Engine Cradle Dimensional Drawing

Nourish

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Dec 2, 2009
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Would anyone have a dimensional drawing of the Commando engine cradle they’d be willing to share - I fancy an aluminium one!
Cheers
 
I considered using a aluminum cradle, most on this forum felt they would flex to much. Till I used thick enough to get the strength, very little gained and lots of work.
 
Nourish said:
They need welding and they no longer do the cradles!
Click to expand...
Yes they need welding, but it still looks like good value vs starting from scratch IMO. My point was, you can save yourself some time and work.
 
mean gene said:
I considered using a aluminum cradle, most on this forum felt they would flex to much. Till I used thick enough to get the strength, very little gained and lots of work.
Click to expand...
Mick Hemmings was against alloy cradles for that same reason, he reckoned they flexed too much.
 
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Fast Eddie said:
Mick Hemmings was against alloy cradles for that same reason, he reckoned they flexed too much.
Click to expand...
Besides the flex, I would worry about the iso tube staying connected and the swingarm tube wallowing out. Also, I would not recommend a center stand due to the pivots wallowing out and the spring digging in. Then there's the problem of if making it thicker, the extra thickness must be on the outside or the gearbox bottom bolt boss must be modified to fit, and if thicker, then it must be machined for accept the width of the swingarm and center stand.

I do not have a drawing, but making a pattern is easy. Lay out a piece of kraft paper with a hole for the ISO tube. Lay the cradle on it and trace. Do the same for the other side. Cut them out and punch all the holes and cut the slots. I have one I made like that for drilling the holes for the oil filter on cradles without them - of course, I only worried about a few holes for my purpose.
 
Nourish said:
Would anyone have a dimensional drawing of the Commando engine cradle they’d be willing to share - I fancy an aluminium one!
Cheers
Click to expand...
It's your ride
And I'm not exactly Mr health and safety
But aluminium is funny stuff
Do all your research first if you go ahead
I'm guessing if someone made hundreds of them and did thorough testing on them for fatigue etc then it'd be ok
 
You'll have to ask someone else, I never made one. Have seen some steel cradles that were drilled to lighten. My thoughts; this is the better way!
 
I made one for my Commando long ago. ( Photo is from pre-digital times)
The weight saving is considerable and flex is not an issue.
Making a custom cradle allows one to make some mods, like altering the cut-out, so that the gearbox can be removed while leaving the engine in place. I also :
1. Raised the swing arm spindle 5 mm ( anti-squat)
2. Extended the cradle for muffler supports.
3. Fixed position of the gearbox. ( no adjusters)
4. Moved the engine max. forward and a little more tilt, to create extra room for the carburettors.
Front iso is also alloy.
I considered extending the cradle forward, drive side only, or both sides, to include a 4th engine bolt, but decided against it.
The plates are 8mm to compensate for the difference in strength.
Because I was concerned about the wear of the swingarm bushes against the cradle, I made 1.5 mm ss thrust plates, which can evt be replaced. ( 90 000 km and still ok)
This means that 8 mm extra with had to be found in the swingarm bushes and/or the swingarm itself.
I took the opportunity to shift the swingarm a few mm to the left, to help align the chain sprockets ( rear wheel is not std)
The swing arm spindle is drilled and tapped for 2 M6 bolts to keep it in place, plus precision fit 8mm wide steel bushes on each side in the cradle to prevent wallowing out.
There are steel bushes with top hat for the gearbox bolts, and also in the gearbox shell itself.
Gearbox bolts are M 12, thinner than std, but engine bolts are M 10x1 (The std 3/8 bolts are a sloppy fit)
I am not surprised that Mick Hemmings had reservations.
The last time I saw him, he showed me his latest then new product: adjustable iso collars.
When I told him I made aluminium collars with no adjustment at all, not even shims, he didn't approve of that either.
Reducing the weight of the bike will also reduce the stress on every component of the drive train, from pistons to rear tire, and everything in between.


Engine Cradle Dimensional Drawing
 
Last edited:
ludwig said:
I made one for my Commando long ago. ( Photo is from pre-digital times)
The weight saving is considerable and flex is not an issue.
Making a custom cradle allows one to make some mods, like altering the cut-out, so that the gearbox can be removed while leaving the engine in place. I also :
1. Raised the swing arm spindle 5 mm ( anti-squat)
2. Extended the cradle for muffler supports.
3. Fixed position of the gearbox. ( no adjusters)
4. Moved the engine max. forward and a little more tilt, to create extra room for the carburettors.
Front iso is also alloy.
I considered extending the cradle forward, drive side only, or both sides, to include a 4th engine bolt, but decided against it.
The plates are 8mm to compensate for the difference in strength.
Because I was concerned about the wear of the swingarm bushes against the cradle, I made 1.5 mm ss thrust plates, that can evt be replaced. ( 90 000 km and still ok)
This means that 8 mm extra with had to be found in the swingarm bushes and/or the swingarm itself.
I took the opportunity to shift the swingarm a few mm to the left, to help align the chain sprockets ( rear wheel is not std)
The swing arm spindle is drilled and tapped for 2 M6 bolts to keep it in place, plus precision fit 8mm wide steel bushes on each side.in the cradle to prevent wallowing out.
There are also steel bushes with top hat for the gearbox bolts, and also in the gearbox shell itself.
Gearbox bolts are M 12, thinner than std, but engine bolts are M 10x1 (The std 3/8 bolts are a sloppy fit)
I am not surprised about Mick Hemmings reservations.
The last time I saw him, he showed me his latest then new product: adjustable iso collars.
When I told him I made aluminium collars with no adjustment at all, not even shims, he didn't approve of that either.
Reducing the weight of the bike will also reduce the stress on every component of the drive train, from pistons to rear tire, and everything in between.


