rear chain tension

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g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

rear chain tension

Post by g.m.c.janssen »

Just fitted new chain and sprockets, the old chain was broken partially. Had luck that I saw it just in time.



But now completely confused how the rear chain tension should be set :banghead:

1) The workshop manual says there should be a person sitting on rear part of the saddle, the owners manual says without a person on the machine

2) the text in the workshop manual mentions a rebound range of 15-20 mm; the figure shows a 15-20 mm distance between chain and swing arm, this fits better with the text in the in the owners manual; but it mentions a minimal distance of 15-20 mm, so 30, 40 or 50 mm would be OK too, I doubt

So what is the correct procedure?
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broken chain
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Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
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Mc tool
paso grand pooh-bah
Posts: 1794
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: rear chain tension

Post by Mc tool »

I hope you didnt get the same chain , looks light weight ,like maybe for a MX bike. Could be why it broke , also could be over tightening chain.
The chain tension changes as the rear suspension moves up and down . The chain is at its tightest when the output shaft (with front sprocket on it ) the swing arm pivot ant the rear axle are in allignment . At this point the chain should have minimal slack but not be pulled tight . If you can be bothered you could use a ratchet tie down and pull the suspension down till these pivots are alligned and set the chain tension to have next to no slack ( but not tight or stretched ) and then release the suspension and see how much slack you now have . This is your correct chain slack ....usually about 20- 25mm .
Chain slack ,(clearance ,tension , whatever you want to call it ) can negatively affect gear changes . If the chain is to slack it can make changes clunky and can even cause missed gears if you have a delicate toe . To much slack can also cause excessive transmission snatch. Properly set up (chain tension ) and well coordinated ( throttle hand and left foot ) your gear changes should be almost be a instinctive thing.
I have had good success with DID and RK
O ring chains but you gotta get the heavy duty ones with thick side plates ...not 125-250cc mx bike chains. A good chain on good sprockets that is cleaned and waxed should last 20,000 miles.
I use water soluable areosol degreaser and a paint brush to clean chain ( on the bike )and when its dry I used Maxxima areosol chain wax ( doesnt fly off ). Remember you are only lubing the chain to sprocket contact and a wee bit on the o rings so you dont have to put heaps on . I liked to clean and lube chain every 1000kms ( 600 miles ). Piece of cake :-)
I wish I was young again............Id be heaps smarter than last time
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randtcastell
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model: 750 Paso
year: 1987
Location: San Francisco Bay, California USA
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Re: rear chain tension

Post by randtcastell »

Thank you for your excellent post. I always learn from you. Cheers! :^)
g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: rear chain tension

Post by g.m.c.janssen »

Mc Tool, thank you for your extensive explanation!

Will check again if my new chain meets specifications. It is a AFAM 520 XSR specified for Ducati 907 and others, the broken one was the same size from DID
Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
User avatar
Mc tool
paso grand pooh-bah
Posts: 1794
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: rear chain tension

Post by Mc tool »

I had never heard of Afar chains ,but then I haven't bought a chain for more than 10 years , certainly looks the part , them Japs make some really good quality stuff and if it's the one the recomend .....
One thing I omitted in my previous post is that the rollers also need a bit of lube . I usually get a longer straw for the aerosol can as it slows down the delivery rate and if you put a kink in it can help your aim . I aim for the spot where the rollers and side plates meet . I lift the back wheel on a w/shop stand . :-)
I wish I was young again............Id be heaps smarter than last time
g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: rear chain tension

Post by g.m.c.janssen »

Hi Mc tool, sorry but I didn't get your last point about the rollers
Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
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Mc tool
paso grand pooh-bah
Posts: 1794
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: rear chain tension

Post by Mc tool »

The rollers are the little steel tubes that contact the sprocket ,situated between the inner side plates . These roll around the bush between the inner plates ( you cant see them) pin that link the inner and outer plates . You need to get a bit of lube between the pin and the rollers .
Google roller chain link ( I cant figure out how to post the pic here) and you can see the side plates , pin , bush and roller
I wish I was young again............Id be heaps smarter than last time
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higgy
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model: 906 Paso
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Re: rear chain tension

Post by higgy »

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Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
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Mc tool
paso grand pooh-bah
Posts: 1794
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: rear chain tension

Post by Mc tool »

Ah Higgy ,you clever bugger ......so whats my feckin password ? My smart phone logs on automatically but my laptop ...not so much , and Ive lost my note book with all my passwords ( I think Di chucked it out ). Just gettin old .
I wish I was young again............Id be heaps smarter than last time
g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: rear chain tension

Post by g.m.c.janssen »

Thanks for all suggestions and clarifications! The chain has been fixed with the additional lube between pin and roller!
Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
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