Monoshock and PR at Daytona 1990

I just ran accross an old Japanese bike magazine, Biker Station, from 1991 that had a section on the two Nortons I took to Daytona for the AMA ProTwins class in 1990. They were nice pictures, so I scanned them and thought I'd post them here. The bikes are the Monoshock I bought from Jim Schmidt when he quit racing, and my old Production Racer, which by then had been pretty modified. Both bikes had 920 cc engines. I was entered on the PR, and my friend Rob Tuluie on the monoshock. In the end, Rob ended up racing the PR instead, and we broke the cases on both bikes.







Ken

Bad ass bikes. Bad breaks too. Thanks for more gear head porno.

Cool stuff!

Doug you are a mystery case to me as Jim's mono shock wonder is about as far from an isolastic Commandos qualities as I can imagine and still be considered Commando-ish. I've read you race competitively a real isolastic Commando against the solid versions, how do you do it, handling wise, which is the reason they race more rigids isn't it?

A solid mount frame like a Seeley has little or no advantage over my isolastic Norton because of some of the handling mods Herb has done. The vibration from the solid mounts can put your hands to sleep too. I have been considering doing a post showing all the mods with pictures, I will get to it one of these days.
If you are going ultra modern, mono-shock with mags, modern forks and brakes etc., that is a whole other ball of wax

No Advantage, No Sir~!

Until I tasted what isolastics allow I'd fallen heels over head into the solid camp too.
Now I've tasted what isolastic allow I fall heels over head on solids trying to match it. I will remain restless until you reveal your chassis mods to fly so surely sveltly.
Not academic but life/death to me on Peel, so when ready please start a new subject line to savor. I know what limits solids-moderns or loose Commandos and see my findings backed up in every new test report of some new elite development, on edge of seat till they mention the buzzy being 'reduced' or steering damper helping to settle things or the joys of Rossi saying electronics has been his main down falls. There is real handling genius lurking in our ole rubber baby buggies.

Hi Doug
I too would be intrested. I ride a Seeley but because of a gearbox problem ended up riding a Norvil proddie racer. Long story I purchased it because the engine is the same spec as mine & it has a Quaife 4 Speed box etc. I am building a Norvil for a friend so two birds one stone so to speak. He gets a roadbike I get quality spares.
Anyway the engine felt flat compared to mine, however it was fast. Is this lack of urgency just the isolastics doing their job? I noticed coming out of Barn at Cadwell (an off camber down hill right hander) that the bike moved out as if it was going to drift wide & as the power was put on it came back on line. Again just the isolastics? On fast corners with a steady throttle it went where I wanted it to go but did not feel as precise as the Seeley. Weight? Not unsettling just more effort required & more movement.The main reason I did'nt enjoy the ride is a combination of the 4 speed & the silly chicanes that have been put into a few circuits here in England. 2nd gear would not pick up & pull quick enough exiting the corner but 1st was too low & I had the back end wiggling under braking. ( standard rear hub, Maney belt drive. I dont know what the front pulley Clutch basket & sprocket are yet) At that speed the front end just dropped into the corner! I found myself jumping the kerb. Not really concerned as the road bike wont be used like that but I would like your thoughts.
all the best Chris

Hey Chris; When you get used to 5 speeds ( I run an NRE box with 5 speed Triumph cluster ) going back to 4 is difficult. Hard to say what is going on with your descriptions- if your rear end is moving around under braking, your rear shocks might be a bit stiff for the bike & your weight. I could see how a stock isolastic frame would feel not as precise as a Seeley, when I have some time, perhaps in a week, I will put up a post with some pics as to how we modified the frame to keep things in line.
Doug

Doug MacRae said:

when I have some time, perhaps in a week, I will put up a post with some pics as to how we modified the frame to keep things in line.
Doug

Click to expand...

I'll look forward to that, Doug. I recall looking at Herb's bikes at Daytona, but that was quite a few years back. I'm sure he's made more improvements since then.

Ken

There are a lot of Commando frames out there being used with some very good riders on them. More power to you Doug.

