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Final drive belt tension.

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  • Far Canal
    Far Canal
    4 years ago
    The HD service manual for my 2008 FXST says that the belt tension can be measured using the right tension tool with the rear wheel off the ground and you should have so much play. Pretty straightforward and how I usually do it.  Or you can measure the tension with bike on ground with no one sitting on it and it should have a different amount of play in the belt.
    1984 FXWG manual says measure belt tension with bike on ground and a person sitting on it and it should have an amount of play different to both of the above.
    I'm wondering if blokes who work on Harleys' all the time tension the drive belts the same across the model ranges eg, shovels,evos,twin cams etc?.
    I adjusted the 84 FXWG tension with wheel off the ground to the same specs as one would a 2008 FXST, imagine trying to adjust the tension and align the wheel with bike on ground and someone sitting on it would be a bad trip.
  • Krash Kinkade
    Krash Kinkade
    4 years ago
    Quoting Far Canal on 14 Dec 2019 09:24 AM

    The HD service manual for my 2008 FXST says that the belt tension can be measured using the right tension tool with the rear wheel off the ground and you should have so much play. Pretty straightforward and how I usually do it.  Or you can measure the tension with bike on ground with no one sitting on it and it should have a different amount of play in the belt.
    1984 FXWG manual says measure belt tension with bike on ground and a person sitting on it and it should have an amount of play different to both of the above.
    I'm wondering if blokes who work on Harleys' all the time tension the drive belts the same across the model ranges eg, shovels,evos,twin cams etc?.
    I adjusted the 84 FXWG tension with wheel off the ground to the same specs as one would a 2008 FXST, imagine trying to adjust the tension and align the wheel with bike on ground and someone sitting on it would be a bad trip.

    I don't know? but I've noticed all the late model Harleys seem too tight. 
  • Neale
    Neale
    4 years ago
    Quoting Far Canal on 14 Dec 2019 09:24 AM

    The HD service manual for my 2008 FXST says that the belt tension can be measured using the right tension tool with the rear wheel off the ground and you should have so much play. Pretty straightforward and how I usually do it.  Or you can measure the tension with bike on ground with no one sitting on it and it should have a different amount of play in the belt.
    1984 FXWG manual says measure belt tension with bike on ground and a person sitting on it and it should have an amount of play different to both of the above.
    I'm wondering if blokes who work on Harleys' all the time tension the drive belts the same across the model ranges eg, shovels,evos,twin cams etc?.
    I adjusted the 84 FXWG tension with wheel off the ground to the same specs as one would a 2008 FXST, imagine trying to adjust the tension and align the wheel with bike on ground and someone sitting on it would be a bad trip.

    Quoting Krash Kinkade on 14 Dec 2019 10:02 PM

    I don't know? but I've noticed all the late model Harleys seem too tight. 

    Hell yes. I have an m8 heritage and i was alarmed at how tight my belt was set.
  • Nutty
    Nutty
    4 years ago
    Quoting Far Canal on 14 Dec 2019 09:24 AM

    The HD service manual for my 2008 FXST says that the belt tension can be measured using the right tension tool with the rear wheel off the ground and you should have so much play. Pretty straightforward and how I usually do it.  Or you can measure the tension with bike on ground with no one sitting on it and it should have a different amount of play in the belt.
    1984 FXWG manual says measure belt tension with bike on ground and a person sitting on it and it should have an amount of play different to both of the above.
    I'm wondering if blokes who work on Harleys' all the time tension the drive belts the same across the model ranges eg, shovels,evos,twin cams etc?.
    I adjusted the 84 FXWG tension with wheel off the ground to the same specs as one would a 2008 FXST, imagine trying to adjust the tension and align the wheel with bike on ground and someone sitting on it would be a bad trip.

    I put the bike on a lifter and drop the shocks out. Then I jack the rear wheel until the axle nut, front cog and swingarm pivot are PERFECTLY in line (checked with an edge tool).
    Then set the belt firm but not tight. It should rotate silently. This is optimum setting. Refit shocks and tighten axle.
    This method gives perfect adjustment on ALL bikes.

