail. Sorry it took me so long to get an answer to you. Things are busy around here. That is a good thing!

-Aaron

GrantB

I don't suppose you're planning to make those couplers for the stock shaft, are you? Admittedly I'm not sure it would work, since the shaft is probably shorter (though I suppose the thin 'flex' sections could be left as-is while making the rest of it thicker). I think there is a void in the market for tougher couplers without dropping $2k+ (thats eating into my Featherlight coilover fund, heh) on a driveshaft. Also, you cannot even source the 10mm guibos from GM.

I shimmed both of my LG solid couplers until I achieved as little runout as my dial indicator could measure, and I still ended up with some odd vibrations and noise. I think some flex (provided it doesn't fatigue the coupler of course, but I assume you've done your homework here) would be beneficial.

Thanks, that is what I was going to check. I think the front carrier bearing is shot, allowing some wobble in the clutch disc. I'm amazed everything has stayed together and running well.

Aaron Pfadt

Grant,

The shaft being shorter is the main problem. I'll think you suggestion over though and maybe we can make a retro-fit part that actually works. It will be heavy, but I think that it is possible.

-Aaron

0DAVID@VASPEED

Looks great Aaron! My wife really wishes you guys would stop this, I've got one hell of a long wish list.

GrantB

Great! I don't think it shouldn't be any heavier than a OE or LG part (the LGs are a bit lighter than the stock bushings)? As a side note, I love how light everything that Pfadt sells seems to be (or at least my sway bars, seat brackets and even bushings are lighter than the competition's).

I did find the cause of my odd vibrations, though. After pulling the motor (lost the #7 piston at Sebring), I found the pilot bearing was destroyed. There still appears to be no (or at most one-half-thousandth) runout in the driveshaft itself, so the shims + LG couplers appear to have done their job. The front torque tube bearing also appears to be fine (or at least it doesn't make any noise, turns freely, and you can't significantly move the input shaft with your hand). I believe the TT bearings aren't tight enough fits to prevent some movement in the input shaft and clutch disc.

I'm chalking the failure up to damage during installation of the torque tube, or some sort of shaft harmonic causing the thing to whip at certain RPMs.