Does this look safe

[gsx]

Going back to twin shocks on me gsx and bloke at Newark was kind enough to show me photos of how he did shock mounts , looks like the rubber bushing in the top mount has been sacrificed to get desired wall thickness. What's my best option ? This or original ish with nut on the end 

[imago]

For starters I wouldn't fancy it straight through the frame tubes like that, too much leverage on the stubs.

You can get inserts to replace the originals, and in the original position they're as good as you'll get. Basically they're just a stepped solid bar for each side which you weld in. The shock eye slips over the smaller dia on the stub and there's a threaded hole which you put a bolt into.

 

[gsxwill]

He's changing the geometry on the rear end, you can see in the photos where they used to be, unless he is slugging and bracing that tube to withstand up ward forces,, 

Not fancying the way he's doing it,,

But I'm sure a more knowledgeable grown up will come along and explain better!! 

[gsxwill]

7 minutes ago, imago said:

For starters I wouldn't fancy it straight through the frame tubes like that, too much leverage on the stubs.

You can get inserts to replace the originals, and in the original position they're as good as you'll get. Basically they're just a stepped solid bar for each side which you weld in. The shock eye slips over the smaller dia on the stub and there's a threaded hole which you put a bolt into.

 

What he said 

[bunk]

Some more structural work and that will be fine. Im not a fan of the oversized holes, those inserts are going to move around when welded. Another issue, what are the odds they are not in the same location side to side.

[gsx]

14 minutes ago, imago said:

For starters I wouldn't fancy it straight through the frame tubes like that, too much leverage on the stubs.

You can get inserts to replace the originals, and in the original position they're as good as you'll get. Basically they're just a stepped solid bar for each side which you weld in. The shock eye slips over the smaller dia on the stub and there's a threaded hole which you put a bolt into.

 

I've got a mate that can do the machining but how big would the tapped bit be ? Without going and measuring I'm  guessing the bushed section is only 12mm . Have you a link to said stepped bushings ? To everyone else ,thanks for input and the hole did have extra bracing to it , it was the removal of the top rubber bush that was bothering me

[imago]

It's a combination of what they're in, and the angle the shocks are meeting it at. If you imagine putting a pair of stilsons on the frame tube at that point and giving them a good heave that's the pressure and direction of torque each time the suspension is compressed. Barley sugar anyone? 

The original position had a gusset fitted to take up the additional pressure and the force isn't at 90 degrees to the tube.

 

Edited January 30 by imago
typo

[imago]

3 minutes ago, gsx said:

I've got a mate that can do the machining but how big would the tapped bit be ? Without going and measuring I'm  guessing the bushed section is only 12mm . Have you a link to said stepped bushings ? To everyone else ,thanks for input and the hole did have extra bracing to it , it was the removal of the top rubber bush that was bothering me

I can't remember who made them, It was either someone on OSS, or someone on FaceBook. That's not much help I know. 

I'm sure @davecaraor @clivegtowill know.

[gsx]

When pops did the gs frames he cut and bent the back y of the frame that goes to the original shock mounts and made new ones , he also moved the bottom mount forward on the swingarm, not to lay the shocks down but to shorten the shock travel in relation to the back wheel movement. Think early moto cross before a linkage was added. Don't have any pictures though . It was all done roughly but obviously structurally 

[clivegto]

1 hour ago, imago said:

I can't remember who made them, It was either someone on OSS, or someone on FaceBook. That's not much help I know. 

I'm sure @davecaraor @clivegtowill know.

Dave Solaman of Butchered Classics. 

 

44 minutes ago, gsx said:

When pops did the gs frames he cut and bent the back y of the frame that goes to the original shock mounts and made new ones , he also moved the bottom mount forward on the swingarm, not to lay the shocks down but to shorten the shock travel in relation to the back wheel movement. Think early moto cross before a linkage was added. Don't have any pictures though . It was all done roughly but obviously structurally 

Bit o bracing n it'll be right. Not the first time it's been done and won't be the last. Take a look at Brian McCall of Centurion Motorcycle Projects 2 race GS1000 bikes 

[clivegto]

@Wescooley19has done a few conversations similar to this for customers. 

[Toecutter]

What actual benefit does moving the shock mounts in this way actually achieve though? When you look at their position in relation to stock,  they are almost at 45 degrees to the swingarm. This surely doesn't allow the shocks to perform optimally.

[LLD]

I would not put the mounts through the tube. Way too little meat around the mount

[LLD]

Cut out with an holesaw (25mm), fitting just around the original studs

[LLD]

New mounting points, with larger diameter to fill the 25mm hole and option to connect both points. Mind you, this will need modification of the inner fender. But mine was damaged anyway, so no broken heart here

Edited January 30 by LLD

[LLD]

Final result

[LLD]

You can have the drawings if you want, just let me know

[LLD]

i forgot this one

[gsx]

7 hours ago, LLD said:

New mounting points, with larger diameter to fill the 25mm hole and option to connect both points. Mind you, this will need modification of the inner fender. But mine was damaged anyway, so no broken heart here

That's the kiddie 

[gsx]

Just found this and well worth a read through 

[Gixer1460]

12 hours ago, Toecutter said:

What actual benefit does moving the shock mounts in this way actually achieve though? When you look at their position in relation to stock,  they are almost at 45 degrees to the swingarm. This surely doesn't allow the shocks to perform optimally.

Sometimes its 'form over function' ie. they fit better that way ! In an ideal world the shock should be perpendicular to the arm through its travel for maximum stroke and damping effect but if you 'lay them down' then for a given spring pressure, they will feel softer and damping will be less - sometimes good, sometimes not!

[clivegto]

As said Mr Yoshimura moved the top shock mount forward and down to improve handling, this is also a popular upgrade on older Z's. 

[DAZ]

When Mr Yoshimura moved the mounting point did the class rules require the bike to retain stock length shocks ? But make no mention of mounting location in the rule book ? Just a thought as to why ....

[TLRS]

6 hours ago, Gixer1460 said:

In an ideal world the shock should be perpendicular to the arm through its travel for maximum stroke and damping effect

 

 

 

 

 

 

 

[TLRS]

6 hours ago, Gixer1460 said:

In an ideal world the shock should be perpendicular to the arm through its travel for maximum stroke and damping effect but

This could be engineered if need be. But they don't.. because progressive seems to be a better solution?