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Shovelhead belt riding on primary cover?

4762 Views 67 Replies 17 Participants Last post by  jonjon
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I opened my primary cover to check the chain tension, only to find that at some point, a 1 1/2" belt drive conversion had been done. It looks like they intended a dry closed primary because blocked off the oil ports in the back of the inner primary case. There is still some oil leaking in, probably via a bearing, but that explains why they left the primary case drain plug out.
What worries me more (other than the shoddy safety wire attempt that I found 馃槵) is that the lower run of the belt appears to rest on one of the case's thread bosses.
The belt tension appears to be in spec with what I've read, and the belt doesn't seem to be in bad condition (no frayed edges, missing teeth etc.). How worried should I be? I have seen tensioners, but with the belt that is on there, I wouldn't have near enough slack to put one on. Thanks in advance for any advice!
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Look at 11 o'clock at you outer clutch hub as i looks like a crack to rivet? In your pics i cant see the rub point you refer to. Also is the outer cover vented as they use to get heat and break belts due to expansion. I ran a 3" and the belt tightened a bit due to alloy pulley on crank
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Look at 11 o'clock at you outer clutch hub as i looks like a crack to rivet? In your pics i cant see the rub point you refer to. Also is the outer cover vented as they use to get heat and break belts due to expansion. I ran a 3" and the belt tightened a bit due to alloy pulley on crank
You may remove some material at rub point. Also fit a new motor sprocket seal with spring facing in. Probably the same with trans and clutch pushrod seal in nut if in there.
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Did the safety wire guy ever see a safety wire job before?
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As Hoges as said, but it's also worth checking your tranny alignment, they tend to walk and rub if something has slipped a little, The tranny I'd imagine has a lock bolt or adjuster w/e you'd like to call it.

I've had mine rub both sides depending which way the tranny was out of line.
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While your safety wire is not done correctly. It isn't a problem as it will still keep the bolts from falling out.
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his problem ISN'T the belt being out of allignement,.... but CLOSE to or touching the lower cover bolt hole boss !!,
read what he said !,...
that can only realy be solved by use of a smaller front pully or smaller rear with probably a different belt,
Personally, I'd just ditch your covers & run it open as belts like to be run,... nice n cool...
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First off, thanks for pointing out that crack, I didn't even notice it, but will definitely investigate! So far, I think the alignment is good, because the edges of the belt don't look melted or frayed or anything. But (at least at rest, in neutral, anyway) the lower run of the belt is resting on the thread housing boss right under that rad safety wiring, which seems bad.
Like tzienlee mentioned, I probably would need different pulley(s) to remedy this. I read in other places that idler bearing tensioners aren't recommended for closed primaries, so that route is probably out. I really would like to keep it closed, just because I like the shiny tins 馃榿
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No need to change either pulley, that would create monumental problems as belts are not available in "any" size.

Find out where the oil is coming from don't shotgun replacement parts, it might be trans juice....

I would install a helicoil in the cover bolt to strengthen the threads and then machine back the cover for more belt clearance.
One of those little belt sanders or a die grinder with a burr would do the job nicely on the bike.
Mark it with a sharpie and take the belt off so you have room to work.
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Thanks for the idea, Rick, makes sense, about the helicoil. Plan of attack is now: seal where the oil is coming in, strengthen the threads before removing material at the rub point, and check out that possible crack in the clutch drum. Before buttoning it back up, check pulley alignment. Then figure a way to get some cooling in there. If I lose a belt after that, it's gonna be open primary time!
Thanks all for your help and advice! 馃憤
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Dont think the outer primary bolt goes in that deep? To need helicoil. You can buy vented inspection & derby covers.
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A) That belt don't appear to be touchin' nothin, and the belt itself doesn't have witness marks so far as I can see.
A.5) If you absolutely have to remove material (I wouldn't), use jewelers files. There is absolutely no reason to go ham and get in there with a power tool. Slow beats fast here.
B) That safety wire job does indeed suck dog balls, but in fairness, that's not the easiest place to do a pretty job and sneak in your safety wire pliers.
C) Vented covers! Jesus wept, the money some of these guys must have. It's free to just leave yours off, or if they're really boss and you have to have them, make some spacers up and use longer hardware. Lots cheaper, works fine.
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Don't leave the covers off!
The first pebble that gets in there will shred the belt.
I've run that set up for years on all my Shovels. Hot as Hell here in Phoenix.
All I do is put a 1/4" spacer at each bolt on the derby and adjuster covers and leave the drain plug out.
Gives it just enough air to cool the belt and stator but won't let anything big enough to hurt the belt in.
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Just so you guys don't think I left that safety wire as was, lol.
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Thanks for the idea on spacers, that's easier than my thought of making new covers (which I might do down the line, since I've pounded my share of tin over the years). It looks like I have an aftermarket outer that has 36-54 oval style derby cover and inspection cover, but all the vented derbies I see are the three hole round style? Thanks again, guys;
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Don't grind your cases. Just put the belt tensioner on there that's meant to be on there. You'll need a bigger (correct) size belt to go with it. The tensioner pulls the belt up and away from that boss as belt comes around from the front pulley.

Here's a pic of one with the belt and tensioner
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I had a similar probelm to you a while back, couldn't figure out how to get the right belt tension. I needed a tensioner. I ended up making a DIY one from some bearings on a bolt, to work with a tin primary: Primary Belt + rotary top + round swingarm, too loose
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Nick, I was thinking of doing that but I had read in a few places that that style tensioner wasn't recommended for closed primaries? Not sure if they meant an oil filled primary (in which case, you wouldn't want a belt anyway!), or if they were referring to a dry but still tin covered primary (maybe because of heat?). In any case, until I can do more research on tensioners, I'll vent the cover to keep the heat down, and just keep a cautious eye on belt condition 馃榾
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Nick, I was thinking of doing that but I had read in a few places that that style tensioner wasn't recommended for closed primaries? Not sure if they meant an oil filled primary (in which case, you wouldn't want a belt anyway!), or if they were referring to a dry but still tin covered primary (maybe because of heat?). In any case, until I can do more research on tensioners, I'll vent the cover to keep the heat down, and just keep a cautious eye on belt condition 馃榾
If you had an oil filled primary, you'd be running a chain. In that case yeah, that would be the wrong kind of tensioner. Chains have the ones that sits below the chain, pushing them up.

The one I mentioned would be all good in your bike, open or closed. This is what they look like. It says "open belt" but they're for closed primaries too
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The one I mentioned would be all good in your bike, open or closed. This is what they look like. It says "open belt" but they're for closed primaries too
Thanks for the additional info. And your post about building your own tensioner also rocks! Great job 馃憤
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Thanks for the additional info. And your post about building your own tensioner also rocks! Great job 馃憤
No problem man. Hope it helps! Let us know how you get on 馃嵒
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I've run a jillion miles with no covers. Stones have never been an issue.

Every single belt I've run with a tensioner has failed spectacularly.

Anec-data.
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