Bringing My '79 Bonneville Special Back to Life

Rear Master Cylinder ... Starting over again

You were right as usual, Les. The small hole was clogged. I cleaned it with a dressmakers pin and followed up with a paper clip that more closely fit the hole.

I took the master cylinder apart again to be sure not to damage the interior parts while unplugging the small hole. I also removed the flat washer and replaced it with one wave washer. There was a hole in the new check valve. I did not replace the dressmakers pin.

I did the adjustment again using the Lockheed instructions and am happy to report that air flows just like it's supposed to.

The master cylinder is fitted to the bike and the brake pedal, "generously greased," is adjusted. The spring was not so difficult. I had a tool that did it fairly easily although the darned thing is quite strong when one is pulling on it.

I'm having more difficulty fitting the rubber hose from the reservoir to the master cylinder than I care for. Working around the frame tubes makes it difficult! I wish I'd had the foresight to fit the hose before installing the master cylinder. Around 5:30PM, I opted for the national news and a cold German beer.

Tomorrow is another day and I think I won't have to work on Sixteen's 924. I found an o-ring at the local hardware store that seems to have corrected the wandering idle. It's holding steadily at 800 rpm with the air conditioning on. I'll probably drop it back to 700 or even 650. Petrol jumped another ten cents today.

Hopefully, tomorrow I can devote enough time to the Bonny to finish it up.

Thanks for all the help!

Al

Re: Rear Master Cylinder

L.A.B. said:

Tulsaalva said:

3. A piece came out that looked like a push pin (An item our American women call a "straight pin," commonly used for sewing.) except it was much thinner and had a round ball on one end with a sharp point on the other.

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Sounds more like a dressmaking pin, I think? But whatever it is, I don't think it should be there!

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I didn't either, so I left it out.

Tulsaalva said:

The number cast into the bracket is 3715-223C. Also cast below the number are two large upper-case letters: "AH."

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3715-223C is the number I would expect to fiund on the rear master cylinder casting. Could AH actually be "8 H" with the H squashed? Which could be the ID of the casting manufacturer?

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It's definitely "AH," Les. I have no idea what it means.

Tulsaalva said:

I'm beginning to think that this master cylinder was manufactured when a certain employee was having a bad day.

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Or somebody has dismantled it before?

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I found a place on the side of the master cylinder that was apparently made when the rear tire went sideways during the customer's evasive maneuver. Therefore, I have to assume the same rear master cylinder was used. At the time the bike had less than 100 kilometers on it. It only has 14,000 now so I doubt the rear master cylinder has been opened before. Anything is possible, though.

Tulsaalva said:

Should I bite the bullet, shell out another $220 and buy a new master cylinder?

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Provided there's no damage or corrosion to the bore, and the piston is OK, then I see no reason not to re-use it, provided you get the bleed hole problem sorted?

In the UK the barrels only, or barrel assemblies can be bought considerably cheaper than the complete units, as it is only the barrel parts that really wear out or corrode and need to be replaced. And stainless steel barrel assemblies are available.

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This one is going to work just fine, I think!

Al

Re: Rear Master Cylinder ... Starting over again

Tulsaalva said:

I'm having more difficulty fitting the rubber hose from the reservoir to the master cylinder than I care for. Working around the frame tubes makes it difficult!

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I noticed in your photo on page 2, that what appears to be the reservoir hose is incorrectly routed, as it appears to be going upwards and backwards from the master cylinder area? As it should go forward and upwards and be hidden by the side panel, as the pipe spigot on the master cylinder connection should be pointing forward?
Also that hose is also a much thicker-walled type than normal, and that could be the reason why the pipe has been re-routed, as it would be too large to go through the gap between the frame and swing arm immediately behind the pivot where it ought to go?
My own Bonneville also has a small Z shaped guide bracket which fits at the rear of the engine plate/frame mounting bolt and keeps the pipe away from the swing arm.

Tulsaalva said:

Petrol jumped another ten cents today.

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It did the same here too a few weeks ago, so is now around £1.20 a Litre in the UK (I make that $9.10 per US Gallon).

Tulsaalva said:

The number cast into the bracket is 3715-223C. Also cast below the number are two large upper-case letters: "AH."


It's definitely "AH," Les. I have no idea what it means.

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The "8 H" I read off my T160's rear unit, but I had a look in better light and it is actually "B H" and not 8 H.

