The trend of snapped half shafts (axles) on the entire 335i & 135i platforms has been increasing rapidly since many people have surpassed the 400 rwhp / 400 rwtq mark. To be honest, the trend is a bit disturbing. We have members on the forums who have broken three sets of half shafts on their car! Some refuse to track their car because they fear breaking more half shafts and they don’t want the embarrassing “tow of shame” home. I will even admit I have been very concerned about slapping on some drag radials or slicks because I just didn’t want to deal with breaking mine. We have seen failures with both the half shaft’s bar and within the inner universal CV. It has even been hinted that one of the tuners snapped his half shafts during a run at the track. This is clearly the single weakest link we have seen thus far on the drive train of all N54s. If we are to move forward with big power on the N54 then it means we have to identify the weak links and find fixes. The big problem is that there have been no option for half shaft upgrades at all… oh, that is until now.
When I decided I was intent upon finding an upgrade option for our weak half shafts, my search continued to come back to the same company. Every person in the speed business suggested the same shop to do the work… The Driveshaft Shop. These guys have been building and upgrading half shafts/axles, CVs, drive shafts, etc. for 30 years. They are a part of an enormous number of the fastest ¼ mile race cars in the world. They also make the half shafts for many of the fastest HPF E46 M3s in the world. The Driveshaft Shop is simply the best and their reputation is second to none. The problem is they didn’t have an upgrade option available for our vehicle, so I decided I would contact them. After a few conversations, they clearly identified the N54 as an important market and said they wanted to offer upgrade options for our platform! They felt they could make us an upgrade that would hold 1000 hp without sacrificing any drivability whatsoever. What they needed was a half shaft they could look at to measure the necessary parts and make the upgrade. I felt this was tremendously important, so I pulled my half shafts and sent them to The Driveshaft Shop to get this project moving along. The result is now the N54 platform has an upgrade option for the weak N54 half shafts and finally we don’t have to worry about snapping them every time we launch the car.
This review will focus on The Driveshaft Shop upgraded axles. I will cover everything from my dealings with DSS, the diagnosis and upgrade of the parts, and the very important thorough DIY of the project.
Experience with The Driveshaft Shop & Their Analysis of E9x axles
I had the fortune to talk with Frank from The Driveshaft Shop a number of times through this process. To say that Frank is an incredibly valuable source of information would be a huge understatement. He has been building axles, driveshafts, CVs, etc. for 30 years and has incredible knowledge about axles and this upgrade. He educated me on materials used in the stock half shafts, the reasons they fail, the process of the upgrade, and the final results. He shared information on the strength of the race and cage used in CVs, and why they fail. Frank even answered emails from his blackberry while he was on the road and on the weekend! That is the real deal on customer service!.
The Driveshaft Shop upgraded axles require you to send your half to them for the upgrade. They can be snapped in half and it doesn’t matter. They will tear your old half shafts down and upgrade the race and cage that comprise the inner CV, then upgrade the bar to much stronger parts. The Driveshaft Shop says their N54 axles will hold 1000 hp. When you order the upgrade, The Driveshaft Shop will give you an order number that you need to print on the box you send them. This will help them identify your order when they receive it and expedite the process. My half shafts were received by The Driveshaft Shop on a Wednesday and I had an invoice with tracking information emailed to me Thursday. They machined my half shafts, upgraded the CV, upgraded the bar, packaged the items, sent them to shipping, and emailed me the invoice with tracking info within 24 hours. That is astounding customer service.
