not normal . I have never noticed it so if it was there it was minimal . If you have to much lateral force it will burn up the magnet and sensor on the end of the motor .
Hmm, strange. I’ll pop the shaft out of the gearbox again and test the fit outside the cart. Thank you.
Ok so here is the motor and coupler outside the cart, on the left is how it sits, on the right I am pushing down with about 30lbs of force I would guess. Does this look right? I wonder if I am getting a hydraulic effect from the grease. In this photo how should the cup shape of the bumper be oriented, opening of the cup top or bottom? My old bumper was unrecognizable and I am questioning everything now. Currently I have the cup with the base down.
Remove the bumper and wash out the grease. the spline should almost completly bury in the coupling. Usually there is enough slop in the splines that it will squeeze out. if you still have the same fit problem remove the obstruction in the coupling.
When you bolt up the motor to the gearbox normal amount of squeeze is about 30/40 thousandths. To much squeeze will heat the motor bearing and melt the magnet OR ruin the small bearing on the end of the input shaft which will get in the gears and total the gearbox.
Here it is with no bumper at all, and the bumper after being forced to compress. That bumper was new a week ago and I don’t drive very far, probably 5 miles at the most. I have another new bumper as well. I’m still curious if I’m using the bumper in the correct direction. It is installed in the same orientation shown in both photos.
Yes That looks normal.
To be safe maybe I should replace the small bearing on the end of the coupler, does anyone know the spec? I’ve got OD=40mm ID=17mm W=12, does anyone know which brand and type is best? KOYO, NSK, TIMKEN or a part number?
I’m reading that there are a ton of counterfeit bearings out there so I’ll stick with Grainger. I’m thinking these are a good bet for my 2007 Gem.
Timken VS SKF?
or this
Update, I noticed the original has 8 balls like the Timken, so that’s what I ordered.
I just received the Timken Bearing from Grainger. The new bearing felt looser than the one in there so I’m not changing it. I did turn it around so maybe it will push on the other side of the race. When I pulled the inner gearbox bearing I noticed it says KOYO 6203 ROM so Koyo seems to be better stuff at least circa 2007. I also replaced the motor bearing which felt loose and was hopefully the problem, I have yet to screw the end of the motor back together, that looks like it will be great fun to align the bearing holder plate inside with the screws from outside. Ugh. Photo is of the inner small gearbox shaft bearing.
To align the bearing plate, take one of the screws for it to the hardware store and get a few 3" screws that match. Cut the heads off the screws and grind them to a point, make them slightly different lengths. Screw the new studs into the plate before putting the motor back together, you will have room to align the studs with the holes from inside the motor. After everything is put back together, take the studs out one at a time and replace with the original screws. This is how I did it and it was rather easy to do.
I was thinking two skinny sticks, I think I have some carbon rods that might work that fit in the threads but slide through the holes, then I would slowly lower the armature into the end cap while on the vise. The third hole should be aligned and I can start there and do one at a time. I like your idea though and I may use it thanks, I’ll see what I have around here today.
Two kabob skewers worked perfectly, I put the motor upright and was able to start the first screw, then one at a time.
During assembely I noticed there was still what seemed like way too much pressure on the two end bolts so I took the bushing out and shaved about a mm off the base. It went together a little easier still with lots of pressure though. There is a very light growling hum that I think it should not make, I wonder if it’s due to the fact I released a slight bit of the sideways pressure on the shaft or something else? I think thew noise is coming from the spline since changing things seems to have a direct effect. Kinghappy, I’m using the Honda M77 assembly grease to rule that out.
Hmm
Too much force on the input shaft will cause the motor bearing to heat and melt the magnet if your lucky. If the small bearing on the rear of the input shaft fails it will destroy your gear box. There should be no more than a MM squeeze when you bolt up the motor. MAKE SURE YOU REMOVE THE SEALS FROM THE SMALL BEARING ON THE INPUT SHAFT. Any oil in the bearing bore wont let the shaft seat. MAKE SURE THE SNAP RING IS SEATED IN THE GROOVE.
Make sure there are no oubstructions in the motor coupling and only ONE rubber bumper. If your splines are real good dont apply excessive grease. It will hydraulically prevent spline from seating in motor coupling.
Thank you for the response, it really spells out the problem. I checked the motor end cap before and after a short drive, it went from 75F to 102F so I suspect you nailed it. As things are there might be 2mm squeeze. It feels like too much, and this is after I shaved 1mm from the base of the bumper. The snap ring is certainly seated and the input shaft seems proper. There are no obstructions inside the spline coupling. All I can think is the motor bearing might not be seating properly in the end cap as I did not investigate the bearing seat before assembly. It’s a hard thing to photograph due to the extra step machined in the end cap, I was almost able to fit a 2mm disk brake measure in the gap so there it probably 1.8mm gap between the bearing shield and the motor end cap at the arrow. I will take the motor apart again and investigate the bearing seat. Do you happen to know approximately how close the bearing shield should be? This seems like the only possibility at the moment. Incidentally it was like this before I installed a new bearing, but I really should have checked that seat before installing.
When I took my motor apart, I noticed the same thing when I reassembled it. I bought a new bearing and still the same thing. I used a shop press and couldn’t get the bearing in all the way. I’m interested to see what others have to say.
I took it apart, used a small brass wire wheel on my Dremel and cleaned out the bearing seat. There was one small particle stuck in there but somehow I don’t think it was my issue. I took extra care to be sure it all seated properly. There is another small step that can’t be seen so the ~1.5mm between the bearing seal and the motor cap that can be observed from the outside is pretty much normal. I removed all the grease and took care to put no grease in the bumper at all and only enough grease in the spline to fit the low spots for the first 1cm. At first used my bumper that I cut down, the gnarls had gotten worse, I picked them all off. Now my bumper was probably half the high it used to be with the combination of me cutting away some of bottom and some of the top getting eaten away from the spline connection. When putting it together the motor went on with virtually zero pressure, maybe a tiny bit at the last 1 mm but with almost no force required. I checked the motor temp it was at 69F, I drove it about 1/4 mile and it growled only under slack, off throttle condition, after that the motor end cap warmed to 80 deg.
I think it was too loose due to my bumper getting eaten away so I put a new bumper in without modification taking care not to put any grease on the bumper and very little on the spline again. It had some resistance for about 2.5mm when putting it back together but not nearly as much as before. It felt much better and runs quiet. I drove it for about 1.5 miles and the motor end cap ended up at 120F. I actually think it felt much better going together this time, and it runs and sounds as it should. I wonder if some heat around the brushes is normal? I guess I’ll keep an eye on the motor temp for a while, but it seems like everything works well now. I think the issue may have been grease in the bumper causing a hydraulic effect, I would advise NO GREASE IN OR AROUND THE BUMPER during assembely.
Grease the splines AFTER the bumper is seated.
I think the hydraulic action would be created by grease inside the cup shape of the bumper, maybe below as well. That’s the only spot I can think where it could get trapped without the ability to squeeze out or around. In my case it may have been a combination of this and a very small amount of bearing seating in the motor, but I can’t be sure. It’s all working well now. Thanks for outlining the possibilities, very helpful for problem solving! I guess you’ve worked on a lot of these. I have never encountered this system, I’m guessing it may be common for many golf carts.
Your input shaft is OVERDONE. How many miles on this puppy? Your motor coupling is probably shot also.