RGM close ratio gear kit

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bill said:
thanks. that is real close to where i am at. it is hard to get some people to understand the sprocket size is NOT the proper question but overall final gear ratio is.
Click to expand...
Your question was going to be my next question. Thanks for asking.
 
ludwig said:
Hortons Norton and Worntorn:
I have alloy clutch centres (rgm) in my 2 bikes.
The first one is anodized, the second not.
Around 150 000 km combined.
Absolutely no wear at all, but then I only use the original full fibre friction plates. IMO still the best, but they must be kept free from oil contamination.
Click to expand...
Hi Ludwig,
Did you need to have the anodized clutch centre anodized by a third party? If so, what is approx. cost od doing so?

Thanks,
Ed
 
APRRSV said:
Did you need to have the anodized clutch centre anodized by a third party? If so, what is approx. cost od doing so?
Click to expand...
No.
Even the not anodized centre shows absolutely no wear after many 1000 km,
But, as I said, I only use full fibre plates.
I don't know what they will do with aluminum or steel core friction plates, and I definitely won't use them with bronze plates.
 
APRRSV said:
Thank you Dave. After looking more closely at the gear ratios of the CR kit, I see your point.

Out of curiosity, who is Johnm?

Ed
Click to expand...
Hi Johnm is me.

I'm not around much these days but 10 to 15 years ago I developed a 500 Norton Dominator for club class classic racing under NZ classic racing rules. At the end and with a very good rider it was very successful. I had measured 51 rear wheel bhp and on some tight circuits the rider could get better lap times than the 750 cc plus bikes. But I then left for overseas and have done nothing for the past decade.

Going back to the RGM close ratio gears.

As Dave said not at all a simple answer.

For a street bike I would not use it. The first gear is terrible for town riding. Maybe if you rode totally in the country but anytime you need acceleration of the line you would be in real trouble.

After lots and lots of experimenting I used the Daytona first gear pair and the rest the latter 850 Mk 11 Commando for the 500 Dommie. Ie the Commando version with the slightly higher 2nd gear set. See also my para below with a proviso about the top gear pair. Most of our circuits are tight with short races and the sprint to the first corner is critical. If you run the RGM CR first gear you will be behind lots of riders at the first corner and spend most of the race getting back to the front. Any 4 speed box is a compromise and while closing up ratios is good once your moving the Daytona first gear pair is as far as I would go.

What SteveA said about push starts and the historical background to CR boxes is also very relevant. The rules and race conditions they raced under in the 50s and 60s are not our current rules.

I will add one last thing with a big caveat that is 15 years ago memory. I think ???? I may also have changed the top gear pair to the RGM CR pair. I think this closes up the whole box a little. Dynodave may be able to confirm or you can check your self.

I'm certain I used the Daytona first gear set and the 850 commando second and third pair . But I might have used the RGM top gear pair. Don't quote me. It's 10 to 15 years ago.

So far as longevity. We never had any problems but on a race bike your not doing the miles. Plus it was a 500.
 
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Thanks johnm for your explanation.
The main reason for me to use a Daytona 1st is for taking tight downhill corners.
When releasing the clutch going into the turn, engine braking can be too harsh.
( freewheeling through a hairpin is a nono ! )
A longer 1st reduces the risk of a rear wheel lock-up, especially on a wet road.

Plenty of roads like this in the Alps:

RGM close ratio gear kit


I loose a little bit in initial acceleration , but that is compensated by staying longer in 1st gear,
and my bike is light enough.
It also makes kickstarting marginally harder.
 
Last edited:
johnm said:
Hi Johnm is me.

I'm not around much these days but 10 to 15 years ago I developed a 500 Norton Dominator for club class classic racing under NZ classic racing rules. At the end and with a very good rider it was very successful. I had measured 51 rear wheel bhp and on some tight circuits the rider could get better lap times than the 750 cc plus bikes. But I then left for overseas and have done nothing for the past decade.

Going back to the RGM close ratio gears.

As Dave said not at all a simple answer.

For a street bike I would not use it. The first gear is terrible for town riding. Maybe if you rode totally in the country but anytime you need acceleration of the line you would be in real trouble.

After lots and lots of experimenting I used the Daytona first gear pair and the rest the latter 850 Mk 11 Commando for the 500 Dommie. Ie the Commando version with the slightly higher 2nd gear set. See also my para below with a proviso about the top gear pair. Most of our circuits are tight with short races and the sprint to the first corner is critical. If you run the RGM CR first gear you will be behind lots of riders at the first corner and spend most of the race getting back to the front. Any 4 speed box is a compromise and while closing up ratios is good once your moving the Daytona first gear pair is as far as I would go.

