How to shove my shaft into a tight bearing

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Makomea

Makomea

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Hello all! I have just finished putting together my new phatmoto all terrain 2023 motorbike together! Woot! Time to feel wind? Nope! It’s troubleshooting time, yeah baby! Turns out, the built in jackshaft directly under the seat post was terribly misaligned. It made the chain rub the back of the clutch housing at the top. Rotating the sprocket by hand, I could feel that there was a lot of resistance and a rumbling vibrational sensation. This led me to conclude the bearings were all torqued up. I hammered the splined axle out of the jackshaft and proved my own theory that the bearing was indeed a failure. There are two, one on each side. The sprocket side bearing was the culprit. The axle seems to be straight by eye. When I got it from factory, you could see the sprocket cambered positively compared to everything else (see picture below). I know I need to replace the bearings with 6203-rs bearings… I can use one of those bearing press tools to accomplish that, but how do I shove that shaft back inside? There are no guides or tutorials that I could find about this. The jackshaft housing looks like a bottom bracket welded under the seat tube…. Please gentlemen, I need your help to shaft these holes without bending my shaft. Should I ram in back in through both bearing with a hammer? Do I install both bearings first? I have no experience, all I can do right now is sit here with my shaft in my hand not knowing what to do with it. Thank you all for any and all advice! Also, is it possible that the bearings alone can cause such misalignment? Because as far as I can tell, the jackshaft axle and housing look straight to the eye….
 

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Makomea

Makomea

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Tom from Rubicon said:
Have you done a google search of (phatmoto bike jackshaft alignment instructions) ?
Whole bunch of youtube how to's.

Tom
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Indeed, I have. None of them are about the actual phatmoto jackshaft maintenance. None that I can see anyways. There is one video that goes into detail about changing to different tooth sprockets, but not about the dis/re assembly of the “jackshaft”. Every other video is about “true jackshaft”, the kind that outputs power to the bicycle cassette but are not about phatmoto jackshaft that is more like a bottom bracket with two pressfit bearings instead of a cartridge system. Same thing, no matter what word play I put into google or YouTube, I am given great info on sliding the bearings onto an output shaft of some kind or another, but absolutely nothing about pressfitting a solid shaft into bearings that are them selves pressfit into another housing.

(Edit:The video you linked to was for the original rover version of phatmoto. Those, at one time must have had another adjustable kind of sprocket set. The new 2023 version is on a splined shaft held on, not with a key but with a bolt and flimsy washer. There are no adjustment screws, and even if I drilled and tapped them my self, there is no extra room for them to slide up or down. I also tried mounting the sprockets different ways, which won’t work because the splines taper, so you can’t get more than half way up the splines with either large or small sprocket backwards. Even if that worked, (which it wouldn’t because I wouldn’t have room to mount the 2nd chain), the extreme camber will cause the chain to snap if I were to start the motor.)
 
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Makomea

Makomea

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Apologies for the late reply gentlemen, had some family come in for a visit, I will write this as I upload all my photos. I can assure you that both the jackshaft and its sprockets came pre installed in the box with the frame. They even hooked up the rear drive chain for me. The clutch came preinstalled too, in a separate box with the motor it’s self. My only “responsibility” as per instructions was to mount motor loosely, place a single pre sized chain from clutch to the large sprocket and clip master link, then move motor forward to take out slack in the chain.” All alignment would have been built into the frame mounts and are non adjustable. (God forbid the frame ever warps, but we will cross that bridge if and when we get to it). It should have been done, just the jackshaft was slanted. Even if I wanted to put things on backwards, I am telling you, it’s impossible to do so. They only fit onto the shaft in one direction. So I couldn’t flip the sprockets. The only issue is, and it’s the whole problem was the jackshaft being so cambered out. I didn’t install it, came that way. Crooked with the top of the sprocket leaning left and the bottom of it crooked inwards. If you could feel the bearing with your finger, you would feel it grind and tremble. There are obviously flat balls inside it. The other bearing also has increased rotational friction, but I am not sure if it is because of a special thick grease or pressure from the outer race and the jackshaft housing, or if it too is also messed up, but no gravely feel to it. I have removed the shaft. It’s a nice chungus piece of metal and I can perceive no warping in it.