Engine Cradle Dimensional Drawing
Click to expand...
Wow!
 
ludwig said:
I made one for my Commando long ago. ( Photo is from pre-digital times)
The weight saving is considerable and flex is not an issue.
Making a custom cradle allows one to make some mods, like altering the cut-out, so that the gearbox can be removed while leaving the engine in place. I also :
1. Raised the swing arm spindle 5 mm ( anti-squat)
2. Extended the cradle for muffler supports.
3. Fixed position of the gearbox. ( no adjusters)
4. Moved the engine max. forward and a little more tilt, to create extra room for the carburettors.
Front iso is also alloy.
I considered extending the cradle forward, drive side only, or both sides, to include a 4th engine bolt, but decided against it.
The plates are 8mm to compensate for the difference in strength.
Because I was concerned about the wear of the swingarm bushes against the cradle, I made 1.5 mm ss thrust plates, which can evt be replaced. ( 90 000 km and still ok)
This means that 8 mm extra with had to be found in the swingarm bushes and/or the swingarm itself.
I took the opportunity to shift the swingarm a few mm to the left, to help align the chain sprockets ( rear wheel is not std)
The swing arm spindle is drilled and tapped for 2 M6 bolts to keep it in place, plus precision fit 8mm wide steel bushes on each side in the cradle to prevent wallowing out.
There are steel bushes with top hat for the gearbox bolts, and also in the gearbox shell itself.
Gearbox bolts are M 12, thinner than std, but engine bolts are M 10x1 (The std 3/8 bolts are a sloppy fit)
I am not surprised that Mick Hemmings had reservations.
The last time I saw him, he showed me his latest then new product: adjustable iso collars.
When I told him I made aluminium collars with no adjustment at all, not even shims, he didn't approve of that either.
Reducing the weight of the bike will also reduce the stress on every component of the drive train, from pistons to rear tire, and everything in between.


Engine Cradle Dimensional Drawing
Click to expand...
This is what I want to hear!
A few questions if I may? -
"precision fit 8mm wide steel bushes on each side in the cradle to prevent wallowing out"
Click to expand...
and
"concerned about the wear of the swingarm bushes against the cradle, I made 1.5 mm ss thrust plates"
Click to expand...
Couldn't these be made as one (each side)? And raising the swinging arm - are there drawbacks to this?
 
ludwig said:
I made one for my Commando long ago. ( Photo is from pre-digital times)
The weight saving is considerable and flex is not an issue.
Making a custom cradle allows one to make some mods, like altering the cut-out, so that the gearbox can be removed while leaving the engine in place. I also :
1. Raised the swing arm spindle 5 mm ( anti-squat)
2. Extended the cradle for muffler supports.
3. Fixed position of the gearbox. ( no adjusters)
4. Moved the engine max. forward and a little more tilt, to create extra room for the carburettors.
Front iso is also alloy.
I considered extending the cradle forward, drive side only, or both sides, to include a 4th engine bolt, but decided against it.
The plates are 8mm to compensate for the difference in strength.
Because I was concerned about the wear of the swingarm bushes against the cradle, I made 1.5 mm ss thrust plates, which can evt be replaced. ( 90 000 km and still ok)
This means that 8 mm extra with had to be found in the swingarm bushes and/or the swingarm itself.
I took the opportunity to shift the swingarm a few mm to the left, to help align the chain sprockets ( rear wheel is not std)
The swing arm spindle is drilled and tapped for 2 M6 bolts to keep it in place, plus precision fit 8mm wide steel bushes on each side in the cradle to prevent wallowing out.
There are steel bushes with top hat for the gearbox bolts, and also in the gearbox shell itself.
Gearbox bolts are M 12, thinner than std, but engine bolts are M 10x1 (The std 3/8 bolts are a sloppy fit)
I am not surprised that Mick Hemmings had reservations.
The last time I saw him, he showed me his latest then new product: adjustable iso collars.
When I told him I made aluminium collars with no adjustment at all, not even shims, he didn't approve of that either.
Reducing the weight of the bike will also reduce the stress on every component of the drive train, from pistons to rear tire, and everything in between.


Engine Cradle Dimensional Drawing
Click to expand...
Hi Ludwig, brilliant piece of work !
Q : What specification alloy did you use ?
txs
TBW
 
Nourish said:
Couldn't these be made as one (each side)? And raising the swinging arm - are there drawbacks to this?
Click to expand...
Do you mean: bushing and riveted plate in one piece?
That would not be easy to make, and even harder to replace.
The bushes are pressed in the plates before welding.

'raising the swing arm' :
The bike is very light, and I want to maximize weight on the front when accelerating out of a corner.
Google ' anti-squat'

for ex:


( or maybe acotrel can tell you all about it .. ;) )
 
Last edited:
"The bushes are pressed in the plates before welding" - makes sense👍
Did you weigh it when you finished it?
 
Ken Mcintosh (NZ) gave me some advice when I was making aluminium alloy engine plates for the ES2 - drill the holes undersize and ream them to fit.
I think, in hindsight, that was excellent advice.
 
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