The Driveshaft Shops Analysis of E9x Stock Half Shaft
When my half shafts were at The Driveshaft Shop, they had the opportunity to analyze our half shafts and diagnose the weak spots. This is obviously critical if we want half shafts that can withstand the torque we are putting on them with tunes now. The first thing The Driveshaft shop did was open our half shafts. They found the inner and outer CV housing to be of great quality and those didn’t need upgrades. Inside the CV housing are parts called the race and cage. If you are curious what a race and what a cage is, well let me show you. This is what the cage in your universal CV joint look like:
This is what the race inside your universal CV joint look like:
The cage can literally explode under the stress of launch and that clearly has been a major point of failure thus far. The Driveshaft Shop said the stock race and cage were quality parts, but not made for high shock factors at all. To remedy this problem, The Driveshaft Shop used a special blend chromoly that still has a good wear factor but now a very high impact race. In addition, the race is now REM polished for perfect fit and will also reduce heat during break-in.
From here, The Driveshaft shop moved onto looking at the bar. They found the material to be a decent chromoly but it was a formed tube or extruded type bar. Basically there is a hole in the center of the stock bar, and DSS believes that style makes the bar about 15% weaker. In addition, they found diameter changes on the bar causing certain areas to twist more freely than others causing stress concentrations in some areas. To fix this problem, The Driveshaft Shop made a solid center bar out of their proprietary aircraft grade material that has a “special design to be torsional with memory built in using special heat treat and temper” processes. The bar was made to be completely smooth without any deviations so it can twist freely and come back without issue. The solid bar will add 1 lb to the half shaft, but now the bar is rated to 6000 lbs. of torque.
The Driveshaft shop finished the upgrade with a high grade and higher durometer boot along with synthetic grease.
Finally, The Driveshaft Shop for all future customers will polish and clean the outer splined section and (sample allowing) make sure they fit back into the hub trouble free. Of course you will still have to clean the hub a bit to allow perfect fit.
The Driveshaft Shop Half Shafts Arrival
As I stated above, The Driveshaft Shop had a very quick turn around and did email me tracking info so I could prepare for the install and I was anxiously waiting for the axles to arrive. When they arrived back, they were packed very nice and very professional.
Everything is very nicely protected and organized. Clearly this is not just a "throw in a box" package.
Each half shaft is protected from the other and secure in a card board section of the box.
It is hard to describe how excited I was when I saw these!
Clearly everything is packaged and protected tremendously well. I removed the half shafts from the box so I could show more detail on the craftsmanship. Notice the new bar (painted matte silver) and the new inner CV with new race/cage.
Here is the OEM looking inner CV section with brand new boot.
On the other end, here is the OEM looking outer splined section of the half shaft with brand new boot.
Finally, a slightly closer look at the bar.
The Driveshaft Shop is a truly professional company the takes enormous pride in the products they create. These items came to my house quickly and incredibly well packaged.
DISCLAIMER: You work on your car at your own risk and take full responsibility for any damage caused to your vehicle. Please understand you can injure yourself or kill yourself if you do not take proper precautions when working on your vehicle. Please use extreme caution when working underneath your car. This DIY is simply an example of the way I removed my half shafts and installed the upgraded Driveshaft Shop half shafts on my own vehicle.
If you have read any of my reviews, then you know I write full DIYs for items I feel the average guy who is good with a wrench can accomplish. If I feel the job is too difficult, then I omit information so I don’t encourage unqualified people from attempting to do the work. This job is not complicated, but it is by no means easy. I have done a number of axles in my life, and these were by far the most difficult axles I have ever installed. The tolerances BMW has on these axle splines is very tight and you need to make sure you do the proper prep work to prepare these for the install. Common sense must be used and you need to make sure that you secure the car well when you lift it. I will be writing all the details I feel you need to do the job. Torque specs, BMW part replacements with part numbers, and unusual tools necessary will all be covered. Let’s jump in.
The first thing we need to cover is the BMW parts you will need to replace and the unusual tools needed. I want to cover the tools first. You will need a 12 point 36mm ½” socket to remove the axle/hub nut from the car. Fortunately Sears sells this for about $9 and it is readily available.
To remove the drive axle collar nut, it will require quite a bit of force since this nut is torqued to about 300 ft./lbs of torque. A breaker bar is a must and I was able to release the axle/hub nut with the following breaker bar and the above 12 point 36mm socket.