My thinking is this, all I need to do to “align” the chain and “true” the sprocket is to replace both bearings with fresh new ones. It’s the only other option I have to try. I am well beyond the manual at this point. And yes I have contacted Gasbike.net and they have been helping me. The whole kit got jacked up in shipping, many parts and components were damaged, a couple missing (handle bar mirrors for the limited edition extras kit). For the damaged and missing parts, they said they have Already shipped out. They are also working with me on the jackshaft issue. They are the ones that requested I remove the shaft to see if it was improperly set. Anyways, I shouldn’t have any problems removing and installing the new bearings. What I do need help with, most of all, is How do I fit the axle back into the new bearings? Do I hammer the axle inside? Do I have to get some special axle pressfit insertion tool?

(Edit: To answer you directly Tom, about the photo #8, yes mine is exactly as shown in the factory photo. In photo 8, you are viewing it from the right side of the bike, my photos are taken from the left side where the transmission cover would be.)

-Cole
 

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Tom from Rubicon

Tom from Rubicon

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"The only issue is, and it’s the whole problem was the jackshaft being so cambered out. I didn’t install it, came that way. Crooked with the top of the sprocket leaning left and the bottom of it crooked inwards. If you could feel the bearing with your finger, you would feel it grind and tremble. There are obviously flat balls inside it. The other bearing also has increased rotational friction, but I am not sure if it is because of a special thick grease or pressure from the outer race and the jackshaft housing, or if it too is also messed up, but no gravely feel to it. "
This image says it all. You ain't fixing that Cole. That is a should have been rejected frame.
The jackshaft bearing tube is out of alignment in two axis. I was a weld fixture designer and builder the last ten years of my career. .25mm was my standard linear tolerance, angular, .5 degree.
You would have to twist and bend the seat post tube to achieve alignment.

Tom

1691032954405.png
 
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Makomea

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Oh dear…. That is bad, so there is absolutely no possibility that the camber was caused by the janky bearing? It’s simply the housing tube? I got it from gasbike.net. It was paid in full for a brand new unmolested phatmoto. I figured it was shipping damage but it makes sense. It came in rough shape. Let me take a few more photos of the area for you. I can make a video for you guys as well if you need to see it. I at the very least very much wish to attempt to install 2 new bearings and the shaft axle and see what happens. If you look at the first and last inside hole pictures, the worst bearing appears in an oval shape looking directly through the bearings into the jackshaft housing. The better bearing, when observed from the opposite side has a nice circular and normal appearance. Either way though, you guys are masters of building bikes. None of you know what the best way or ****, any way at all of shoving that shaft into the bearings without wrecking them? It doesn’t even need to be a phatmoto example, any example at all of someone putting any shaft into any press set bearings. I just need a general idea of what to do. If it’s still torqued up after that and all cambered, I will throw the towel in and request an exchange.
 

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Tom from Rubicon

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While you are thinking of plan B Cole, consolidate your two threads into one. The forum will be better served by a single thread link about Phatmoto. Good or not so good.

Another thought, GasBike is a sponsor of this forum so it is safe to say that they should be eager to maintain a untarnished reputation. Retailing a fully engineered product should not be fraught with risk.

Tom
 
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Makomea

Makomea

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Tom from Rubicon said:
While you are thinking of plan B Cole, consolidate your two threads into one. The forum will be better served by a single thread link about Phatmoto. Good or not so good.

Another thought, GasBike is a sponsor of this forum so it is safe to say that they should be eager to maintain a untarnished reputation. Retailing a fully engineered product is fraught with risk.

Tom
Click to expand...
Indeed, and so far I have spoken with them every day. They got a tech that has been having a rough couple days there which has slowed the process a bit. For the record, I must state this now, I have no issue with Gasbike.net. I completely understand that things happen and handling mistakes can occur especially in high stress, 0 time environments. Everything that has gone wrong with the shipment they have addressed and are actually pretty cool and professional. The last thing either of us want to do is have to return/exchange the the bike over something simple. Last suggestion I got from the Tech was to remove and jackshaft and see if the axle was bent or something else. I wished I had a better way to measuring the axle for warping. By eye alone, I really can’t tell if it’s “trued”. The two sprockets that fit are perfectly trued, and I have gauges as such that prove it. The geometry of the axle is a bit complex for my measuring tools currently. @Venice Motor Bikes has a great idea, and can’t wait to try it. I overnighted 4 timken 6203RS bearings, Antiseize, and a bearing smasher. I will be able to know for sure when I place the new bearings in and the axle, spindle, shaft (I am not sure of its proper name haha!).

