New Belt Drive

Hello all,

A quick update on this thread:

First thanks for the info on the shims. As you correctly pointed out the shims were not behind the primary and that is why it cracked at the front. I purposely removed the shims as the primary inner was bowed and I thought it would un bow if I removed the shims. Then ultimately of course I gave up anyway and went with the belt drive. No worries though as I have another primary casing.

My biggest worry right now is the gearbox main shaft and clutch wobble issue. So I took everything off and set up my dial gauge. As you know it is threaded on the end of the mainshaft and of course very difficult to measure with a dial gauge. Based upon checking many times I have come up with the conclusion that the mainshaft could be bent by 5 thou. I am going to check it again today and try and put a sleeve over the threads.

So I called Quaife and they told me Mick Hemmings is the outlet for their parts. I called him and he said the clutches do wobble a bit due to having that ball bearing in the clutch. I was told Quaife do not make standard gearbox parts and he told me to get a Norton one and it will be straight.

So my plan is to order a new stock mainshaft, fit that to G/B and have another go at this. I will shoot another movie with the new mainshaft and we will see if the clutch still wobbles. The problem with this kind of thing is that if I dont change it I will be riding my bike like a nut in the mountains as I do and I will be thinking about my clutch wobbling,

All for now Jerry

I will be making a serious attempt to make my belt primary clutch basket not wobble.

The motor is out for a complete refreshing so this is a good time.

New clutch hub should be arriving today.

Heinz Kegler believes much of the wobble is from the hub having too small of an area to tighten down onto, and the snap ring limits really hard tightening.

So, Heinz is going to weld a large diameter steel washer in the back of the hub and eliminate the snap ring.

We are still a few weeks away from the install but this should be a really good test of fixing the basket wobble.
Hopefully, I will remember and take some pictures of what Heinz ends up with. Posting a video will be a real challenge, not very computer tech savvy.

Hello mate-- If you take the video and email it to me I can post it...

Try a Maney belt-kit (preferably on a Quaife mainshaft) and you will see it running straight for sure.
But indeed Let's go ridin![/quote]


Agreed 100% I have Maney belt drives on both my Quaife boxes, and the clutches do NOT wobble!!

Mine is wobbling because the mainshaft is bent. Quaife dont make a drop in mainshaft for the standard 4 speed box...

What would happen if you used a roller bearing instead of a ball?

High Desert

I cant see how welding a washer in the back of the hub can eliminate the snap ring. This is a parralel shaft that has to have a snap ring put onto it to give the hub, or welded on washer, something to register against.

Maybe there is a possibility that the snap ring grove is not exactly straight on the shaft or the snap ring itself is not the same thickness all round.
If the hub is a good fit on the splines though, it would largely overcome imperfections in this area.

Jerry. You should be able to check the run-out on your mainshaft with your DTI probe located in the centre, in the end of the shaft. This will be where it was supported when the diamertrs where machined anyhow.

Regards

Bob.

highdesert said:

So, Heinz is going to weld a large diameter steel washer in the back of the hub and eliminate the snap ring.

Click to expand...

Is this procedure along the same lines as braizing in the spark plugs or tig welding the primary cover closed to eliminate dripping on the newly epoxied garage floor? Or am I totally misreading this?

It seems to me that with all the new belt drive installations, we get a lot of posts pertaining to CBWS (clutch basket wobble syndrome). I can only assume that the majority of this is due to the fact that we can now run the bike with the cover off and then notice a clutch basket wobble that may or may not have been there when it left the factory. Add the fact that 1 inch slop for the belt to allow the thing to run free'er. I have never known a clutch basket to be ridgid.
After saving up for a respectable RGM unit, it is a litte difficult to just trash it for another because of a slight wobble that has IMHO been there all along and does little or no harm. Unless Maney is giving these units away, I don't see this or a mass change over to a Quafe gear box by the majority of Commando owners as a viable options. Although I would love to have one.

YES! I meant to say welding a larger diameter thick washer to the outside of the clutch center, sorry!

I don't see how this would allow you to torque this any higher than the already too high specs of 70 FtLb's.

pvisseriii said:

I don't see how this would allow you to torque this any higher than the already too high specs of 70 FtLb's.

Click to expand...

