Modern Vespa

This help any?

You put the shock on? Is that not important to line it all up?

Pheasant Plucker!
Yes - that's what I needed.
Brilliant.
(Please tell me it wasn't on/in the box which I discarded in my hotel room when consolidating for travel...)

Shock holds the part from rotating - but is unrelated to centering.
See two pics below - subtle - about a washer's thickness of distance... of the disc centering in the caliper.


Caliper perfectly centered on disc - but hub has movement. Will try Pheas's washer stack as per image provided

Depending on how you stack the washers, the caliper relation to the disc (center to center) changes. Off center about 1mm here.

Little hard to tell - the disc has its edge painted black. The high spots on the waves interfere with the caliper as they pass through. It's likely the caliper spec.

Recently I had a closer look at the AF setups, and found there was a pdf to download that had an exploded view. Not sure which site though, I'll find it in my downloads folder after work if you like.

Ah, PP beat me to it.

Pretty sure the washers/shims/spacers are there just in case you need them.

Here's the links you were after:
Fork Swap for 150 Super
Disc brake setup for oldie

Ginch - Thanks!
Yes - woke up this morning to find the exploded view from Pheas' as I sipped first coffee of the day - allowed me to put the washers in with a little confidence - nice to have a win to start the day after wrestling with trying to solve it at days end yesterday.

Me in shop at 4:00 pm yesterday: A-F parts? What does that stand for? A -bsolutely F-ucked up? A-int it F-unny we don't tell them what order to assemble? A-nother F-rustrated customer?

Then this morning - coffee high - exploded view in hand: Boy - these guys make a nice hub. Just look at that machining. A-bsolutely F-abulous.

:-)

BTW - Those were the links I was looking for. Chapter and verse for anyone that is tackling this and wants some insights before starting.

I wanted to see the chart and your thinking on it.
I've got a pretty good solution for drawing the shock in - similar to yours.
I bought an offset mount - and I spun it around backwards - to push the top of the shock in - along with some grinding of course. Worked on it today - looks pretty nice - happy with the effect.

Now i'm working on my solution to minimize/eradicate chopper look - or large gap at horncast. Pics to follow on all. As you noted - love the look of the VBB and don't want to totally trash that - but if you think the brakes and dive are bad on a stock one - try putting a sidecar on it... Really gotta update it for my rig.

Anything you find useful, add it to your favourites (yellow star top right). Makes it easy to find again via Forum/Favourites.

Done.
Cheers.
Question:
Why did u have the fork cut in the middle rather than grinding off the weld, shortening, then re-inserting the trailing link. Isn't it just an insert that is welded at the collar (arrow) at factory?
(Welder did a sweet job with the weld)

I certainly did think about cutting it there and figured it would be very neat. In fact when I took it to the welder I made that suggestion, but he said he felt more confident of a good outcome the way he did it. Afterwards (I think) I saw that S&S did it that way, and was a bit relieved tbh!

Interested to see what you did with the top shock mount.

It's probably a bit late (sorry) but some shocks have much less happening at the very top, so can lend themselves to less work on the guard & mount. Probably the best example is the Malossi RS24. I've noticed a few pictures where these have been used and there is no apparent alteration to the guard. See the spring is shorter than a regular type of shock so should tuck in more neatly.
For me though, the price at around 5 times the price of the YSS made it an easy choice!


YSS

RS24

Ginch - Thanks for not just rolling eyes into head - "great - orange sidecar bodge with California electric motor dream guy is asking me why I didn't do it differently..." Good insights with your feedback. Perhaps your welder looked and saw the end piece is cast - and thought - that might not have a slug that goes up into the tube - they would have to machine that or cast over an inner tube. Now that you confirm S&S also cuts tube rather than removes the end - I am thinking that may be the case - your guy mighta been on to something. Little investigation may be needed here. (has anyone ever seen the end lug removed from the end of a fork?)

