Vgt rebuild

[Perro903]

I've seen the videos rawze has posted on vgt and watched other videos and documents. I have yet seem to find the answer to my question. Can the motor be disassembled to replace the bearings?

[Rawze]

(09-23-2024 )Perro903 Wrote:  I've seen the videos rawze has posted on vgt and watched other videos and documents. I have yet seem to find the answer to my question. Can the motor be disassembled to replace the bearings?

- The overall answer would be no .. you cannot replace those 2 bearings if they have gone bad ...

(diving deep into why I say this)...

The motor itself is built into the top housing. There is a bearing at each end of the motor shaft itself.

A)> The bearing in the face of the motor itself is behind a tightly press-fit gear to the shaft... so that would be a no for the face bearing of the motor itself. the gear is press fit so tightly that it damages or snaps the shaft by even trying to use a puller on it ... this, even if it is heated.



youtube series on rebuilding the actuator otherwise ...
https://youtu.be/fPCykBQjvWs?si=CV0F86Tw2QeZlI5e

B)> The bearing in the back-side of the motor itself is buried into the housing behind the motor. Removing the center piece for the motor gives access to this, but the whole center piece (motor itself) is press-fit very tightly into the housing.

The motor itself is a permanent magnet brushless 3-phase motor. Getting it out of that housing is damned near impossible without destroying it. Any measurable amount of heat beyond a couple hundred degrees or so on the motor itself, wakens the magnets and warps or melts all the plastic in the top of it. I found out these things when trying different methods of possible removal.

(other things tried already) ...
== The motor itself is waaay too tightly pressed into the housing to remove. After removing the 4 screws (seen in the photo above), the ears / tabs at each corner just break off if you pry up on them. This happens even if you pry on all of them at the same time with even amounts of force, and a jig.

Thus, the failure rate (the tabs breaking off) by prying on it, even with applying heat and a proper jig is about a 95% chance of failure. Heating the whole housing up just does not help, and the plastic center melts and warps long before you can get it anywhere near hot enough to do any good. Also, any measurable amount of difference heat like that, once it reaches the center of the motor itself, de-mags the rotor, making it permanently inoperable.

== I even tried to hard-freeze the whole assembly, and then rapidly heat the outside only.. and it does not budge without breaking the ears off (rendering it impossible to remove once they break off) more than 95% of the time.

(getting it apart successfully without damage)...
== Someone can machine out (under-cut) the entire flange that the motor is is press fit into, using a 4-jaw rotating chuck on a milling machine, leaving behind only the 4 corners for the tabs to sit on + screws. This works to get it out successfully, and it can be properly re-assembled without any negative effects.

The only problem is that it is precision (machining) work requiring a milling machine and 4-jaw chuck. It also only allows access to the back side bearing, once the center piece is out. The face bearing is still unable to be replaced.

- I have done this successfully several times in the past, but it is NOT worth all that effort to only replace the one back-side bearing. I found that most of the time, that if the bearing is bad, and has been bad for a while ... the back-side of the motor shaft itself gets eaten up real bad too. This means it is still unrepairable when this happens.

[Mrkentee]

What do they do to a reman if this is so difficult?

[Rawze]

(09-25-2024 )Mrkentee Wrote:  What do they do to a reman if this is so difficult?

I have often wondered the same thing. I would suspect that the outer casting is worth re-using, so its anyone's guess as to how they might remove that motor from it.

- It is also highly possible that they do not bother, but simply replace the whole top as a unit... as I have seen a few remans where the bearings in the motor were already worn by quite a bit.