VBB disc conversion

[3narf]

Hi

I'm shortly going to be converting my 150 standard to front disc. I've done it before with my old ETS, although that didn't involve a fork swap.

I've got an LML Star Lite front end - fork, shock, disc, hub, caliper, hose, master cylinder etc. £130 off ebay.

I need to find a tatty VBB mudguard I can cut to clear the shock. I also need to either modify the headset or switch housing/brake pivot to take the master cylinder. I'll post a whole load of pics when I start the work.

Why are you posting this now, I hear you ask? I'm in the back of the car on the M4, and bored sh*tless! 😄

Warning - once you've converted a classic Vespa to disc brake, you can't EVER go back to the crappy drum front end.

[maxifields]

I'm thinking of converting my sprint would lml star fit ??

[mijapxman]

Apr 15, 2019 9:30:56 GMT 3narf said:

Hi

I'm shortly going to be converting my 150 standard to front disc. I've done it before with my old ETS, although that didn't involve a fork swap.

I've got an LML Star Lite front end - fork, shock, disc, hub, caliper, hose, master cylinder etc. £130 off ebay.

I need to find a tatty VBB mudguard I can cut to clear the shock. I also need to either modify the headset or switch housing/brake pivot to take the master cylinder. I'll post a whole load of pics when I start the work.

Why are you posting this now, I hear you ask? I'm in the back of the car on the M4, and bored sh*tless! 😄

Warning - once you've converted a classic Vespa to disc brake, you can't EVER go back to the crappy drum front end.

Look forward to reading/ seeing more about this, Bud👍

Mij☺

[3narf]

May 24, 2019 18:40:33 GMT maxifields said:

I'm thinking of converting my sprint would lml star fit ??

Hi, I think you would also need the PK/Star Lite fork...

[3narf]

I'm hopefully going to make a start in the next couple of weeks.

I'm just contemplating what to do with the headset; I think I might remove the switch housing/brake lever mount pin the throttle tube and fit a dirt bike master cylinder and throttle unit. The alternative is to get the PX m/cyl mount plate and have it welded to the switch housing, like I did with my ETS.

[maxifields]

I'm in the middle of fitting lml forks to my sprint for my brake disc conversion, all going well so far, will update when I've finished .

[mike141]

Oh Please post pics, I’m interested to see how this is done!

Mike.

[3narf]

Wish we could post pics!

[maxifields]

I'll update when I've finished.But  although I have photos this site won't allow any more than 1mb attachment.I may put them on youtube .Will let you know  

[3narf]

I made a start today! I pulled the new for apart and gave everything a clean. It all looks usable although I'll be replacing the shock with something more sporty. 



I was going to paint the fork black but the link actually cleaned up nicely so I might leave that, and paint the fork with aluminium silver. The caliper mount looks good, too.



The hub looks a bit more tatty so I'll spray that black I think.



The tape lines on the mudguard follow the line of the fork; They're there for if I decide to modify the mudguard. I like the idea of being able to remove it without dropping the fork.

[3narf]

I really got stuck into it this afternoon so here's a couple more pics.














It's all been straight forward so far; as I'm going to be using a QA throttle and bar mounted master cylinder the only problems I can see currently are the lock stops being completely different, and the steering lock. Also, I'm going to have to find some way of fitting switchgear - lights, horn and kill switch.

[3narf]

I have a choice between modifying the lock stop plate on the frame for the PK (LML Star Lite) fork, or cutting the lock stop off the fork and repositioning it. I'm currently favouring the latter option in case a future owner wants to fit an original style fork, won't be me though!

[3narf]

Let me know if this is boring everyone!

Today's problem is that the headset won't tighten onto the steerer; not really a problem with the conversion, though, because it was the same with the old fork. I'm going to use a stainless shim rather than buy a new headset (which could be equally bad).

I cut off the lockstop casting from the new fork and confirmed that the fork fits in the frame and protrudes the correct distance above the bearing. Also took some measurements for a new lockstop and also the steering lock (why does steering lock mean two different things, both of which are relevant to this conversion? From now on I'll say travel stop or steering lock).

The headset part of the job looks like being reasonably straight forward. I just ordered some bits, which is always fun.

[3narf]

Some progress today:








Measuring positions of steering lock fitting and travel stops on original fork









Fabrication of steering lock fitting




Fabrication of one travel stop. 

So far everything is spot on! I came in for my tea but just the other travel stop to make tomorrow.

[3narf]

Progress since last post:


Second travel stop made






Fork dry assembled to determine ride height - looks fine. I'm going to keep the factory finish on the hub, link and caliper mount because it looks good. the fork leg will need masking and spraying.

I shimmed the loose headset with 1/2 hard stainless 0.25mm shim and it now tightens down nicely!


Cut lines (black) on the mudguard; It's going to expose the shock and also be removable without dropping the fork, like this:

Just waiting on some new cutting discs!



RH bar is now fixed in the headset.


With new switchgear, dirtbike m/cyl and throttle. The bar is worn right where the m/cyl mounts, so I'm going to replace it with 22.2mm mild steel tube.

[mike141]

Looks good 👍

[fattaff]

i know this is an old thread but bloody splendid work old chap !!!!! great pictorial story