Belt Drive Ventilation

steveyacht · May 23, 2011

I removed the Chain drive from the primary opting for a belt drive. Lighter, quieter, one less place for a leak and all that rot. Should I get another outer primary and have it drilled for cooling, run with the inspection plugs out or just leave it be?

pete.v · May 23, 2011

I have seen it go both ways. My RGM hub swells when hot and the adjustment has to be just right. If too loose, it will jump teeth on the crank hub when kicking over. Too tight and clutch function fades. I am not saying that there is a fine line, it just has to be "just right" in my particular instance. Cutting holes and drilling my case help widen the window.

askdoctorday · May 23, 2011

I have slots and holes machined into my cover, but I keep the inspection plugs in because I think it looks sloppy without them. Just my $.02

ejd

geo46er · May 23, 2011

Hi Steve,
During the installation of my primary belt kit I followed a suggestion from "Dynodave" and pulled the tin plates/felt seal out of the inner primary case. To prevent any water from pooling in there I drilled a small hole up from the bottom in the lowest area of the outer primary cover, so far I have had no problem.
I think leaving the plugs out of the outer cover just wouldn't look right.
Buying a used cover to poke full of holes sounds like a good idea as they can usually be had for a reasonable price, and will give you a chance to "express yourself" with the design, http://www.clubmanracing.com sells plain fiberglass covers for just such a purpose.

Hobot · May 23, 2011

Ventalating a belt drive primary is purely for accents, which I verified from every vendor Kenny Dreer to Steve Maney included. When I got bored I made a forced air vent in front of inner cover and its lower rear. W/o the inspection plugs it looks like pieces missing, similar to lower IQ looks of us hicks with front teeth knocked out. Not the best idea I had and will not do it that way again for obvious reasons.
The main weakness of belt drive is its edges, get grit enough and side un ravel till belt piles up behind pulley and alternator. Proper belt tension cold is just able to twist long bottom run 90's, then can weld gear box in place as this is loose enough cold to work a belt on and off by hand and probes. Belts do transmit shock about as much as a chain btw.

DogT · May 23, 2011

Boy, looking at that front slider, how many times has it hit the gravel Steve? I thought you polished things to 2500? Norvil (Les) says his belt drives don't need any ventilation. I guess that's his opinion. I don't have one, yet.

Dave
69S

bill · May 23, 2011

I have 30,000 miles with a closed primary and belt drive with NO issues and that includes a few 650 mile days.

Hobot · May 23, 2011

Roadholder forks do not touch THE Gravel in crashes, edge of rims do, to get pebbles shoved into the bead and rim chewed. What ya see above is just mad spray steaks off tire going fast enough they fly straight back. It just scrubs off to reveal the shiny under neath. Note the Al skip plate or Iso and cases get abraded away. At Texas Mile I learned about clear helicopter leading edge tape, only about $100 a 2"x30' roll.

No opinions needed, belt drives are fine to run sealed oil tight in highest heat of summer hard runs. I did have a fiber air filter trapped behind the screen so not much grit got in and after water crossings it just slings out the rear vent. Anywho Peel's 1' cover stayed intact sexy art deco profile.

1up3down · May 23, 2011

12 years now with a belt primary.

Completely stock inner and outer primary covers. No inspection plugs removed or crafted ventilation.

I live in the desert southwest USA and ride for hours at a time in temps hovering around 100.

No issues, no problems.

I did put on a new belt a year ago. The original belt went 10 years and could have gone longer. Just thought it time.

Hobot · May 23, 2011

Note the sand blast on header bend? Sometimes stones get flung off tire and hit my shin through boot so hard it breaks the skin. I often go faster over THE Gravel than hwy d/t lack of THE Fuzz. Peel can out accelerate and out maneuver racing ATV's blasters in their own elements and deer don't stand a chance if I see em first. Do carry a spare belt and tools enough to remove alternator for a few 1000 miles till ya know for sure how well your install can be relied on. Ugh l sure will.

Belts can stand holes in their center but not much resistance to edge abrading.

DogT · May 23, 2011

I used to work in the post office with the automated sorting equipment for the mail. They used Kevlar belts in them. They were tough, but couldn't stand much bending or warping. When they did break, we had some guys that would patch them with duct tape and they ran fine as long as there was not too much tension on them and I'm talking 50' belts with several 5HP 3 phase motors on them but no teeth, just rollers and flat belts. Just a side note. Wonder what kind of belts these primary ones are?

Dave
69S

gjr · May 24, 2011

I have 15-20,000 miles on a Norvil belt drive primary. No ventilation. Works fine. 500+ mile days in warm (90+F) conditions don't seem to be a problem.

Greg

DogT · May 24, 2011

Greg, I was thinking about the Norvil belt drive. Sounds like you are happy with it, was shipping a killer? Pretty much drop in unit? Not to hijack the thread too much. Les seems to have the only one that comes with all sorts of gearing ratios as far as I can tell? I'd like to keep my 19 tooth ratio.

Dave
69S

Matt Spencer · May 24, 2011

2 or 3 vertical slots in front of the Alternator and outlets in the INNER cover aft ( behind clutch ) IF youre going to ventilate it .

For cooling , the Outlet is as important as the Inlet , and likes to be 2 1/2 to 3 times the inlet size ( area ).
The fine filter material inside on inlet obviously stops grit circulateing .

Air through will cool air inside , but air traveling IN one side , and OUT the other of the mechanism will col the mechanism .
If you wanted to be stupid , vanes on the rear of the clutch angled into the atmo. would FAN it out through radial holes behind .

The British bike Rider always knows the longest road home . :lol:

Hobot · May 24, 2011

I don't need no stinking fan blades on the belt of clutch to fan air out Ms Peels
exit vent. Look up Tesla turbines or just feel the breeze of opened up belt drive. But as me/we have learned, vents are purely decorative and for pilot pleasure, even racers.

Next Ms Peel with Drouin thin belt drive and 40 mm Maney 1' belt and extra heat and speed - I've configured a forced air scoop up high next to cylinder where tire splash don't reach much - so air first flows around blower drive pulley then into 1' drive pulley then out behind the clutch basket via the gaps in inner case to fit Maney out rigger bearing support. Side view of Peel will show no vents, just art deco smooth sexy Hoover vacuum like style.

Belt Drive Ventilation

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