Britbike forum Forums Thread Like Summary - Wet right hand control housing - '78 T140V

The right hand switch housing on the '78 Bonneville is weeping...  Rut-ro... I should conclude that the master cylinder boot seal is leaking by.  

The brake works well.  My concern with replacing the boot is that I don't know if I will disturb any seals besides that boot, I have not been into one of these particular master cylinders previously. 

Obviously I will thoroughly clean the inside of said switch housing with contact cleaner.

Thanks for any advice on this...

Best,
Rob 

If fluid is leaking past the boot then it is the piston seal that has failed. A good chance the cylinder is also scored or corroded.

http://classicbike.biz/Triumph/Main...heed_Hydraulic_Brakes_Triumph_Norton.pdf

Hi Rob,
If the barrel is scored or otherwise damaged (corrosion affecting the end under the seal?), afaik you can just replace the barrel with a stainless one; I was able to do that a few years ago.

Whether you buy just a stainless cylinder or a complete master, L.F. Harris ones are the 'best' but the bore still needs checking to ensure there aren't any burrs where the reservoir vent holes were drilled; regrettably, even Harris have been known to be careless about this, the burrs then nicking the seals when assembled. Then perhaps just as well to install new seals?

Also if a new complete assembly, don't assume the master cylinder has been positioned correctly in the mounting; position it as per the Lockheed destructions - they've always worked for me although JH commented some time ago they don't always even on LFH cylinders, you have to resort to the earlier 'blowing into the end' destructions in the Workshop Manual.

I grease the pushrod end of the piston before mounting; the possibility of grease somehow reaching and damaging the master cylinder seal has caused teeth-sucking elsewhere; never caused me a problem but use rubber lube if it concerns you.

I grease the master cylinder threads in the mounting before reassembly.

Finally, I always fit a stainless locking grub screw and, if present, front brake switch mounting screw:-

. original grub screw thread is 10-32, '80-on or new are M5 ime (but check?);

. original front brake switch mounting screw is 4-40, '80-on or new are M3 ime (check?); I also fit longer to fill the thread in the mounting casting completely.

Hth.

Regards,

Master cylinder? You'd use the same master cylinder. It's only a matter of inserting the T-piece into the brake line to take the hydraulic switch.

Hi Robert, Ordering from one vendor is often not possible. Prices for exact same part can vary wildly if that matters to you. Since covid took hold parts inventory has been selling out quickly. Looking like owners finding spare time to fix up their bikes.

Was looking at Baxter Cycle's website just now. They sell some pre made braided hose for T140. I didn't look a full selection.

Making your own certainly allows for a perfect custom fit. Buy some extra hose just incase.... Very easy to wish you did it different. I sometimes just plain mess it up & spoil that hose. Plus you may need some spare to practice with.
Don

Hi Rob, Sent you an email with the photos.
Don

Re- measuring in awkward spots

Using a wire coathanger can help, straighten it out and use it to map the route of the pipes then measure that.

I know I'm coming in late but here's info on the length of the rear brake hose, the short 8 1/4" one is for the low mount caliper. The upper mount caliper hose is longer at 9 1/4 ".

Hi Rob,
Yes, I did it that way because, as I say, I was after "looks standard at twenty paces".

Yes, wrap the hose tightly with 'gaffer tape' (cloth tape sticky on one side) where you want to cut, cut through tape and hose with a hacksaw or Dremel cut-off wheel - tape stops the braid splaying.

In GB, Goodridge supply hose in multiples of 1 metre; if you're happy to have all pieces with the same-colour plastic coating, one metre will probably do all the pieces from master to caliper.

I'll PM you a full list of Goodridge part numbers and hose lengths fyi. Goodridge have always put assembly instructions in the back of their catalogues; 'til recently, they had their last (2015) full catalogue online but have recently taken it down; The link to similar instructions on one their British resellers' websites is below but I'll also include it in the PM.

Mmmm ... basically Assembly Instructions For Goodridge 600 Series Brake (& Clutch) Hoses.

In addition, before "Step 1":-

. If I'm making up more than one piece of hose, I start with the longest distance between two components, on the basis that, if I do cut the hose too short, I can use the cut length between two components closer together ...

. I connect the fittings to the components without their Sockets and Olives, so the fittings' spigots are exposed.

. I slide the hose end on to one spigot and hold the hose up against the other spigot - I move the hose to and fro against the second spigot so I can see how the hose curves out of each fitting - I'm aiming to have the finished hose exiting from both sockets in line with the fitting before it curves towards the other fitting; if the hose isn't in line with the fitting, I made the hose too short.

. When I think I'm happy with the hose length, I measure it, round the measurement up to the next-nearest centimetre (or half-inch, whatever suits you) and gaffer-tape across the new measurement.

. Final check before "Step 1", I check the new hose measurement between the two relevant fittings' spigots. If I'm not happy, I repeat the last two steps. If one or both fittings' spigots are awkward to reach, and I'm not sure if I've got the length correct, I'll add one or two centimetres before cutting.

Before "Step 2":-

. Once I've cut the hose to length, I slide it on to both fittings' spigots to see how it looks. If it's too long - not in line with the fittings and first curving away from the other fitting before curving towards it - I gaffer-tape and cut off one centimetre at a time 'til I'm happy with the line. Sounds a bit tedious but I (almost ) never end up with any hoses too short. If you think you've cut off one too many centimetres or half-inches, adding the Olives at each end increases the hose length a little ...

"Step 3" onwards. At "Step 5" (fitting the olives), be aware you will stab your finger on the braid ...

Admire your perfect custom fit before moving on to the next hose/task.

Hth.

Regards,