1 Piece Aluminum DCT Driveshaft Install

[patroklai]

Yeah I reached out and heard the same.

[Adriano917]

I just installed the DS and over 70mph I’m having a slight vibration nothing really crazy but you can tell. Do you have any vibrations ? I’m gonna reach out SLG and ask for an opinion.

[nevaland9]

Just installed the same driveshaft on my DCT E90 M3. I chose to put the spline boot on the transmission side.

I was super mindful to tighten all bolts in a star pattern (like when tightening wheel lugs). I have zero vibration, i actually have less vibration that i did with my oem driveshaft (bad cv joint).

Ive got solid subframe bushings, poly diff bushings and full spherical bushings in the subframe (0 oem rubber bushings). The diff whine exists at 80mph but Tbh the diff whining was louder with the oem driveshaft.

Overall i have absolutely nothing bad to say about this driveshaft. The car feels sooo responsive and peppy. It actually kicks sideways into second instead of just chirping like previously. Its actually crazy how much the guibo dumbs down this motor feel.

This might be one of my favorite mods, the clunky driveline feel was really hurting the driving experience of these cars. Love it, would recommend!

[GioMart1nez]

Also just installed this same driveshaft on my e92 m3, tightened everything in a star pattern and I have zero vibration at any mph.

Make sure to push up on the ebrake cables during the install to give the DS more clearance, and tighten it all in a star pattern and you shouldn't have any issues. 10 out of 10 part.

[TheGr33k]

Also just installed mine on my E92, drove it home 80 miles and through a variety of speeds and transmission modes it feels awesome. Zero vibration at any speed tested and zero NVH added. Really happy with it, great alternative and SLG has had outstanding customer service.

[nycplumber]

Why do people choose this one when you can get a CF one at ecs/turner for only $350 more

[nevaland9]

Originally Posted by nycplumber

Why do people choose this one when you can get a CF one at ecs/turner for only $350 more

For me its peace of mind and serviceability. SLG is based in the US and i can pick up a phone and call them at anytime. While im sure i could call ECS also, they dont manufacture the driveshaft, replacements/repairing may not always be available and their customer service can be challenging to deal with sometimes. I can also bring the aluminum driveshaft to almost any driveshaft shop for service/repair if needed. I also dont have to worry about a rock chip or road debris causing catastrophic failure. While i know carbon driveshaft failures are far less common (or less documented) they do happen and its always a possibility. I drive my car hard and often, its just one less thing to have in the back of my mind.

[MaximusB]

Originally Posted by nevaland9

For me its peace of mind and serviceability. SLG is based in the US and i can pick up a phone and call them at anytime. While im sure i could call ECS also, they dont manufacture the driveshaft, replacements/repairing may not always be available and their customer service can be challenging to deal with sometimes. I can also bring the aluminum driveshaft to almost any driveshaft shop for service/repair if needed. I also dont have to worry about a rock chip or road debris causing catastrophic failure. While i know carbon driveshaft failures are far less common (or less documented) they do happen and its always a possibility. I drive my car hard and often, its just one less thing to have in the back of my mind.

What rock chip or road debris? You planning on leaving the heat shield off?

[nevaland9]

Originally Posted by MaximusB

What rock chip or road debris? You planning on leaving the heat shield off?

I always forget that theres typically a heat shield covering the driveshaft. I havnt had my rear heat shields on for a couple years. It was all mangled by the previous owner and when i took it off to do the driveshaft i never put it back. Havnt noticed any negative effects or additional heat in the cabin

Regardless, i do recall reading of carbon driveshafts that failed due to being chipped or damaged one way or another. Again, my preference my be different to others but i just prefer as little variables for failure as possible. Very similar to why people would buy the Apex Endurance wheels over their lighter Sprint line or why people remove CCBs for steel rotors on the track. They just want a product that they dont have to worry about failing from prolonged abuse.

[jvictormp]

Originally Posted by nevaland9

I always forget that theres typically a heat shield covering the driveshaft. I havnt had my rear heat shields on for a couple years. It was all mangled by the previous owner and when i took it off to do the driveshaft i never put it back. Havnt noticed any negative effects or additional heat in the cabin

Heat plays a role on speeding up corrosion and material deterioration.

[M3SQRD]

Originally Posted by nevaland9

I always forget that theres typically a heat shield covering the driveshaft. I havnt had my rear heat shields on for a couple years. It was all mangled by the previous owner and when i took it off to do the driveshaft i never put it back. Havnt noticed any negative effects or additional heat in the cabin

Regardless, i do recall reading of carbon driveshafts that failed due to being chipped or damaged one way or another. Again, my preference my be different to others but i just prefer as little variables for failure as possible. Very similar to why people would buy the Apex Endurance wheels over their lighter Sprint line or why people remove CCBs for steel rotors on the track. They just want a product that they dont have to worry about failing from prolonged abuse.

