I own an 1999 Arctic Cat 500 Quad which is designed to be 4 wheel drive all the time (there is no 2 wheel drive option). I recently drove over a log on the path I was riding and when the back wheels went over the rear diff housing landed on a part of the log (clunk !). There was an immediate loss of drive train and the drive train seemed to be slipping out of gear (loud gear grinding noise from bottom rear area of rear drive train), I could see the whole rear diff housing and rear drive train shaking while the gear grinding noise was happening. I immediately cut back on the throttle and put the quad back in 1st gear. Very gingerly I applied a bit of throttle and the quad began to move forward but as soon as I came to a small hill or hit a small bump the gears start jumoing and grinding again. I was 20 miles back in the bush when this happened so it was a very long slow drive to get back to the road. I can change gears no problem but I must be going very slow (1st and 2nd gear only) to avoid bumps or increased drive train pressure by going up steep dips and hills. I lost the front wheel drive as when the gears started jumping/slipping on the rear end, the fronts had absolutely no pulling ability? I have 2 Arctic Cat service reps where I live and called them but both mechanics I talked too never heard of the problem and asked me to bring it in for evaluation/estimate and repairs. I'm trying to avoid going that route (costly !) as I am quite capable of doing the repairs myself and I do own the service manual for my quad.

I did slow down before rolling over the log in question and I can assure you that I do take good care of my quad, it was just a a bad decision on my part to try driving over the log instead of moving it first (won't make that mistake again!).

I would really appreciate any insight as to what and where the problem might be. The one mechanic I talked to said I should have still had my front wheel drive after the incident happened and indicated the problem might be inside the engine housing where the two drive trains join (front and rear) and not inside the rear diff where the drive train gears are that join the rear diff axel?

Kindest regards,

Stevie J

 

Never heard of that happening either. Im not sure what to tell ya other than since your mechanically inclined,start evaluating the situation. Take it apart and see what might be broke. Since the whole drive train is connected,you may have ruined or broke a little more than you thought. If you need parts,you may be able to find used ones somewhere on the net.

 

A friend of mine had an issue similar to the one you describe with his 2001 AC500. What he theorized was that a small needle bearing on a gear (input shaft on the rear differential) went out causing the gears in the rear end to separate.

If it were mine I would start by taking the rear end a part to see what was going on in there. I have also replaced the rear wheel bearings on a 250cc yamaha that would either make weird grinding noises OR totally lock up the rear axle. The wheel bearings were so far gone the pieces of the race would jam together and lock up the axle.

I am assuming this has a solid rear axle? Find a good parts diagram OR use a service manual if you have one and see what is going on inside the rear end.

Hope this helps

Swampy

 

Hi Swampy,

Thank you for your reply to my problem, it makes perfect sense to what I am experiencing with my quad. Question, in my service manual (Rear Bevel Gear Assembly 1999 Arctic Cat 500 4x4) I see a Part #6 Bearing stopper pin, would that be what you are referring to as the small needle bearing. Question, what is the quickest or recommended way to get at the gear set and into the Diff housing, do I have to remove the tires, brakes, axles, take apart the diff axle and the whole nine yards or is there a more simple way. I also do not see a needle bearing on my service manual diagram at all so I am not sure where to look exactly. It looks to me that I will have to totally disassemble everything I listed above but I thought I would ask in case there is a better way of doing this. FYI, I have already replaced all my rear wheel and axle bearings just prior to having this problem but I have not replaced any of the diff axle bearings since I bought my Quad. Also my quad has a total of 600 original miles on it as I only use it to go Moose hunting in the fall, I have not used it at all to go recreational driving.

Sounds like you are on the right track swampy, I really appreciate your help, if you can think of anything else, please post.

Thank you,

Stevie J

 

Stevie J,

We were not sure 100% if there were needle bearings in the differential but it was my friends theory. Sounded good but....

In reality...he may have gotten some water in the differential and either lost a bearing on the pinion gear which caused the pinion gear to bind, shearing off a few teeth which in turn sheared off some small pieces of his ring gear. Not sure of the cause for sure but the result were obvious.

He basically had to rebuild the rear end. But, ebay to the rescue, and he found one that just bolted in for half of what parts would have been. He was back in business.

He did not find any of his problem out until he removed the differential from the machine and took it a part. Yes you have to remove both rear axles and A-arms on the side with rear brakes only, remove the drive shaft, remove the 2 bolts securing the differential. Then lift up the differential slightly , turn it on its side and remove it from between the frame rails on the side you removed the A-arms from.

Then place it on a work bench and remove the bolts holding the cover in place. That should let you see what is going on inside.

600 miles! you need to hunt more! Don't feel bad about the recreational driving, I don't do that either I use mine for work and hunting.

Swampy

 

i had the exact issue going on with mine one time,it would grind under a load.So i took the easy way out and bought another rear end cuz i figured the ring and pinion was shot.After the fact i noticed the bearing that supports the input shaft were totaly shot causing the shaft not to be inline with the pinion,i think the bearing is $70 or so but cheaper than paying 300 for a USED rear end.