Spada brake proportioning valve

Hi All
I have the full proportioning valve on my Spada which I have had apart and cleaned, however I now have to reassemble and other than the rear brake which goes in the end I am flummoxed as to which connection goes where, I can find no photo or layout which shows the connection so a photo or some help would be much appreciated.

Isn’t it something like top one is bundy tube to front disc, middle one is the hose from the M/C, and bottom one is for brake switch?

If you download the Spada 1000 manual supplement

its in there :-)Cut and paste the links below and there are the drawings of the valve :slight_smile:
Keef Mayhem2014-09-27 12:34:28

Top one out of the back takes the hard line up to the front disc,Second (middle one) at the back is the feed in from the master cylinderLower rear one is the switch for the brake light.The one out of the bottom goes to the rear caliper.

I hate being right all the time.

well then this is the problem, two of you say top is to front, middle is master cyl and bottom is brake switch.
HOWEVER one of you sent me a link which shows top master cyl, middle front brake, bottom brake switch.
So im even more confused

OK just looked in my MG workshop manual, which mostly witters on about G5 and SP1000 ~ an exploded components diagram for the linked brakes definitely shows the flat topped manifold block as per the SP, and shows: top: front disc (metal bundy tube); middle: master cylinder (banjo); bottom: brake sw (direct screw in). Just looked at mine which is top, fr disc, middle, brake sw, bottom, M/C, but then it isn’t a Spada. You may well find that when you come to connect it up it’s a case of which tube will actually reach which hole, and is a clue to how it was connected before. Maybe. (?)

Thanks for that Mike unfortunately I bought the bike in bits with a load of braided hoses so I isn’t apparent,
ive found a Spada 2 layout which shows yet another layout with the brake switch in the end connection the front brake in the top one, rear brake in the middle and m/c in the bottom one
Im beginning to wonder if it matters !!!

Ah!! I see I was wondering that too… although for Spada, rear caliper hose must go into the bottom end one, 'cause that’s the one that the internal valve affects. But you’re problee right the other three just connect the remaining hoses and brake sw together so I doubt it matters which order.

Ageingrooveryou say its the full proportioning valve, which if it is will have the 4 connections to it.this is used on the late model spada’s and lemans V, if you look at the graphs in the manual is shows the graph on how it proportions the pressure between the front and rear brakes depending on how much pressure is applied, the pictures I posted are from the genuine guzzi manual and are how my LMV is plumbed up.Earlier bikes don’t have this valve and only have 3 connections in what is nothing more than a junction block, this is whats fitted to my LM4.You will probably find that the ports C & D in the drawing are linked as all the brake switch needs to see is pressure to operate it, you could always simply blow though it to see if thats the case

Keef Mayhem2014-09-29 02:21:56 is the graph which also tells you that ports C & D are linked as I thought.if you look you will see at low pressures the brakes are applied at almost the same force but at high pressures the front is twice what’s applied to the rear, so it is important to get it right if you have the 4 port valve :slight_smile:

No Spada 1 had it as well. Mine was a Spada 1, and it had it on. (reg.d 1979.)

and only have 3 connections in what is nothing more than a junction block

No still has to be 4, M/c, brake sw, fr caliper, rear caliper. Unless you mean LM5 does not have linked brakes? (PS [edit] even the plain junction block type still has 4 connections, 'least mine does.)    Apparently there were variations of the proportioning valve design as well, with different pressure ratios and so on, just to confuse the issue further.       

Mike H2014-09-29 10:54:08

My Spada one, 1978, has the proportioning valve. Standard fitment when the Spada first came out.

Running my 1979 T3 with -

Top = Front brake
Middle = Switch
Bottom = M/C
Lowest = Rear brake

Part No embossed on manifold = 06737210

Pretty sure this is just a manifold with nothing fancy inside .

That’s how my convert is!
part number
08 2372 10

ianboydsnr2014-09-29 13:53:46

Converts and T3’s are different as they are just a splitter valve.
The Spada valve is supposed to proportion the braking effect between the front and rear hence it is probably important to get the pipes in the correct order.

50/50 braking force front/rear, until you press harder, then it increases on the front only. If memory serves. To get the 50% on the back the bigger P9 caliper & pads are used (increased friction area). PS (edit): There was also some balancing in terms of choice of pad hardness front vs rear.
Mike H2014-09-29 16:44:50

Larger piston caliper diameter = less pressure on the rear hence the split actually works out 70 / 30 as far as I am led to believe and from a vague memeory of A level physics all those years ago.

Larger piston means more leverage surely? 70% front / 30% rear yes OK, after the valve has closed down fluid supply to the rear. In theory…

Larger piston = less pressure as it is spread over a larger area. Its all due to hydraulic forces