differential spline wear and motor alignment questions

[wuntunearlybko]

ok so in 2018 i bought a 1996 CC DS for great price but needed a lot of work. I replaced everything except for the batteries and motor. in 2019 i felt like the stock motor was lacking and was due for replacement. i contacted Scottyb to see what he recommended and he pointed me over to Chuck at Emp Inc. I outlined my details and specs and we agreed on a replacement upgraded motor. got the motor back, put it all in, and the golf cart has been great and we love it.

fast forward to late 2022 and my cart started shuddering at low speeds. the batteries were quite a few years old so i chalked it up to needing to replace the batteries. i decided if i was gonna sink money into batteries i would just upgrade to lithium so i got with Scottyb again and bought his kit. i finally had a chance to install them just in time for Memorial Day weekend so we could go see the fireworks. To my dismay the shuddering not only continued but got worse. I checked all connections and tested everything and couldnt find any issues. I contacted Chuck at Emp, Inc. and he said to send it in for diagnostics.

This is where i need some help. in discussing the issue with him over the phone he did not see any signs of overloading (which we have not, we use it for family outings on golf cart paths in our community) nor any abuse. He noted down excessive or unusual wear on the output shaft of the motor. he mentioned that Kawasaki axles, like the one installed in my cart, had some quality issues and sometimes the shafts were not aligned well enough and could cause an issue like i am experiencing.

SO here is my dilemma, to rebuild the motor (again after 3 years and no abuse) will be another $800. I cannot afford to rebuild every 3 years so i really need to figure out what happened if possible. I worry that my axle may not be aligned but when i look at the splines on my input shaft, i dont notice any abnormal wear.

I would love anyones input and.or assistance would greatly appreciated.

Thanks,
Jason

[wuntunearlybko]

Here are Chuck's notes on the motor:

=========== INSPECTION SUMMARY ===============================



MOTOR

Before disassembly, following observations made:

- Externally motor had normal dirt/dust/etc for motor of this age

- visual inspection on “open” end of motor displayed some armature endturns which appeared burnt

- spline found to be worn/oversized

- Field winding was grounded as received



ARMATURE

- Armature showed areas of banding tape which were darkened/burnt.

- Commutator appearance poor with visible signs of damage (significant arcing/sparking damage)

- Electrical tests (after wash/bake/cleanup) confirmed armature shorted

- Armature varnish is still present everywhere except for obviously burnt conductors

- In general, armature did not appear to have been subjected to any long term overload

- Spline shows as worn using attribute gauges



BRUSH MECHANISM & ENDSHIELD

- Brush mechanism darkened and burned.

- The brass brush holders were all loose at their connection to the thermoset backplate.



STATOR

- After wash and bake, electrical tests showed field coil OK with no evidence of any faults.

- Coil resistance measured normal for this model





OVERALL SUMMARY

The fundamental issues:

- Armature is shorted.



POSSIBLE CAUSES

-------------------------

This type of failure can result from a variety of factors, including 1 or more of the following:

- insulation failure between wires which can be caused by:

- initial manufacturing deficiency

- shock/vibration in application

- overheat/overload conditions

- arcing across commutator bars which can be caused by:

- very high amp levels caused by intermittent overloading

- high amp levels caused by long term overloading

- shock/vibration which can lead to arcing/sparking

- any other factor which can lead to poor brush filming or commutation issues.


I very much doubt that this issue came from long term overloading as there were not other signs of such an issue in the motor. (Long term overloads usually cause darkening throughout the motor… not just heavy brush dust, but scorched conductors.) However, other possible causes I mentioned may be a part of this issue.

SUMMARY

--------------

Motor failed with armature short. Exact cause of short is not possible to determine. Motor is out of warranty.

I know you wanted to talk on the phone about this, but wanted to get the details of the analysis to you first. I wish I had a more exact failure mode to point to, but there are many cases with failure analysis that exact determination of root cause can be impossible.

Chuck
EMP
1-877-455-1599
6/29/2023

[CP241]

I’d suspect the shorted armature was the cause of your shudder. Not the splines.

Look at the splines on the input shaft of your rear end. Do they look worn or rounded off? You can replace the input shaft without too much trouble but that’s not the cause of your issue. The shorted armature and burnt and arcing on the commutator would cause some problems for sure though, that would get worse with better batteries (more voltage/current on tap)

[wuntunearlybko]

Chuck explained that if there is severe misalignment (enough to cause excessive wear) then it can lead to premature armature failure.

no the splines do not appear to be worn at all on the differential.

i just want to try and mitigate whatever issue there is so i dont have to do this again

[Volt_Ampere]

I disagree. If the splines do not show wear and damage, then there is not an alignment issue. If it were me, I would go with a different motor vendor.

[CP241]

EMP rebuilds stock motors stronger like plum quick does. I’d say if the splines are still nice on your rear end then they were likely worn on the motor when it was rebuilt. Does your input shaft have any play or is it nice and tight?

I’d agree with volt. I’d get a motor from somewhere else. I’d pick up an Admiral or D&D and be done with it. Be cheaper than $800 as well and you’re getting a brand new everything instead of a rebuild.

https://www.revolutiongolfcars.com/motors give David or email. Great guy to work with

[Volt_Ampere]

My brand new D&D for my Yamaha cart was WAY less than $800. My last one was $466 directly from D&D including shipping. (January 2021) I dealt directly with D&D twice with good results. I told them what cart I had and they quoted me the correct motor. I'm sure the price has gone up some in 2 1/2 years.

[wuntunearlybko]

thanks guys, i will look into D&D and see what they offer. I to thought $800 was pretty steep

Originally Posted by CP241

Does your input shaft have any play or is it nice and tight?

nope, its nice a tight.

[Volt_Ampere]

If your input splines look good, then you should be fine with a new motor. My D&D motors are brand new - not rebuilt and I have 7 plus years on one and 2 1/2 on the other in my two Yamaha carts. My carts get used a lot! Around 20 miles each per week minimum.