Just wondering if anyone has had a go at servicing/refurbishing the linked brake splitter from a SpadaNT? I have a grotty spare one and was thinking of having a go at refurbishing it.
If any one has done this could the let me know how they did it and the sources for any parts such as seals. I have had a peruse of ye olde parts list and there is no break down of parts for the splitter
Hi Gwen, the Spada splitter has an upper piston fixed to a lower bobbin with fluid passages, the upper piston is spring loaded and, as the brake is pressed, the fluid goes to the rear brake and as pressure increases it lifts the piston allowing fluid to the front brake. Due to its position on the bike it sometimes gets corroded. The drill is to remove all brake fittings including switch, remove upper rubber cover with a small screwdriver around the edge, take out upper circlip and remove spring. Then drift piston out upwards via lower orifice, carefully, using a 3 or 4mm parallel punch. I cleaned mine up with a rotary brass brush in a Dremel, taking care to avoid the seals, re-assembled with brake grease and Robert is your aunties’ husband.Cheers, Gerry.
Unfortunately it was about 30 years ago I took one to bits, I remember it had like a rubber grommet thingy around the piston bit, and maybe it was all held in with a circlip, but memory is lost in the fog of time. My manuals say nowt about it either.
However I think I figured it out that actually it works like the ‘normal’ connector block, therefore passing fluid to both front and back equally, until the pressure reaches a threshold then the piston moves and this grommet thingy closes up a channel going to the rear caliper, I think. So no more fluid to the rear, all further must then go to the front.
I think in my case I’d stopped getting this shift of emphasis to front braking when the pedal is pressed harder, hence leading me to investigate.
The grommet had got distorted with ‘tiredness’ so was still letting fluid through to the back when it wasn’t supposed to.
Something like that.
The bit about the rubber top cover moving up is right I think, a way of checking that the piston is moving. Doesn’t move much though so best test it by a finger on top, easier to feel than see. Possibly…
With mine, you have to press quite hard to get the piston to move up to a point where you can feel it pressing under the rubber top cover. I guess this is when it closes off the rear supply to avoid locking the back brake.
I junked all the fittings and hoses on my Convert and fitted a simple Y banjo on the master cylinder, a stainless braided hose to one front and the rear disc. Never locked the rear yet. I thought braking force on these models was determined by disc diameter. Is the Spada different than the T3/Convert?
Not sure why they fitted the Spada with a sophisticated splitter device yet as far as I know the others are just a union to join the pipes together. The Spada discs are the same as the others, it has a larger diam P9 rear caliper and that gives a lighter braking effect for the same pedal movement, reducing the risk of locking the rear wheel.
The Spada III (and similar) had a later version with a valve to delay the front brake activating. The rear brake is pressure limited.
Causes problems at MOT time with testers who have no knowledge of linked brakes.
I guess this is when it closes off the rear supply to avoid locking the back brake. >
Sort of …
The idea is (was?) to achieve 50/50% braking front/back for ‘light’ pedal pressure. Albeit the rear disc is smaller diameter, this was achieved by making the pads larger area (requiring the P9 size caliper), to get more ‘bite’. In theory.
When the pedal is pressed harder the emphasis of braking force is focussed on the front.
The idea was you preferably want 50/50 on a wet road, so use the pedal gently, but for a dry road you can stamp on it.
Bear in mind different pads each with a particular friction coefficient (or whatever it’s called) were originally specced as well. But can’t remember what they were, might have involved extra soft ones on the back. (To be even more grippy.)
I had a butchers at the valve this weekend. The circlip that holds every thing in looks a right swine to get out. None of my circlip pliers would fit in. I tried using some needle nost pliers and that didnt work. Ah think Ill shove it in the drawer for some other time when I have got hold of some finer circlip pliers (ohh goody more tools to play with )
Did have a look at the one on the Spada apart from some nasty congealed grease on the top of the valve every thing looked nice. Cleaned the gungey grease off and put some lovery new clean grease in. Probably shall never look at again for years.
As far as I know they are rare. I have a spare I am hanging onto.
Unless you know better the splitter puts the rear on almost fully before the front comes on.
I have not taken one apart or seen any diags though.
Looking at the close-up pic on the other thread, since the feed to the rear caliper still comes out the bottom it reminds me (if hazily) that there was like a long rod or somesuch down to the bottom; on the end was like a piston type thing with the grommet thingy around it, but, with cut-aways in the piston so the fluid could get past. (Through the centre hole of the grommet that is.) IIRC the piston is pulled up actually (the fluid pressure tries to push the rod out of the top end of the housing), and the raised bottom round end of the piston closes off the centre hole of the grommet thingy. (The necessary pressure to achieve this depends on the spring strength obviously.)
The other fluid holes further up the housing are I’m pretty sure essentially the same as the standard “manifold” so no such restriction to front brake.
Add in ageing / wear / incorrect pad friction it gets even more variable
I notice “four-way”, that’d be master cylinder, front brake (bundy tube), rear brake and hydraulic brake switch. Same as ‘standard’ manifold then.