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The Process


Thanks for visiting the website and if you are here, you are probably wondering about how to repair your leaking CVJ boots. I also did the same, and designed a tool to deal with the problem of replacing the boots without all the disassembly required in all the other procedures. This illustration is on a 2006 BMW 325XI.

Here's the original CVJ Axle Press:

This was my prototype. It's made out of aluminum, because I could band saw it, and because you can run aluminum past a router if you mount a 1/4" end mill in it. I used some stuff called Nikx Stikx to lube the mill, but it still dulls after a while because of the speed of the router. You can see some of the milling marks where I spun the tool.

A typical CVJ boot repair requires disassembly of the entire front suspension. This is because there is no real good way to swing a hammer at the CVJ joint when it is still mounted in the axle bearing. The axle bearing would dissipate much of blow, and the possibility of damage to the brakes, wheel speed sensor, etc is too great.

Here's the tool mounted to a piece of aluminum tubing that represents the axle.

The idea is to put pressure on the inner CVJ to axle connection in order to pop the joint apart in a clean, controlled manner.

This prototype is way overbuilt, but I had read so much about how tough the joint comes apart (a BMW tech told me that it was almost a press fit) that I made sure the tool would do the job. After making and using this unit, I made a new style unit, much simpler to use.

The original tool used four 1/4" bolts to clamp the press halves together. In using the tool, getting the holes to line up to start the bolts proved to be a headache. This unit has a 5/16" studded press clamp, and is much easier to use when movement is limited under the car. I also added the re-assembly turnbuckle to the same clamp to simplify the procedure.

I slotted the push plate rather than use a band clamp to hold the original two pieces together, another improvement on ease of use. The pressure needed to pop the CVJ from the axle is nowhere near the original level of construction. The original carriage bolts are 1/2". The new design uses 5/16" press bolts threaded through the tool, and the latest design only uses two 3/8" press bolts. The pusher plate has an extension so that the tool pushed on the CVJ itself, and not the bowl housing. It's hard to get the axle to line up square with the CVJ bowl housing, so the extension allows easier use.

I bought two other tools to make the repair simpler. A boot clamp squeezer:

And a ball joint separator:

I didn't like this particular ball joint separator. It was too bulky to fit well between the CVJ housing and the top of the ball joint nut. Hard to see, but here's a closeup without the tool.

Not much space there. Look at how precariously it is caught on the edge of the nut in the picture below. I have the nut on far enough so that the bolt is just level with the top of the nut. Not sure what's a better make. I got it to work, but there have to be better units out there.

Ok enough of the lead in explanations, Here's the repair in detail:
Wheel off, I pop the control arm. This is the only nut that I removed from the car during the entire repair. Note that I left the nut on the top so that when the control arm popped, it didn't fly around.

Once you've popped the swing arm, you can move the outboard axle assembly around pretty easily so be careful not to pull on the brake line or the wire to the wheel speed sensor. There's also a leveler under the passenger side that senses level for the headlights. Use care.

Here's the tool mounted on the axle, and in use:

I alternated between two of the bolts, using a wrench on the flats of the press bolt and the nut to push the joint apart. You probably now understand why I redesigned the tool to use a through thread press bolt. With the limited work environment that presents itself on a creeper, trying to swing two wrenches proved to be frustrating.

Once the Cir-Clip popped, I could just use one of the press bolts to push the joint apart the rest of the way.

Again, once the cir-clip popped, I was pleasantly surprised that this joint was not hard to pull apart. I probably could have used a pry-bar to speed up the process, but I wanted to take it slow and controlled, so I just used the carriage bolts to slowly pull the axle from the joint

I'll spare you pictures of the gritty details of cleaning the joint, but I disassembled it, cleaned everything thoroughly and reassembled it. Here's the joint ready for re-greasing and reassembly. I squeezed the entire tube into the center of the joint, and worked it back and forth until grease squeezed out between all the bearings. That's the new cir-clip on the drive shaft, and you can see the mating slot inside the CVJ assembly.

A little explanation is in order for the reassembly jig shown here. I originally made this 3/8" turnbuckle tool, thinking that I could do both the dis-assembly and reassembly with this simple jig. It turned out that I could not get near enough pushing pressure to pop the cir-clip with the turnbuckle, it easily folded in half. A 1/2" turnbuckle was too long to fit in the space available, and may have failed as well, so the jig shown here was the origin for the tool shown throughout the rest of this site.

It did occur to me that the axle clamp would give more clearance for the new boot but I had this little jig handy and just lying there all sad from it's previous failure, so I gave it a job. Besides, I was too greasy for drilling and tapping operations anyway.

You can easily draw the axle into the CVJ by turning the turnbuckle by hand for about 3/4 of the way. To start, pull the axle in up to the cir-clip, then put a very slight amount of pull on it as you push the cir-clip in with a flat screwdriver. If you can't turn the turnbuckle by hand, your cir-clip is not seated and you are binding on it. Back off on the turnbuckle and start again. Make sure the open side of the cir-clip is pointing toward the floor. Easier to get to that way.

Draw it in. Sooner or later you will need more purchase than just your hand. I used a small wrench slid through the slot of the turnbuckle. When you are getting close, be quiet and you can hear the cir-clip snap home. It's faint. Turning more on the turnbuckle brings up resistance, letting you know that you are there.

You are now on the home stretch. Fit up your new boot and clamp it tight. Then put the swing arm back in place as shown here. I used a jack stand, and let the car down slowly onto the swing-arm. This puts pressure on the ball joint to keep it from turning as you tighten the ball joint nut. Don't let the full weight of the car down on your swingarm, you might bend it.

About this time, I was 3 hours into the project, both wheels were on the car and I was done. I don't really know the rest of you reading this, but I strongly recommend popping a beer at this point, leaning back against the back door step, and basking in the limelight for a moment. Your wife will be along soon to remind you to clean the garage floor and that she's conveniently written a reminder of the next project looming up for you on her little whiteboard in the kitchen.

I now professionally cut these tools with a waterjet cutting machine. I've hand made four prototypes, and with band saw cutting, drilling and tapping, the whole tool takes five to six hours to create. With the waterjet cutter, the whole tool is cut in less than 10 minutes. The new tool is available for $125.00, just search Ebay for the CVJ Axle Press.

I spoke with a garage mechanic, and he said that built this way, this tool would work with 85-90% of the cars made. If you don't have a BMW, measure your axle diameter. The standard BMW axle diameter is just shy of 1" so if your car is the same, the unit should work. If you have a different axle diameter, contact me and I'll make sure that your tool will fit your axle diameter.