EZGO Express S4 2017 (electric 48V)

[Viktorr]

So here is my story, I'm new to carts and this is the first one I bought. When I test drove it I didn't really notice the noise. (yeah I know, I'm naive and just trusted the seller that everything is A OK.
So after a week I noticed I had an occasional rattling noise coming from right rear side, specifically during deceleration - so I decided to take it to a mechanic.

He says it's my differential that makes that noise. I asked how much it would cost to fix and he says that on the express S4 the whole differential axel needs to be replaced and its $$$$. I was wondering if anyone one knows if there's also an option to replace specific parts that I can order to fix it or should I give up bc I definitely can't afford replacing the whole rear differential kit.

I can also send a video of the differential moving although it looks fine and doesn't make any noise when the cart on a lift.

Would really appreciate some advice




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[Michael Eddie]

Congrats, nice ride!

So replacing the input shaft bearings can help in many cases but it only fully resolves the issue about half the time and even then some noise might remain.

The input shaft gear itself or the gear it meshes with may be worn or damaged which can worsen the noise. Sometimes it requires the replacement of the entire input shaft or the meshing gear. Pretty common for EZGO with this rear setup. You can try experimenting with different lubricants first just to see if it helps.

The rear takes about 25 oz fluid recommend 75-90 gear oil. Some owners use a mix of 50% Lucas oil stabilizer, 50% gear oil, and 2 oz of friction modifier for extra insurance especially for noisy posi units. While others actually prefer Yamaha's "friction modified shaft drive gear lube" (part number "ACC-SHAFT-LU-00"), you can also use any 75-90 GL-5 gear oil with a friction modifier just to see if the different fluid reduces or eliminates the sound.

[Viktorr]

Hey Michael! Thank you for replying so fast


This is where he said the problem is.
He said that part can't be ordered separately from the whole kit for the S4.
He said that TXT and S4 have a different rear axle kit and he doesn't have the part numbers to order separately.


I guess I wanted a confirmation, in case maybe I just need to find a different technician. Or atleast the particular part number that would fit the S4.

How can it be possible that when the deferential starts making noise, a whole new transaxle kit is required? It costs about 5k and that's what I paid for the whole cart...

I'll attach a video of the differential spinning

[cybercart]

U mean this ??

[Viktorr]

U mean this ??

Yep it's the part.
However it's very confusing to understand whether it's for an S4, since they have a sturdier rear axle. ie parts from a TXT rear axle won't fit an S4.

[cybercart]

Yep it's the part.
However it's very confusing to understand whether it's for an S4, since they have a sturdier rear axle. ie parts from a TXT rear axle won't fit an S4.

i found this after a quick search, lmk

https://www.ebay.com/itm/326168231890?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=8AJi5fmkQha&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

[Viktorr]

i found this after a quick search, lmk

https://www.ebay.com/itm/32616823189...mis&media=COPY

Yep that seems to be the full assembly without the LSD (loose slip differential), however the LSD is exactly that part im looking to replace instead of buying the full kit. Kinda giving up that this part can be found without the full kit. But if anyone has a better idea, I'd love to hear it.

The Axle is now taken apart so without the wheels and the car on the ground it doesn't make any noise. I'm praying that maybe just an oil change would take care of it - the technician said it had half of the amount required bc it wasn't serviced in a long time.

[Viktorr]

Yep that seems to be the full assembly without the LSD (loose slip differential), however the LSD is exactly that part im looking to replace instead of buying the full kit. Kinda giving up that this part can be found without the full kit. But if anyone has a better idea, I'd love to hear it.

The Axle is now taken apart so without the wheels and the car on the ground it doesn't make any noise. I'm praying that maybe just an oil change would take care of it - the technician said it had half of the amount required bc it wasn't serviced in a long time.

*Typo correction - LSD (limited slip differential)

[Michael Eddie]

For the S4 2017 there was the Express S4 and the Express S4 High Output offerings. Both came with optional LSD differentials. The HO Express S4 came equipped with a 400 amp controller and a rear axle ratio of 12:44:1. The standard Express S4 had a 250 amp controller and 14:76:1 ratio.

Ezgo shows the 14:76:1 LSD rear under part number 617150 with a current list price of $785.06

For reference, the parts book shows the following controllers in the Express S4 vs Express S4 HO (see attached images)

[Viktorr]

For the S4 2017 there was the Express S4 and the Express S4 High Output offerings. Both came with optional LSD differentials. The HO Express S4 came equipped with a 400 amp controller and a rear axle ratio of 12:44:1. The standard Express S4 had a 250 amp controller and 14:76:1 ratio.

Ezgo shows the 14:76:1 LSD rear under part number 617150 with a current list price of $785.06

For reference, the parts book shows the following controllers in the Express S4 vs Express S4 HO (see attached images)

Thank you again Michael
That is indeed an important observation!!

I'm gonna check again with the garage. However I believe that mine is the standard express S4.
I will ask the technical for the number of the rear axel and update it here.

I'm also checking with other dealers if they have this part used in the area im in.

Bottom line seems like this axel is designed for way more heavy duty than driving it to the beach like I do. I think I can manage to keep using it regardless of the noise.
Since it's not really buzzing, whistling and grinding but just a subtle clanking noise when I slow down (I'm trying to use the most precise euphemisms for these sounds ).
Correct me if I'm wrong but I think this condition won't get much worse after some oil change, and meanwhile I'll start looking for a used rear axel.

After I get the cart back I will work on some rust maintenance, a change for the ignition key and cosmetics. I will share the progress.

And obviously I'll update when there's any news.
Thank you all for your help, I learned a lot from what you gave me and its greatly appreciated!