As for the shock - below is my understanding and my approach.
- The YSS & Malossi you show are ~195MM shock lengths - suitable for the PK forks.
- Shock length determines trailing link angle (assuming top mount is fixed)
- BMG has one as well which is what I bought (SC web site shows it as 205, but you can swap out the top mount - to one that is 10mm shorter and get 195).
- The importance of 195 is, when matched with a PK fork, it gives the right trailing link angle - of roughly 100+ degrees.
- All of these shocks will still interfere with the mud guard - it is a width issue rather than a length one. So moving the shock inboard is still required with all these shocks - if you don't want to flare the mud guard.
- My goal was to move the shock inboard to the same width as the mudguard side tab that is on the PK fork - so that the width is no wider.

The shock is on about a 6 degree angle (est).
Im not so concerned about the shock wearing out - it will likely not last as long due to the angle - but I have mostly smooth streets and don't use it as daily commuter.

I'm more concerned with the stress on the top shock mount. It is going to act as a swivel joint - every time the trailing link goes up. I need to make sure the shock doesn't bind - and then fulcrum - off the AF hub mount. I am going to use some clearance gauges - compress the suspension - and see if it is hitting.

If yes - I will need to figure out how to relieve it from doing so - or it might rip out the shock from the hub.


I started with this for my shock mount. It is offset 4mm outward - but I spun it 180 so it moved the shock inward

Then I cut both the shock adapter and the fork mount back. I assembled so I could have a nice straight line. Here I have already cut the adapter and am cutting the fork

This is before final grind - you can see I cut back both fork mounts. I also cut out some of the "webbing" between them to fit to the new adapter. since is is tapered - and I wanted to minimize cutting, I also tapered the under side cut of the

the spring is pretty close to flush with the fork mount tab. To get here - I had to also shape the A-F (A-re you F-ucking kidding) hub. see next pic.

In order to tilt the shock inward, I needed to shape the top of the hub where you can see the grind. Limited meat there - so was careful in my depth - just enough to allow a bit more pivot from the shock.

I also had to reshape the holes of the shock slightly to allow it to pivot inward. I put the bottom bolt in, and rotated it inward - then could see how much I needed to remove from the top hole. Prior step of grinding the hub was critical to do first -

Pretty sure the holes in the bottom shock mount are not a tight fit, so if you tighten the top first, you can then tighten the bottom to let it sit in a position where it is not in tension from the outset... if that makes sense.
Mine has been installed for some years now and not showing signs of odd wear.

The angle of the swingarm is also going to depend on how much is cut from the fork itself. Since they don't admit to cutting anything that is a bit of a 'suck it and see' situation.

On my conversion I had to cut the mudguard tab off the fork - on a friend's using a Rally guard it was just covered. Will be interesting to see where yours end up.

I'm enjoying this Charlieman. I do like seeing stuff done that was never meant to be done (though not in the bodge sense!).

Makes sense. Thanks. I was surprised to see how the shock sort seams to float on the hub - thought I was doing something wrong/figured I was going to have to crank down on the shock and it was going to pinch the hub. Still getting to know this thing...

Shock came with a shim that fits the hole pattern where it bolts to hub (see below) but I bought a couple extra - not having any idea how they worked but figuring a thin nicely shaped shim that matched my shock wold be a good thing to have in my tool kit for $2.00 - so I got a total of three - and then promptly trashed one by using it as a protective layer under the nuts - folded into a complete gnarled mess - but hey - it protected the shock's paint...

Note: website said .80mm. Receipt said .20MM. Parts sent were 20. One that came with the shock was .80. Would be a nice thing to have a few extra of these in both thicknesses to nail the fit and minimize and play in the hub when brakes applied. Seems crazy to have opted for radial brakes - then have play in the hub as it moves against the shock. These little shims should help tune.

Feels to me like just 80MM one on one side of the shock is insufficient. Probably why they have .20 mm for sale as extras. Pic below of the ones I ordered.

Couple additional pics also:
1. Shows a better shot of how I took a little material off the A-F hub.
2. Shows the interference area on shock before I ground hub. I moved everything around with the bolts loose to intentionally mark the shock - then took apart to see if I was getting any scrubbing - which I was due to how steep I have the shock angled in.

Other two shots self explanatory.


