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Final drive belt tension.

Final drive belt tension.

Far Canal
4 years ago

This arvo I got all technical regarding the belt adjustment.
Wanted to work out how to adjust the belt with rear wheel in the air and no one sitting on it so that in the future I can do the adjustment with no assistant.
The workshop manual only gives a measurement with the right tension tool with rider on bike, bike on ground.
First up I measured distance from rear pulley to fender bracket wheel in the air. 146mm.
Then measured the same distance with bike on the ground and me sitting on it. 131mm.
Next put the bike back in the air and using a ratchet strap cranked the swingarm up till it was 131mm, simulating me on it.

Then set the belt tension at the tightest spot (see liquid paper marker on belt just in front of deflector) to exactly half way between workshop manual specs 19mm.
Then torqued up the axle bolt.
Out of curiosity I re-checked the tension after torquing up the axle nut and FUCK ME DEAD!, it had changed to an out of spec measurement.
So faffed round some more checking the tension with the axle nut torqued up till I was happy with the play.
So that is checking the tension with myself on the bike (even though I wasn't).
Next step was to see what the play in the belt was when the ratchet strap is released and pissed off.
To my astonishment there was only a cunt hair of difference between the measurement on the tensioner gauge, still way within the specs.
My conclusion is therefore, in the future check belt tension with wheel in air to factory spec (no accomplice needed), BUT check it with axle nut torqued up. Manual does not say that and I'll be buggered if a bloke in a dealership would be this thorough.
I'm not pedantic or anything.
Might just go and check my letterbox bolts are torqued up to spec now.

brucefxdl
4 years ago

Quoting Far Canal on 30 Dec 2019 09:29 AMedited: 30 Dec 2019 09:45 AM
This arvo I got all technical regarding the belt adjustment.
Wanted to work out how to adjust the belt with rear wheel in the air and no one sitting on it so that in the future I can do the adjustment with no assistant.
The workshop manual only gives a measurement with the right tension tool with rider on bike, bike on ground.
First up I measured distance from rear pulley to fender bracket wheel in the air. 146mm.
Then measured the same distance with bike on the ground and me sitting on it. 131mm.
Next put the bike back in the air and using a ratchet strap cranked the swingarm up till it was 131mm, simulating me on it.

Then set the belt tension at the tightest spot (see liquid paper marker on belt just in front of deflector) to exactly half way between workshop manual specs 19mm.
Then torqued up the axle bolt.
Out of curiosity I re-checked the tension after torquing up the axle nut and FUCK ME DEAD!, it had changed to an out of spec measurement.
So faffed round some more checking the tension with the axle nut torqued up till I was happy with the play.
So that is checking the tension with myself on the bike (even though I wasn't).
Next step was to see what the play in the belt was when the ratchet strap is released and pissed off.
To my astonishment there was only a cunt hair of difference between the measurement on the tensioner gauge, still way within the specs.
My conclusion is therefore, in the future check belt tension with wheel in air to factory spec (no accomplice needed), BUT check it with axle nut torqued up. Manual does not say that and I'll be buggered if a bloke in a dealership would be this thorough.
I'm not pedantic or anything.
Might just go and check my letterbox bolts are torqued up to spec now.

Might just go and check my letterbox bolts are torqued up to spec now........lol. just checked mine too ,big storm about to hit,mail box should still be there in the morning.it seems to me [ and i only know my own '-7 dyna ] that there a few different factory methods for different models,....and a few personal opinions on how to ,or not to.mine gets the fine vibes it its a bit to tight.cheers

skirtster
4 years ago

I like your theory, I would not have thought a ratchet strap, when you take your bike to a dealer and they adjust belt do they need to know your weight to adjust belt or before you ride 2 up do need to readjust belt.

Far Canal
4 years ago

Quoting skirtster on 30 Dec 2019 10:19 AM
I like your theory, I would not have thought a ratchet strap, when you take your bike to a dealer and they adjust belt do they need to know your weight to adjust belt or before you ride 2 up do need to readjust belt.

My 08 softail gives a tension measurement with wheel off the ground so I guess dealers go by that.
What flummoxed me was the difference between the specs with the axle nut torqued up and not on this older bike. Will definitely check this next time I do the tension on the 08 softy.

Baloffski
4 years ago

Extremely interesting subject, as enlightened by the methodologies given on correct belt tension. Thanks for the knowledge, much appreciated.
I for one am now jumping on board to follow proceedure/s on correct way to adjust and monitor drive belt.
Shhhesh, didn't realise the complexity of the whole exercise, which is leaving me a little 'tense'.

PappaSmurf
1 year ago

Quoting Hoodeng on 17 Dec 2019 10:09 PM
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.