I also checked the one on my Bonneville this time, and that is indeed "A H".
The A or B markings would seem to either identify the castings in some way or maybe it just identifies the casting pattern that was used? Either way both units appear to be identical, and I've rebuilt both units with no problems. The "H" I would guess to be some type of manufacturer's mark, as Norton front brake master cylinders also have that H mark cast in to them?


I think you are still working from the '73-'78 manual? So the instructions given for bleeding the rear brake will not apply, as your model has the later overhead caliper.
In order to bleed the overhead caliper unit, the torque arm must be disconnected, the R/H shock removed from its lower mounting, and the wheel spindle/axle nut loosened, so that the caliper and mounting plate can be swung forward far enough to place the caliper in a near vertical position and so placing the bleed nipple uppermost.
If the caliper isn't placed in the upright position for bleeding, then you will not be able to remove all the air from the caliper.

Re: Rear Master Cylinder ... Starting over again

L.A.B. said:

Tulsaalva said:

I'm having more difficulty fitting the rubber hose from the reservoir to the master cylinder than I care for. Working around the frame tubes makes it difficult!

Click to expand...

I noticed in your photo on page 2, that what appears to be the reservoir hose is incorrectly routed, as it appears to be going upwards and backwards from the master cylinder area? As it should go forward and upwards and be hidden by the side panel, as the pipe spigot on the master cylinder connection should be pointing forward?
Also that hose is also a much thicker-walled type than normal, and that could be the reason why the pipe has been re-routed, as it would be too large to go through the gap between the frame and swing arm immediately behind the pivot where it ought to go?
My own Bonneville also has a small Z shaped guide bracket which fits at the rear of the engine plate/frame mounting bolt and keeps the pipe away from the swing arm.

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That hose has been replaced, Les. The rubber was cracked. Besides, it looked suspiciously like a BMW fuel hose, with the woven cloth cover. I suspect the original hose was the source of the brake fluid leak when the tire went sideways and was replaced when the new parts from Meriden were fitted.

Although the new hose has been rerouted to a more forward position, you're absolutely right that it is too big to fit between the swing arm and the frame. I'll pop over to the hardware store and see if they have a thinner walled replacement.

L.A.B. said:

Tulsaalva said:

Petrol jumped another ten cents today.

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It did the same here too a few weeks ago, so is now around £1.20 a Litre in the UK (I make that $9.10 per US Gallon).

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It's George Bush's fault.

L.A.B. said:

Tulsaalva said:

The number cast into the bracket is 3715-223C. Also cast below the number are two large upper-case letters: "AH."


It's definitely "AH," Les. I have no idea what it means.

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The "8 H" I read off my T160's rear unit, but I had a look in better light and it is actually "B H" and not 8 H.

I also checked the one on my Bonneville this time, and that is indeed "A H".
The A or B markings would seem to either identify the castings in some way or maybe it just identifies the casting pattern that was used? Either way both units appear to be identical, and I've rebuilt both units with no problems. The "H" I would guess to be some type of manufacturer's mark, as Norton front brake master cylinders also have that H mark cast in to them?

I think you are still working from the '73-'78 manual? So the instructions given for bleeding the rear brake will not apply, as your model has the later overhead caliper.
In order to bleed the overhead caliper unit, the torque arm must be disconnected, the R/H shock removed from its lower mounting, and the wheel spindle/axle nut loosened, so that the caliper and mounting plate can be swung forward far enough to place the caliper in a near vertical position and so placing the bleed nipple uppermost.
If the caliper isn't placed in the upright position for bleeding, then you will not be able to remove all the air from the caliper.

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Which is exactly why I got out of bed a few minutes ago and came upstairs to the computer to ask you about this situation. The manual I have does not cover the peculiarities of the T140D.

There are two 3/8" X 24 threaded holes in the caliper, one on the back and one on the side. The hydraulic line is fitted to the rear one and the bleed valve on the side. The front caliper is fitted the same way.

Are they interchangeable? When the caliper is rotated forward, the back hole is exactly on top, which would make an ideal place for the bleed valve. I've tried and can fit the hydraulic line on the side. The bleed valve fits nicely in the back hole but I'm unsure if there is a flare inside or if such flares might be different for the banjo bolt and the bleed valve.

Al

Re: Rear Master Cylinder ... Starting over again

Tulsaalva said:

Are they interchangeable?

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You could change them around - but I wouldn't advise it.