Side view - you can see how I angled the grind better - and I can see that I didn't get it very even. Haha - will have to go back and clean that one up a bit on final assembly.

You can see where the shock was hitting - may still be hitting at full compression. Need to check. If it fulcrums on this point - it might rip the holes out of the shock base - need to make sure shock can bottom out - and this not hit.

Gratuitous scooter porn shot of the assembly - 'cause I kinda liked the way it looked.

Sip speedo cable electronic wire. Radiused hole a bit - and put in grommet in to protect wire from wear.

Shim - they shipped .20mm, not .80. Would be nice to have a set of both to get a snug but non binding fit.

Grommet size and shape used - fit thickness of fork and wire nicely

Looking v. good. Is the caliper still contacting the rotor now the shock is on?

What's the clearance from the tyre like since you angled the shock in? I wonder if you are 'getting away' with that modification of the top mount b/c a 3.0-10 rather than a 3.50-10... about a 6.5mm difference. But then easier to get the mudguard right...

I'm snapping at your heels....

If these forks have been shortened, then I don't reckon they are short enough.

There is still a lot of space above that tyre. I see why S&C are truly superlow. Their mount jacks it all up another 10mm (with the fork likewise cut) - at the cost of the shock poking through the guard though. Hmmmm. I think I'm gonna get a bigger guard - the VBB guard is too little for me.

And yeah... this was an absolute plucker of a job. No instructions... The Pinasco kit had no axle washers/shims/circlips. The top mount for the shock isn't right for mounting like this - but I can't see how else to mount it to the 'conversion' base plate. And I have to force the shock in towards the wheel to fit to the base plate.

It's late and my brain hurts.

SIP makes a few different widths of the tubeless rims (2.1", 2.5"). Which width did you get?

Pheas' - Smart to throw it together quickly to have a look - total PIA to find missing grommet or needed washer at last moment - not like you can buy any of this stuff at the local hardware store...
Great looking set up BTW.

Ok: I've done an assembly at the weekend to get a sense of where I'm at - so a bit to share worth seeing.

The caliper still contacts the disc - right up in the top of the U shape (if a U was boxy with no radius) I went with a Galfer disc - got tipped off by the tech at SIP that it was best value: low cost, wasn't noisy like some of the more expensive brands, and "looked cool" to use his words. The downside is, it is about 1mm too large in circumference. No big deal - bit of careful grinding inside caliper to relieve is best fix.

I bought a GS mud guard - it was about 70 euro - figured I'd take a flyer on this and have it at the ready - not knowing how I would handle this issue. Had it sprayed last week - and have been dicking around with it for fit off the bike. It really doesn't look that fat - I thought it would - and still has the "stockish" look that I was hoping to maintain.

If you are grabbing a few spares in the mail, and you want to have some tools at hand to problem solve with - I would grab some of those shims I showed in prior post for shock in .2 and .8, and one of the offset mounts.

Laughed when I saw your top of shock - I did the EXACT same thing trying to figure out:
1. WTF
2. Seriously - does anyone know how to provide a f*!king explosion image in the industry?

See pic below for assembly order.

You are gonna need two of these - SIP part # 21620900 - if you don't already have them randomly in your stack of parts.[/i]


Here is the washer stack - silver part goes in to shock first, then thick bushing SIP 21620900 (hard to see first one cause its under the adapter), then adapter plate, then another 21620900, then large fender washer (also sold by SIP and others 17408800)

Pic of side clearance - I've torn this down - but i plan to build it up again to double check everything - will take a measure (mm).

First effort. That is the GS 1 mudguard - from SIP 76029000. It's not attached - and the angle is wrong - but it gave me an idea. It's close - but a little higher than I was hoping for.

Front view (also first effort). Seems nicely scaled to me for width. Crome center part will help break it up too. Let's see how it looks on the bike.

