Author Topic: Rebuilding a Chinese ATV  (Read 2442 times)

Carpenter84

Rebuilding a Chinese ATV
« on: April 30, 2022, 10:28:00 AM »
So, about 3 years ago I spent a significantly long period of time on a renovation job (day job) about 45 mins from home. The homeowner was a lawyer (not important) and co-owned a very large construction management company. A specific project to mention was the $550 million renovation the SkyDome in Toronto recieved a couple decades ago.
So, very "boardroom" mentality of doing business. I was mostly there on my own as many of the tasks did not require multiple people. The client and I would have daily meetings/briefings over progress, plans, details, and ideas. Point of this is the client and I developed a very good relationship.
Long story short, he gave me his sons gas ATV. His son out grew it. I was elated, and so was my son.
Being that it's chinese, Costco style, it's rather inexpensively built. But these 50cc motors are bullet proof. The carbs are so cheap there's no sense in rebuilding them every spring, you just buy a new one for $25 off Amazon and the engine runs like new.
However, all the suspension linkages, bushings, pivots, bearings, etc, are ALL shot, missing, or severally worn out. Making driving the thing rather squirrelly - even tho it'll carry my fat butt at 60km/h.....
I've been saying for two winters now that I would rebuild it so it was safer and easier to ride but time never permitted and the darn thing just keeps going!
Well, another client dropped off his Banshee quad for more work (I've worked on this clients off road toys numerous times in the past). This has put a fire under my butt to finally address ours.
So, I'll try to catalogue my progress here. I'm going to try something a bit different tho... I recently obtained a GoPro camera. I'm going to try my hand at the.... talking hands videos. No pun intended. I'm sure it will be painful to watch at first. I'm not photogenic by any stretch. I certainly enjoy talking, but usually don't want to listen to myself talk. So, green right out of the gate.
 
However, should be a fun project. I have some plans in mind of how I want to rebuild. Most of the bushings are just steel sleeves over bolts, and linkages are cheap rubber over bolts. I've ordered some bearing bronze, some bearings, some shoulder bolts, etc. There's not a lot of movement in the joints so I figure bronze should be plenty good. I'm not going to put bearings where steel sleeves once were.

We'll see how it goes.
I forgot to take a photo of the tear down as it was a spur of the moment decision. But, here's a security camera view of the carnage on the floor.

Oh, I should mention. I better get this done quick, or that little guy's gonna have my a$$! It's getting warm which means riding season...

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #1 on: May 02, 2022, 02:39:11 AM »
First item, which would have made good video, but I still don't have a camera mount to actually mount the camera... The rear drive shaft. I made a new one because I want the quad to have a bit wider wheel base. It can be a bit tippy.
The bearing flats are within 10 micron, yaaa, I've been slowly finding myself using metric a lot more...
I ordered new bearings, better ones than what came in the machine. New seals.
Next items will be to poke the Cotter pin holes and cut the splines. The shaft fits in a 31/32" 5C collet in my spin indexer, and with 24 grooves, it is divisible within the confines of the indexer. However, what kind of a cutter should be used to cut splines?

Also, the chip that came off the shaft due to the cutter I was using was pretty neat.

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #2 on: May 02, 2022, 03:05:00 PM »
What kind of cutter should I use to cut the splines? I've never cut splines before.
Shawn

RayH

Re: Rebuilding a Chinese ATV
« Reply #3 on: May 02, 2022, 06:40:07 PM »
I have never designed anything which incorporated a spline and I've never cut a spline.

With that disclaimer out of the way . . .

I think there are more than one type (design/form) of splines.
The first thing I would want to know is the number of splines. Twenty four = progress

Next bit of information: Are the flanks of a spline parallel to each other or at an angle?
Ray

RayH

Re: Rebuilding a Chinese ATV
« Reply #4 on: May 02, 2022, 06:50:12 PM »
There are also involute splines (look like gear teeth) but your pictures don't look like involutes to me.
Ray

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #5 on: May 02, 2022, 09:31:54 PM »
I don't have Photoshop on the shop computer to draw out the circle and dissect its form. I have PS on my laptop at home. But in the mean time, I'll post the photos.
The cuts just look round. I will say, they are not spectacularly tight fitting. In fact, I assume the shaft spline is rolled/formed, not cut. And the bores are broach cut.
I suppose I could make a fly cutter style tool, but it would be nice to buy a tool. I have not cut a spline before, as I mentioned, so great opportunity to try it on a house project before encountering someone walking in the door. In which case, I should probably have a semi-professional setup already figured out.
Shawn

RayH

Re: Rebuilding a Chinese ATV
« Reply #6 on: May 02, 2022, 11:21:16 PM »
Well, the flanks are definitely not parallel so that leads me to think you'll need some sort of form cutter.