  • Hoodeng
    Hoodeng
    4 years ago
    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.
  • Far Canal
    Far Canal
    4 years ago
    Quoting Hoodeng on 15 Dec 2019 04:10 AMedited: 15 Dec 2019 04:11 AM

    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.

    I was not wanting to hear that answer but I know it makes sense.
    I wonder then if I do check the tension(using deflection tool) with bike on the ground and somebody sitting on it, then once that is set measure the play with wheel off ground to see what it is and use that for future reference?. Don't usually have an assistant in the shed, plus I found aligning the rear wheel and belt hard enough with it in the air. Reckon it'd drive me to drink doing it on the ground.
  • robnicko
    robnicko
    4 years ago
    Quoting Hoodeng on 15 Dec 2019 04:10 AMedited: 15 Dec 2019 04:11 AM

    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.

    agree, as per manual

    tension will always be looser when rear wheel off the ground cause of the swingarm pivot point being between the front & rear sprockets. when off ground the rear wheel actually comes towards the front a little loosening the tension, as it rises from suspension compressing it tightens and then when really compressed loosens slightly again

    Compressing rear suspension to the point where the swingarm is parallel / in line with the front pulley is the tightest point, above that it slightly loosens again, i have set the chain on my dirt bikes this way and works fine. some euro bikes pivot at the point of the engine sprocket making this very easy 
  • Ken in Cairns
    Ken in Cairns
    4 years ago
    It should be you sitting on the bike Far Canal, or someone else the same weight as you.
    Think ur idea of doing a comparison between the two person and up in the air doing it solo could work, would need to be pretty accurate with the initial measurements though.
  • Birtyyy
    Birtyyy
    4 years ago
    I just got my missus to sit on the bike holding a 20kg bag of dog food to bring it up to my weight.
    (I didn't really do this but would be hilarious if someone did)
  • Hoodeng
    Hoodeng
    4 years ago
    For your 08 Softy they give two check points, one is on the side stand and no additional load, and the other with bike wheel raised clear of the deck, there are two different dimensions to aim for with the 10lb preload.  there are also two different readings to be obtained depending on what model you are dealing with.
    The raised reading is preferred as it gives the same sag each time.
    And as the book says,cold setting and rotate till you get the tightest point to do the adjustment.

    Cheers.
  • tussuck
    tussuck
    4 years ago
    Or.... Just have the shop do it when they replace the rear tyre!  
  • Far Canal
    Far Canal
    4 years ago
    Quoting Hoodeng on 16 Dec 2019 03:07 AM

    For your 08 Softy they give two check points, one is on the side stand and no additional load, and the other with bike wheel raised clear of the deck, there are two different dimensions to aim for with the 10lb preload.  there are also two different readings to be obtained depending on what model you are dealing with.
    The raised reading is preferred as it gives the same sag each time.
    And as the book says,cold setting and rotate till you get the tightest point to do the adjustment.

    Cheers.

    Thanks Hoody. Yep I've got the service manual for the 08 and have that one under control.
    Also got the service manual for the 1984 FXWG but it only specifies the measurement for the tension with bike on ground and someone sitting on it.
    If you have access to a measurement  for the latter with the wheel in the air then I am all ears!, hint hint. Heck, I will even buy you a beer next time I see you at church.
    Regards
  • Far Canal
    Far Canal
    4 years ago
    Quoting tussuck on 16 Dec 2019 03:24 AM

    Or.... Just have the shop do it when they replace the rear tyre!  

    Call me old fashioned Tussuck, but I usually only take the wheel to the shop.

  • Hoodeng
    Hoodeng
    4 years ago
    For the 84, bike vertical and one American rider [100kg] same 10lb pre load and 5/8 to 3/4 deflection. I think you will find this a lot looser than a late belt. Trying to make the same routine work for both bikes will probably result in a problem down the track.

    Cheers.
  • Far Canal
    Far Canal
    4 years ago
    Quoting Ken in Cairns on 15 Dec 2019 11:38 PMedited: 16 Dec 2019 11:33 AM

    It should be you sitting on the bike Far Canal, or someone else the same weight as you.