This was what was required mods of the front shock tower mount to fit the mud guard. This will be your limiting factor with the GS 1 mudguard. Note:
1. Left mount cut back closer to bolt
2. Scooter Center 4MM offset mount spun 180 degrees, and then sh

And here is where I would like to go. Not sure if possible. I've shortened the shock here by moving the lower shock mount up on the shock body. I've also got it set to its stiffest spring rate. That may be okay for me - I have a side car - but I also

Measures about 96 degrees - corresponds to the lower of the two mudguard fits seen above. The fix would be to shorten the fork. Before I do that - I want to take the existing fork off, compare the two. I want to be careful about lowering the front end

Yes - You are nipping at my heels - but have you considered that I might be here?!

I reckon your guard is looking good. I've been told that getting the guard right is the hardest part of the conversion fwiw.

Could I ask a favour - can you side-by-side compare your vbb mudguard with the GS one?

Here's something interesting...

Pretty sure this is an older GS160 done by S&C. PK fork. I think this looks 'right' - the hub was made for 10" so that makes sense. But... the rake and trail look right.

Note the distance from the edge of the guard to rim. Yours is very close to this with a slightly more acute swing-arm angle.

But then see the more recent modified px fork jobs... to me it looks like the rake is steeper on the part of the fork before the swing arm (probably optical illusion?). The wheel looks much closer to the leg shield. It is probably the result of being superlow - being shortened has to bring it closer right? Ginch will probably know a lot about this as I think he has been messing with and researching these forks for a while... Advantage of P Series Fork Over Earlier Bikes?

That white vbb looks extra superlow - it's sloping forward and appears to have some serious top shock mount work to have the top of the shock actually above the horncast! Not just the S&C superlow shock mount adaptor plate anyway.









Last edited by pheasant plucker on Wed, 27 Mar 2019 08:30:23 +0000; edited 1 time

Anyway... point is this is definitely a 'can't have it all' situation. Some compromise has to be made - and you have to choose your poison. Want more wheel in the guard? Gonna have to pop a hole in the top and have a wheel closer to the leg shield.

I have no idea what this does to the rake/trail and handling. My instinct tells me the GS would ride better - but then wouldn't the wheel closer to the leg shield increase trail leading to more stability at speed?

But for some reason the superlow reminds me of shopping trolley wheels tho. Turns out I have a limit to German Street Racer modification! Learning new things about myself all the time.

Pheas' - great pics.

Ironically, I was already trying to measure the same thing you were asking for.
- Hard to measure as I will need to customize a clamp to get some readings - but on the way.
- What I could see was - some areas are no wider than VBB - but area around shock is... and that is the pay off.
- Also - depth at shock is deeper - also helpful.
- Finally - shape of lower lip at wheel is a bit different - part of perceived fit & look from side.

Will have something back up here a bit later in the day.

Scooter and Service are the kings at this - agreed.
My opinion - they are doing the most refined/coolest work/most knowledgeable.
This black one is basically my target - stockish looking mud guard. See below.

Also - if you look at my current VBB - it doesn't fit as low rider as the Super Flow street bikes - that is their own look - cool - but actually lower than stock (as you note).

Hole in top really sits the fender down - but too street racer for me.


Superflow with non hole punched our flared mud guard. Mud guard looks GS to me

Same super flow/ stock VBB with 10" hubs

Super LOW, not Super FLOW!!

Huh!? Makes sense now doesn't it?

PX... no I don't know how they did it... all I know is they didn't think a bit about a shorter shock!

Damn Ginch - that is a nice one.
Pheas' - measures below.

Couple things I see.

- mud guard is seamed.
- bottom edge is VBB profile
- careful look and you can see the VBB indented swoosh line on side
- PK or PX fork - likely cut to keep trailing link angle steep - looks like shortened shock to me - or they don't have it in its mount/ altered at top?
- shot from little bit above - rather than wheel height - so it helps make the wheel to fender edge provile distance look closer.

I'm guessing - they pulled on the sides and widened the fender through the middle - a little like you did on your VBC. I am not opposed to that if I can avoid making it look pregnant.

