Norvil belt drive conversion

I've got it most of the way together, but I'm curious about belt tension adjustment. I've got a 74', and thought I heard something about the need for a secondary gearbox adjuster??? I haven't even figured out exactly how I adjust the one I have. Once the inner chain case is seated, it doesn't seem like I can move things. What am I missing?

The inner chaincase has a sliding seal holder that fits round the gearbox shaft that allows for gearbox movement, it's part of the chaincase. Yours should have one, it looks like 2 big steel washers that sandwich the alloy inner case. It has a felt seal in the centre. You slacken off the top & bottom mounting bolts for gearbox & can then use the adjuster to move gearbox to get correct tension. I find it best to not have the top & bottom mounting bolts too loose when adjusting things. If the rear chain is fitted make sure there is plenty of slack in it so that it can't hinder your primary adjustment.

The important thing with a belt drive, as well as the correct tension, is to make sure that the crankshaft & gearbox mainshaft are parallel. This is why a lot of people with belt drives use an extra adjuster on the drive side of the gearbox top bolt so that the gearbox can be kept parallel. I have one on mine. You can get them from most of the leading Commando specialists & it should come with a new longer top bolt.

There's lots of info on here about belt drives, do a search, & peoples love or loathing of them. Personally I like mine.

Ian

I think it was comnoz that told me if only one adjuster is used on a belt drive it's best on the drive side, not the timing side like it normally is.

Dave
69S

Greetings,
I have had my RGM belt installed for some years now and I only run one timing side adjuster, no problems so far.
As I remember the installation instructions said to use the back axle drive chain adjusters to pull (or release) the transmission
in order to establish proper belt tension. Of course you have to do the normal primary adjuster at the same time, once you get it all set and tightened you should have no problems.

GB

geo46er said:

Greetings,
I have had my RGM belt installed for some years now and I only run one timing side adjuster, no problems so far.
As I remember the installation instructions said to use the back axle drive chain adjusters to pull (or release) the transmission
in order to establish proper belt tension. Of course you have to do the normal primary at the same time, once you get it all set and tightened you should have no problems.

GB

Click to expand...

I use the standard timing side primary adjuster on a fairly snappy Combat, it is fitted with the Maney belt drive system. It took a few trials to get the belt tension correct but it now holds just fine. Being able to turn the belt 90 degrees at mid run is a good start for tension, check it when hot to insure that there is still decent slack. The best proceedure I found for setting tension after a good initial run-in was to use the adjuster to force slack into the belt, rather than to use the adjuster to tighen the belt; make sure that your drive chain has appropriate slack so that you can introduce more slack to the belt when needed.

Bill.

Unlike a chain, a belt can and will run out or in. The second adjust allow for a finer adjustment and the ability to tune the run out ( or run in), and to square the hubs. I have mine with a slightly open alignment. This does two things, One, it compensates for the inherent slop of the sleeve gear, and two, brings the belt nicely to the inner primary side to help reduce axial load.

These adjustments are almost impossible with only the one timing side adjuster.

Just repeating above wisdom above.
Belts very sensitive to pulley alignment to stay on pulleys w/o any side plate on the front pulley. If the sleeve bushes &/or clutch center bearing allow any detectable basket wobble, then its just a fairly short time before the belt edges fray on front side plates and belt completely comes apart to end up all melted and crumbled compacted in front primary area. Once tranny-clutch is stable inside then one or two gb adjusters work to align pulleys so belt stays on through many turnings to test it walking off one way or the other, then nip up tranny bolts good and should hold fine. Its very much easier to adjust belt alignment with two adjusters though. All toothed belts no matter their run length should be fairly easy to twist 90' when cold but best double checked as power plant heats and increases belt tension so still able to twist with some effort almost 90's twist. As belt and clutch and alternator don't need oil for lube or heat dumping most will just remove the felt slider seal. There is no need what ever to ventilate and I shun that in real life as grit is enemy of very fragile belt edges, but its cool to see the various artistic designs - that would leave me stranded again if I tried that on THE Grit paths.

Its not good to turn engine over much w/o oil pressure and cam lobe splash and it can take a LOT of pulley turning to see if belt stays centered or begins to gradually work off, so I do most my fine tuning w/o the woodruff key in front pulley so just spins on shaft, till belt aligned and tensioned loose enough. Belt alignment and tension once set does not have to ever be changed and should allow belt to be worked on and off w/o any extra slack moving tranny like a chain does. IF ya can't work belt on/off with just hands and probes then it will be WAY too tight once at full temp.

hobot said:

IF ya can't work belt on/off with just hands and probes then it will be WAY too tight once at full temp.

Click to expand...

