# Disassembling Tesla Gearbox



## kennybobby (Aug 10, 2012)

You might need to make a flange plate for the puller jaws to grab. This would be a 2-piece collar clamp that, ideally, would be machined on the inner diameter to match the two bevels and the "flat" near the end of the gear shaft. 

Here is a ascii drawing of the end of the gear shaft, the collar clamps fit over this end and the two halves are bolted together to make a solid flange surface to grab for the pull.



/‾\_____

>----------centerline

\_/‾‾‾‾‾


----------



## electro wrks (Mar 5, 2012)

IGNORE THIS POST AND REFER TO POST 7. A puller tool that might work is this 2-piece collar clamping system, like kennybobby refers to. Or a modified version of it: https://www.harborfreight.com/Pulley-Remover-and-Installer-Set-12-Pc-63068.html

Don't use a slide hammer tool. It would not be good for the ball bearings. Also, I suspect at least one bearing is a ceramic unit. Although I haven't seen it, there's probably a delicate ceramic seal on the other end of the motor shaft of the Tesla induction motors. It would be part of the rotor cooling system.


*CORRECTION: If this removal method is used, unnecessary force would actually applied to the motor bearing and seal that need to be protected.


----------



## brian_ (Feb 7, 2017)

The _Tesla Large Drive Unit Gear Set 4.5:1_ from Zero EV replaces that shaft (so the original shaft must be removed to install the new gear set), and that product web page has an installation video. The video shows the original shaft already removed, so it doesn't directly help, but it does show how the retainer works (but you have already removed that)... and the people at Zero EV might have some suggestions for pulling the shaft.

One potential idea: since the retainer plate fits between the gear and the housing, a custom plate for pulling could also fit there.

The problem with the gear puller is that is based on a screw pushing against the centre of the end of the shaft to pull something off of the shaft, but in this case you are removing the shaft (complete with the gear which is integral to it), so there is nowhere for that screw to push on. You need to use inertia (a slide hammer), or push against the motor housing.


----------



## Tomdb (Jan 28, 2013)

Those shafts are always a pain, slid hammer will do the trick. However its tricky gripping it. When doing it at zero ev we used a slide hammer with a big jubilee clip around the shaft t keep it in place.


----------



## kennybobby (Aug 10, 2012)

jubilee clip = worm-drive screw hose clamp for folks on this island

Does that gear shaft have a step in the internal diameter? If so then a blind internal bearing puller could be used to grab it and make the pull with a slide hammer (gently). Shouldn't take much to get it off since it's just a sliding spline fit.

But the motor shaft end does have a countersink such that a screw puller could be used.


----------



## electro wrks (Mar 5, 2012)

After a second look at this problem, I think the main clamping force holding the primary shaft on is the exposed bearing pressed on the shaft and in the motor housing. The splines probably just float or have a very light press fit. So, a slide hammer or a clamp that presses on the housing, like brian says, would be the way to pull it off.

The split clamp jacking screw, referred to earlier, pushing on the end of the motor shaft through the hollow(I'm guessing) primary shaft would put unnecessary force on the motor shaft bearings. So don't try it!


----------



## kennybobby (Aug 10, 2012)

electro wrks said:


> After a second look at this problem, I think the main clamping force holding the primary shaft on is the exposed bearing pressed on the shaft and in the motor housing. The splines probably just float or have a very light press fit. So, a slide hammer or a clamp that presses on the housing, like brian says, would be the way to pull it off.
> 
> The split clamp jacking screw, referred to earlier, pushing on the end of the motor shaft through the hollow(I'm guessing) primary shaft would put unnecessary force on the motor shaft bearings. So don't try it!


How do you figure--did you not watch the video of the assembly?

The only way to not stress the motor bearings would be to press on the motor shaft and pull on the gear shaft--to slide the loose fit bearing out of the housing and the loose spline fit off the end of the motor shaft without putting any reaction load on the motor bearings.

