Forum › Forums › Tractor Operation And Maintenance › 4 wheel drive
- This topic has 10 replies, 6 voices, and was last updated 10 years, 12 months ago by dogdoc.
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November 7, 2013 at 6:51 pm #30832
I tore down the shaft and connectors on each end of my Jinma 254 and both sets of ball bearings had fallen out, plus the shaft is slightly bent (ran up on a rock last summer). Currently nothing between the gear box and transfer case. I have all the parts for the job and was wondering if there is a suggested order for reassembly.
thanks
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November 7, 2013 at 8:46 pm #36514
It doesn't matter which end of the driveshaft you put on first. If you put a dab of grease in each slot it will glue the ball in place while you work the shaft into position. The shaft just barely fits if it's compressed to it's minimum length. It may feel like it won't fit but it will.
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November 8, 2013 at 6:22 am #36515
You need to make sure the circlip did not break that's what will also let the balls fall out.
If you look in your parts book it will show you all the parts and there position
2- Couplers
1- 8mm pin
1- 4mm pin
1- Star washer
1- Circlip
12- Ball bearings
2- rubber dust caps
1- Spring
1- Spring washer
I would recommend if the shaft is bent that you replace it
Tommy
Affordable Tractor Sales
“Your Jinma Parts Superstore”
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November 8, 2013 at 9:00 am #36516
I agree have at least the shaft straightned at a machine shop or replaced and the driveshaft tube reworked or replaced it will make the reinstallation easier if it slides together easy.
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November 11, 2013 at 8:20 am #36518
got all the parts plus extras including the new shaft from tommy, hopefully it goes together this weekend
thanks
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November 12, 2013 at 8:36 am #36521
just a thought but has anyone looked at a mod using universal joints to connect the gear box to transfer case?
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November 12, 2013 at 10:26 am #36522
I wouldn't over think this part. The balls falling out or the clip breaking is a way of saving the front differential and/or the transfer case.
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November 12, 2013 at 5:11 pm #36524
that's kind of what I thought the ball bearings are a connector and slip joint. just wondered as I thought the orange and green tractors used universal joints. just came back from north Dakota and was with people who do a lot of tractor work and they never heard of the ball bearing system
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November 12, 2013 at 6:43 pm #36525
It is kinda oddball, almost a home made CV joint . I did see somewhere a fellow made 2″ pins to replace the balls as they stayed in place much better. But he was a machinist with all the toys and knowledge to do the job. I just can't justify the time and money involved in making the driveshaft and yokes and all to replace the stock unit on something that doesn't even reach 10 mph.
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November 13, 2013 at 1:52 pm #36526
I agree – the ball in groove system works fine as long as the balls stay in place. The usual cause of problems is the circlip breaking and dripping the balls. While I've never seen this system used in a vehicle before, I have seen it used in other power transmission applications where the shaft needed to have significant end play in the couplings. I think that's the reason they used it here, as these front ends move a good bit when under heavy use and might not do well with a rigid coupling system like a universal joint.
The balls do tend to wear the grooves a bit, so changing them to short cylinders will increase the contact area many times over, resulting in longer life. You just need to cut some short sections of 8mm rod to about 10mm long and you're good to go. 2″ won't fit, not even close. But just going to a cylinder 8mm long is an almost infinite increase in contact area since the balls contact only on a tangent.
Rob (3RRL over on Chinese Tractor World) did the first ball-to-rod conversion and he did his usual meticulous machining job on it, but another guy did his just using pieces cut from a grade 12.9 8mm bolt and that worked just dandy, too. If mine comes apart for any reason I'll probably do mine the same way as it only takes a few minutes to cut down some bolts and dress the edges on the belt sander.
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November 13, 2013 at 8:29 pm #36527
that sounds great, just did a quick look on mc master carr and they have an abundance of 8mm rod stock to play with. looks like a good winter project
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