+1 on that.

I have the RGM unit. These hubs are prone to swell when hot, alot. The hard lesson is when you lose clutch function.
The real hard lesson is when your mainshaft fails. I have experienced the former but thank goodness not the later.

I had set mine so loose that when kickstarting it would jump the front hub teeth occasionally. I brought it in just enough so this did not occur. Solid ever sinse. This is a very "set it and forget it" situation.

Thanks for the help. My adjuster is on the timing side. Seems like it would hit the chain guard fin on the backside of the inner chain case. Does anyone have a pic of this double adjuster setup?

I was also concerned with turning the engine w/o oil. How do you install engine sprocket key after the fact? I'm assuming that's what Steve meant by the woodruff key.? Seems like pulley is supposed to be driven on there pretty good. Do you just pry it off after you get alignment set, and reinstall with the key and that's it?

Snorton74 said:

Thanks for the help. My adjuster is on the timing side. Seems like it would hit the chain guard fin on the backside of the inner chain case. Does anyone have a pic of this double adjuster setup?

Click to expand...

Snorton
You need to have the second lollypop adjuster facing the opposite way (the threaded assembly facing forward on the primary side) there is no room to use a wrench if you put the hole facing to the rear as per the timing side. I believe clubman racing has a picture of the twin Lolly adjuster http://www.clubmanracing.com/beltdrivesnorton.php
Cheers,
CNN

Here are photos of one I put together for my project:

Drive Side:



Timing Side:



and a top view:



Russ

CanukNortonNut said:

Snorton74 said:

Thanks for the help. My adjuster is on the timing side. Seems like it would hit the chain guard fin on the backside of the inner chain case. Does anyone have a pic of this double adjuster setup?

Click to expand...

Snorton
You need to have the second lollypop adjuster facing the opposite way (the threaded assembly facing forward on the primary side) there is no room to use a wrench if you put the hole facing to the rear as per the timing side. I believe clubman racing has a picture of the twin Lolly adjuster http://www.clubmanracing.com/beltdrivesnorton.php
Cheers,
CNN

Click to expand...

Just what I was looking for. Thanx

Distinctly nicer better easier to adjust and hold alignment with two adjusters. Peel got the SS 2 adjust top bolt kit. Must give some thought to reaching this adjuster
with primary case on. It could be done flipped to rear but harder to access even if not fouling. No the out rigger will not fit to allow out the box fitting of the SS bolt kit with 2 adjusters.

Note the out rigger will not fit to allow out the box fitting of the SS bolt kit with 2 adjusters.

Just to add a bit more to this Hobot, I had to lathe the lolly's back evenly on both sides to make up for the thickness of the Maney outrigger so you could get a nut on. On the rigger side lolly I lathed a small step in it for a better fit aswell.

Caution: BEFORE you ever turn a wheel after adjusting the belt, sit on the bike and compress the shocks to check drive chain tension where the range of motion of the swingarm as axle, s/a pivot, and mainshaft align, producing the tightest drive chain position.

If you had adjusted the belt with the bike unloaded (typical) and the drive chain snug, without compensating for the drive chain pulling at it's max stretch position, it will do nasty things when it hits that position while running under load. Think "snapped mainshaft"...

Yes I had to modify Peel's SS bolt and outrigger mount flanges to split the removals proportionally and enough threads showing to fully secure, but just. Leave drive chain slack while getting the belt set easy 90' twist then just do rear chain like always, but best to put at max swing arm arc length to fine tune for least slack jack.

Has anyone gotten anything from Clubmen recently? Can't seem to get them on the phone or an email reply.

I finally got one of Clubmens dual gearbox adjusters ordered. Does anyone think it's necessary to use fine grinding paste for matching the tapers on the front pulley.

I got the dual gearbox adjuster in the mail today. Once I have that installed I want to wrap up the belt drive. Still no opinions on the fine grinding paste/ front pulley install?

My experience with belt drive front pulleys is that the aluminum pulleys will eventually expand somewhat in use from the force of the crankshaft nut pulling them onto the steel taper, requiring occasional tightening of the retaining nut. In two cases I've eventually had to shim the taper with brass shims keep the pulley from rubbing on the cases (thicker Maney cases and a set of stock cases with reinforcing disc welded on). Just my experience, and only on race bikes, so you might not have an issue on a street bike with stock cases. I'm not sure what you would gain by lapping in the taper with grinding paste. There's enough force on the pulley from the nut to pull it very tightly onto the crankshaft taper. I could see where you might find some gain in lapping in a steel pulley/sprocket, although I've never done it. Then again, I never had a problem with the stock steel sprocket getting loose on the shaft.

Ken