Speed triple swing arm in slingshot

[KennyKak]

41 minutes ago, Joseph said:

I think you'll find that the slingshot bushes will slip into the K bushes which avoids machining stuff or waiting for inlaws 

That would be great if I actually had the sodding bushes and it cost over £60 for the pair

Edited October 1, 2023 by KennyKak

[Graeme]

Decision made, pre modified triumph arm sourced!

Progress will be posted in my build thread, when any happens.

[Digs]

On 10/1/2023 at 10:51 PM, KennyKak said:

 If you do use the early K series swing arm you'll need to move the lower linkage mount to make it work, so I've been told. Had quite a bit of conflicting info on that one (It's what I'm trying to fit)

There’s a bit of ‘works well enough for me’ with the k series swap. In my view you need to actually do some work: cad, spreadsheet or pen and paper to make sure whatever you setup has a proper motion ratio and can transfer the loads properly. Moving the lower mount down and closer to the original k series geometry is a good idea, as is spacing the top mount out. It’s not the only way to do it, but it is a good way. 

 

[Graeme]

4 minutes ago, Digs said:

There’s a bit of ‘works well enough for me’ with the k series swap. In my view you need to actually do some work: cad, spreadsheet or pen and paper to make sure whatever you setup has a proper motion ratio and can transfer the loads properly. Moving the lower mount down and closer to the original k series geometry is a good idea, as is spacing the top mount out. It’s not the only way to do it, but it is a good way. 

 

Once I have everything in front of me I'll have a better idea, but I will try and replicate the stock geometry of either the slingy, the triumph the arm came from, or the k4 that the shock and linkage on the triumph arm is off.

 

The issue come when I need to mix and match parts, bit I might not need to. I'm happy to move shock mounting points if need be.

I'll post some better pics later, try and find out exactly what the shock and linkage on this arm is off.

[Upshotknothole]

6 hours ago, Digs said:

There’s a bit of ‘works well enough for me’ with the k series swap. In my view you need to actually do some work: cad, spreadsheet or pen and paper to make sure whatever you setup has a proper motion ratio and can transfer the loads properly. Moving the lower mount down and closer to the original k series geometry is a good idea, as is spacing the top mount out. It’s not the only way to do it, but it is a good way. 

 

The shop that did mine had a computrac system and did all the measurements and calculations. My 89 7/11 is almost identical to a mid 00's 750 as far as geometry goes, the wheel base is only like I think 20mm longer. Handles great, but definitely sits higher than a stock slingshot 750.

[KennyKak]

21 hours ago, Digs said:

There’s a bit of ‘works well enough for me’ with the k series swap. In my view you need to actually do some work: cad, spreadsheet or pen and paper to make sure whatever you setup has a proper motion ratio and can transfer the loads properly. Moving the lower mount down and closer to the original k series geometry is a good idea, as is spacing the top mount out. It’s not the only way to do it, but it is a good way. 

 

I've got a k1 750 I'm going to try and take measurements off. The lower mount is probably the one I'm going to be the harder one to get right. I do have an old shock that I'm going to strip and use to test everything moves as it should. I don't have access to the same kit as you so any help is appreciated mate

[Graeme]

1 hour ago, KennyKak said:

I've got a k1 750 I'm going to try and take measurements off. The lower mount is probably the one I'm going to be the harder one to get right. I do have an old shock that I'm going to strip and use to test everything moves as it should. I don't have access to the same kit as you so any help is appreciated mate

If 750 k4 dimensions are the same as 1000 k4, if be interested in those measurements too. Knuckle mount to frame and top shock mount, in relation to the swingarm pivot would be handy.

[Graeme]

I need to replicaye this. I have the linkage and the shock, just need to work the frame mounts out.

[KennyKak]

If i remember correctly the swing arm is the same not sure about the linkage tho. Just need to learn the best way to measure everything. I may need to remove some fairings

Edited October 5, 2023 by KennyKak

[Upshotknothole]

If you search, someone on here was selling lower bolt on brackets for fitting busa arms, they work with the K arms as well. Measurements should still be on here too. They bolt to where the exhaust hanger attaches to the frame below where the stock linkage attaches.

[Joseph]

18 minutes ago, Upshotknothole said:

If you search, someone on here was selling lower bolt on brackets for fitting busa arms, they work with the K arms as well. Measurements should still be on here too. They bolt to where the exhaust hanger attaches to the frame below where the stock linkage attaches.

Available through @Danm54but last i heard a friend who inquired was told that they're out of stock at the moment ?

Excellent stuff though 

Edited October 5, 2023 by Joseph

[KennyKak]

1 hour ago, Upshotknothole said:

If you search, someone on here was selling lower bolt on brackets for fitting busa arms, they work with the K arms as well. Measurements should still be on here too. They bolt to where the exhaust hanger attaches to the frame below where the stock linkage attaches.

I messaged danm54 a week or so ago but he hasn't seen or responded yet unfortunately 

[Graeme]

Anyone got a link to the measurements of that bracket?

[Upshotknothole]

7 minutes ago, Graeme said:

Anyone got a link to the measurements of that bracket?