What SteveA said about push starts and the historical background to CR boxes is also very relevant. The rules and race conditions they raced under in the 50s and 60s are not our current rules.

I will add one last thing with a big caveat that is 15 years ago memory. I think ???? I may also have changed the top gear pair to the RGM CR pair. I think this closes up the whole box a little. Dynodave may be able to confirm or you can check your self.

I'm certain I used the Daytona first gear set and the 850 commando second and third pair . But I might have used the RGM top gear pair. Don't quote me. It's 10 to 15 years ago.

So far as longevity. We never had any problems but on a race bike your not doing the miles. Plus it was a 500.
Click to expand...
Thank you Johnm for telling me(us) your history. Amazing results from a 500!

Your info on the CR gears is very informative. I hope you can check in to the forum more frequently and give us your expert advice.

We need your expertise!

Ed
 
ludwig said:
No.
Even the not anodized centre shows absolutely no wear after many 1000 km,
But, as I said, I only use full fibre plates.
I don't know what they will do with aluminum or steel core friction plates, and I definitely won't use them with bronze plates.
Click to expand...
ludwig,
are you using the 750 surflex fiber plate setup, or did you convert it to an 850 pressure plate and added another friction plate and steel plate?
cheers,
Tom
 
ludwig said:
Thanks johnm for your explanation.
The main reason for me to use a Daytona 1st is for taking tight downhill corners.
When releasing the clutch going into the turn, engine braking can be too harsh.
( freewheeling through a hairpin is a nono ! )
A longer 1st reduces the risk of a rear wheel lock-up, especially on a wet road.

Plenty of roads like this in the Alps:

RGM close ratio gear kit


I loose a little bit in initial acceleration , but that is compensated by staying longer in 1st gear,
and my bike is light enough.
It also makes kickstarting marginally harder.
Click to expand...
Hi Ludwig,

I understand. Once your moving the Daytona gear set is more usable in many road situation. Just not in traffic in town.

And from what I have read you have lightened yiur bike considerably so that help too.

Any 4 speed box for racing is a compromise and the Daytona gear worked ok for the 500 on our circuits. At the very end we went up a class and used a 6 speed TT box. That was very good. But 5 speed would be a better choice on a Commando on the road.
 
CanukNortonNut said:
ludwig,
are you using the 750 surflex fiber plate setup, or did you convert it to an 850 pressure plate and added another friction plate and steel plate?
cheers,
Tom
Click to expand...
NOT Surflex, but the original full fibre plates.
The ones you can crack like a cookie.
This is what a Surflex plate looks like after 10000 km (on a steel centre):

RGM close ratio gear kit

a few 1000 km more, and no more drive.

I sure won't add , when I get the same effect by removing.
Instead of adding plates, I made the clutch basket narrower.
4 friction plates, 3 steel, back and pressure plate alloy.
 
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ludwig said:
NOT Surflex, but the original full fibre plates.
The ones you can crack like a cookie.
This is what a Surflex plate looks like after 10000 km (on a steel centre):

RGM close ratio gear kit

a few 1000 km more, and no more drive.

I sure won't add , when I get the same effect by removing.
Instead of adding plates, I made the clutch basket narrower.
4 friction plates, 3 steel, back and pressure plate alloy.
Click to expand...
Hi Ludwig,
Do you have a part # and source for your full fibre plates?

Ed
 
Matchless said:
I have the RGM gear set in my 750. I like it a lot except around town. On the oped roads it's much kinder to the engine not having such a large gap between gears. As for longevity it's only done about 6,000 miles as I have quite a few other bikes to ride, but up to now it's fine. My prefered option is the five speed TTi on my 920 as the first gear is 2.35:1 as opposed to 2:05:1.

Martyn.
Click to expand...
I have found that when racing. If the gears are closer, the motor does not have to slog as you come up through the gears, and it is much gentler coming down. It is an all-round better deal, except when first gear is too high.
 
If you are looking for a performance mod, a close box is a good investment, You will get more go from that, than most other mods. With BSA Gold Stars, the RRT2 gearbox is great except for first gear. It was OK for push-start road races, but nor much else.
 
APRRSV said:
Thank you Johnm for telling me(us) your history. Amazing results from a 500!

Your info on the CR gears is very informative. I hope you can check in to the forum more frequently and give us your expert advice.

We need your expertise!

Ed
Click to expand...
A Dominator usually has a fairly long stroke. With 51 BHP, it would be lovely - not nasty.
 
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