RGM Motors MK3 Belt Drive Kit

I bought the setup from them that is for use on a MK3 Commando where the starter motor is used.

I am curious if anybody has a picture that shows the kit once installed?

Thanks.

Bob in Fresno

RGM should have one, they have an illustrated catalogue you can buy so must have photos.

I have asked RGM if they could send me a picture of what the installation looks like. They supply a new gearbox top mounting bolt as part of the kit for the MK3. I was trying to figure out what side the bolt goes into. I guess the bolt is used to somewhat align the gearbox shaft and the motor shaft. There was not an illustration in the instructions. I am assuming the cam side of the bolt will be on the inner primary side of the gearbox. I will find out when I try and fit the belt drive this weekend. It will take me a few days to clean of 34 years worth of road grime from the back side of the inner primary and the frame.

This is what there kit looks like installed. I bought the kit for keeping the electric start and decided to not install the electric start pieces. It was a pretty easy installation. The belt is tight with little deflection and little adjustment. It is quite and no more noise from the hydraulic tensioner.




It will be interesting to see how long it will hold up. Everything runs true and looks good.

Bob, tight when cold is not good. At dead cold the belt needs one inch of play or it will pull very hard on the transmission. This lock up the shifting and you will spit on belts by the time you are done , stop do a long read on this.

I did do quite a bit of reading on this. I plan to talk to the RGM people tomorrow via email. The gearbox is as far forward as it goes. Their kit for the MKIII comes with a top gearbox bolt that is ground down with a cam end on it to allow some adjustment. As it sits now, it is adjusted as loose as it gets. I will post their response.

Tight cold is not good as the clutch drum will heat up and expand substantially. I like RGM and do not have too much praise for the other well known seller of belt drives but they at least understand the issue with Mk3's and offer 3 pulley and belt combinations based on the crank/gearbox centres. It is possible that their drum does not expand the same as RGM's but if it's already tight? I have the chart for theirs if you're interested on photobucket account.

norbsa and Keith - Thanks for the input. I had a feeling it was too tight. Keith - I will check the chart on your photo bucket account. I have sent the inquiry to RGM.

Keith1069 said:

Tight cold is not good as the clutch drum will heat up and expand substantially. I like RGM and do not have too much praise for the other well known seller of belt drives but they at least understand the issue with Mk3's and offer 3 pulley and belt combinations based on the crank/gearbox centres. It is possible that their drum does not expand the same as RGM's but if it's already tight? I have the chart for theirs if you're interested.

I can't get the belt length column to show even with a resize. Full size is on photobucket account.

Click to expand...

Is this the right chart?

Keith

The funny part of the chart is the wording at the bottom..

"The variance in MK3 sizes is because there is no adjustment between the engine and the gearbox, and the differences between the Norton drawing and the Norton machining has to be seen to be believed."

Thanks for the link to the chart. I printed it out on 11 x 17 paper this morning. If I cannot use the RGM kit in my MK3 I am sure I can use it on one of the other Nortons.

I take it that you opted to use the 35 tooth front and the 72 tooth clutch setup with a 920 belt?

Bob in Fresno

Bob
That's the one. Mine is a 750 with full box adjustment but I'm using 35/72 for a little extra gearing and it's what they had on the shelf. I run 30mm cold play which reduces to 20mm hot but that is a different belt and drum source to yours. Good luck with it.

I tried to get a copy of the belt drive chart from photo bucket but could only get an unreadable thumbnail. Possibly because I don't have an account. Any chance some-one could pm me a copy? It would be much appreciated. Thanks.

Zotz. Send me your email to bobs850@aol.com and I will send you a copy.

Bob

zotz said:

I tried to get a copy of the belt drive chart from photo bucket but could only get an unreadable thumbnail. Possibly because I don't have an account. Any chance some-one could pm me a copy? It would be much appreciated. Thanks.

Click to expand...

The problem is that there are two pictures in his photobucket (one big which I posted) and one thumbnail. I don't know if they are the same.

Yes one I reduced in size, the other is the full size version. For some reason I couldn't get it all to show as an 'img'. Will PM if needed.

I have been talking with RGM on my project. They have been very helpful. Once I figured out that I needed to loosen my new rear drive chain to give me the desired movement in my upper gearbox mount, I got my project back on track. Their kit for the MK3 simply repositions the upper gearbox mount forward enough (about 1/8 of an inch) to give the desired belt tension.
A partial bit om my correspondence with them is as follow:

"I did loosen the rear drive chain. It did make a big difference. I think if I had to do this all over again I would approach it as follows.

Remove the old primary drive components and remove the old primary inner cover.
Remove the upper gearbox bolt.
Loosen the lower gearbox mount bolt.
Loosen the rear drive chain.
Fit the crankshaft drive pulley.
Fit the spacers and gearbox clutch basket.
Fit the belt.
Adjust the gearbox position to get the desired 30 mm free play for the belt.
Tighten the lower gearbox bolt.
Inspect the upper gearbox mounting hole.
View how much of the gearbox casing is visible through the upper gearbox mounting hole.
Look at the cutaway in the new bolt supplied with the kit.
Take the new bolt to your local friendly machine shop and have them to radius off another 1/16 inch from the two notches in the bolt.
(This is where I am at. I am hoping to have the bolt back from the machine shop in a few days. )
Get the bolt from the local machine shop..
Loosen the lower gearbox bolt.
Fit the upper gearbox bolt.
Adjust as necessary to get the 30 mm free play.
Tighten the lower gearbox bolt then the upper gearbox bolt.
Remove the pulleys and the belt.
Get the inner primary cover close enough so you can attach the alternator leads.
Green wire with white stripe goes to single connector
Green wire with yellow stripe goes to double connector.
Fit inner primary and attach single nut to hold in place.
Refit drive pulley.
Refit spacers, clutch pulley and belt.
Check belt tension. Go back and adjust if necessary.
Finish up installing the rest of the pieces."

My backup plan was to today order the necessary gaskets and tab washers to put the hydraulic tensioner back in.

Good to hear RGM helped and it worked out OK. Never thought that you'd have enough play in the mounting holes to do that!

Don't forget to let us know how it worked out :wink:

I know this is an old post, but I have fitted one of these belt drives to my MK3 . What I have found is the belt rubs against the gear (06-4707) I even went as far as drilling the recess in the Plate outrigger to allow the gear to be 1mm further out (toward the primary cover) and it seemed to work. Just removed the primary cover after running for a short time to find small amount of belt. I hate to think what would have happened if I did not do the mod above the belt would have destroyed itself in no time.

I have spoken to RGM (as I will again tomorrow) who said they have only had a customer with this issue once before. What I wanted to know has anybody else had this problem and what they did to fix it?