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Front axel slipping, '86 fourtrax TRX350

10008 Views 16 Replies 4 Participants Last post by  Pain
By now you've all read and are probably growing tired of seeing new threads about my recent purchase.

This question is about the front axel. I've mentioned that I hear clunks when turning the wheels sharp, mainly at slow speeds, but I'm not turning the wheel extremely sharply at high speeds, so there you are....

Last week I noticed while riding that while going down a rather steep hill and applied the front brakes, I could hear the gears in the front slipping, or what I assumed was slipping.

Today when trying to get the drums off, I had the bike jacked up and when I tried to turn the front wheel nut, I could see and hear the axel slipping. I had to put the wheel back on and drop the bike to the ground before I could loosen the wheel nut. That happened on both front wheels.

Long story short. What is the best guess of the problem?

I don't really intend to try to fix it, at least not right now***. It rides fine, and for my purposes as long as it doesn't deteriorate to where it has no 4 wheel drive, then I'll use it as is. It's never slipped while riding it up or down hills, except when aggresively applying the brakes doing down a very steep hill.

***Unless you say, OMG! Fix it else it will trash the whole transmission!

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If you're hearing "clunks" when you steer, it's one or both of the CV joints on the front axle(s).

When loosening the nut on the front wheel, with the front off the ground, did you notice the opposite wheel spinning? I don't know what type of front diff these things have, but if there is a planetary gear diff up front, the opposite wheel will most likely spin the opposite direction of the wheel you are turning (if the front drive shaft is engaged or has enough drag to prevent rotation). If the front drive shaft is allowed to spin freely, both wheels would most likely spin the same direction.
This beast has full time 4 wheel drive, so all four wheels are locked together permanently, so the other wheel didn't spin at all.

I don't know the terminology for the gears, but I must only assume that the main gear in the final drive is worn, or there is a bearing shot, which is allowing the shafts to slip.

Without removing the boots, is there a way to test the CV joints?
Grab the center member and see if you can move it laterally. You can also put the front up on stands, turn the wheels sharply to one side or the other, and spin the wheels while watching the shaft. If it has a bad CV joint, you'll see the shaft jump...if it's good, it should spin smoothly on one axis.
I'll check it out, but I have to put the whole machine on jacks to spin the wheels, because all 4 are locked together.

That will a test for another time when I need something else to fix. ;)
Also, do I assume correctly from what you said that the CV joint might also slip if it's worn out, and that could be what is slipping, and perhaps not anything in the final drive?
OK, somewhat unrelated and equally disturbing at the same time.
Also, do I assume correctly from what you said that the CV joint might also slip if it's worn out, and that could be what is slipping, and perhaps not anything in the final drive?
It could.

Very disturbing.
Alright, so I did more research and most opinions say, as Green said above, that clicking or clanking when the wheels are turned is an indication of bad CV joints [and by extension might also cause axel slipping, but thats unconfirmed on my bike].

I started looking, and like a lot of parts for this model ATV, the half shafts are not available from the dealer, or from aftermarket suppliers. They are available for ’87 an above, but not ‘86.

I found a guy on EBay that I have bought from before who had the left and right knuckle and shaft for $75 each, so I bought them figuring that if one or both of mine aren’t bad then I can sell them again. Also, considering that the price for these used parts ranges from $75 [what I paid] up to over $200, I decided it was worth it even if I just turn around and sell them.

With all that said. How hard is it, and what do I need to do to remove the shafts and replace them. I’d rather not remove the whole knuckles from my machine. I’d prefer to just take the shafts out of the knuckles I bought and replace them on my bike [then sell the extra parts of course].
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With all that said. How hard is it, and what do I need to do to remove the shafts and replace them. I’d rather not remove the whole knuckles from my machine. I’d prefer to just take the shafts out of the knuckles I bought and replace them on my bike [then sell the extra parts of course].

For the purpose of documentation in case it helps others, here are 2 different procedures I found that might [or might not] apply, and they also might be to replace the joints or boots, but it will be similar. If anyone else has something to add, please do.

Version 1

1) Remove the wheel
2) Take the brake calliber off - if you have disc brakes (two cap screws)
3) Disconnect the tie-rod (there is a cotter pin there too)
4) Remove the large nut holding the wheel housing onto the axle (there is a cotter pin there too)
5) Dicconnect the upper and lower ball joints and slide the wheel housing off the CV stem
* At this point the axle is free on the outside. - Don't let it just dangle as damage to the inner CV could result. (Per AC instructions)
6) Cut the bands on the inner boot and slide the boot back.
7) There is a large 'C' ring on inner CV joint that need to be removed - start it with a small screwdriver and grab it with needle nose pliars.
8) Slide the inner CV joint out of the housing
9) Remove the small 'C' clip from the axle
10) Slide the inner CV joint off the axle.
11) Cut the bands off the outer boot.
12) Slide both boots off the axle.
13) Install new boot and reverse the above steps.