You will also need a reverse torx E12 socket to remove the M10 screws from the inner CV that are used to secure the half shaft to the differential.
Finally, you will need a torque wrench that can support some serious torque to lock the drive axle collar nut at the end of the project since again the torque spec is 310 ft/lbs of torque. Unfortunately, you cannot rent a torque wrench with that supports that much force in my area, so I bought a ¾” torque wrench for the job. Harbor Freight sells one for $75 and you can use the 20% off coupon.
BMW suggest replacing the M10 screws that hold the half shaft to the rear differential. BMW also suggest you replace the M27 drive axle collar nuts that hold the half shafts to the hub. The BMW part numbers are as follows for all BMW E92 manuals:
(12) M10 torx screws – 33207572716
(2) M27 collar nuts – 33411133785
(2) M27 collar nuts – 33411133785
Here is what each item looks like:
Finally, for reference, here is a picture of the axle assembly courtesy of realOEM:
That covers what you need to do before starting this project.
Removal Of Your Stock Half Shafts
As I said above, you will be removing your stock half shalfs and sending them in to The Driveshaft Shop for the upgrade. That means this DIY begins with the process to remove your half shafts. The first thing you will need to do is raise you car up, remove the wheels, and support your car appropriately and safely with jack stands. Make sure you do not attempt to do this on jacks alone! After you have removed the wheels, you need to do a little prep work to make sure the half shafts can be easily removed from the car once you remove all fasteners for the half shaft. The rear section only on your exhaust just needs to be lowered. You just need enough clearance to slide the half shaft passed the differential once all fasteners have been removed. I simply removed the rear section bolts on my exhaust, then lowered the pipes out of the way. Continuing the prep work, it is wise to brace the half shaft so it cannot fall when you remove the bolts. I am a fan of just using a metal wire hanger to hold the half shaft in place by simply bending it to wrap around the subframe above and around the bar on the half shaft. Here is what that it will look like when you brace the half shaft and lower the exhaust:
This demonstrates how lowering the exhaust will give you the clearance needed to get the half shafts out past the differential.
Now it is time to begin the real work on this project and you will begin by removing the drive axle collar nut shown below.
You will notice that in two spots the edge of the drive axle collar nut is bent to prevent the nut from backing out. You will need to use a flat head screw driver to unbend the edge as shown below by the blue arrow.
The red arrow shows the direction you will need to bend the collar nut to allow the nut to loose freely.
After you have freed these bind points, it should look like this:
Now you are ready to remove the drive axle collar nut using the breaker bar and 12 point 36mm socket you picked up earlier.
There are many methods to remove the drive axle collar nut, but I chose the jack stand method. Basically you need to make sure the socket does NOT come off the nut and you need to be able to apply the necessary force. The jack stand method helps hold the socket in place and gives you a great fulcrum point to apply the needed pressure to loose the nut. I placed the jack about 1-2” away from the 36 mm socket to help support the pressure and keep the socket on the nut.
Once I felt good that the socket was secure, I cautiously began to apply pressure until the nut began to loosen. A helper could be useful here to assure you will not slip off the nut. This could be bad. I cannot emphasize enough that you need to use caution to make sure your socket does not slip off the collar nut. After you loosen the collar nut, remove it completely from the half shaft (axle).
Now, that we have removed the nut that fastens the half shaft to the hub, we need to begin removing the screws that hold the inner universal CV on the half shaft to the differential. The UCV (universal CV) on the inside of the half shaft is held for (6) torx M10 screws. You will notice 3 of the M10 screws on the inner universal CV in the picture below:
To remove these screws, you will use your E12 reverse torx socket with a short extension to maneuver around the rubber boot. Remember the boot will be replaced by DSS during your upgrade. Take each screw out individually and you can throw them out since you have a new set, however you will need to reuse the small metal braces so keep those somewhere safe. If you need to rotate you axle during the process, just make sure the car is in neutral (the front tires chocked) and the e-brake is released. That will allow you turn turn the axle using the brake rotor. After all bolts are removed, the half shaft will still likely remain in place due to clearance issues. Before you actually remove the driveshaft from the hub, you need to create the necessary clearance for the half shaft. That is accomplished by jacking up the rear hub about 4” as show below.
