Vespa disc brake conversion:
On this page we hope to explain the various ways in which we acheived either semi or fully hydraulic disc brake conversions. The models covered include a 1958 VNA, SPRINT, SUPER, RALLY, VBA, T-5 CLASSIC & MARK 1 T-5. All the models required some sort of modification to either the, mudgaurd, horncast, forks, headset, so we are not trying to tell you it is an easy or staight forward job, because it isnt. We have used both PX and PK forks with different shock absorbers.
VESPA VNA 125cc:
This model is decribed in great detail elsewhere on this website, so i will try and expand on what we did here. The steel head set was modified where the front brake lever fits, in this instance we cut away the lever housing and welded a metal plate cut and finished to the excact shape of hydraulic housing, similar to that of the PX disc. Iwanted to incorperate an electric start so a small oval was cut underneath with 2 small holes either side for the start button.A hole was then drilled into the headset lower with the hosing travelling down the PK XL fork tube and comes out where the normal brake cable should. We also use a 10mm drill bit to make both holes at the bottom of the forks larger so that it is easier for both cables to be fed thro' the forks. A SIP LML traditional looking disc hub was used with standard caliper and a beefy Malossi RS24 front shock.
On the forks the top steering lock postion had to be changed and the bottom steering stop was also altered. Please note that SIP sell PKXL forks modified for this type of conversion at great expence, be careful when purchasing these as they are not without their problems when installing, more about them later.....
Now the mudgaurd, this modification was rather straight forward, with a piece of tin cut out the top and a template made to then weld the same bit of metal in another location, 3 hole were drilled and 1 on the side. It does appear to sit a bit high but when the wheel is on and the scooter is on the road it actually not too bad.
VESPA 150 SUPER:
The Vespa 150 super provided us with a few problems in as much the front mudgaurd was a bit thin and our customer wanted us to utilise various parts he had in his garage, this is certainly a good budget way of getting proper stopping power on his classic (if rather grey) Vespa 150 super.We got the axle grinder out and cut the mudgaurd in half, straight down the seem. Then a strip of metal was welded down the middle to make the mudgaurd larger and fit on his powder coated PX disc forks better. At the headset end of things again the housing for the brake lever was removed but this time instead of welding a plate to the headset, we fixed a manufactered plate of metal to the headset, along with the PX type housing all fitted well and looked like it should have been there all along!
Again the 2 holes in the fork stem were drilled larger and the steering lock and stop modified.
The hub was a PX disc (star shaped) type hub and both steering bearings were from the PX model.
A bitubo front shock was fitted, to help handling and stability.
VESPA SPRINT:
DJ Rob's set up is something special and it had to be built twice!! first of all if you like was a dry run with brackets to fit his chromed front mudgaurd without alteration which was very involved. the steering stop was welded into place by SIP, but they still had to be modified to actually work, also the position for the steering lock was not altered, so that had to be done as well!! Now a word of warning!! our friend bought these PKXL forks brand new from SIP and they stated that they were already modified, but that was not the case, as we still had to make them fit!! German engineering my arse!!
The first build went well then Rob stripped it all down again and got the whole lot chromed and gold plated, once that was done he brought it all back to us for the rebuild and bleeding of the brake.
the top housing is a manufactured plate similar to the super, the forks are PKXL and the hub is the star shaped PX disc type with a PK front adjustable bitubo shock, all looking lovely as i'm sure you will agree.
VESPA T-5 (MARK ONE & CLASSIC):
One model 2 different headsets, same principles, scooters getting faster and faster, but hang on how do they stop?! Both of these T-5's have PX forks so it is quite a simple process to install the disc brakes on these models. At the headset the manufacturered brackets were fitted, on the mark one T-5 we fed the hydraulic hose down behind the horncover PX disc style because the mark one has locking rings at the top of the forks, if we fed the hose down thro' the fork we would have encountered problems every time we have to remove the headset.Both these scooters have bitubo front shocks front and rear as both these scooters have been tinkered internally by Paul and are therefor very fast, hence decent brakes.
VESPA RALLY SEMI HYDRAULIC CONVERSIONS:
On Vespa Rally conversions we have to unfortunatly change the forks, PX forks are ideal and readily available for this conversion as there is a different damper and spring set up on the Rally forks.
We did the semi hydraulic conversion so to retain the features of the rally headset at the top, there is then a standard brake cable fitted as normal and links with the hydraulic housing located on the bottom fork stem. We had to alter the mudgaurd in a similar fashion to the VNA, also trim about a mill of the bottom of the horncover so that the mugaurd could move freely form side to side. Again the fork stop and steering lock had to be altered on these models. Both have again Bitubo shocks fitted and it all looks very busy at the bottom of the forks 
and hub region.