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Rebuilding Post 1977 rear brake master cylinder #784281 09/14/19 8:53 pm
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peter berry Offline OP
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After reading the AP Lockheed manual it makes reference to the rear master cylinders are not rebuild able. Has anyone tried or had any luck rebuilding one. Peter

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Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784282 09/14/19 9:06 pm
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Loads of people do it. The kit includes all the seals that you need

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784287 09/14/19 9:29 pm
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peter berry Offline OP
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Anybody done a rebuild on the late master cylinders my Triumph is an 82 T140. The Lockheed manual says rear masters are not rebuildable past the 77 model year.

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784289 09/14/19 9:44 pm
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L.A.B. Offline
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Originally Posted by peter berry
The Lockheed manual says rear masters are not rebuildable past the 77 model year.


Well, it's incorrect.

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784293 09/14/19 10:18 pm
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peter berry Offline OP
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Good to know Thanks

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784297 09/14/19 11:33 pm
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reverb Offline
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Hello; I have that manual; I think that you are confusing things. They say that is not recommendable to dismantle both parts. You can service; is more difficult but possible, to change the pistons and seals without tear it apart.

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784299 09/14/19 11:40 pm
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The seal kits include the seal that goes between the two halves.
No big problem to separate the halves for a complete rebuild—I have done it a few times.
HTH

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784303 09/15/19 12:09 am
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Although 'rebuildable' if original then the piston and cylinder are often worn/scored/corroded so it's not always worth the trouble and can be better to just replace the barrel assembly (with a stainless steel one?).

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Re: Rebuilding Post 1977 rear brake master cylinder [Re: Tridentman] #784304 09/15/19 12:13 am
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Originally Posted by Tridentman
The seal kits include the seal that goes between the two halves.
No big problem to separate the halves for a complete rebuild—I have done it a few times.


That's the caliper not the master cylinder.

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784312 09/15/19 1:34 am
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Thanks for correcting me,Les.
I plead old age (again)!

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784327 09/15/19 4:57 am
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Hi Peter, Have you taken old master cyl apart yet? I've not been involved with too many master cyl, but every one has had rust/corrosion inside.

I put LF Harris stainless master cyl on in each case. Some are a few years old now. Mine is 6yrs old on front brake. All are still working perfectly.

The LF Harris stainless is easy to come by in USA/Canada & a good choice in my experience. I've gotten master cyls from Bonneville Shop.

The adjustment of master cly is critical regarding the feed port opening relative to piston position. Read over manual & practice with old cyl. Once you see what you are trying to accomplish the adjustment will be correct & successful.

The bikes I've been involved with, owners want to keep stock. They've have used factory made stock type rubber hoses. I used stock type Nelson brand on my front brake hoses. Again all have worked well. Stainless braded is good too, depends on what you want it to look like.

These are the exact hoses I've used & have worked well, fit well. Made by Nelson. DOT approved. This is the only brand I've used. Lots of places sell this Nelson brand. It says Nelson DOT etc on hose in white ink. Shop for what is best place to buy for Canadian resident.

Last few I got here:
https://vintagetriumphsupply.com/search?type=product&q=brake+hoses

On a side note I see Bonneville Shop is selling stainless master cyl. in 13mm (one mm smaller piston dia.). I've only ridden one T140 with front 13 mm master cyl & it was a huge improvement in feel & effort. I don't know about the rear. But something to think about. There has been some threads regarding 13mm on rear also. It is said feels better. I've ridden a few T140 with normal rear cyl, but never a 13mm rear.

Don


1973 Tiger 750
Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784491 09/16/19 6:02 pm
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Kenneth Million Offline
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I have rebuilt both caliper and master cylinder on my 77. Went to a stainless master cylinder. No problem. Just be careful and clean. Bleeding the system was the only problem. Took quite a few tries to get it done properly so it didn't drag.


Kenneth Million
1977 T140v
1971 TR6R
1971 T350 Suzuki
1968 CA160 Honda
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Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784498 09/16/19 6:57 pm
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Rebuilt mine twice (both master cylinder and caliper) since 2001.

Regarding the caliper: the first time I rebuilt mine I found red loc-tite on the bolts holding the halves together. I assume this was from the Lockheed factory as my dad bought the bike brand new and he tells me the caliper had never been apart. If you can't get the bolts to release, use some local heat (400F to release red LT).

Some advocate replacing the bolts, I reused mine and used blue Loc-Tite instead of red. Never have had a problem with those bolts. Prolly goes without saying, but it's much easier to remove the caliper pistons with brake fluid or air before separating the halves.

Steve


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Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784539 09/17/19 3:12 am
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linker48x Offline
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I rebuilt mine too. The rear master cylinder on my 79 T140D resembles the description of the horn on the Norton Commando. They started with the master cylinder and then built the entire bike around it. It was not easy to get at, remove, replace, or adjust. To say the least!

Last edited by linker48x; 09/17/19 3:13 am.
Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784555 09/17/19 7:39 am
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I have gone to the trouble of replating and honing a front master. It all worked but I wouldn't bother again. Just get the stainless 13mm.

Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784560 09/17/19 8:04 am
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Originally Posted by peter berry
Triumph is an 82 T140.


Assuming it has the later overhead caliper, it must be repositioned so the bleed nipple is at the top before attempting to bleed the system or air will remain trapped in the caliper. To do this the spindle/axle nut needs to be slackened, the RH shock released from its lower mounting and the torque stay unbolted from the carrier allowing the caliper to be moved forward as described in the later ('81) T140 factory manual.

A different procedure must be used for bleeding the underslung caliper where the carrier plate is removed from the spindle/axle and dropped down so the bleed nipple is positioned at the top. The inormation is in the early T140 factory manual.
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Re: Rebuilding Post 1977 rear brake master cylinder [Re: peter berry] #784650 09/18/19 3:48 am
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reverb Offline
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Hi L.A.B. I know about the different positions of the brake but do you know why the factory changed the place?
About a year ago, the rear brake (PO put a Japanese one) bolts loosen and the caliper had hits the road and bumping and I almost flew away; very dangerous so I imagine that with the caliper on top could be a total disaster...

--I am asking because I want to retrofit all the original stuff there (still searching for parts)

Thanks

Re: Rebuilding Post 1977 rear brake master cylinder [Re: reverb] #784663 09/18/19 9:17 am
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Originally Posted by reverb
do you know why the factory changed the place?


Probably to reduce the amount of road dirt and water getting thrown at the caliper and it's also easier to check the condition and change the brake pads.


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