I have a 1989 350 Fourtrax and a 1995 400 Foreman.
Been riding for along time, in my 60’s now I started on 4×4’s, 74 Bronco with 38′ Monster Mudders, lockers, then a 86 Bronco, 35" All Terrains, which I re-built a 1969 429 cu in and adapted it to fit in the truck, made my own motor mounts etc.. I am a fairly good mechanic, Jack of all trades. Make my own tools if I have to, good at figuring mechanics out, and I am a private pilot.
Enough with the preamble so you get to know mw a little.
My 1989 350 Fourtrax is making some noises that I am having troubles isolating. The noise it makes is very similar to a rock caught in a disk brake on a so equipped vehicle, the 350 is not so equipped. The noise is only present when the ATV is in gear and moving and not all the time but seems to be getting worse.
What have I done to isolate the issue?
I have removed the Front driveshaft (between engine output shaft and front swingarm). I replaced the bearings on the front driveshaft a few years back. When I look at the front drive shaft all splines and bearings are in excellent condition, no issues there.
I removed the front drive shaft (from back of swingarm to differential input). The splines on the shaft are also in excellent condition, the u-joint has no play in it, functions normally. The shaft has only a nominal amount of rust on it in 27 years so there has been no moisture penetration in my opinion.
I have removed the rear swingarm. The rear driveshaft splines are also in excellent condition. The u-joint is good as well, no play, functions normally. The rear shaft also has nominal rust on the bare metal so I believe no water penetration here either.
The spines on the output shaft on the output gear case, both front and back are in excellent condition. I can spin the shaft and hear nothing and feel no abnormal grinding or roughness. There is no play in the output shaft.
If I run the engine and run through the gears in this state (driveshafts removed) I hear nothing but there is no load on the output shafts. I ran through the gears with only the front driveshaft and wheels connected and heard nothing but load was minimal as the ATV was off the ground.
The noise IMO is not coming from the swing arm bearings as the noise is not related the ATV flexing over terrain, rather coming from the turning of the drive train. I have had all four wheels off the ground as well and run through the gears with no noise but again, little load on the drivetrain as wheels are off the ground.
I would really appreciate any insights any members may have with regard to my screeching noise and isolating the fault. Right now I am thinking of putting it back together and trying again, maybe a rock fell out somewhere I did not see.
Thanks for taking the time reading this and considering any options I may have.
