Rebuilding Nosedrives


How they work          diagnosing problems          porting and polishing          rebuilding nosedrives          Swaps and upgrades          Adding a boost gauge         

replacing needle bearings     adding a nosedrive drain          supercharger oil change          pulley size suggestions          links, references, and sources


CONTENT ADDED AND UPDATED FEB 2010

A great deal of money can be saved by rebuilding your own nosedrive.  All that needs to be done is to replace the bearings and seals.  If you're not up to this work, simply buying a rebuilt nosedrive from a vendor listed in my links may suit you.

The first thing to do is make sure you'll have a hydraulic press available.  Most machine shops have them, and some high school shops and community colleges.  Some of these facilities will let you use their equipment for little or no cost.  If you have one available at work, or have a friend that owns one, all the better.  You'll also need to buy the bearings and seal from one of the vendors listed on my links page.  NOTE:  When ordering a new nosedrive seal, Viton is a bad idea for most high-mileage M62's. Over time, the original seal will actually wear a groove in the shaft. Viton is less flexible, and takes a LONG time to 'seat' in the grove of the input shaft. Nitrile should be the primary choice of any M62 still on the road. Your chances of leaks are far less, and it will easily outlast your ownership of the car for less money.

For the M90, you'll have to begin by removing the oil from the nosedrive and unbolting the nosedrive from the supercharger.  Draining the oil is usually done with a syringe and tube, or the spray from a Windex bottle.  Put a rag down under the nosedrive and unbolt it.  The oil smells worse than you can imagine.  For the M62, you'll need to remove the entire supercharger from the car in order to remove the nosedrive.  You can also 'gravity drain' the superchargers by removing the plug and flipping it over, or you can simply unbolt it from the supercharger housing and let it dump, but have a tray or pan there to catch the smelly gunk (supercharger oil has animal fats in it, and after it cooks, it's nasty......but your dog will be strangely attracted to the new and used oil, so be careful)

Teardown

M62 shown, M90 is the same procedure

After draining the oil and removing the nosedrive, remove the pulley or MPS hub (if equipped).  You'll want to take some measurements and write them down.  This is just for sanity and safety, to make sure when you're all done, you've pressed the bearings and shaft to the right depth.  This can be a tricky procedure, especially if you don't discover until later that something didn't fully seat.  But before you can measure, you'll need to remove the clip and seal.  A screwdriver is all you need for the clip.  Once it's removed, carefully punch a couple holes in the seal and pry it out, but take care NOT to damage the aluminum.  Pry against a small piece of wood, plastic, or dense rubber:

(seal removal not pictured, but it's not rocket science)

Now measure the depth of the OUTER bearing (closest to the pulley), as well as from the base (surface that mates to the housing) down to the drive plate (the thingy on the inside end of the shaft with 3 pins that mate to the coupler.....on that note, make sure you remove the coupler first, it may be stuck to the nosedrive plate, or to the drive plate on the gears in the housing).  Write these numbers down (M62 shown, M90 will be measured the same way, but have different depths):

 

Now press the shaft INTO the nosedrive.  Use a block of material (aluminum in this case) to prevent damaging the end of the shaft.  This step can also be done by using a large hammer, but use a block of wood in between to protect the shaft.  Make sure that if you use either method mentioned, the base of the nosedrive is FLAT and firmly supported.  It may take a good bit of force to free the shaft, and you don't want to break the nosedrive doing this:

 

The spring pictured above is used to help distribute oil to the outer bearing (closer to the pulley).  Don't forget it's placement on the shaft during reassembly.  I've seen some nosedrives without them (and no evidence they were ever on the shaft), so don't worry too much if you don't see one.  Notice in the pictures above, one of the bearings didn't come out with the shaft.  Let's go after that one now.  Do NOT use a hammer for this step.  In order to prevent damaging the seat for the bearing, it must be pressed out perfectly straight.  Select a large socket that fits through the nosedrive housing from the inside, but is large enough to stop when it hits the inner race of the bearing.  Then press it out the bottom using the hydraulic press.......this step is not pictured, but isn't rocket science):