My old race buddy Fred Eiker usually beat my first featherbed classic job with his Commando because he out raced me most of the time, (but not everytime). I do remember Freds bike wobbling now & then. I won most of my races on that featherbed (see below), it was faster than it should have been (home-made guillotine slide carbs).

Yes solid frames can put your hands to sleep - but thats why I came up with the lightweight pistons - and now its no longer a problem. And they make life easier for Commandos as well.

Jim

I like isolastic a lot, but I'm also pretty fond of Jim's old Monoshock bike. Most of it's appeal comes from Jim's most excellent frame design and geometry, but the modern mag wheels, radial slicks, and disk brakes add a lot to it's ability to run with more modern bikes. No, it's not a Commando, but it is the last Norton to place on the podium in an AMA national race. Third place in ProTwins GP2 at the Willow Springs national in 1990, with my friend Rob Tuluie riding. Made us pretty happy, as you can see. Be sure and notice the "spare no expense" team uniforms. Should have brought a better quality of bubbly, maybe. It's like the song says, "those were the days, my friend, we thought they'd never end."



Ken

Out of this world to me with a long head start!

it was faster than it should have been (home-made guillotine slide carbs).

Click to expand...

Q-1, are any of these solid chassis/mounting using the engine as a structural member? I'd be pensive about that in a mostly real Norton engine, so assume they just sit tight and the tire?

Q-2, What is the mono shock advantage over duals?

Hi Doug

Thanks look forward to the reply. Rear shocks were Hagons which were on the bike so not sure of spring rate. Bikes gone now The 4 speed Quaife has gone into the Rickman project. I have got myself a Nourish box refurbished last season 5 meetings, so I am well chuffed.
all the best Chris

The engine is not a stressed member - not a good idea for a Norton. I ran the same frame with dual shocks and monoshock. The monoshock was smoother and didn't kick you in the but as much - Rear tire stayed glued to the ground for steeper lean angles.

Ok thanks Jim, was thinking no one uses Norton elastic-brittle engine to carry major chassis loads. Btw I think your ladder frame mono is the most efficient use of materials, next to maybe the mono coup. My next question is whether its the mono shock geometry you felt as more secure or just a better shock than what's available in that vintage era duals. My main question always is - making Cdo as rigid as
moderns best or just taming the wimpy isolastic chassis not to rebound on its distortions taking up road and power loads. I think GrandPauls road going mono he sold at a loss at Barbers was the slickest and most hidden mono appearance wise.
I could easy see it had no dual shocks but had to peer in close to see the install.

I just know I can't get away with the stuff I do on Ms Peel with other Cdo's or moderns I've tried and crashed on and now have sworn off of risking trying.

BTW what is that pink filled box thing on front?

Hobot, the stresses involved in employing a Norton lump would instantly show themselves far stronger than the 3 little bolts holding the primary case onto the crankcase, or the 4 studs on an e-start 850. That, and the top end-to-crankcase connections are already pushing thier luck confining the strains of combusion, compression and valve actuation to have to try and deal with imparting structural support to any kind of chassis loads.

hobot said:

BTW what is that pink filled box thing on front?

Click to expand...

Battery

Ok I didn't think it wise to use engine as chassis structure. I've seen various ways of removing the down tube part of frame so not sure if engine just hung in or what.
This custom stuff is hard on me so glad I'm happy with mostly Norton basics. I may have to put battery out in front too as part of splash shield on Peel. Got to admit Jim's ladder frame is hard to get out of mind thank you.

willh said:

hobot said:

BTW what is that pink filled box thing on front?

Click to expand...

Battery

Click to expand...

The bike as I got it from Jim had a small battery inside the left fairing upper. When we raced with AMA, we had to add 25 lb to meet the minimum weight limit. I had a couple 25 lb lead bricks that were left over from the shielding on an old linear accelerator, so we bolted one to the bottom front of the chassis. We found that it made the front end chatter go away, so I later replaced it with a larger battery in the same location.

Ken

Ken, very interesting food for thought to me. Chatter relief? hm. I think I know what that is in modern stiffy's and floppy Commandos. Peel need some battery might as well place it where its mass don't interfere, if I can get it nice looking and non fouling. Basically good news as mean the child seat on front fender may work out fine.