I recently bought a 2016 GEM E4 with about 1,600 miles on it. This car was customized by IMS in Arizona back in 2017. This car was sold by Dustin (now longer with IMS). I am having some noise issues and power issues with the car. I would love everyone’s input as I see a lot of knowledgeable people on the forum and I am a total novice.
Noise Issues
Part of the upgrades listed when sold to me included “custom installed high speed gears” and a “larger 8.6kw motor” allowing for tops speed of 35-37mph. Upon receiving the car I found it to be on the louder side. I attributed the noise to be the high speed gears at first but then noticed there are really two distinctive sounds. The person who picked up the car to take to the dealer suggested it was the input shaft bearings but the dealer said they thought it was the motor but they don’t work on modified motors. It turns out the motor is the stock 6.5kw motor and not and 8.6kw. I am including a link to the audio recordings of the motor sounds. Does anyone recognize this sound? Any tips on having a quieter ride? It seems like IMS might cut some corners so I wonder if their gearing is poorly done or maybe controller not corectly matched. "Slow Mode"
I also realized the car was not charging properly and would actually discharge while plugged in. The battery meter on the dash would also read very low when the battery levels were actually above 80%. I got the local dealer to install the Polaris recalls and clean-up the improper wiring done by IMS. IMS claims on all their cars to had added an auxiliary 12v battery to power the stereo and added LED lights. They have really just replaced the existing 12v batter and then wired to it. The Polaris dealer said this was not proper. The recalls and the rewiring corrected the charging issue but created a new issue. Sometimes upon starting the car I find it to be lacking the full power and almost in a “slow mode”. I pull over and restart the car and the issue is gone. This has happened a full charge or a partial charge, on both the first start of the day and in between stops on other days. It does not occur every usage. I question if IMS caused issues by replacing the 12v battery with a different battery type than was stock. Has anyone had a similar issue? I have also not verified my charging profile is correct for the 6v Distance AGM batteries that I was told were installed Oct 2020.
Did IMS or the dealer rubber mount the transmission?
I would not expect much performance with all the lead weight and little motor. @Old_Houseboater can help with the transmission noise. I think that if you put in a 16s lightweight battery it would perform much better. It will not fix any “real” issues, but it may just be too heavy for the high gears. @grantwest has done it all.
Well it looks like you did not get what you were told.
It clearly says on your Motor that you have the 6kw Motor NOT the 8kw motor you were told.
Noise: if you happen to have high speed gears. You either have 12:44 or 10:35. Rodney reports that 10:35 Gears are super loud. I know from first hand experience with aftermarket gears and The Noise related with them. I can tell you that a car with out the Noise Isolation mounts is very loud. I have done DB readings with and with out mounts so you can see “or hear” first hand what the mounts For your car.
It sounds like your car could do with a High Speed/High voltage conversation.
Thanks Grant. I have seen your upgrades on this site and youtube. Long term, I do plan do do some upgrades and would live to hear more about the work and costs to do the conversions.
I plan to install the noise mounts in the next week and I will post an update after.
That was me that did the skateboard bushings, they DO help a lot.
I am testing a new gearbox from Rodney now that should be much much quieter if you would like to buy quiet gears in the near future this should be an option.
PS - those sound files, that is just the new gearboxes, it sounds exactly like mine and every other 16+ gear box.
The little chip you hear during de-acceleration is the regen kicking in. It does not sound like you have much regen in your controller. I have mine set high so when I let off the throttle is instantly goes into that growl sound and it just stays on rather than popping in and out.
Bottom line, I don’t think there is anything wrong with the gears other than they are just loud.
Thanks Mike. The chirp was the more concerning sound so I will look at increasing the regen to at least make it consistent. And I will talk to Rodney about new, quieter gears.
One of the Many upsides to a High voltage 9kw kit that Dave sells and I install is adjustable regen.
I don’t know how one adjusts regen on a stock Gem. But if you go with a high voltage kit 80+ volts the Sevcon Controller (same brand as your stock gem controller) but this controller is unlocked and allows the user to program whatever settings you like. Example higher Regen or Torque. It’s very fun.
I think your Gem could be suffering from lack of power. Example when you go with the larger gears your gem has a harder time Or needs more power to turn the larger gears. Your stock 6kw 48v system might not have the power or torque setting to move your Gem they way you had hoped. The upgrade is a 80v 9kw power system, much more voltage and power to get the job done. I live in a very hilly aera. My car has no issues going up the steepest hills. I have big After market wheels and 12:35 Gears.
Hey that’s great News. I just so happend to discover my Rubber bushing kit needs replacment. Here are some pictures of my wore out bushings. Can you give me some info
On your bushings .
Nice job!
What have you tried? using? (looks like a couple of skateboard bushings)
How much time have you spent on McMaster-Carr?
If eating too many bushings- figure out a way to add more mounting points? Weld a couple of tabs on the inside of this mount (if there is room?) so there will be 8. Remember- The more you lock it in, the more noise will be sent back to the frame.
Is it eating fronts more than the back? Maybe concentrate on one end more than the other.
Or - have a piece of angle iron welded across the bottom and add a few more inline.
Or - Is there a place to mount a torque link off the top of the trans and run it to something coming off the ram horns?
@grantwest My setup is actually a little different than you drew it. There are custom sized-cupped washers that come with the bushings. So I have a washer then the cupped washer then the bushing then the Mount. I used the first washer because the stock bolts had a built-in washer and a then a split-lock washer.