I'm pretty sure I've seen the drawings in the custom builds section. I think it might have been in @Digsbuild, but not positive.

[Upshotknothole]

1 hour ago, KennyKak said:

I messaged danm54 a week or so ago but he hasn't seen or responded yet unfortunately 

Maybe if enough of us show interest he might do another batch of them. I wouldn't mind having one in case I should decide to go that route with another build in the future. I still have a couple 95 GSXR 750w braced swing arms that are an easier swap, but they're getting harder to find and don't really look as nice as the newer stuff in some builds.

[Jdeac]

24 minutes ago, Upshotknothole said:

Maybe if enough of us show interest he might do another batch of them. I wouldn't mind having one in case I should decide to go that route with another build in the future. I still have a couple 95 GSXR 750w braced swing arms that are an easier swap, but they're getting harder to find and don't really look as nice as the newer stuff in some builds.

Don't suppose you have one from an 1100 do you

[Upshotknothole]

3 minutes ago, Jdeac said:

Don't suppose you have one from an 1100 do you

Nope, I've only got two of the 750 ones, and they're both currently in bikes to keep them rollers. I've seen the braced 750 swing arms go cheap on Eblag from time to time, but seems like all the 1100W stuff is going for stupid money now.

[KennyKak]

1 hour ago, Upshotknothole said:

I'm pretty sure I've seen the drawings in the custom builds section. I think it might have been in @Digsbuild, but not positive.

Digs has made his own bracket but it might be to his spec seeing as his is all designed to his custom set up. Some bloody good work from what I've seen of his 3D scans

[Digs]

On 10/5/2023 at 11:00 PM, KennyKak said:

Digs has made his own bracket but it might be to his spec seeing as his is all designed to his custom set up. Some bloody good work from what I've seen of his 3D scans

Cheers @KennyKak much appreciated. 

Yeah mine was a little different to the design shown above. The mount was a little further back and quite a bit lower to suit my use case.

This probably shows it best.

 

I also machined out the central part of the mount and machined out a couple of slots on the underside for the lower frame mounts which let it sit directly on the lower frame rail. 

Finished mount looks like this. 

 

Happy to modify my cad model and share it here to match the mount shown in this thread. 

Edited October 7, 2023 by Digs
Moving a picture

[Jukka]

I also made custom lower mount, have not yet managed to get bike rolling, but at least without spring the swingarm movement seems progressive as it should be. I had few test units first done as 3d print to ensure correct position and progression. Found inspiration from here but no drawings so with a help of friend made my own.

1100n frame, k1 1000 swingarm, k5 1000 shock and a mix of k1-k5 linkage parts.

Most likely needs custom dog bones to get balance right. Might even need repositioning of top mount, plan is to make all fit without cutting anything on frame.

few pics attached

 

[Graeme]

@Digs@Jukka

My thoughts were to make a lower mount that's in the same position at the k4, hopefully do the same with the top mount, and then, hopefully with it all basically being stock k4, it will work well.

 

How come you both seem to have gone with a different lower mount position that stock K? Although alot closer to stock position by the Looks of it.

Is it because your top mounts aren't in stock k position? Or because the mix of parts doesn't sit the shock through the arm well? Or some other reason? Is it going to be messy if i try and replicate the top mount too?

[Digs]

1 hour ago, Jukka said:

I also made custom lower mount, have not yet managed to get bike rolling, but at least without spring the swingarm movement seems progressive as it should be.

Good work so far, and you can check that very easily. 

Unload the suspension and place a scissor jack or similar under the rear wheel. Measure every 5mm of shock travel and compare that to rear wheel travel. Once you’ve done that plot a graph with the data and you’ll have your motion ratio. 

 

[Digs]

1 hour ago, Graeme said:

@Digs@Jukka

How come you both seem to have gone with a different lower mount position that stock K? Although alot closer to stock position by the Looks of it.

Is it because your top mounts aren't in stock k position? Or because the mix of parts doesn't sit the shock through the arm well? Or some other reason? Is it going to be messy if i try and replicate the top mount too?

So my suspension setup is quite a bit different to any of these bikes stock.

I made my setup for maximum adjustability in terms of motion ratio and swingarm angle. 

I’m using a shorter shock (309mm from memory) from a 2018 gsxr1000r and have different linkage plates for different applications. 

There were definitely issues with parts fouling to start with, and I did change shock a few times but it’s all resolved now. I spent a lot of time in cad going through it all. But that’s just the way I like to work. 
 

 

 

[KennyKak]

On 10/7/2023 at 4:59 AM, Digs said:

Cheers @KennyKak much appreciated. 

Yeah mine was a little different to the design shown above. The mount was a little further back and quite a bit lower to suit my use case.

This probably shows it best.

 

I also machined out the central part of the mount and machined out a couple of slots on the underside for the lower frame mounts which let it sit directly on the lower frame rail. 

Finished mount looks like this. 

 

Happy to modify my cad model and share it here to match the mount shown in this thread. 

I'd be interested in the cad drawings. Could see if my mate could 3D print one and test it it a little before committing to get one machined up.