Oh yeah, Tom! About consolidating the two posts, this wasn’t supposed to be about the phatmoto in particular. I know this is the gear, hub, sprocket area (can’t findem, grindem). This topic was supposed to be purely about how I can install an axle and two bearings into a bottom bracket like housing (phatmoto jackshaft housing). I don’t know how to perform that procedure and I don’t know what is analogous or similar to compare it too. Which means I don’t even know the keywords to use in google or YouTube to find a similar procedure. Despite my best efforts, all I can find online with my personal lack of knowledge is how I can slide bearing onto the axle. How would you do it Tom? Would you press fit the bearings into the jackshaft housing and use a hammer and beat the axle back in Would you install the bearings on the axle and then beat all 3 of them inside of the jackshaft housing simultaneously? I have a huge C-Clamp or two laying about. Maybe I could slide the left bearing on the axle, then use a c-clamp and a thick washer to press fit that assembly inside as they pretty much need to be flush anyways, then use the other c clamp to press the 2nd bearing onto the pertruding axle and then finally into its proper place in the housing? You see, I don’t know. I really could use any advice. I am more of a theoretical kind of guy with little to no practical experimental experience. I tend to over complicate simple things that would be so obviously quick and easy for those whom are more practical engineering type of guys. I don’t need a step by step guide, just a general idea of a decent way of doing the job otherwise I’ll probably go with what I best know which would be blasting the inner race with a ton of heat and freeze the axle and pray the thermal shock doesn’t crack anything. I will attempt to consolidate posts as soon as I figure out how.
 

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Tom from Rubicon

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How would you do it Tom? I am more of a theoretical kind of guy with little to no practical experimental experience. I tend to over complicate simple things
There are a lot of ways to skin a cat Cole.
Myself being next step below owner of many companies, very often meant overthinking a mechanical solution. With tight budgets it is normal. Get it right or go home. That is why I have my own Tool and Die shop these days.

Pity is you live so far away. Listen to Norm/Venice and Tony. Both have been here long before me.

Tom
 
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Makomea

Makomea

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Hello Georgie! You are correct, there is indeed a post on this very forum. His cambered photo is uncannily similar to mine. Almost within a degree haha! However, he was able to see a noticeable bend in his shaft. I don’t know by how much though. One would assume if the housing is true, if the bearings are undamaged, then a bent axle would induce a noticeable amount of wobble especially with the main end sprocket if you attempted to rotate it by hand. Like if your sprocket is positively cambered and you hand rotate by 180 degrees, it should be equally but negatively cambered by the same amount. There wasn’t any wobble on mine when rotated by hand, at least none that would be outside of a reasonable margin that couldn’t be explained by bad bearings. Which mine are unfortunately both terrible bearings that are unevenly pressed inside the housing. Tom’s answer as to why I am out of alignment scares me most which is my pucker factor is probably proportional to his accuracy. Alas, I had taken the shaft out on request from the Gasbike tech. When I reseat the new bearings and shaft I will know for sure. If Tom is correct about the tube alignment, then it will not matter how perfect the bearings are nor the shaft, I will have around the same amount of camber when I reinstall the sprockets.
 
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Makomea

Makomea

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Yup, the jackshaft housing was improperly welded to the frame just as @Tom from Rubicon said. I even took it to a local bike shop and he concurred with the assessment. I don’t know how this is going to play out, I hope gasbike.net is willing to exchange bikes or at the very least, I can strip the frame and they could send me a bare one. I will ask them. I promise the very moment I get some free time I will figure out how to migrate this post to my original thread (unless a moderator has such powers, I would really appreciate it!). Wish me luck guys, my future riding with you all is now in the hands of gasbike. I can’t that you all enough for all the help and advice, especially making me feel like part of a team or community… that means the world to me.

-Cole
 
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