I know it’s been a long time since your post, but do you happen to remember the tension given for the Gates Krikit gauge. I have one of those and it I think it would be far easier to check the belt tension with one of those.

Hoodeng
1 year ago

I don't know of a reference from Gates regarding the Krikit being used on a Harley Davidson belt drive.
The Harley tool does not work the same way although the outcome is similar.
Best way to compare would be to set the belt using the Harley tool then check it with the Krikit and see what it reads.

Cheers.

brucefxdl likes this post

Neale
1 year ago

Is it just me or does the belt tension on an M8 seem to be tighter than that of an old twin cam like my 08 Electra glide.
I asked the dealership when I bought my M8 heritage new and they said it was where it should be.
I know that if I ran my EG belt that tight it would make the tranny howl.
Dunno if it’s some new design or not.

Ultramick
1 year ago

Quoting Neale on 06 Apr 2023 09:39 AM
Is it just me or does the belt tension on an M8 seem to be tighter than that of an old twin cam like my 08 Electra glide.
I asked the dealership when I bought my M8 heritage new and they said it was where it should be.
I know that if I ran my EG belt that tight it would make the tranny howl.
Dunno if it’s some new design or not.

That's right Neale, it is tighter on the M8s. ( Not sure if the Heritage set up is the same as the EGs) Without having a look at my manuals I know my 03, 07 and 2012 Ultras definitely had a looser tension. I do have one of HD belt tensioner gauges somewhere, prolly in my bottom drawer, but I don't use it any more. I just do it up tighter than I used to. Maybe my 2020 Ultra has about 10mm ? I can check it for you if you want. When ever I remove and replace the rear wheel I use a bit of duct tape or masking tape from the swing arm to the axle cam washer, mark a straight line between the 2 parts, cut the tape at the gap and line the marks up when I replace the wheel. Dunno if that makes sense to you, but I know exactly what I mean !

Neale likes this post

Ultramick
1 year ago

Just looked at my owners manual and for my 2020 Ultra the deflection should be 9.5 -14.3 mm.
A 2020 standard EG, Road Glide, Road King and Street Glide should all be 6.4 - 11.1 mm.
Who knows why the difference and who knows why it is 14.3 or 11.1 mm. Surely 14 or 11 mm is near enough. I guess the computer said so and we are not to argue with them.

Neale likes this post

Neale
1 year ago

Quoting Ultramick on 06 Apr 2023 11:57 PM
Just looked at my owners manual and for my 2020 Ultra the deflection should be 9.5 -14.3 mm.
A 2020 standard EG, Road Glide, Road King and Street Glide should all be 6.4 - 11.1 mm.
Who knows why the difference and who knows why it is 14.3 or 11.1 mm. Surely 14 or 11 mm is near enough. I guess the computer said so and we are not to argue with them.

Thanks for the reply. Appreciate it.

tussuck
1 year ago

And cold not hot. Do you have the presssure tool as well?

408
1 year ago

Quoting Ultramick on 06 Apr 2023 11:57 PM
Just looked at my owners manual and for my 2020 Ultra the deflection should be 9.5 -14.3 mm.
A 2020 standard EG, Road Glide, Road King and Street Glide should all be 6.4 - 11.1 mm.
Who knows why the difference and who knows why it is 14.3 or 11.1 mm. Surely 14 or 11 mm is near enough. I guess the computer said so and we are not to argue with them.

You have to remember that the the Harley engineers come up with this stuff and they work with imperial measurements.
9.5 mm is 3/8" and 14.3 mm is 9/16" so the requirement is for the setting to be within 3/32" either side of 15/32".

Grease Monkey likes this post

tussuck
1 year ago

I heard that a rule of thumb (if you do not have the gear) is to twist the belt to 90 degrees.... thats pretty close to the right tension.

408
1 year ago

I've read 45° mid run on the top and used that method to adjust the tension in the past.
I checked with the tool against that method when I got one and it seems good.
But everyone is going to have a different grip and twist strength.

Neale
1 year ago

I’m probably just overthinking it.

Far Canal
1 year ago

Quoting 408 on 07 Apr 2023 10:51 PM
I've read 45° mid run on the top and used that method to adjust the tension in the past.
I checked with the tool against that method when I got one and it seems good.
But everyone is going to have a different grip and twist strength.

"But everyone is going to have a different grip and twist strength."
That is absolutely correct 408. Even on chain final drive bikes there was an ideal amount of play in the chain(according to the workshop manuals), measured half way between sprockets, BUT it never mentions how much force to put on it to get the play right.
That is why in my opinion it is well worth the few bucks for the Harley tension tool.

Ultramick
1 year ago

Quoting Neale on 08 Apr 2023 02:37 AM
I’m probably just overthinking it.

That's better than UNDER thinking it.

Far Canal likes this post

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