Both holes do have the flare at the bottom, the rear caliper is as far as I am aware, identical to the front one (same part number) the front normally has a rigid flared brake pipe and sleeve nut fitting into the caliper and not a banjo fitting so the brake line hole is not bored as deep, and the rear underslung caliper (same caliper) also had the flared fitting before *1980* (See edit below).
The bleed holes are drilled deeper, so if you swapped the fittings over then the bleed valve would not be held by as many threads.

Tulsaalva said:

When the caliper is rotated forward, the back hole is exactly on top, which would make an ideal place for the bleed valve.

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It would be true to say that with the caliper in the vertical position that the banjo entry point would be highest, however, the angles of the two drillings are different, the banjo hole being more vertical, but the "lower" bleed hole is bored nearer to the horizontal, which actually places the internal bleed valve drilling higher than the banjo drilling.

So in my opinion, there's no need to swap the fittings over.

*Edit________________________________

Just to avoid any confusion, the T140D models had the overhead caliper from 1979, the standard E models continued to use the underslung caliper for 1979.

Thanks, Les! Your depth of knowledge is amazing!

I shall proceed accordingly.

Al

Several days went by while I dealt with a broken cam in my 928, idle problems with Sixteen's 924, and designing business cards and sales brochures for my wife's new business.

Today I finished installing the rear brake and filled the reservoir with DOT-4 so as to do the bleeding. The brake fluid does not flow freely from the reservoir to the rear master cylinder. In fact, it doesn't even ebb.

What might I have done wrong?

Al

Tulsaalva said:

What might I have done wrong?

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Probably nothing? Are you pumping the pedal with the caliper bleed valve well open?
The fluid should work its way down the pipe eventually?

Try tapping the pipe gently, if air bubbles are rising into the reservoir then fluid will be finding its way down the pipe to the master cylinder.

I'm so embarrassed I probably shouldn't tell you this, Les, but the truth is I had forgotten to clean the reservoir.

I took it off and dissembled it and found crud worse than the master cylinder. Yep, the two elongated holes were totally clogged with some sort of ugly material. I had to punch it out with an awl and then scrub the entire shootin' match with DOT-4, a toothbrush and scotchbrite. By the time I was through, it was sparkling!

Refitted, the bleeding was quick and easy. I now have a smooth and strong rear brake just like the front.

Tomorrow, assuming I don't end up designing sales brochures or tweaking old Porsches, I'm going to check the tightness of the fasteners from front to rear, install the battery and take it for a ride!

As they say in Texas, Grandpaul... YeeHaw!

Al

Well done!

...that was easy.

Kick Starting tips, please?

Not as easy as we'd hoped, Grandpaul!

When we started work on the braking system, the bike had been started by a local mechanic on the first kick. He remarked about how easy it was to start.

Unfortunately, neither Sixteen, Eighteen, nor myself were able to get it to fire. We haven't touched the ignition, carbs, and (of course) there should have been no change in the compression.

I think it's just that we just aren't able to kick it right. I'm sixty-eight and weigh 134, but Sixteen and Eighteen are both six feet tall and about 190. Age may be a factor on my part but is certainly no excuse for my sons.

How can they learn to start the bike?

Al

Re: Kick Starting tips, please?

Tulsaalva said:

How can they learn to start the bike?

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Shouldn't really be that difficult, as Triumphs normally start easily if they are set up correctly?

First, I would"free the clutch", by pulling the clutch lever in and kicking until there is no resistance felt at the kickstart lever (clutch plates are then free).

Your T140D has Amal MkIIs, so turn on the main (or reserve?) fuel, select choke on for a cold engine (push lever down), turn ignition on, and make sure the kill switch is set to "RUN".
Use the kickstarter to turn the engine *just* over compression, allow the lever to return, hold the throttle *just* off the stop, then give a full kick and it should start? Warm up and switch off the choke when it will run without it.
If it doesn't start and you continue to kick, then it will begin to flood, so the chokes may have to be turned off?

Each British bike seems to have its own ideal throttle positions for hot or cold starting? So you may have to modify what I said to suit your own bike.

Les, You're a genius!

Sixteen kicked the bike over using your instructions! (Four kicks, a break, and it started on the second kick after the break. He was so proud he shut if off and started it three more times on the first kick each time. His mom came outside to high-five us so he shut it off and kicked it again. It started on the first kick.)

