400 series Yardman 400 series tractor keeps throwing rear drive belt

frank50e

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
I have as stated a 400 series Yardman rider which keeps throwing the rear drive belt.There is a misalignment between the idler and trans pulley,the idler is higher which is causing this.I can effect an alignment by shimming the idler down or the trans pulley up.But it bothers me that I can't see any reason that this occured have owned the mower several years and nothing has happened that would have caused this and there doesn't appear to be anything bent or damaged and no built in adjustment for either so this concerns me.Anyone familiar with this tractor is there a common trait or cause of this happening.
 

Rivets

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
Have seen this happen when the bolt holding the idler pulley on wears or the bearing wears causing the pulley to tilt. Also if i remember right there should be a 1/4" spacer on the topside of the pulley that might be worn.
 

frank50e

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
Well I solved the alignment problem by flipping over the idler pulley however when pulling the trans pulley the splined shaft that holds it came up out of the trans.Slid it back, in test drove the thing everything seems to be working fine but kinda queasy about this shaft.Anyone with experience on this?
 

reddragon

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
the tranny spline shouldnt move more than an 1/8 inch...and that is very loose.......you may have lost the c clip in the tranny:frown:
 

frank50e

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
There is a c clip on the right about where it meets the housing there is no provision on the shaft yes I pulled it all the way out for another.If there is no c clip floating around in the gears will it operate this way seems to at present?
 

frank50e

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
According to MTD the c clip ia on to of the housing and has come out of a slot which holds it in.Will update.
 

frank50e

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
Reddragon you were right and the tech at MTD was misinformed or just didn't look at his diagram very closely.Pulled the transaxle because there was no slot for the C clip on top to fit into.Called a local parts place that was kind enough to print me out an exploded parts diagram of transaxle.There is a tiny wire clip that goes on the end of shaft and up inside the pinion gear.Must order I am sure it's specialized enough that a hardware search would be fruitless.I build bobbers and racing m/c so I have several lifts.the whole process of pulling transaxle and splitting open took less than an hr.using an air rachet. There are very few parts inside.Digging thru the rancid grease for the wire clip was a less than pleasant task,but will clean up,pack with fresh grease ,reattach pinion, and button up.The problem was caused by the two bolts on the front of the trans that go thru the cross member came out causing trans to tip forward causing misalignment.One of the bosses had a piece broken, and the other hole the threads were stripped ,weld and retap broken piece, and helicoil the stripped threads, and should be up and running.Thanx for your input.This is worthwhile info there are hundreds of thousands of these out there under different names.Cub Cadet,Troybuilt,Yardman.Yardmachines,Dynamark and more.As an aside, I was on hold after 7 attempts to reach someone at MTD ,for over an hour,for bad information.
 

reddragon

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  • / 400 series Yardman 400 series tractor keeps throwing rear drive belt
good to hear!.....i never liked the grease packed idea....i wish they would put oil in these things so the lubricant could circulate...its good to take out contaminated grease and replace it....but never mix white grease in to it...it will liquefy [ big mess]....good luck:thumbsup:
 
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