So here is one other thing to think about.
Some of the styling and shape of the mud guard comes from production constraints.
- The seam down the middle is more than just a cost saver or visual element.
- It was done in production for a reason.
- The seamless GS mud guard was beautiful - but it was pressed from a single sheet - intended to go over a larger wheel.
- Single sheet has some limitations - which are seen at the profile of the bottom edge.
- The issue is, you can only draw and compress a piece of metal so far - before you get wrinkling at the extremes. They draw the part - there are probably wrinkled areas around the perimeter, so they cut the perimeter profile to give final shape - and it has to be repeatable. That forces some issues with profile options for any given piece you draw.

But

- When you make the mud guard in two parts - you have more options - because you are not reaching the same extremes when drawing only half a mud guard. This allows you to make it more "closed" at the nose in front of the tire.
- If you look at the GS - 1 piece - they had some limits - and so they end up cutting a bit more material off the nose - it slopes up (see comparison below).
- On the VBB - they were able to have the nose lower - though they didn't take the sides down quite as far - cause it was an 8" wheel.

Have a look at the pics and measures below.

The VBB has a sexier lower edge in my view - as it closes more over the front of the tire - where the GS has a more beautiful round shape - but they had to trim it a bit at the nose - in all likelihood - which is why it goes up at the front.

That also explains why the VBB has a swoosh shape on the side. They made it in two halves - so it wasn't a "negative" draw in the mold to add details to the side. Some designer thought that would be cool - when they were making the new molds in two halves - "hey, we can add a detail here for free!" (in Italian accent).

The GS - one piece - has to be expanding in width from top to bottom - or it wouldn't come out of the mold - negative draw issue.

I'm looking forward to pulling my VBB and fitting it to see how it looks vs the GS one. I frankly prefer the VBB side profile along bottom edge - due to the front of wheel - more closed - though I like the GS curve/seamless look and width/depth at shock...


GS ~ 208MM

GS - about 170MM deep from low point

VBB ~ 160 they could have made it deeper over the wheel if they had wanted to - no production constraint - but it was over an 8" wheel.

VBB ~ 185MM at shock/middle width - ~ 20MM+/- more narrow

Best angle I could find to compare bottom profile. look at the front - you can see they had to cut the GS back a little - profile turns upward for last 75mm or so.

I reckon they absolutely thought about shorter shocks but like the boosted guard look. Can pretty easily get 175mm shocks... reckon those would negate the need for a hole in the top of the mud guard.

https://www.sip-scootershop.com/en/products/shock+absorber+bitubo+racing_70011500

But I think you know this - suspect that is what is going on in the pic with the red guard? Is that your work? A shortened PX with 185mm shock? Note the swing arm angle is quite steep - intentional? Obviously not shortening the fork as much would make the angle flatter and what your thinking around this is.

Guessing the trail is dependent on some mix of shortening the shock (short = more trail) and swing arm angle (flatter = more trail).

Thinking about it - what S&C do must give more trail - which would make the bike less responsive/nimble? Like a shopping cart trolley!

Cheers c-man22. Thanks heaps for checking those measurements out. The original guard on your VBB with 10" looks pretty sweet in terms of fit to me. I wonder if it is a standard VBB guard on there. But understand why you went GS - not having to mod the guard to bits is definitely worth the $70 - the width will pay off in your case I reckon. Hope that angled shock behaves ok - I'd keep a close eye on that.

Could I get one more measurement though - what is the length of the GS guard (and for interests sake your VBB one too)? Want to compare that to the guards I have because at the moment they just look too little for the setup. Might just be because I can't get them down the fork (yet).

I think S&C use either a GS or Sprint guard on their setups - rounded no detail vs flat with detail. Dunno what that Struzzo has, but probably a GS I guess.

But 350 euro..!

I've got a pretty beat up VBB guard that has date with a hammer coming up I think. Might as well have a play.

According to the Christoph - SIP tech expert - goal is 100+ degrees.

Combo of shock length/mount and fork length will determine - agreed.

The other item to watch for is bike height. The scooter and service superflows are lower to the ground - and they match the back.

So short shock and short fork may deliver on wheel to mudguard - but leave bike lower than desired (if lower ain't ur thing)

Pheas'. Where is ur mind at for mudguard? U've got more to deal with than me - wide tire/ bad ass reservoir. Thoughts?