Not only does it run; it runs great! Sixteen has been riding it around the neighborhood, getting used to it (It's a Triumph, y'know.) and loves it! He came back grinning and saying, "It's fuuuuunnn!" Now he wants to take it around and show it to all his friends, but it's still not ready.

We have a few issues:

The speedometer doesn't work.

The turn signals don't work. I found the blinker relay inside the headlight. It's a round thing, set in rubber with a rubber clip to fit a metal tab. There is a pronounced rattle therein... sounds like a bolt is loose. There seems no way to take it apart.

Can y'all help?

The chain is loose but that'll be easy to fix. I also need to redo the alignment, which I messed up when I removed the rear wheel to work on the rear master cylinder and reservoir.

Two bolts vibrated off the mirrors while Sixteen was riding but we'll replace them with nylon locking nuts, available at our local hardware store.

We can't say "thank you" enough for all the help in this project. Sixteen is sitting beside me and just asked, "Dad, would we ever have gotten this done without the guys on this website?"

"NO!!!," I replied.

Al

Thats GOOD NEWS! Congratulations to all of you!

I hope you have some fun with it anyway?


OK back to business,

Speedo? Could be a snapped cable? or it could be the unit itself?

It should be easy enough to pull the inner cable out to check it?

I would expect the instruments to be Veglias? If the unit isn't working then it's a job for a specialist, or maybe find another replacement?

Blinker/flasher relay? I would replace it with an electronic one, as any similar auto unit would do?
And your 'D' electrical system is Negative Ground, so you shouldn't have any problem finding a suitable replacement?


But have you checked the rest of the blinker circuit/s & bulbs?

The ground connections from the bulbs can cause problems? As the return circuit from the bulbs has to rely on the "chrome" coating on the plastic Lucas blinker heads for an electrical path back to ground!

A modification that sometimes improves the blinkers would be to feed a ground wire along the stem and connect it between each bulb holder and ground, but in any case that may not be the problem if the blinker/flasher unit is a dud?.

Clutch plates stuck again

Today Sixteen started the Bonny and was going to take it for a test ride but when he shifted into first gear the engine died. We tried holding the clutch lever and kicking it but were unable to get the lever to slide through. The clutch plates are stuck together again.

Since the bike was ridden three days ago and the clutch worked smoothly, it seems strange that we are back to this problem. We can, of course, take the plates apart and free them again but are we going to have this problem regularly? Should we, as a matter of course, daily kick the bike through while holding the clutch lever? What could be the cause?

Al

The abnormally sticky clutch syndrome can be caused by the friction material being old? Even when left for a while, a couple of easy kicks should normally free off the plates?

You may be better off fitting some new (Surflex?) clutch friction plates?

I've heard of owners who have removed the friction plates and cleaned them with petrol/gasoline. That is supposed to improve the sticking problem, but it may not be a total cure? You could try it? But if the problem returns, then you may have no option but to fit a new set of friction plates?

Clutch discs are no longer stuck

Here's what I did to free the clutch.

I tied the clutch lever hard against the hand grip with the transmission in first gear. I folded the foot lever out and pushed the kick starter aft until I felt resistance. With a five-pound plastic-headed mallet, I rapped on the lever itself, sending shock waves ( hope) through the clutch. About the tenth blow the plates separated and the lever can now be pushed through with no resistance as long as the clutch lever is squeezed. The clutch works fine!

It beats hell out of taking the clutch apart again and seemed to work much better than kicking the kick starter and seems far better than placing the front wheel against a curb (kerb) and doing a burn-out.

Thanks, Y'all!

Al

L.A.B. said:

The abnormally sticky clutch syndrome can be caused by the friction material being old? Even when left for a while, a couple of easy kicks should normally free off the plates?

You may be better off fitting some new (Surflex?) clutch friction plates?

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If this problem persists, Les, I'll fit new clutch plates. What are "Surflex" discs and how do they differ from the usual replacements? We have plates made by Barnett here in the Colonies that seem to be the hot ticket.

Al

L.A.B. said:

I've heard of owners who have removed the friction plates and cleaned them with petrol/gasoline. That is supposed to improve the sticking problem, but it may not be a total cure? You could try it? But if the problem returns, then you may have no option but to fit a new set of friction plates?

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The gasoline bath is what you recommended when we first had the frozen clutch problem. I did that and it worked well.

I think, perhaps, if we ride the bike more the problem will lessen. Maybe? If not, I still have the mallet. As long as I don't whack the kick start lever too hard, I shouldn't think I will do any damage?

Al