I'll propose the high cost, best technical option first. Contact a custom cutter grinder and send them the original shaft. I'm thinking about a 4" diameter cutter w/ 20ish teeth and a profile to cut one complete tooth crest and 1/2+ of both adjacent valleys. Maybe $300?

I didn't think you'd like that one.

Alternatively, contact a custom cutter grinder and send them the original shaft. request an end mill modified to cut one complete valley and 1/2 of the adjacent crests. Maybe $100?

The problem with a fly cutter is "one tooth" = slow progress.

If it was me, I think I would try to determine what module or DP and pressure angle involute gear would best approximate the shaft spline form. Buy that Involute Gear Milling Cutter set (and an arbor?)
Ray

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #7 on: May 03, 2022, 06:38:14 AM »
The problem with a fly cutter is "one tooth" = slow progress.

If it was me, I think I would try to determine what module or DP and pressure angle involute gear would best approximate the shaft spline form. Buy that Involute Gear Milling Cutter set (and an arbor?)

Damn right, it would be slow… in that case I could just start counting grey hairs and use the shaper. Haha. Which would work. I bet there’s enough clearance under the ram for the shaft to extend inside the shaper far enough before it hit the rocker arm…. But no, just no!

I think you’re right, gear cutters is the best direction. I bet it would work just fine. I’ll see what I can find for an economy brand cutter set.
Shawn

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #8 on: May 03, 2022, 06:46:19 AM »
Last night's progress was the main rear end linkage. This was the worst worn part on the bike. Stock was just a long bolt through two steel lined rubber bushings. One side was completely gone allowing the sub frame to sway wildly back and forth.

Cleaned all that junk out. Turned some bearing bronze bushings. Pressed them in, and held with two jam grub screws, even tho the press fit would have been sufficient. Then reamed to 5/8". And a stainless 5/8" shaft lapped to a good sliding fit.
A grease zerk added, and an oil groove in each bushing.
I will turn and thread the ends of the shaft to fit the frame to allow bolting tight to the frame with nylock Lock nuts allowing the rear end to pivot freely under the shock absorber.
This alone would be a huge improvement and could really stop here. This pivot was the main culprit. But of course we have the rear shaft to finish, and I want to rebuild all he front end steering and suspension linkages too. Those rattle all over and create a huge amount of play.
I took video of a few projects but now I have to figure out how to edit it all... And figure out how to get over hearing myself speak on a recording...

jpigg55

Re: Rebuilding a Chinese ATV
« Reply #9 on: May 03, 2022, 07:48:59 AM »
This video might help on the spline issue: https://www.youtube.com/watch?v=vxCV4TGGKls
Logan 6560H, SB 9A, Clausing 8520, Sanford MG 612

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #10 on: May 03, 2022, 02:08:11 PM »
Looks like he's using a vee cutter. I read in the comments that it's a sharp vee - no radius in the root.
I'll likely be looking at a gear cutter.

Also, this project just got slammed to the back burner, unfortunately. I had 3 jobs walk in the door this morning and received a PO that will include about 60 hours worth of work due in the next 3 weeks... Shop just became overwhelming busy...

4GSR

Re: Rebuilding a Chinese ATV
« Reply #11 on: May 04, 2022, 08:48:37 PM »
Shawn, if you have a Machinery's Handbook handy, look under involute splines.  There are standards for them. There is a flank angle to the teeth of the spline.  Some of the common one are 25°, 30° that come to mine.  There is a pitch to the matrix too.  Once you have identified what you have then you can start looking for form cutters.  Most are hobs used on a gear hobbing machines.  And there is a Chinese standard on them also.  I believe it follows the DIN specifications for splines.  But I believe they are all based off of the SAE standards on splines with metric equivalents insteard of inches.   
Ken

Carpenter84

Re: Rebuilding a Chinese ATV
« Reply #12 on: May 05, 2022, 01:57:58 AM »
I will have a look, thank you
Shawn

kopcicle

Re: Rebuilding a Chinese ATV
« Reply #13 on: May 06, 2022, 05:58:05 PM »
What kind of cutter should I use to cut the splines? I've never cut splines before.

a sharp one

couldn't resist :-)