Hadn't seen your second post when I replied. Nose to tail, VBB is actually a few mm longer.
Best I can measure:
GS ~ 498MM
VBB ~500MM

The VBB comes down a bit more at the nose. The GS is trimmed back - so it's radius doesn't reach the extra few MM.

So while the GS is slightly shorter by a few MM - it is not as encompassing - so no difference there.

I like your VBB/hammer approach. The one issue you have to deal with is, the VBB actually steps in (prior dissertation) at the side swoosh and maintains that narrower fall from swoosh down to bottom profile. - but a bit of skilled hammer work could take that out flat - making it ~ just as wide as a GS.

Interesting. Mine too are ~500mm. I had assumed the guards for 10" would be bigger. Seems a fair bit wider, but only 10mm deeper. Although 10mm can make a big difference at the front end it seems (since that is the additional drop to become superlow).

Messing around I think modding my guard is worth a bash! (two puns for the price of one there

Not mine. There was a guy in the UK that had a website and had several examples of his conversion work. They were all PX forks according to the blurb. It's probably the original 255mm P shock judging by the look.

My mate who got me into this did a PX conversion on his Super with no cutting and it always looked odd. But that was with a Super guard... he went to a 210mm PK shock and Rally guard (still no cut though) and it looked better.
When I did mine, I went for the swingarm angle that most closely matched the PX because I had guessed Piaggio worked it out. It also protects the fork a little from force directly from the front to my way of thinking... not all the force is applied directly upwards in a vertical direction. But happy to be instructed differently!

Charlieman, where did the 10 degrees figure come from? And what was the thinking behind that?

I had a little conversation with Joe Casola of Saints Cycle Works who does a number of these conversions, and he said the shorter shock (we were talking 210 vs 195mm at that point) tracked better in his opinion... PP's supermarket trolley I guess!





I think perhaps that the GS guard may be broader at the top? Would be interesting to see a comparison between the two guards in this view.
When fitted on the scooter in thier natural habitat, I wouldn't be surprised if the the nose of the GS is possibly lower than that of the VBB, mainly due to the attitude of the VBB... it's sticking right up, not centred on the wheel at all. I just don't like that look. I see on your 10" conversion they have dealt with that.

Lastly I think you could fit the trim from the VBB mudguard to the GS one... you may not have the sculpting on the sides but the trim would break up the big flat area and give it a bit of a shadow line.

At first look I thought that wheel was buried in the guard (without a hole in the top)... but it's just the angle of the shot I think? And that makes a big difference.

And of course it is one thing to sit the guard on the fork... but then you have to get the fork in the frame and make sense of the alignment with the leg shield!

"Charlieman, where did the 10 degrees figure come from? And what was the thinking behind that?"
"I had a little conversation with Joe Casola of Saints Cycle Works who does a number of these conversions, and he said the shorter shock (we were talking 210 vs 195mm at that point) tracked better in his opinion... "

Ginch - I think these are one in the same. Joe certainly knows his stuff - good source. The SIP guy - Kristoph - who is a talented builder in his own right - pretty much said what Joe was telling you I think. His point was - you don't want to go under 100 degrees - trailing link to front fork angle. 100 degrees looks like about what I get (106 by my measure) when I put the 195mm shock on the stock PK fork (stock from shock mount down). Reposting pic from previous post - this is what I was getting at.

If you drop below 195 (say, 180/185) in shock length - but keep PK fork length stock - you get about 96 degrees between fork and trailing link. According to Kristoph - that is too flat.

My take - there is a limit on how much trail you want before it gets too much - aka 96 degrees. SIP guy showed me his with about 90 degrees on it - told me it was not nice to drive at that point - needed to maintain min 100 degrees.

Pheas - like the cardboard test piece. Probably a pretty good tool/indicator.

