750 WP with VFR 750 single side arm

[Ade]

I have been asked to fix a 750 WP with a 94-97 VFR 750 swingarm fitted. At the moment it has (I believe) the WP  shock linkage with cut down dog bones and a Hagon shock. The shock hits the swingarm and it's so stiff the suspension doesn't work. Has anyone got any pictures of how they have fitted. It is being dropped off with me next week so I'll take pics of the set-up as it is before I start to fix it. It needs at the least a shorter linkage, like a Hayabusa one, or changing to the VFR triangle plate set up. It has Ducati 916 exhausts fitted and the dog bone bolt hit the exhausts. 

[bluedog59]

I'd steer clear of it. Unless you can replicate the stock VFR setup it will probably handle like a three legged cow in a sand pit, then it will hit the stupid exhausts (which probably screw the engine up as well ). Even with the best efforts you'll end up with an asthmatic camel with a dodgy back leg.

[Ade]

12 hours ago, bluedog59 said:

I'd steer clear of it. Unless you can replicate the stock VFR setup it will probably handle like a three legged cow in a sand pit, then it will hit the stupid exhausts (which probably screw the engine up as well ). Even with the best efforts you'll end up with an asthmatic camel with a dodgy back leg.

I like a challenge. I have got a 600 SRAD link coming which should cure the shock clearance to the swingarm. Then I reckon I will make a new top mount., I fancy making an adjustable one, but might just make an offset higher one to make it work. I could just use the VFR 750 triangle plates, single dog bone and shock, then make a new top mount, but the Hagon shock in it is fine so I am trying to use what he has to keep costs down.

[bluedog59]

I know what you mean about a challenge, turn a pig's ear into a decent setup with some lateral thinking and clever engineering. If you're going to do it, go "full on", adjustable mount, everything top notch.

Just to raise the bench mark for his project. 

[Madb]

I hope that frame has beefed-up to take that shingel shydid arm. Looks only. ruins a prefect bike. but me is bias as fuck really.

 

[Ade]

Why does the frame need beefing up? The frame can't tell what swingarm it has. The mounting points are what matters, you have the pivot where the swingarm spindle fits, the shock linkage and the rear shock. That's all that connects to the frame. What swingarm hangs out beyond that don't matter as long as you take the time to make the suspension work.

 

[Ade]

A friend has a GSXR 1100 that I worked on for him and looked after for years. That had a 1216 motor. It has a VFR 400 NC30 single side swingarm with a Triumph 6" wheel and NC30 cush drive less sprocket carrier. That 1216 motor must be close to 150bhp ish. Then he got me to fit a 150bhp NOS kit, it came with 3 sets of jets, 50bhp, 100bhp and 150bhp. It's an old school single shot kit so the full 150bhp in one press of the button and will stay on as long as the button is pressed, or until the NOS bottle runs out. Not like the modern timed stepped bhp kits. That NC30 swingarm came from a 54bhp bike yet it has been in my mates GSXR 1100 for over 20 years and works great and copes with the extra power.

[Ade]

I fitted the SRAD shock link Sunday and it was a lot easier than I had worked myself into believing. I took the WP link and Hagon shock out, the original builder had tried to offset the WP link by removing one of the bearings and pushing the one remaining bearing into the centre of what was left of the WP link, they had cut it down to offset it to line up with the VFR arm shock mount. They just had not cut it down enough, it didn't line up perfect so the shock was a bit pissed. They had left the WP link pivot bush the full length to fit in the brackets on the frame so it was only the dog bones keeping it all in place, the link could slide  either way on the pivot bush. The pivot bush in the VFR arm was similar, it was a full width bush the same width as the dog bone mount on the WP linkage. It could slide in and out on the VFR arm. I measured the width of the bearing mount on the VFR arm then cut down the bush that was fitted to give 2mm of play each side. I measured the width of the front pivot before I cut the WP front pivot bush down to the same length as the SRAD one, the front bush outer diameter was the same in the WP and the SRAD links. The front pivot bolt diameters are different, the WP is 14mm, the SRAD is 12mm. I could have bored out the SRAD bush but the WP bush was in better condition. The bushes are hardened steel so cutting down the WP one was easier than boring out the SRAD one. A parting off tool struggled to cut the bushes but a stainless cutting disc went through them, then a facing off tool cut them OK. I measured the dog bone pivot bush, then worked out what spacers I needed to centralise the SRAD link and dog bones. I needed a 27mm spacer each side of the VFR arm shock mount pivot bush to centre it. I offered it up to the bike and the SRAD link fitted perfectly to the left hand side bracket on the WP frame. I was gob smacked, I thought it would be a lot of fettling and measuring to work out spacers. All it needed was one 27mm spacer to fill the gap to the right hand bracket. There was one minor snag, the SRAD link had an extra bit of ally cast on the bottom, a raised flat section. One end of that raised section hit the WP frame and restricted the movement of the linkage. A few minutes on the linisher took that end of the raised section off so the SRAD link has full range of movement. I used the SRAD dog bones to get an idea of where everything fits and when I took the bike off the stands and jack it sits too low but at least the suspension works after being a hardtail with the shock jammed against the swing arm! Even the offset WP top shock mount will work so I might not need to make a new top mount. Next job is to work out what length dog bones I need to get the bike to the right height. The SRAD dog bones are 150mm between centres. I have some 120mm ones to try which might be too short but will give me an idea of where to go with making new ones.