This will allow you to lower the inner universal CV away from the differential, but still held dangling by the wire you installed earlier. You can see how this will look:
Now onto the final stages of the removal process and that is removing the half shaft from the hub on the car. BMW has a special tool they suggest using which is a simple axle press. I did not use the BMW tool because the threaded section of the half shaft protects the entire splined section of the axle. I used a ½” socket extension and a small mallet to knock the axle out of the hub. I placed the end of the ½” extension on the half shaft end poking out of the hub as shown below.
In retrospect, I would suggest using the axle press to remove the half shafts since the splined section of your half shafts will be re-used on your new upgraded set from DSS. You can get these axle presses at Autozone to rent for free, so it is probably worth the short trip. I will say I did check the entire male splined section of my half shafts with a micrometer after knocking them out of the hub and there was no mushrooming of either the threaded section or splined section of the half shaft. Again, it is probably a better idea to use the axle press, but that is the information you need to make your decision.
Then I patiently knocked the half shaft through the axle being careful not to damage the half shaft or the teeth on the hub. Once I had the half shaft almost clear of the hub, I removed the wire hanger supporting the half shaft and I got in a good position to brace the half shaft so it wouldn’t fall once it cleared the hub. With it braced properly, I finished pulling the half shaft entirely through the hub and removed it from the car.
Repeat this process on the other side of the car. Note which half shaft came from the driver’s side of the car and which half shaft came from the passenger side of the car. On my car, the driver’s side half shaft is the shorter half shaft. In the picture below, the driver’s side is on the top and the passenger side is on the bottom.
Once both are removed, you are ready to ship them to The Driveshaft Shop for the upgrade.
Re-installation Of The Upgraded Driveshaft Shop Half Shafts
Fast forward to a couple days later when you have the half shafts back. The Bentley Service Manual says simply, “Installation is reverse of install”. Wow, thanks for the help!!! This install is straight forward, but at the same time it is not a cake walk. Please read this entire section before attempting the installation. Here a some important things to note...
- Use the new hardware you bought to fasten the half shaft to the car.
- Tighten the inner universal CV to differential M10 screws in an opposing star pattern method first, then torque to spec in the same manner. Don’t forget the metal braces!
- Lightly oil the side of the drive axle collar nut facing the hub that secures half shaft to the hub.
- When you secure the half shaft to the hub, firmly tighten the drive axle collar nut first but do not torque to spec yet.
- To torque the drive axle collar nut to spec place the wheel back on the car, lower the vehicle, then you will torque the drive axle collar nut to spec with the car on the ground.
The torque specs are as follows:
M27 Drive axle collar nut to half shaft – 310 ft./lbs (420 NM)
M10 inner universal CV to differential screws – 51.6 ft./lbs (70 NM)
Road Wheel to hub – 88.5 ft./lbs (120 NM)
M27 Drive axle collar nut to half shaft – 310 ft./lbs (420 NM)
M10 inner universal CV to differential screws – 51.6 ft./lbs (70 NM)
Road Wheel to hub – 88.5 ft./lbs (120 NM)
The installation of the Driveshaft shop half shafts begins and ends with prep work. If you prep the axles and hub for the installation well, then you will save yourself quite a bit of time and headaches in the long run. You want the splines on the half shaft and hub to look like new… and I mean so shiny you can see your reflection. Begin prepping the axle splines using emory cloth to remove any burrs, dust, imperfections, etc. Any home improvement store you have exactly what you need. This is not just the ridges of the axle, but the depressed sections too.
After you have worked the splines well, and I mean well, you will use a metal brush to remove any shavings on the splines.
Finally, spray it clean using brake cleaner and it should look like this.