BTW - did a little research on the fork cutting option. Below are some pics shot from inside the fork - using a scope. I took a wire and ran it down - with a mark on it relative to the hole drilled in the fork. Looks to me like the cast lug at the end of the fork we were discussing does go up in the fork - but appears to be only about 5mm. additionally, I suspect it is basically just domed - so it fits up in the fork - but does not truly "sleeve the fork".[/i]


Blue tape on wire shows depth

Matching wire now on outside - shows about 4 MM to where I think the fork tube ends

Wire inside fork. You can see the lug looks a little domed - and has a rib in the center - I am measuring the lowest point. Also - looks like the lug is not precision fit to the fork - but rather the fork sits on a "shoulder" of the lug. My g

From prior post - the angle being measured - little out of focus - this was 96 degrees of angle with about 15mm of shock shortening

How's the project going? I've been down another rabbit hole figuring other parts of my build out. Waiting on the PK bushes to arrive. But figuring that they will take me well over the 100deg mark. Hopefully not too far... It's interesting that the PX fork I took apart didn't have any bush between the shock and base-plate - only 2 above. Could have been assembled incorrectly, be because of the factory shock, or some difference for a PX - will try figure out why. Assuming they are pretty important for the conversion to allow for the shock to be on that slight angle.

Also thought this from the S&C website was worth posting...

"Adapter front shock absorber Scooter & Service PX CNC

CNC machined steel adapter for the upper shock absorber mount on the fork, fits all Vespa PX handlebars. By means of this component, the front of the vehicle is placed 15mm lower, the swing angle is flatter: The resulting lower center of gravity and the longer caster improve driving stability at higher speeds significantly. HANDMADE: This product is a Scooter & Service - own development. Made in Germany."

So yeah... the shopping trolley effect!

Incorrectly assembled. Should be one above one below I see now.

Pheas - similar rabbit hole.
Spent week tuning in side car and angles/ carb tuning/ ordering bits and bobs - which was a pretext for taking lots of test rides.

Damn - these things are pure *(choose your best explicative) fun.

Work travel eating up a few days now - but here are some shots/ learnings from weekend.

Present goals:
- Match distance of axle center to fork lower bearing seat: Pk to VBB specs.
- Maintain min 100 degree angle trailing link (target spec for improved tracking without overshooting/ poor responsiveness.
- Attempt to fit a VBB mudguard to PK set up.

Below some shots of attempts taken. Results are advancing - but imperfect. Some finessing on mud guard still needed - and I am headed to shortening the PK fork.

Width - looks like success - tilting in of the shock angle allowed me to fit the VBB mudguard to my set up. Shock spring is a hair inside mud guard - may need a touch of widening of mud guard to avoid squeaks/ abrasion.

Height - Close - not there yet. Focused on area around flare at hole where fork goes through. This flare on GS & VBB does not seem to match PK fork - leaving mud guard somewhat elevated on fork. Some subtle work there might allow sweetening of fit.

Back from travel mid week - will have closer look and share some shots.

Q: Where is your mind at on your mudguard. One thought - what ever you determine is best solution for width at shock - the finessing of the bulge on top of guard - at hole where fork goes through - may help bring it down and help it seat more nicely based on my first look. Lemme know your thoughts. GL.


VBB ~ 372MM 10" hub. Stock shock and factory spring recently renewed.

~403.mm

A-F hub top bolt hole has limited meat to grind
at point of interference ( caused by my leaning in of the shock). Decided to cut away the shock mount instead - see area of black that has been cut away in U shape. Bolt that connects shock to A-F hub al

The PK fork is ~25ish-30mm longer than the VBB from lower bearing mount to axle center.
There is 25MM+ of threads on the shock. Pic here shows it set to full stiffness and bottom mount raised to use the "free" shortening between shock mount a

Not quiet there yet. Bit of an overbite at front. looks to me like the bulge where the fork goes through may need some hammer finesse

Does it matter enough to shorten the fork though?

I realised that I had the fork mount rubbers in the SIP fork conversion mounting kit (starting to lose track!) But using them I had a fork angle of 110deg. So made some mods... Widened the lower hole on the BGM lower mount at the back with the dremel (allows just a smidge of angle taking the side-pressure off the shock), and used alternative rubbers... And ground the stupidly wide shock mount bolt thingy down (to prevent the possibility of contacting the base plate).

Sitting at 105deg now.

