Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 31 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1
1. K, line up the dots.

2. Loosen the tensioners.

3. Remove the belts.

4. Put the belts on, lining up the dots.

5. Adjust and check the horizontal belt tension in place because the motor is at TDC on that cylinder (5mm allen key goes, 6 mm does not).

6. ***SPIN THE MOTOR TO PUT THE VERTICAL CYLINDER AT TDC.***

7. Adjust and check the vertical belt tension.




The issue is with step #6. Why would I do that? The Haynes manual doesn't require it, and the tension on the belt should NEVER change throughout it's rotation... if it does, there would seem to be a big problem with the belt system... belts are supposed to maintain constant tension throughout their travel - that's one of the reasons the tensioner is there.

I can do it, I just don't understand WHY to do it.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #3

·
Registered
Joined
·
954 Posts
Would it take the closing-spring tension off of the cam on the vert.pot?, This would give less "pull" on the belt for a better belt tension-reading?

& no, never done that myself either. :D
 

·
Registered
Joined
·
94 Posts
By doing the 5mm - 6mm method of adjusting there is no reason to do step 6. There is just too much room for it to make any measurable difference.
 

·
Registered
Joined
·
293 Posts
The valve closing springs are pretty strong (try rotating the camshaft pulley with the belt off). It will cause tension difference between the sides of the belt. I would adjust the belt tension in a position where both valves of the cylinder are closed, for example at tdc.

I have tried this on a desmoquattro, don't know if the due has weaker springs.
 

·
Registered
Joined
·
527 Posts
I found the whole 5-6mm alien key thing open to a lot of interpretation, if you have a iPhone there’s a app (Gates Carbon Drive) to adjust the belt harmonically.
 

·
Registered
Joined
·
247 Posts
Yeah i skipped step 6 too.
 

·
Registered
Joined
·
165 Posts
I found the whole 5-6mm alien key thing open to a lot of interpretation, if you have a iPhone there’s a app (Gates Carbon Drive) to adjust the belt harmonically.
Interesting app, thanks for posting about it. Last summer I read about an Android app (guitar tuning) that displayed Hertz instead of just sharp or flat. I looked and couldn't find anything similar for the iPhone.

I dislike the 5-6mm allen wrench test. I'm a bit ham-fisted and find that I can squeeze either sized allen under the belt if I try hard enough. So I just tensioned as I felt appropriate but have been really concerned about riding since then (probably 100 miles on the bike since I tensioned the belts after replacing them). It doesn't help that the vert belt was melting and the idler bearing was seized when I pulled everything apart to do the belt change.
 

·
Registered
Joined
·
7,083 Posts
I have only changed mine once, so I am not an expert. I will just say in general that it never hurts to follow directions. I rotated the motor several times while checking that the marks lined up and adjusted tension til I was comfortable with the results. I thought the 5-6 mm thing was kind of vague, but my Harley drive belt tension tool was set to the same tension, so I double checked with it. Ended up a tight 5 mm to match 10# tension. They are bound to stretch a bit over time.
 

·
Registered
Joined
·
3,977 Posts
i always tension them without load from the cams, which means each cylinder at tdc firing. that's why you rotate the engine. there is a little difference, as the cam is trying to pull the belt when a valve is open.

how you do it is up to you, you're free to make up your own method.
 

·
Registered
Joined
·
3,261 Posts
Yep don't think step 6 is needed, believe in LT Snyders book he says it's not needed.

Can you do the twist check on a two valve, ie on the longest section of the belt, twist it 45 degrees and that's a good tension. FYI, I just bought the moto reva harmonic tuner, but after LT Snyder's seminar I'd probably be equally comfortable doing just the twist check.
Chris
 

·
Registered
Joined
·
266 Posts
tension - no tension - tension - etc.

only have a 5 month riding season up here, so i detension the belts for the off-season on my 96 900ss/cr. i re-tension using the 5/6mm wrench method.

at only 1400 miles per year, belts look new, all is clean inside where the belts reside, tensioners feel nice.

changed 'em at 6000miles, now at 9000 miles but at the 2 year "limit".

where'd that come from anyhow? a ducati service buletn? my manual says to replace belts at 18000miles.
 

·
Registered
Joined
·
3,977 Posts
i've just had a look through all my manuals and the first reference to two years is in the1999 996 manual. then all the 2000 manuals have it.

strange, the first time i got told it was sept 98, when we had a customer's 916 break a belt at 2 and a bit years and 10,000km and we got told very quickly "every two years" by the importer. it was really critical on the 4v until they updated the belts. lots and lots of 748 and 916 broke belts. 2v do it very, very rarely.
 

·
Premium Member
Joined
·
99 Posts
I don't know how much difference it makes, the tension range that is acceptable is likely to be quite large. But I did mine recently (4 valve) and found 2 things:
-My droid app (gstring) worked as well, giving identical readings, as the more dedicated and costly tool I bought to read frequency
-Checking the tension at TDC vs. On cam made a very large difference in the measured tension. On the range of frequency of 108 at TDC vs. 135 on cam.

Again, I don't know if that makes a huge difference in practical terms, but its so easy to simply rotate the vertical to TDC why wouldn't you do it that way?
 

·
Ducati Acolyte
Joined
·
819 Posts
I found the whole 5-6mm alien key thing open to a lot of interpretation, if you have a iPhone there’s a app (Gates Carbon Drive) to adjust the belt harmonically.
Thanks a bunch. I just downloaded the app. You just saved me a bundle on buying the MotoReva unit :)
 

·
Registered
Joined
·
165 Posts
I don't know how much difference it makes, the tension range that is acceptable is likely to be quite large. But I did mine recently (4 valve) and found 2 things:
-My droid app (gstring) worked as well, giving identical readings, as the more dedicated and costly tool I bought to read frequency
-Checking the tension at TDC vs. On cam made a very large difference in the measured tension. On the range of frequency of 108 at TDC vs. 135 on cam.

Again, I don't know if that makes a huge difference in practical terms, but its so easy to simply rotate the vertical to TDC why wouldn't you do it that way?
gstring :D
 

·
Registered
Joined
·
32 Posts
Discussion Starter #20
only have a 5 month riding season up here, so i detension the belts for the off-season on my 96 900ss/cr. i re-tension using the 5/6mm wrench method.

at only 1400 miles per year, belts look new, all is clean inside where the belts reside, tensioners feel nice.

changed 'em at 6000miles, now at 9000 miles but at the 2 year "limit".

where'd that come from anyhow? a ducati service buletn? my manual says to replace belts at 18000miles.
That's the million dollar question right there folks...

If you can get 18,000 miles out of them, then I think I'd rather do that after changing this set than do this every couple of years.
 
1 - 20 of 31 Posts
Top