If you press against the housing then the load reaction path directly loads up the motor bearings at the opposite end.

The shock of a slide hammer puts brinnel marks into the bearing races.


----------



## retrEVnoc (Mar 23, 2019)

Thanks all. Tom I had thought about the jubilee clip technique but haven’t tried it yet. The other two gears (intermediary and diff) came out without too much trouble using gentle force. 

There is no lip to grab on the interior of the gear shaft. 

Tom, what’s up with those 4.5:1 kits? Last I heard from ZEV you still aren’t selling them due to unanticipated noisiness. Want to send me one for further testing? 😀


----------



## electro wrks (Mar 5, 2012)

kennybobby said:


> How do you figure--did you not watch the video of the assembly?
> 
> The only way to not stress the motor bearings would be to press on the motor shaft and pull on the gear shaft--to slide the loose fit bearing out of the housing and the loose spline fit off the end of the motor shaft without putting any reaction load on the motor bearings.
> 
> ...


 Which video?


----------



## electro wrks (Mar 5, 2012)

Is this the one you are referring to? :https://www.youtube.com/watch?v=_GigD0s47RI
In the video, the primary shaft exposed bearing is a hand press fit in the housing. retrEVnoc's bearing must be in with a tighter fit. retrEVnoc have you tried pulling it out by hand or carefully tried to pry it out with a couple of screwdrivers?


----------



## kennybobby (Aug 10, 2012)

Yes that's the one, it was in the link posted by Brian_

What do you think, shouldn't that shaft just easily pull free once the bearing retainer plate is out of the way? The shaft is hollow so easy enough to access the end of the motor shaft with the countersink if a puller is needed.

It appears that the OP gear has hit the retainer and knocked the corner edges off the end that faces the bearing, or is there a slight chamfer ground on the gear ends? Something in there looked like some jagged edges.


----------



## electro wrks (Mar 5, 2012)

AIR Tesla had problems with the early LDUs. There could easily be some design variations through the years. Does anyone know if all of the bolt-in bearing retainers were in the original design? Or, was there more reliance on pressed-in bearings. The retainers are great. But, can you imagine what would happen if just one of those retainer screws backed out and fell into the gears. 

The problem I see with pushing on the end of the motor shaft is that there's got to be another bearing (and maybe a oil seal)just inside the motor housing, next to the primary shaft bearing. So, the motor's rotor is supported on its own bearings and the primary shaft on its own bearings. The only mechanical connection is through the sliding fit splines. This is a common set-up for an electric motor hooked-up to a gearbox. It's just that Tesla has set it up backwards. It means a minimum of the axial and radial(side) loads generated by the helical gears is transferred to the motor shaft. This allows the motor shaft to be lighter and the rotor/stator air gap tighter because there's less of a bending load and deflection of the motor shaft. 

So, if you press on the motor shaft and pull on the primary shaft, depending how tight the primary shaft bearing is in the housing, at least one of the motor shaft bearings, the rotor coolant seal, and the primary shaft bearing could be damaged. The primary shaft bearing is quite large, so it may not be damaged. But, it may be discarded anyway along with the primary shaft for a direct motor hook-up. A better way to remove the primary shaft is to pull on the shaft and push against the housing- like brian wrote about. Or, the careful use of a slide hammer pulling on the primary shaft like Tomdb wrote about. Remember, very little force is transferred to the motor shaft(and its bearings) by either removal method because the primary shaft will just slide easily off of the splines.


----------



## retrEVnoc (Mar 23, 2019)

Thought I had already replied to this thread but apparently not. Tom's advice of using a jubilee clip (or 'hose clamp') did the trick. I was able to tighten the clamp around the gearshaft, and grab the clamp with the slide hammer. I was then able to remove the lockring and bearing by clamping the gearshaft between some blocks of wood in the vice, and unscrew the lockring with lockring wrench.


----------