"Shock absorber and top end adaptor must not be modified under any circumstances..." How about it if doesn't fit?
"Modifying the shock absorber can lead to damage, injury or death". Meh.

Planning on taking to the guard with hammer and tongs. Need to work out how to get the damn fork mounted first though!

VBB w/ PK Fork Conversion - Lower Bearing Race Help!

The no label bag of parts can be a challenge for those of us that hadn't assembled before - though now that I have done it 25 times in an attempt to perfect fit and remove interference, I'm fully versed.

Im taking 25MM out of the PK because it is a full 30MM taller than my VBB. I want to get back to the std road height. If I do that by ONLY shortening the shock - I get to about 95 degrees of trail. 25MM out of the fork will put me back at a good angle - AND - set my bike at the stock height.

I've learned a bunch just assembling and re-assembling as I have experimented with VBB and GS front mud guard fits - fork has come in and out of the frame at least 15 times - conservatively...

Here are a couple things to watch out for.
- As you get lower angle on trailing link (95 instead of 110 for example), it will cause the bike to "lift" in height when you steer left and right. This will give you better high speed centering - but it will also give a "heavy" feel to your steering - that I want to avoid.
- Too high an angle - 110+ - and it will likely be down right twitchy - but light. Too low an angle <100 and its downright heavy feeling in my view.
- The VBB mud guard will have some holes that line up for you on the PK fork. However - something about the geometry of the PK means that if you slide the VBB mudguard all the way back to where the bulge is on the curve of the fork and holes line up (natural thing to do) - it will loose its proper angle with the leg shield. See below pic. To my eye - this is part of the "chopper" look I don't like (not shown in pic). This can be solved by sliding the back of the mud guard hole up to the back of the fork where it goes through - the mud guard angle becomes more well aligned with the leg shield - and everything lines up better.
- Be patient on drilling the hole on the side of your VBB mud guard to fit to the fork - assuming you are using. Suggest you get your fit right on the bike first - remove the rim from the hub while everything is in place, and mark it from the inside for drilling.
- You may wanna consider giving top rubber mount same treatment if you find interference with mud guard. In my experience - the mud guard is a close fit to the upper shock tower - anything protruding will interfere - and that is with the shock tower cut back on the sides. Of course - you are flaring your mud guard - but the top of the shock area may still be a little problematic and easier to just modify rather than the mud guard - will be interested to see your end solution.

- last but not least - it might be helpful to pull the shock off and use a wire or dowel to hold the angle on your trailing link while you fit the mud guard. This will let you quickly fit and re-fit the mud guard angle and lock that down - before you take hammer to side of mud guard to shape it for the shock.

My $.02 after lots of tweaking of fit to get what I wanted.


This pic (ignore the inches) shows how the mud guard fits to the leg shield "stock" 10" wheel on stock VBB fork. If I didn't rotate the mudguard forward when putting it on the PK fork, the front lip would sit high, tail low, and chrome cen

Issue with the upper shock tower is the unthreaded section of the mount adaptor - need the upper rubber to clear that (and in fact may have to lift that rubber with a washer or two). Reluctant to mess with threading that section but have considered it. Could shorten the existing a little as planning on a nyloc anyway (M10 1.25 thread if anyone needs to know - slightly weird thread). Also, good luck finding anything for the lower thread into shock itself (if you had to) - very weird thread size.

Approaching the fitting of the guard from a very different angle... This guard's fork mounting hole was munted already. This having to take the fork off to fit the guard shit has to end!

Hahahahahahahahahahahahahahahahahahahahahahahahaha!

Awesome.

I like this topic, i wish i saw it before i grind a hole in my vbb fork to adapt the p series fork in case u curius i cut 7cm of the px fork and use a smallie shockbreaker for several year till recently found a aftermarket shock.. i know i cut the fork to damn low but what can i said i am short

Good luck with the project and cheer guys


And i still think its not lower enough

Brother E - you are the king of creative modification and inspiration for all my bodgery! That 12" conversion you did still blows my mind. Kymco rims... If I can work out a way to send you the bits I don't need once I've finished then I totally will. Hopefully in a suitcase when I visit for a rally.