Modern Vespa

When thinking about a disc conversion for a pre-P largeframe, the conventional wisdom says put a PK fork in it. Which is fine if you live on the outskirts of Munich, Naples or Barcelona. For the rest of us it's generally a bit harder to find one. However, P forks are plentiful, and potentially cheap. So what's the difference? This table from a T5 forum has the dimensions:



My friend did a conversion with a PX fork and Scoot r s disc setup. It was great for braking but I never liked the too-tall look - too much air between the guard and the tyre. He did a pretty neat job creating a bulge for the top of the shock and it's mounting bracket, but it was clearly a bulge that wasn't meant to be there. Some people cut a hole, but I wanted something that looked a bit more "natural".

Eventually I got hold of a PX fork with a drum brake and everything on it (except the guard which apparently had been autographed by Manny from the Stone Roses!). According to the table above and a comparison with a spare Super fork, everything else was pretty much the same except for the lower section - 'Degree lower bearing seat to control arm pivot point' - was approximately 35mm longer than the original.

Crappy photo sorry.

So I was a bit apprehensive about cutting the fork... I went to a local automotive engineer who said if he were to do it and certify the modification it would cost me hundreds. But he also said if it was his, he wouldn't even think about not doing it... and put me on to his welder. The welder cut, sleeved and tig welded the fork by 35mm and ensured the original direction of the swing-arm was maintained. I was really pleased with his job, which he charged me $80 for.



Now that I had a shorter fork, I needed a shorter shock as well. I'd been browsing SCK one day and saw the nice YSS pro adjustables... I had a look at the others in the range and saw that the PK was exactly the same design, but 45mm shorter! And if that wasn't short enough, a Zip shock is shorter again! P/PX=255mm, PK=210mm, Zip=185mm.

If you fit this fork, you need to grind down the 'platform' that the guard sits on a bit, otherwise it will sit too high at the front. The other thing that I did was move the top of the shock mount inwards about 10mm, which means less bodywork on the guard to leave clearance.



After that I cut the hole bigger with a pattern from a P guard (thanks again Rob98801!) using the front bolt hole as the datum point. I drilled a new hole at the side. Then I beat out the rhs of the guard, making a gentle bulge along the top side section. Now there's maybe 5mm clearance from the bracket to the guard. You can tell it's a little different from one side to the other. Though with the bulging, moving the shock in and grinding back of the shock mount, I think I ended up with something that doesn't instantly look modified...except to everyone here!

Nice work. I think drum brakes look better on these old scoots.

as a side note, I used to cook lunch for manny when i was a chef in manchester too long ago. johnny marr too. should have got them to sign something.

Thanks. The drums do look good but I have a Scoot r s disc setup that I am keen to get on there... anyway from the other side you can't tell it's a disc.

That's one of the things I really like about that kit you got.. I dig that.. stealthy.. at least from one side!

Excellent work on this fork G... you're an inspiration to Superists everywhere! Really... great stuff brother!

Cheers

nice mods mate, now i am curious to see how u gonna put the disc i am always curious on the brake and if only i were closer to you i will weld cut the fork for free especially for a nice friend like you

have a nice evening and cheer mate

I used to see Mr. Marr all over Portland when I lived there.

Thanks for the encouragement guys!

Ebeth, the disc part will go on as you see on the scoot r s site, but the master cylinder I want something a bit different, so I didn't get their m/c.
This is the initial picture that inspired me to go in this direction... to me it looks almost factory-produced.
I love the welding you do, it's always impressive! Can you weld aluminium as well?

LTH actually sell the alloy plate for the MC to mount onto. I would've grabbed one but I opted for a PX'98 lower headset.

Thanks Travis. Can you please post a link to that? I can't find it on the LTH site. I see they also have the steel bracket as well, but 35 euro is a bit steep.

I was just going to make up the plate from scratch and have my guy weld it in.

I saw your post on the GSF the other day and didn't have time to get to read it... sounds like the px headset is quicker and easier.

never try one and i think i'll need a sharpen eyes for the weld gun.. but if it a brass nor a forged steel like the one in the bar i can do that easily as u can see in my not so normal smallie project

keep the pics coming along the proceed, i am tailing u for sure

have a nice mad day and cheer mate

I've now fitted the disc brake and continue the thrill-packed story here - Disc brake setup for oldie

In using a different fork has anyone checked what happens with the alignment? Even a few mm's will impact handling. And if you put a spacer on the rear wheel the wheels wont be aligned with the centre of the scooter.

I'm thinking about doing this but looking for an answer about this before I proceed.

Tx
David

I know that the PK fork moves the centreline of the wheel across. From memory it's something like 5mm. I've checked the alignment with the PX fork fitted and I would say it seems to be as per original.

Veey inspiring, awesome
Im looking for this thread
Thanks, bro (y)