    Think ur idea of doing a comparison between the two person and up in the air doing it solo could work, would need to be pretty accurate with the initial measurements though.

    Cheers Ken.
    Glad someone got the drift.
  • Hoodeng
    Hoodeng
    4 years ago
    I would stick with the bike lifted on the late model, and 100kg on the 84, the reason is we are looking for a repeatable setting point. The belts tension is not about who or what is loaded on the bike it is about the belts setting relationship to the bike. And yes we know the belt changes tension throughout its arc of operation,the factory also knows this, that is why they changed the setting procedure to exclude variables like rider weight or load. The observation that the belt seems really tight is a personal observation, not what the factory wants.

    In a much earlier life i did maintenance on heavy track machines and earth moving equipment, and we were getting variable drive belt life on fans ,these were in the metre diameter or more range and used Gates green stripe matched set of belts x3 or 4, you can't get much better than these.We were getting a real mix of belt life on these machines.

    On consultation with the suppliers and ultimately Gates what was decided was that the belt pre tension and service tension was most likely the problem. We were issued with a 'Gates Krikit tension gauge 91107'  this gauge gives a pound loading reading in the middle of the belts run, what we found was that what we thought was the tightest setting was no where near what it should have been, they were all loose according to the gauge, when tightened to spec they felt like bow strings, much to our surprise these spec tensions resulted in almost a total elimination of failures.

    And as a side comment, can you guess the tightest belt tension i have ever encountered? An XF Falcon air con belt, f ckin spastic tight, adjust this thing to spec and you can bounce rocks of it, you would swear the unit or the belt would shit itself in short order, no, perfect.

    Cheers.
  • binnsy
    binnsy
    4 years ago
    Quoting Birtyyy on 16 Dec 2019 01:22 AM

    I just got my missus to sit on the bike holding a 20kg bag of dog food to bring it up to my weight.

    (I didn't really do this but would be hilarious if someone did)

    Ha ha, Id need two bags of dog food !!!
  • Nutty
    Nutty
    4 years ago
    Quoting Hoodeng on 15 Dec 2019 04:10 AMedited: 15 Dec 2019 04:11 AM

    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.

    The deflection tool is a pain unless fitted with a roller adaptor IMO. The combination of front cog run out, rear cog run out and localised belt streching needs to be checked over quite a few rotations. 
  • Hoodeng
    Hoodeng
    4 years ago
    Quoting Hoodeng on 15 Dec 2019 04:10 AMedited: 15 Dec 2019 04:11 AM

    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.

    Quoting Nutty on 17 Dec 2019 11:22 PMedited: 17 Dec 2019 11:29 PM

    The deflection tool is a pain unless fitted with a roller adaptor IMO. The combination of front cog run out, rear cog run out and localised belt streching needs to be checked over quite a few rotations. 

    That's why they want you to rotate the wheel to the belts tightest point. And yes, you do have to spin it around a few times to seat things.

    Cheers.
  • Nutty
    Nutty
    4 years ago
    Quoting Hoodeng on 15 Dec 2019 04:10 AMedited: 15 Dec 2019 04:11 AM

    Use the method described in the manual for your specific year and model, and yes the methods can deliver different deflections for a given load, and yes the late belts run pretty tight,this is normal compared to earlier belts.Also use the deflection tool at all times, i have seen belt tensions vary wildly when not used.

    Cheers.

    Quoting Nutty on 17 Dec 2019 11:22 PMedited: 17 Dec 2019 11:29 PM

    The deflection tool is a pain unless fitted with a roller adaptor IMO. The combination of front cog run out, rear cog run out and localised belt streching needs to be checked over quite a few rotations. 

    Quoting Hoodeng on 17 Dec 2019 11:38 PM

    That's why they want you to rotate the wheel to the belts tightest point. And yes, you do have to spin it around a few times to seat things.

    Cheers.

    True! It was OK on the 34:68 equipped bikes but with the later funky gearing it can take a lot of wheel revs to find the true tight spot, especially if the belt has a short area of localised stretch. 
    Another thing Hoodie, a lot of what some riders feel as suspension harshness is actually the rear end cranking tight as it comes into the tight belt zone. Something I'm always conscious of. 
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