 

Time to get nasty now.  We need to get that other bearing off the shaft.  Insert the shaft in the press as pictured, and select a piece of steel slightly smaller than the shaft end diameter.  Be aware that the shorter this piece is, the safer it will be for you while you're standing there wearing your safety glasses or face shield.  Just make sure it's longer than the length of the drive plate, so it can properly eject the shaft out:

 

At this point, clean all the parts (except the two old bearings), but don't use an abrasive.  Solvent only (especially in the areas of the nosedrive where the bearings sit and on the shaft where they ride).  Any degreaser and a NYLON brush will be enough. 

GET A BEER.  YOU DESERVE IT........

 

Reassembly

Time to put it back together now.  Get the new bearings out, and tear open the smaller of the two.  Get a socket (deep well is best) that is the same diameter as the inner or outer race of the bearing (inner preferred, both examples shown....pressing the outer race can damage the bearing as it is pressed onto the shaft), but deep enough to allow the bearing to fully seat and the shaft to extend up in the socket.  Press this bearing on the INSIDE (non pulley) end of the shaft.  It's the end with the tiny splines for the drive plate:

 

Now select another socket that is larger inside than the diameter of the shaft, but small enough in outside diameter to fit within the 3 pins, and use it to press the drive plate:

 

Now let's press the larger bearing into the seat in the end of the nosedrive (pulley end).  Notice I'm using a socket again, but this time it's upside-down so the large flat face presses evenly on the inner and outer races of the bearing at the same time.  It's critical to be CAREFUL here and make sure the bearing is started perfectly straight and flat.  Press it in until it stops:

 

Now put the spring back on the shaft (if equipped originally), and insert it into the nosedrive and large bearing.  Press it into the nosedrive with the socket used in the step above preventing the larger bearing from being pressed out by the shaft.  This step can be done with then nosedrive pointing up or down, but you'll be using TWO sockets.  Pressing only from either end will try to push the other end back out:

In the end, when things are seated correctly, it should spin like this:

VIDEO

Now lightly lube the inner and outer edges of the new seal with light oil (WD-40 will work).  This will prevent the seal from tearing when you press it on.  Press it just like you did the upper bearing (using a socket on the press).  Lightly tapping this down with a hammer will work.  You don't want to press so much that it deforms the seal, so be careful.  It should be inserted deep enough to expose the groove for the clip.  Once it's deep enough, reinstall the clip:

NOTE:  When ordering a new nosedrive seal, Viton is a bad idea for most high-mileage M62's. Over time, the original seal will actually wear a groove in the shaft. Viton is less flexible, and takes a LONG time to 'seat' in the grove of the input shaft. Nitrile should be the primary choice of any M62 still on the road. Your chances of leaks are far less, and it will easily outlast your ownership of the car for less money.

 

Now apply the sealant that came with your kit (never use normal RTV, it should be anaerobic sealant) to the flange of the nosedrive as shown.  IF you removed your rotors and replaced the needle bearings, you should also apply a lesser amount (half the bead width shown here) between the rotor plate and housing to prevent boost/vacuum leaks.  Assemble the nosedrive and supercharger, as well as the coupler, and torque all bolts to 19ft/lbs.  It's best to torque them in a random pattern gradually until you reach 19ft/lbs on the last rotation:

 

You deserve more beer.  Keep in mind that you can install your pulley now, but the nosedrive may feel 'tight' at this point.  Perfectly normal, so don't worry about it.  It's also not uncommon to have minor leaks until the new seal breaks in to the shaft.

 

 

 


How they work          diagnosing problems          porting and polishing          rebuilding nosedrives          Swaps and upgrades          Adding a boost gauge         

replacing needle bearings     adding a nosedrive drain          supercharger oil change          pulley size suggestions          links, references, and sources


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