# John Deer Lawn Tractor Drive Chain Breaking



## truenorth777 (Mar 28, 2006)

*John Deer Riding Lawn Mower Drive Chain Breaking*

Hello

I am the owner of a John Deer R-70 riding lawnmower

The problem I am having is the Drive chain keeps breaking. the owner has replaced one of the wheel pullies and put in a new chain but it is still breaking chain. 

what I would like to know is what causes the chain to break and how to adjust the chain tension.

Thanks


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## bsman (Jan 22, 2006)

Chain is too tight, give it some slack... a little though


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## truenorth777 (Mar 28, 2006)

I am fairly new to riding lawn mowers so could you give me some instructions of how I will loosten the chain.

Do I loosen the rear wheels and slide them forward the power transit unit or is there an adjustment bolt somewhere.

Any tips will be helpful.

Also does anyone have a repair manual for this model?

Its a R-19 and theres a picture of it on this page http://www.themotorbookstore.com/ridlawmowser.html

Hope to hear back from you soon and thanks for your post.


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## tom tilson (May 1, 2006)

If the chain is to tight. and you don't know where the adjustments are I am wondering how you got the new chain on to begin with. I may be missing something here, but would you clarify the proceedure once again please? I am thinking that with the info that I have that the chain is so loose it is trying to go back around the drive pulley and breaking. Anyway, there has to be an adjuster somewhere and when you put the chain on, make your adjustment, probably by shifting the axle. Make sure the axle shaft is adjusted the same amount on both sides or it may start jumping off the sprocket. Adjust the chain so that when you grasp it half was between the pulleys that it wil deflect about 3/8 inch. I hope this will help


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## truenorth777 (Mar 28, 2006)

Actually it isnt my mower yet I'm thinking of purchasing this mower because the previous owner doesnt want it anymore and baught a new one 

I just wanted to make sure that there wouldnt be too many repairs involved to get it working good.

The chain seems to just slip right onto the sprockets with no problem and without adjusting the tensioner this is most likely the problem however there seems to only be about 3/8" of play in the chain so maybe it just needs to be tighter.

There is also one bolt which is broken in behind the wheel and the owner wasnt sure if that was the cause or if it was something more major.

Hope this clarifies the question more

And thanks for the posts I look forward to more.


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## bsman (Jan 22, 2006)

IF it can be adjusted, you might be able to find markings in order to tell the tightness of it. Throw up a pic of the back end if you can, would have too see it to better understand.

When does it break?? When you first start going, or does it break after a while??

That bolt that broke off, may be for adjusment purposes.


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## truenorth777 (Mar 28, 2006)

The way I understand it as the owner explains it is that it breaks as soon as he starts going.

At the moment the mower is a few hours away from my place so I wont beable to send a pic at the moment but maybe later on.

So BSMAN I have a question..

If the chain breaks when you first start moving than would it be too tight..

And if it was to break when it was going after awhile would the cause be too loose or would it be another problem Im not thinking of such as worn cogs, bearings, pullies etc.

hope to hear back soon thanks.


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## truenorth777 (Mar 28, 2006)

Extra message posted in here so had to edit it


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## bsman (Jan 22, 2006)

you know, if it would be too loose and the sudden jerk of taking off, that action could break it right their. Bearings could be shot, or stuck busting the chain when you try to go...

...when you get a chance, try and move some things, oil it up, fill any grease fittings, ect. If its broke it can be fixed!!


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## certifiedtech (Jun 30, 2006)

Drive chain Adjustment for R70
Adjustment is performed with the seat and shroud assembly raised.
There is no need for mower deck removal or other disassembly.
> Loosen axle bolt for idler sprocket and move idler bolt in it`s slot under transmission platform. Tension is correct when chain can be flexed 1/2 inch at mid point between drive and driven sprocket in top strand. If chain is defective, loosen adjusting sprocket and pull master link. Chain then can br removed for cleaning, lubricating,repair or renewal.


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## certifiedtech (Jun 30, 2006)

Block the front wheels, start the engine, raise the back tires off the ground, put it in gear and watch the spocket to see if there`s any wobbling. If so, the sprocket may be bent or not installed properly.


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## truenorth777 (Mar 28, 2006)

Awesome thanks that is what I like to get for posts 

Straight to the point and easy to understand.

Thanks again bsman & Certifiedtech


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