Simon Crafer Gyroscopic Effect and Inertia

baz said:
That's the bit I'm missing then
What's the difference between the early commando yokes and the 1971 yokes?
Click to expand...



It's there in the dynodave post I copied.

"1. series 1 commando rolling chassis (68-69-70) used 27 deg (as I said in post #3) 2-1/4" offsert same as featherbed/all late slimline but all UN threads on commando triple trees

2. series 2A commando/ 71,72,73 750 rolling chassis still 27 degree but increased new fork offset and style top2.777" bottom 2.783"
"
 
L.A.B. said:
It's there in the dynodave post I copied.

"1. series 1 commando rolling chassis (68-69-70) used 27 deg (as I said in post #3) 2-1/4" offsert same as featherbed/all late slimline but all UN threads on commando triple trees

2. series 2A commando/ 71,72,73 750 rolling chassis still 27 degree but increased new fork offset and style top2.777" bottom 2.783"
"
Click to expand...
So if I'm reading this correctly the difference between the early yoke (slimline type)and the 71 -73 yoke is just the offset and slight rake IE (top 2.777 bottom 2.783)
Were there any other differences in the width /bearing arrangement etc?
 
From Dynodave

1. series 1 commando rolling chassis (68-69-70) used 27 deg (as I said in post #3) 2-1/4" offsert same as featherbed/all late slimline but all UN threads on commando triple trees

2. series 2A commando/ 71,72,73 750 rolling chassis still 27 degree but increased new fork offset and style top2.777" bottom 2.783"
Click to expand...

So offset went from 2.25" to 2.78" , I am assuming that 2.777 to 2.783, a difference of 6 thou would not be planned but a tolerance issue on machining.
 
kommando said:
From Dynodave



So offset went from 2.25" to 2.78" , I am assuming that 2.777 to 2.783, a difference of 6 thou would not be planned but a tolerance issue on machining.
Click to expand...
That'd be a big tolerance
Was it that bad back then?
 
The point I've been trying to make quite badly it seems
Is I had always thought there were only 3 types of yoke for a commando
The slimline type
The first disc type
And the de raked ANG type
 
baz said:
The point I've been trying to make quite badly it seems
Is I had always thought there were only 3 types of yoke for a commando
The slimline type
The first disc type
And the de raked ANG type
Click to expand...

Yes, but not first disc type.
 
baz said:
That'd be a big tolerance
Was it that bad back then?
Click to expand...
We don't know how it was measured by Dave, maybe the yokes were bent after being made or were made wrongly. But 6 thou over a distance between the yokes of 8" is nothing.
 
kommando said:
We don't know how it was measured by Dave, maybe the yokes were bent after being made or were made wrongly. But 6 thou over a distance between the yokes of 8" is nothing.
Click to expand...
I'm not clever enough to work out how much difference that'd be between the top yoke and the centre of the wheel spindle?
 
L.A.B. said:
Yes, but not first disc type.
Click to expand...
I'm going to have to give up here
I'm not getting it
Either I'm using the wrong terminology or something I don't really know
But if you could list each different set of yokes maybe I'd get it ?
Sorry about this
 
baz said:
I'm going to have to give up here
I'm not getting it
Either I'm using the wrong terminology or something I don't really know
But if you could list each different set of yokes maybe I'd get it ?
Sorry about this
Click to expand...
1. Early Atlas type

2 Late 750 type

3 850 type

The later 750 yokes covered a period when first it was drum only front wheels and then went to mixed drum/disc with the disc becoming more common over time. So you cannot say the later 750 yokes were introduced either with or because of the disc brake.
 
kommando said:
1. Early Atlas type

2 Late 750 type

3 850 type

The later 750 yokes covered a period when first it was drum only front wheels and then went to mixed drum/disc with the disc becoming more common over time. So you cannot say the later 750 yokes were introduced either with or because of the disc brake.
Click to expand...
Yes I get the early atlas type
I get the 850 type
When you say late 750 does this mean disc type and drum being the same yoke?
I thought the width would be wider for the disc?
 
baz said:
Yes I get the early atlas type
I get the 850 type
When you say late 750 does this mean disc type and drum being the same yoke?
I thought the width would be wider for the disc?
Click to expand...
Yes same yokes used for drum and disc.

They probably should have been wider for the disc but instead they are the same as the drum, instead they drilled the rims at different angles left to right and you end up with one sides spokes being virtually vertical with that making wheel truing difficult.
 
kommando said:
Yes same yokes used for drum and disc.

They probably should have been wider for the disc but instead they are the same as the drum, instead they drilled the rims at different angles left to right and you end up with one sides spokes being virtually vertical with that making wheel truing difficult.
Click to expand...
Oh I see
I never knew the same width yokes were used for disc and drum
Thank you 👍
 
Increasing the trail can change the transition point in corners and help it to be able to made earlier . It makes the corners faster.

 
kommando said:
Yes same yokes used for drum and disc.

They probably should have been wider for the disc but instead they are the same as the drum, instead they drilled the rims at different angles left to right and you end up with one sides spokes being virtually vertical with that making wheel truing difficult.
Click to expand...
With a bike the weight of a Commando, twin discs are probably needed on the front. If you are inexperienced, you might believe a single disc to be sufficient. Same with the gearbox, some people believe a torquey motor does not need a close ratio gearbox. I have tried both of those options and went backwards - single disc and wide ratios are useless. Most people probably race what they already have, before spending on upgrades.
I don't know if anyone makes the other fork slider for the second disc on a Commando. I could not find new disc pads for the AP calipers which were effective for the relatively slow speeds. I don't think the pads used on later bikes get hot enough. Nortons are not real fast.
 
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