Don't forget that it's actually recommended to only torque to 45lbs.....70lbs can theoretically shear the circlip. You can tighten the washer as hard as you like against the mainshaft.....the spacer/circlip won't be needed or used. Look at how a pre-commando clutch works!!!

I have not heard of this before. Is it something we can all do? Is it something that we should do? Where can I see this diagram? Everthing seems to be Commando and on.

Update:
AND I need advice guys

Well good news is my mainshaft is not bent. Bob thanks for the tip I measured it like you said. I pushed the dial guage on then zeroed it. The dial is 1 thou increments:

Move measuring shaft: http://www.jerrydoe.com/beltDrive/shaft.MOV

Next I measured my clutch center and it is not running true: http://www.jerrydoe.com/beltDrive/clutchCenter.MOV

This is the most concerning thing. I measured the new drum: http://www.jerrydoe.com/beltDrive/drum.MOV

It is clear to see the new RGM drum is the problem along with the center. (Mainly the drum).

I took my old center and drum to a machine shop and had them press it in. As far as I was concerned they did it right. Now fellow forum memeber what the heck am I going to do? If I call the place where I got the belt drive they are going to say I screwed it up when I pushed the center in. All in all its a bit of a mess. At this time I would advise buying an RGM (or tell me why if you disagree). I suppose I will have to cut my losses and get a Steve Maney belt drive.

Please give me your thoughts, I appreciate it,

Jerry

I do not see how you or anyone else could screw it up. They are meant to have the center pressed in. With the shaft being .001 out so close to the center may translate to a much greater degree as you move out making the center and subsequently the hub appear out of spec. Hence the further out you go the more wobble will show. You were measuring the ID where the rod goes in with about a 1/8" radius.
.001 per 1/8" of radius.....do the math. Example is 2" radius may show .008 to .016 inches of wobble which is rough;y what your videos were showing and the hub was out even further.
The way I see by your vids, the center and hub are aok. Main shaft out a bit.
The video's told the story.

Jerry. Your video sure shows your drum to have serious runout. The problems I have generally seen with RGM drives usually have been with the crank taper too large causing the crank pulley to rub the crankcase and the clutch diaphram snap ring groove being to close to the end of the outer splines which keeps the spring from being able to apply pressure to the plate if it needs to go concave to do it. I put a RGM on a customers bike a week ago and paid particular attention to the runout. I found with the indicator bearing on the edge of the drum I had around .004 thou when holding the center stationary and turning the drum. When I held the drum stationary and turned the clutch center I had around .020 TIR at the edge of the drum indicating either the mainshaft was bent or the clutch center was not true. I took it back off and installed a new snap ring and looked it over close and reassembled it with no change. It's working fine. Jim

PS You might want to press the bearing out of the drum and make sure there isn't a piece of swarf behind it making it crooked.

I am pretty sure the center was not pressed in correctly or something in this area is the issue. I have taken the whole thing to my good friends at Mission Motorsports who have a press and they are going to take it apart and put it together properly and I will try again...

As stated, wobble is common but not "normal"
I think comnoz has best sampling of what to expect.

I've hot two to run true, one chain and the other belt primary.
Main issue was the bushes in sleeve gears, then main shaft
bent then clutch bearing.

Long shafts like this usually don't bend in one plane but
cork screw and takes stages to unwind if you can.
Out rigger bearing ain't a bad idea if jerking on gear box
hard.

I suspect over tensioned primary chain event is
what bends the majority but Norton parts mechanical
to electrical should never be assumed ready to go as is.

hobot

Commando clutches almost always wobble under light loading but straighten up when revs and torque come into play. After nearly half-a-million miles on my '72 Combat I now shim the primary to let the clutch center seat solidly on to the splines without any circlip. Primary triplex chain drives on Commandos are as bulletproof as any load-bearing mechanism from that era if the crank, gearbox mainshaft, bearings, lubricant and adjustment are in gee--I'm on my second chain, third mainshaft bearing, third clutch center and third mainshaft--and probably my fifteenth or twentieth clutch pack.

When I got my first pair of 114 body DOHC Mercedes in the '70's Helmut the mechanic wearily answered my constant queries about this and that with, "Just drive it." I've found that to be excellent counsel.


Tim Kraakevik
kraakevik@voyager.net
Three Commandos