I should note that The Driveshaft Shop has offered to help make this process easier for all N54 owners by polishing and cleaning the splines before returning them to the owners! If they can get a hub, they will also test fit all the half shafts before returning them to assure trouble free installation.
Next, you will use the emory cloth to clean the splines on the hub, then use the metal brush to clean all debris from teeth, and finally thoroughly spray the splines clean using brake cleaner.
The final step to prepare the axle male splined section to be inserted in the hub is applying either white lithium or “no seize” grease to the splines of the axle.
The splined section is now ready to be installed, but I found it is quite a bit easier to complete the job if you thread all the inner CV bolts now using the metal braces. Remember, you must use new BMW screws as listed above.
Now, it is time to install the new half shafts. Remember the axles are not the same length, so make sure you have the correct axle for the side you are working on. I suggest wrapping the half shafts to protect them during the install from scuffs. You will want to hang the half shafts or place the inner CV on a jack stand so you can brace the half shaft. Now you insert the half shaft the way you removed the half shaft. Make sure you correctly line up the splines!!! This means it should slide partly in before it gets difficult. Once you are sure you have it line up correctly, you will have to really work it over and over to get it all the way through the hub. This is by far the most difficult axle I have ever threaded through a hub in my life and took some elbow grease to get it through the hub. I suspect the polishing and cleaning that DSS will now provide us will make this considerably easier. No secrets though, BMW clearly specs the tolerances very tight and it is a very tight fit.
After the half shaft is fully through the hub, spray off the axle splines liberally with brake cleaner to remove any grease or debris. Now, you can put the axle collar nut onto the axle, but remember to apply a thin coat of oil to the face of the nut that will contact the hub. Tighten the nut, but don’t torque to spec yet.
With the half shafts now inserted in the hub, it is time to bolt up your inner CV on the half shaft to the differential. This is when you will be happy you threaded those bolts ahead of time. You will notice some plastic zip ties on the CV casing and now you can cut them away. Jack up the hub about 4” as you did earlier to allow enough clearance to get the inner CV up to the differential, then (with the e-brake off and car in neutral) you will spin the half shaft until it lines up perfectly. Tighten the bolts, but don’t torque things yet.
Once you have everything bolted up it is time to start torquing the inner CV bolts. You need to torque these in a star pattern like you would with lug nuts. It is wise to use something to help you note which screws you have torqued to spec and I used painters tape on the end of the screw to identify the torqued screws. I put painter's tape on each screw that was completed, so there is no question about whether it was torqued to spec or not.
Clean everything up by spraying liberal amounts of brake cleaner around the hub and brake components you touched.
You are done now with one axle and the exact same process will be used on the other half shaft on your car.
Now it is off to the final step and that is torquing the M27 collar nuts to spec. You must have your wheels installed and the car sitting on the ground for this process. Well you won’t be able to see the collar nut with the center caps on you wheels, so remove those before re-installing the wheels to the hub. Make sure the car is in park or in gear with the e-brake engaged for this process. I would strongly suggest you have a friend present to help you torque the drive axle collar nut to spec. You will need at ¾” torque wrench to get to the necessary 310 ft./lbs of torque. Your friend needs to make sure your 36mm socket does not come off that nut. Again, I used the jack stand method to properly torque the collar nuts to spec. Use caution when tightening the nut to spec because this is a lot of torque and you can injure yourself, your friend, or your car if you are careless. I would heavily protect your wheels in case for some reason you came off the nut while apply the necessary force. This is how it looked when I dressed up my wheels.
The last step is the staking the collar nut and well you cannot do that with the wheel on the car, so jack the car up again and remove the wheels. Once the wheels are removed you can stake the collar nut. Once it is done, it will look like this. Note the blue arrows pointing to where the collar nut it staked.
Finally, torque your wheels to spec which is 88.5 ft./lbs (120 NM) and you are done. Look everything over to make sure nothing is out of place and that you don’t have extra parts sitting around anywhere.
