Full Torque One Piece Driveshaft

[Kcalhoun27]

Well, ive been chasing a vibration in my drivetrain and after replacing the engine mounts, trans mounts, guibo, csb, and rebuilt the diff, along with new diff bushings, and dont the subframe bushings, i am left with the driveshaft as my next thought for replacement

As it turns out, a factory drivesaft is currently $2200 and a CF is similarly priced. I worry about the issues that a CF can have, so decided to stick with steel for $1100. There were a few options and i went with Full Torque because they were in stock and had free shipping. I dont have any knowledge about driveshafts beyond what a website says and they all swear theyve built winning racecars etc, so i took a chance

First impression, it was wrapped well for shipping. Came with new hardware and its a very pretty piece. Appears to bolt from the trans to the diff, no more bushings to deal with. Once its finally not 10 degrees outside ill install it. But, figured id share it incase anyone else was looking for parts

[discoelk]

Interesting option. This is an upgrade I want to do soon but I want greater weight loss vs the F80 driveshafts. Odd design with the cardian joints and a slip section instead of the stock CV. Can you weigh it?

Curious to see if you have high speed vibration issues.

[0-60motorsports]

That looks interesting. I wonder how it'll fit with M3's on the CMP Subframe bushings and SMG.

[Kcalhoun27]

Interesting option. This is an upgrade I want to do soon but I want greater weight loss vs the F80 driveshafts. Odd design with the cardian joints and a slip section instead of the stock CV. Can you weigh it?

Curious to see if you have high speed vibration issues.

Using the bathroom scale, it came out to 26.6 lbs.
If i had to guess, id say they probably use those joints because they are in idaho and do more 4x4 stuff vs sports car stuff. But, i cant imagine they would want to put their name on something that sucks, so im hoping that i dont have vibration issues.

[Kcalhoun27]

Update for those that care: I installed this over the weekend. The bolts holes were not drilled quite right, so I had to slightly clearance the holes after talking with one of the builders at the company. He was very helpful and even FaceTimed me in order to show him what I was having an issue with. After putting the car back on the ground to go for a drive, I was getting a rubbing noise above 2k rpm. I thought it might be the heat shield, so I lifted it back up and made some room there. Went for another drive and it came back. I decided to let it rub a bit and see what I could find. Turns out, the rear u-joint is big enough that once you get a bit of speed going, it impacts the driveshaft tunnel. It was late on a Sunday when I finished, so I will address this with the company tomorrow.
I will say, this is a bit disappointing, but I suppose that's a chance you take when you buy aftermarket parts. I am hopeful for a solution that isn't "clearance" the tunnel with a hammer, but I will have to wait and see.

[0-60motorsports]

Update for those that care: I installed this over the weekend. The bolts holes were not drilled quite right, so I had to slightly clearance the holes after talking with one of the builders at the company. He was very helpful and even FaceTimed me in order to show him what I was having an issue with. After putting the car back on the ground to go for a drive, I was getting a rubbing noise above 2k rpm. I thought it might be the heat shield, so I lifted it back up and made some room there. Went for another drive and it came back. I decided to let it rub a bit and see what I could find. Turns out, the rear u-joint is big enough that once you get a bit of speed going, it impacts the driveshaft tunnel. It was late on a Sunday when I finished, so I will address this with the company tomorrow.
I will say, this is a bit disappointing, but I suppose that's a chance you take when you buy aftermarket parts. I am hopeful for a solution that isn't "clearance" the tunnel with a hammer, but I will have to wait and see.

Thanks for the update. Hope they have a solution soon.

[Kcalhoun27]

Added a photo of the impact. Its not a ton, but in my opinion any is too much.

[9kracing]

This is a known issue, and has been addressed by other manufacturers. I guess I'd stay away from Full Torque.




" The E46 M3's driveshaft challenge.


The E46 M3 presents unique challenges to develop a carbon driveshaft. The engine and transmission sit at a slight angle with the rear subframe and differential. The driveshaft and chassis do not sit at perfectly parallel.

BMW M's original 2 piece steel driveshaft solves this problem by using a tapered tube design, a center supporting bearing and a U-joint as seen below.

The downside to this design is reduced performance & feel from increased weight and reduced stiffness. These components will eventually wear, clunk and vibrate.

Unfortunately, BMW driveshafts are not rebuildable. It's partly why we upgrade to a carbon driveshaft.

The V2's carbon tube limitations.


With carbon tubes, we have neither options available to us.