A tiny chip or delamination in a CF DS will not result in rupture or ultimate failure. 10 fiber diameters away from the impact spot, the CF DS has no idea it’s been damaged. Even a small delamination won’t create a structural integrity issue unless it starts to grow/spread. Type 2 and type 3 crack/delamination growth is a lot harder than type one which won’t occur under a pure torque loading. More commonly would be the failure of the adhesive bond between the CF DS and the metallic end plugs which just results in the loss of torque transfer/drive. However, the probably of this type of failure is low and would occur almost immediately after installation (bond surface contamination and/or a badly designed bonded joint without sufficient strength testing).

Aluminum DS - I hope the lateral bending mode of the driveshaft is higher than the critical driveshaft speed (in Hz). For an 8400 rpm redline the driveshaft frequency is:

F_ds = 8400 * 1 min/60 sec = 140 c/s = 140 Hz

So you’d use a factor of safety of 2.0 (human life involved so min 2.0) so Aluminum DS critical bending speed should be 280 Hz.

For a beam with pinned ends and uniformly distributed mass mds and concentrated central mass mc, the equation to calculate the bending speed (frequency) is:

F_critDS = (1/(2*pi))*sqrt(48*E*I /[(mc+0.5*mds)*L^3])

where
E = Young’s Modulus of Aluminum
I = cross-sectional area moment of inertia
L = length of DS
mc = central concentrated mass (consistent mass units, not lbm)
mds = mass of DS (consistent mass units)

F_critDS >= 280 Hz (without central support)

If F_critDS < 280 Hz ultimate failure as well as fatigue life (requires a load spectra, % of applied load/stress per specified number of cycles, given in 10% increments; e.g., 90-100% max load with w cycles, 80-90% max load with x cycles, 70-80% max load with y cycles,…, 0-10% max load with z cycles). If it’s randomly distributed then you can define the load spectra based on a Rayleigh Distribution + assumed number of redlines and a distribution for shifts from 2000-8000 rpm.

Max load would be engine torque multiplied by transmission gear ratios to calculate peak torque applied to the DS torque.

Does anyone know if SLG performed these calculations, in addition to bonded joint strength sizing, if there are any (bonding in end plug joints can be less costly than machining them integrally into the DS) and analysis, etc. or is everyone assuming the single continuous Aluminum DS was designed and analyzed correctly?

Does anyone know the OD and ID of the Aluminum DS?

[TheGr33k]

Originally Posted by nycplumber

Why do people choose this one when you can get a CF one at ecs/turner for only $350 more

Because I can easily service/maintenance the SLG one and repair at any reputable machine/driveshaft shop for essentially nothing without any of the headache of the questionable companies who sell the CF driveshaft. If you are counting ounces and pounds than sure go the CF route, but for me I was looking to eliminate the two piece design and center support bearing all together and this was the way I chose for the aforementioned reason. Them being a US based company with a US made product sure didn’t hurt either.

[amrazM]

Originally Posted by TheGr33k

Because I can easily service/maintenance the SLG one and repair at any reputable machine/driveshaft shop for essentially nothing without any of the headache of the questionable companies who sell the CF driveshaft. If you are counting ounces and pounds than sure go the CF route, but for me I was looking to eliminate the two piece design and center support bearing all together and this was the way I chose for the aforementioned reason. Them being a US based company with a US made product sure didn’t hurt either.

agreed, having a normal serviceable joint on there goes a long way.

[smoothmacdaddy]

Just wanted to add my experiences with this driveshaft after getting it on this week. The car is much more responsive when coming off from a stop or slowing down over a dip and then accelerating again. Also seems like the up shifts catch the next gear more aggressively but I also got a DCT pan service done the same day I got the driveshaft installed. Overall super happy with the SLG driveshaft. Didn’t realize how much slop the stock 2 piece driveshaft had until it was changed out. And of course no more clunk reversing or going forward from a stop or cowbell noises

[nycplumber]

Originally Posted by smoothmacdaddy

Just wanted to add my experiences with this driveshaft after getting it on this week. The car is much more responsive when coming off from a stop or slowing down over a dip and then accelerating again. Also seems like the up shifts catch the next gear more aggressively but I also got a DCT pan service done the same day I got the driveshaft installed. Overall super happy with the SLG driveshaft. Didn’t realize how much slop the stock 2 piece driveshaft had until it was changed out. And of course no more clunk reversing or going forward from a stop or cowbell noises

Did you have to order an extra parts to make it work?

[smoothmacdaddy]

Originally Posted by nycplumber

Did you have to order an extra parts to make it work?

hey, nope, nothing else is needed. I was between this SLG DS and the YCW carbon fiber DS from ECS / Turner ($1850 after tax) but then going that route, i'd have to get a new OEM guibo ($150) coming in at $2000 all in. The SLG driveshaft was $1350 shipped (no taxes either idk why lol) and you get their proprietary metal guibos / adapters for the transmission and differential attachments, thus eliminating all rubber from the driveshaft. hope that helps!