 

[Ade]

So it's an SRAD 600 shock link, all the link needs is a little area of extra ally on the bottom removed near the front pivot. The WP front pivot bush is modified to fit the SRAD link using the WP washers each side of the link and a 27mm spacer takes the length back to fit the WP mounts on the frame with the WP 14mm bolt. The VFR swingarm pivot bush is now 40mm long with a 27mm spacer each side to centralise the SRAD link. The WP top shock mount has been offset to the left to line up with the VFR mount. I have some 5mm thick 316 stainless flat bar to make new links. I'll make ally ones to try different lengths first, then make stainless ones when I know what length I need.

[Ade]

To be fair I might not have needed to linish the extra area of ally off the SRAD link as it only touches the frame on the lowest dangle. At the time I didn't know how much movement I would need for the link so I removed it. I'll check it when I have the right length dog bones worked out. It doesn't hurt to remove it but I could have been over thinking it.

 

[ARNO]

I would love to see some pics of this mate!

[Ade]

7 hours ago, ARNO said:

I would love to see some pics of this mate!

I'll put some on when I have finished.

 

[Ade]

After some trial and error the SRAD linkage is fitted and works. 

The bike bounces on it's own suspension instead of being a hardtail with the shock jammed against the swingarm.

I tried making adjustable dog bones at 120mm and 130mm centres, using the original top shock mount, but that jacked the rear up too much.

I decided to try the 150mm SRAD dog bones as a base setting and make an adjustable top mount.

Now it all works but the shock in it is too soft. 

I am looking for an SRAD 750 shock ideally, or a 600 one will do.

I used a ZX6R top shock eye and made the adjustable mount to fit the standard shock mounting points with the eye offset to line the shock up with the offset link.

I'll put some pics up now I have the fabrication side worked out.

 

[Ade]

[Ade]

That shows the SRAD link with dog bones I bought in, a standard WP link and the cut down WP link.

The first pic is when I started showing the shock jammed against the swing arm.

I first off sanded some of the raised area off the SRAD link to get it to move properly in the WP mountings, you will see there is a small blob of ally on the frame that was restricting the movement of the link sot I had to remove nearly all of the raised area and sand a little notch in the link to stop anything fouling on each other.

I made some 6mm ally test dog bones to try different hole spacings.

I made some 316 stainless adjustable dog bones at  110mm, 120mm and 130mm.

They 120 and 130mm centres ended up jacking the rear up too much, I did think about just lengthening the side stand and going with the 130mm centres but decided I could do it better.

[Ade]

[Ade]

The original top mount had been offset with the frame bar drilled and tapped to suit. 

That part is thinner than where the shock mount is supposed to fit and it was bolted down across the original raised section with a 2mm gap at the bolts.

I made some 2mm stainless shims to fill the gap at first, but didn't like the idea.

So I decided to make an adjustable top mount. I used some 12mm flat as the base with some 8mm plate for the top and some 5mm gussets.

It is a bit heavy but I tried to err on the side of strength and use stuff I already had in.

When I do another one I will buy in some 8mm thick steel angle, or even a section of H beam and cut it down from a single piece of steel, I'll work that out when the time comes.

I used a ZX6R top eye because they are easy to get and cheaper than if I made one from scratch.

I made a 15mm thick ally spacer to move the shock away from the front of the swingarm.

Just need to find an SRAD shock now as the one that was in it is too soft with the SARD link and dog bones.

Edited September 23, 2021 by Ade

[denisd]

Nice work, tedious but satisfying I bet. 

[Ade]

4 minutes ago, denisd said:

Nice work, tedious but satisfying I bet. 

I like a challenge.

 

[Ade]

It's great that you can attach pictures direct from a PC to the forum now. It used to take ages going from a photo hosting site, copying the link, then attaching it to a forum.

[Gixer1460]

You've always been able to do that, it's just the site had a size limitation that meant 'hosted' pictures could be larger. Now the site is self hosted the limitation is no more but big files still eat into storage and bandwidth so if adding pics - don't take the piss with 10+Mb images LOL!

[Joseph]

It compresses the crap out of the quality though, even on small size files.

I host them elsewhere and add the link

Anyway, great job on the swingarm

Edited September 23, 2021 by Joseph

[Dezza]

I think your 'dog bone checker' is a great idea

[Ade]

9 minutes ago, Dezza said:

I think your 'dog bone checker' is a great idea

It makes things easier. I tried 130mm and they worked but it lent over too much on the side stand. I tried 120mm and it was even worse. I went back to the 150mm SRAD ones as they put the link in as close to the SRAD angle of dangle as I could get. If necessary I can go to 140mm. By trying 10mm increments you can see which direction you need to go in so if 130mm and 140mm aren't quite right you can do some in the middle at 135mm.

 

[Ade]

Just had a result. Looking at an SRAD shock on Eblag, found one that looked decent for £30 or offers. I offered a cheeky £20 expecting them to come back with a counter offer. They accepted my offer so I have an SRAD 750 shock on it's way. Some people are asking well over £100 for shocks that look like they have been dredged from a canal! This one looks pretty good. I'll still whip the spring off and clean it up but it should do the job.