Due to their winded carbon construction, the carbon tubes cannot be tapered nor conform to transmission tunnel shapes.

As previously discussed, carbon tubes stiffness generally increases with diameter. With the V2, the original diameter developed for the E9x M3 and E6x M5/6 was retained due to its extensive development time.

Its strength and heat resistance has been demonstrated on over 1,000 + M cars with extremely low failure rates. The V2's selected diameter is stronger than its original steel counterpart with a torque rating of 4,000 ft/lbs.



The E46 M3's V2 development focused on new flanges specific to the E46 M3. It featured a smaller flexdisc and PCD compared to the E9x/E6x M cars.



The SMG2 also presented clearance constraints with the shifter linkage - an elongated flange was designed as a result. The V2's flange also required longer bolts.



Additionally, the E46 M3's original shaft uses a constant velocity joint without a cap due to tighter flange clearances. The bearings are thus exposed - and will require greasing. Below is an example with the carbon driveshaft.



Many will confidently state the E46 cannot be fitted with a 1 piece driveshaft due to the driveline's angle. The challenge is not the angle per say, but rather the tunnel clearances.

The constant velocity joints are specifically designed to absorb driveline shock and movement in any angle within its mechanical limitations. I've uploaded a short to my YouTube channel explaining this here.

My limited V2 experience.


In 2022, I fitted the V2 carbon driveshaft to my E46 M3 6spd. Back then, my E46 M3 was close to stock with original suspension, bushing and mounts.

I was able to drive the car in the Fall prior to its complete tear down for restoration and modernization of the body. I reported no issues at the time.

The product's manufacturer had been selling this variant prior to my installation and hadn't raised any concerns. Under my scope, the V2 carbon driveshaft was sold to dozens of E46 M3 owners worldwide starting in 2022.

This is where I failed: too much trust and not enough verification.

The V2's problems.


In late 2023, issues started arising in an E46 M3 race car with vibrations above 200 kph.Vibrations are not normal on this carbon driveshaft design considering the use of the original flexdisc and the constant velocity joint.

Upon further inspection, the carbon tube had come into contact with the chassis, leading to structurally damaged tubes.

In early 2024, 3x new cases were reported to me with all being on SMG2 equipped M3s. Upon further inspection, the same tunnel contact problem was identified. This was an identifiable pattern that would be later confirmed with new cases in late 2024 including the first 6spd equipped cars with a stiffened chassis. Local testing.


As my car was not available for testing, I provided a V2 driveshaft to a local E46 M3 for hands-on testing. It was a 6spd car with stiffer bushings and lowered, stiffer suspension. The owner tracks the car at local HPDEs.



Vibrations arose at 190 kph. Upon inspection, tunnel contact was also identified specifically where the original center supporting bearing is installed.

Below are pictures of the expected damage if it was caught early on. Continued driving would eventually lead to tube failure; it would split completely.



Additionally, I added pictures of what will likely happen if you fit the constant velocity joint with the cap. There are signs of contact with the differential pinion flange. This likely played a role in further vibrations.

In 2024, I pressed my concerns with the manufacturer.

They agreed to engineer a new variant with a smaller diameter carbon tube, along with upgrades to flanges along the way."

[Kcalhoun27]

This is a known issue, and has been addressed by other manufacturers. I guess I'd stay away from Full Torque

Thanks for the insight and i suppose thats a fair explanation. I am willing to see if a solution is available from them. Its a problem that is certainly solvable without going to great lengths, imo. As im already into it for the price of the component, i am willing to try and see what could be done for a permanent fix. Putting aside the issues i have, the current price of a new oem driveshaft is ~$2200, plus a guibo and csb. I could buy a second 1-piece and still be under that price.

i will happily admit when ive lost the battle, but i dont believe im there just yet. Im putting this info out there for anyone who might be going down the same path as me.

[Kcalhoun27]

Final Update:

The saga concludes with a fairly simple return to manufacturer. The driveshaft they produce is built specifically for race applications, but it did not say that on their website and it made it seem like a clean plug and play option. The sticking point is that I have factory bushings in my differential and it was designed to be used with solid or very stiff poly bushings. Although I do think that's reasonable, I did not have that information. or I would not have purchased it because it did not suit my needs. All of that said, they were super professional and helpful in the return process. If I was looking for a full racecar driveshaft, I would not have an issue looking into their product. In this case, it just isn't a good fit for my car.

So, a happy ending was my hope and it's what I got.