• Husqvarna Motorcycles Made In Sweden - About 1988 and older

  • Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

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    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Chain Tensioner Spring Info Needed

Crashaholic

Crashaholic

Husqvarna
Pro Class
I've been thinking about a chain tensioner for my 75 450 for a few months and finally got the bug to proceed. I tried a universal tensioner but it looked mickey mouse so I decided to build one like a tensioner on the early 80's Huskys.

I'm at a point that I need to purchase the spring and with my nature to second guess everything do I can't bring myself to decide on a spring rate. I could spend $40 and buy five different ones but I don't feel right unnecessarily throwing money at something, even if its at my Husky. So I'm looking for someone who has an early 250, 430 with a chain tensioner, and a calipers, to gather a few measurements for me.

1. The wire diameter.
2. The number of coils.
3. The degrees of wrap around the spring hub to reach the arm that has the tensioner wheel. Is it 90 degrees, 180 degrees or what?
4. Whatever info you think will help with a spring decision.

The pic is a templet of the tensioner mounting plate from the left side of the bike. Its bolted on the two front chain guard brackets. Let me know if you see something that I've overlooked that may cause a failure or may not work in the first place.

The reason for this project is due to longer shocks and the 75 WR swingarm shock mounts are about an inch forward compared to the older swingarm design. This causes the shocks to mount at less of an angle, more straight up and down. This lowers the axle, or raises the seat height depending on how you look at it, creating more chain slack.

I've got other pieces fabricated so maybe I'll post some more pics, after I take a nap.
 

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Don't have any Huskys that new, but maybe a pic or two to help - from HVA Factory and HVA Poland (Part # 15 15 454-01 / 1980 to 84 chain tensioner spring):

CT1 - Copy.jpgHVA Poland - Copy.jpg151545401 - Copy.jpg
 
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Thanks for the information Vinskord. Before starting my project I checked out HVA Factory and Husqvarna Parts for costs and ideas. I wasn't aware of HVA Poland, fun site to window shop. Thanks again!
 
I've checked out the tensioner parts offered on HVA Factory and HVAPoland plus Husqvarna-Parts and the cost for a complete tensioner ranges between $150 to $200. Being retired and enjoying tinkering provides me with the time needed to research and build a tensioner from scratch with parts I already have, with a few exceptions. I needed a spring and McMaster had one I liked for $7. Took me a while to figure out how torsion springs are rated and how the different variations in windings worked. McMasters also had some nifty shaft mounted grease seals for $2 each and a bag of o-rings for $5. I even got a 12 inch piece of 3/4" x 1/2" steel tube for $6. Then there was shipping, only $14.

I think my parts cost so far will be about $55. Fabrication labor and research looks like it will entail about 20hrs. So thats 20hrs X $80 per = $1,600 + $55. If any of you would like me to build one for you just let me know. :lol:
 
Some food for though - in a number of videos of motorcycle chains in motion - near the countershaft the chain is still somewhat close to the sprocket. A much greater chain gap to the sprocket is at the rear (video attached - at 1:04). This is why a majority (not all) of chain guides / tensioners are located towards the rear of the swingarm. Of course having both is ideal.

View: https://www.youtube.com/watch?v=G3vxURWjLnA
 
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The slack in that drag bike chain is insane. I'm surprised they're running the chain that loose. Having that chain come off with 500hp behind wouldn't be pretty. Its my guess that there was no tensioner below the countershaft.

After looking over the springs that come on the early 80's Huskys and researching spring rates I purchase two springs, one with 21 inch/lbs of torque and another with 32 in/lbs. This is determined when the spring is loaded to the point that both legs are parallel. The 21 spring seems plenty for my 450 if its at least 80% loaded when installed. That drag bike could use a tensioner loaded with at least 50 in/lbs 100% loaded, maybe more, and mounted below the countershaft. With that much torque I suppose having it closer to the back would be better.

The rub block tensioners, i.e. no wheel, are okay but I think reducing drag is better but then theres the maintenance issue with the plastic block wearing out vs. bearings in the wheel.
 
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