It should be noted again that this install was not complex at all, but the tight tolerances of the stock half shafts made the fit very snug. In the future, The Driveshaft Shop will polish and de-bur all the half shaft splines before they are shipped back to you. If they have a sample in house, they will also check and make sure they fit back in the hub for a trouble free install. This will make this job really routine for a decent DIY guy.
After you have everything button up, it is time for a drive.
The results are obvious in a sense because we now have 1000 hp axles, but I want to cover a few other components like weight, fitment, any extra noise, and holding power during hard launches.
The package left my house to go to The Driveshaft Shop at 29.5 lbs for both axles, so that is abuot 14.75 lbs per stock half shaft. The upgrade axles from the Driveshaft Shop weighed about 32 lbs. That is an average of 16 lbs per axle or an increase of about 1 lb. Pretty nominal considering the strength you are adding!
Although the tolerances were very tight, fitment was OEM on both the inner universal CV joint connection to the differential and the axle spline to hub. Again, it should be noted that The Driveshaft Shop will be prepping these half shafts for clean fitment before shipping them to you in the future. That is a great service to add!
I wanted to test these under hard driving and casual driving. Under both casual driving and hard driving, I think there may be a pinch more road noise, but to be honest it is nearly impossible to tell you have upgraded axles. The car rides basically just like stock and takes off just like stock. Again, there may be a tiny more noise, but it is only a guess since the difference is tiny at most.
I was able to do three different hard launches at about 3500 rpms to test The Driveshaft Shop half shafts. They didn’t flinch and the car just goes! I also ran these with and without nitrous and they didn’t flex even an inch. That is about 525 rwhp / 515 rwtq 3k launches and when you launch the car goes. Also remember, I have a Clutch Masters Twin disc so when you drop the clutch it grabs HARD. I also tried hard gear shifts through multiple gears and the axles accept the power beautifully. The bottom line is the fear of hard launches breaking your half shafts is now over.
The half shafts on the N54 have now officially been shown to be the weak spot in our drive train. They break at the bar as well as the inner CV and the problem seems to be worse for those that have lowered the car. There were no upgrade options, so we stuck paying about $500 per axle plus labor for the replacement. The bigger problem is that we know the stock half shafts are ticking time bombs. We now have an upgrade option thanks to The Driveshaft Shop.
My experience with The Driveshaft Shop was extraordinary. Frank was informative, intelligent, and very helpful through the process. He even answered some of my questions from his Blackberry while he was on the road and on vacation. This kind of customer service is rare and should be noted. Their turn around time was incredibly fast (less than 24 hours). The do note that the average turn around time is 3-4 days. The Driveshaft Shop provided tracking info to me so I could prepare for the install. Overall this is an “A+” review for the customer service The Driveshaft Shop provides.
The Driveshaft Shop axles will now hold 1000 hp. The race and cage have all been upgraded with higher quality chromoly with a very high impact value but retaining a good wear factor. Where the stock half shafts may have lasted for 115,000 miles, The Driveshaft Shop half shafts should last a good 85,000 miles. The bar on the half shaft is also upgraded to a solid bar design capable of handling 6000 lbs of torque. All the upgrades only add about 1 lb to each half shaft total. The car still drives basically the same as stock with a tiny or no increase in noise. The half shafts held easily under 3500 rpm launches at about 525 rwhp / 515 rwtq. In multiple gear hard shifts, the half shafts performed flawlessly. The Driveshaft Shop half shafts have been race proven and will not break like the junk half shafts that come stock with the N54. Honestly, this is the best possible result I could have imagined.
The price for this upgrade is listed as $999. Considering that is the cost of the stock half shafts and these are completely rebuildable, that is a very good price. If you are interested, you can call The Driveshaft Shop at 1-704-633-2380 and the part number for the upgrade is BMWE92R-1.
We are lucky they chose to prioritize the N54 market and get these made for us so quickly. I wouldn’t hesitate for a fraction of a second to purchase from The Driveshaft Shop again.