Tonyp 285 #1 Posted September 23, 2016 (edited) UPDATE AT BOTTOM of thread. Here is the 42" for the 315-8 that I recently acquired. Something appears odd to me but it could easily be me just not knowing how the idler system works. In the Photo, A is where the spring supplys tension on the arm and B is to prevent to idler arm from "straying" left or right. I think...This bolt at B is not snugged down. The A position , if I remove the spring, the idler arm does not move forward or back, so the spring basically does nothing. Perhaps because the A bolt is tight and should not be ? The idler arm will swivel if I remove B bolt. There is NO idler arm movement to let the idler pulley "move" to adjust tension while operating, Is this correct ? Is swivel Bolt A installed incorrectly ? This is a model 78350 deck and it calls for an 89" belt . The new belt was indeed very tight to install and the same length as the original belt. The photo has the original belt. I'm almost thinking that a 90" or 91" belt would be better. Any and all comments appreciated ! Edited September 24, 2016 by Tonyp Share this post Link to post Share on other sites
daveoman1966 3,807 #2 Posted September 23, 2016 (edited) That 'idler arm' should slide back and forth just a little to maintain tension on the belt. There should be TWO nuts on A and ONE on B. The spring should be between the two nuts on A. To set this right, do this: 1)take of the top nut and remove the spring. 2) adjust the nut on A and B so that the idler arm slides easily by hand, but not sloppy at all...slight drag is ok. 3) replace the spring and put the top nut back on. NOTE... don't oil or grease this apparatus...that is just a dirt magnet. Keep the belt covers on to prevent stick and debris. After you get the belt back on , pinch it by hand between the pulleys and you should see the idler arm move back and forth a little. If it doesn't, then it is too tight. Another thing...be sure you have the 4 nylon glides (the black thingys) on correctly....and that they aren't squashed or worn out of shape. Edited September 23, 2016 by daveoman1966 4 Share this post Link to post Share on other sites
Tonyp 285 #3 Posted September 23, 2016 Thanks Dave, your description is how I thought it should be. The photo is of the deck the day I brought the 315 home and yes I took the covers off. Since then it has been fully serviced, cleaned, underside painted, greased etc... But I did decide to replace the primary belt , which I did. I am taking it apart again today to check the idler system, as I am not 100% certain if bottom BOLT A is too tight. I know B is not. I do need to check both nylon glides. It just appeared that the belt was WAY to tight with no play in the tension. I didn't much think about it until I read another thread about tension a few days ago will advise... Share this post Link to post Share on other sites
TDF5G 2,072 #4 Posted September 23, 2016 If you need the nylon washers, Glen has them available here: 1 Share this post Link to post Share on other sites
cleat 7,030 #5 Posted September 23, 2016 I think the center pulley might be on upside down. Parts manual shows the small pulley at the bottom. 5 Share this post Link to post Share on other sites
doc724 925 #6 Posted September 23, 2016 Sharp eyes there Cleat! You are right-up side down. That would explain why the belt seems too tight. 2 Share this post Link to post Share on other sites
Tonyp 285 #7 Posted September 24, 2016 (edited) 9 hours ago, cleat said: I think the center pulley might be on upside down. Parts manual shows the small pulley at the bottom. WOW Good eye and good catch, it is indeed according to the parts manual upside down, that explains the "too tight" scenario and why I was was thinking I needed a longer belt. This is the position it was in when I acquired the 315, evidently the previous owner either knowingly put it on upside down or did it in error. I will reverse it this morning. BIG Thanks ! Edited September 24, 2016 by Tonyp Share this post Link to post Share on other sites
Tonyp 285 #8 Posted September 24, 2016 (edited) All fixed but not as simple as I assumed it might be.( never is) Thanks to all above for sharing wisdom ! - yes the center pulley was UPSIDE down. THANKS CLEAT ! - removed the idler pulley and idler arm - both nylon spacer glides at A and B were not allowing any GLIDING movement . Bolt A bottom was pretty tight not allowing any movement. -cleaned and wire brushed the idler arm -cleaned the nylon glides , it took some filing of the idler arm insets and nylon glides to get them to be able to GLIDE freely -reassembled the idler arm assy -cleaned the idler pulley and bearings , reinstalled the pulley to the idler arm. -removed the center pulley and reversed it, small pulley on bottom -reinstalled the 89" belt -all is well ! My hunch, previous "someone" did some maintenance, probably replaced the nylon glides and reinstalled the center pulley upside down. The nylon glides fit but were VERY snug, not allowing the idler arm to GLIDE. I doubt they were the originals. Who can say why the pulley was upside down, whoever did it probably didn't even realize it, I know I didn't ! Edited September 25, 2016 by Tonyp 1 Share this post Link to post Share on other sites