Version 2

1. Jack your vehicle off the ground and secure it from rolling
2. Remove the wheel
3. Remove the axle nut (large nut on the outside of the hub)
4. Remove the lower control arm bolt or ball joint from the hub assembly
5. The hub will be able to swing out away allowing the outer cv joint to be slipped out through the back. This may require a tap on the threaded end of the outer cv joint. Put the axle nut back on half way so that you can tap on it without damaging the threads.
6. The inner u-joint will be the only thing holding it axle in place. That can be removed by knocking out the roll pin which holds it to the front differential. If you have an inner cv joint these are held in by a “c” clip, just pry it away from the differential and it will pop out. Now you should be able to pull it off the stub shaft.
7. Once the axle is out of the vehicle. Hold the cv axle by the shaft close to the inner cv or u-joint and hit the outer cv joint off of the shaft with a hammer (I use a 5 lb sledge. (wear glasses, grease may fly!) It usually comes off with one or two good blows with the hammer. However, If it doesn't come off put the axle in a vise and try again. If it still doesn't come off use your hammer to break the cage and remove the ball bearings. This will expose the race. You'll need to press the race off of the shaft. You can use a punch and hammer to punch the shaft back through the race. Other wise you'll need to use a press. Or cut it off with a cutoff saw. Cut the race in the direction of the splines on the shaft. That way it won't affect your new joint going onto the splines.
8. Now that the joint is removed cut away the old boot and clamps and clean the shaft with parts cleaner or Brake clean.
9. Put on the new boot and slide it toward the inner out of the way.

ADDED: And, then there is this of course, from the 'Bearing How to' posted on this site. Steps 1 - 9 posted below.

Version 3, probably the way to go:

1:Thoroughly clean the machine, making sure to remove all debris around the wheel hubs, axles, a-frames, and shocks.
2:Raise the machine up, and brace it with jack stands or other solid and stable objects.
3:Remove the wheels.
4:Remove the cotter pin.
5:Remove the castle nut (sometimes this requires an impact wrench)
6:Remove the brake hub.
7:Remove the lower shock bolt from the a-arm and swing upwards out of your workspace.
8:Remove the two lower a-arm bolts holding it to the frame.
9:Swing the lower a-arm away from the machine and physically pull the axle shaft out of the steering knuckle.
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To close out this thread, to replace the half shaft and knuckle on the 86 [sorry, no pictures, I was too dirty to hold a camera]. Remove the wheel and drum. You can remove the 4 bolts holding the brake hub in place and remove the hub, or not. If you don't remove the brake hub, you can leave the drum on, too.

Remove the cotter pin and tie rod bolt attaching it to the knuckle, and lift it out of place. Remove the 4, 17 mm nuts holding the knuckle on. Remove the blots holding the brake line in place. Then, just remove the knuckle.

That's it.

I bought a new set of knuckles and half shafts on ebay, along with the brake hubs. Basically a whole new front end. Replaced the left knuckle, half shaft and brake hub, bleed the brakes. And it works! No more clack clack clack when turning sharply, and I have front brakes! Woot.

I might or might not replace the right side, but it seems all my troubles were on the left, so I can either sell or keep the right side parts. Probably keep them.
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Nice Job!!!!If it were me I would just keep the parts just in case.
I've been reading your threads about fixing up the '86 fourtrax. I recently got the same model, same year quad and I have similar issues (clicking front axle, non-functioning brakes). I need to grab some new sockets and I was wondering if you could let me know what size the castle nuts are on the front and rear brake drums. I also like the look of the tires you're riding on - what are they?

How's the quad been running since you've fixed it up?


Hi Mike.

The machine has been running really great. I was out last weekend and took it through some pretty intense stuff, at least in my view. It was pretty impressive, and I've already concluded that having a quad is an absolute must have machine for working around a farm or in the woods.

The front castle nut [the nut holding the wheel to the shaft, if that's what you mean] is 22mm.

The tires are Kenda Bear Claw.

I finally took it to the shop to have the starter clutch repaired...I decided it was more than I wanted to tackle.... and now I have electric start. Woot. However, there were more parts in the clutch assembly that were unavailable. The defective part was available, but there were some warn parts they had to reuse. Actually, that saved me some money, but it made me realize that the age of this machine and the unavailability of parts is a bit more troubling that I'd like, so I think I'm going to put it up for sale.

With all the parts I bought and the shop fees, I have around 2 grand in it, and I think I can probably get that if I hold firm and wait for the right buyer.

I'm currently looking at a 99 300 fourtrax in excellent condition that I might buy for about the same price, and it's 13 years younger.

BTW, if I do end up selling it, I have some parts I'll sell you for what I paid plus shipping. I have the right-front knuckle with shaft and brake drum, complete set. I bought both sides, but only needed the left.

Where are you located?
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With all the parts I bought and the shop fees, I have around 2 grand in it, and I think I can probably get that if I hold firm and wait for the right buyer.


Where are you located?
Does the 2 grand include what you paid for the quad?

I'm located in Williamson, NY near Rochester. I may take you up on those leftover parts once I have a better idea of what needs fixing (and once I find the spare cash to start fixing!)
Yeah, I paid 1k for the bike, and about $500 in misc parts that I installed myself. I bought the front knuckles and shafts and brake drums for about $250. Brake shoes for the back, 2 new plastic side panels [purely cosmetic, but I'm anal] and the starter reduction gears on ebay and a used fuel pump. Then I paid the shop $450 to repair the starter clutch.

If I sell all the parts I bought and the bike in current condition and get around 2k, I'll be even. It's now running great and in acceptable condition for me, but I figure if something else unknown breaks, and I can't get parts, then I'm screwed. I'd rather sell it now while it's running and get something newer.

When I bought it I was looking at something newer, but I had never had one before. So, I decided to get something cheap, use it to learn on and decide if I wanted/need a quad. It served it's purpose and now I can move on.
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