Results 1 to 6 of 6

Thread: Twin leading shoe brake cylinder fitment

  1. #1
    Join Date
    Jul 2012
    Location
    Brisbane
    Posts
    1,689

    Twin leading shoe brake cylinder fitment

    Hello again from Sherwood.

    Striking while it's hot - ie. getting the odd response - I have another query concerning the brake overhaul on my truck.

    I am re-fitting the twin leading shoe setup from a six cylinder truck to my 88". It actually had this setup on it when I bought it, although it hadn't been set up correctly at the time.

    Anyway, I pulled the old brakes completely off it a couple of years ago and the new cylinders didn't come with the bleeding screws. So, there are three plugged threaded holes on each cylinder respectively for brake hose, bleeding screws and interconnecting pipe. According to the parts manual the bleeding screw is the same as the one on the rear cylinder and I have a couple of those from the earlier strip down.

    I am trying to nut out which of the holes is the correct ones for the interconnecting pipe and bleeding screws. None of the various diagrams in the manuals, web sites etc actually show the back of the cylinder with the various hoses, screws and pipes connected.

    It may be intuitive, but I'd be happy if someone could help me out there?

    While I am at it - are the hoses, pipes etc simply screwed into the cylinder holes or do they need some sort of thread sealer?

    Cheers,

    Neil
    Hon Secretary - SLOw Inc

    1975 S3 88" - Ratel

  2. #2
    Join Date
    Jan 1970
    Location
    Central West NSW
    Posts
    21,803
    I just looked at my four cylinder 109 - It's cylinders have only two holes, top one has the hose in the angled one towards the back, both cylinders have the interconnecting pipe on the straight hole, probably the centre one on yours. I suspect the three hole cylinders are a later mod to allow left and right interchangeability.

    All fittings have a conical seal, and no sealant is needed or permissible (Bits of sealant accidentally getting into the hydraulic circuit could block small holes).

    A possible issue you may come across is that I'm pretty certain the threads on the fittings changed during production, and there could be problems with new parts. Probably changed from BSF to UNF to metric. Since the brakes have been upgraded, you probably have no idea what they came off originally!
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

  3. #3
    Join Date
    Jul 2012
    Location
    Brisbane
    Posts
    1,689

    Stand corrected and thanks

    Quote Originally Posted by JDNSW View Post
    I just looked at my four cylinder 109 - It's cylinders have only two holes, top one has the hose in the angled one towards the back, both cylinders have the interconnecting pipe on the straight hole, probably the centre one on yours. I suspect the three hole cylinders are a later mod to allow left and right interchangeability.

    All fittings have a conical seal, and no sealant is needed or permissible (Bits of sealant accidentally getting into the hydraulic circuit could block small holes).

    A possible issue you may come across is that I'm pretty certain the threads on the fittings changed during production, and there could be problems with new parts. Probably changed from BSF to UNF to metric. Since the brakes have been upgraded, you probably have no idea what they came off originally!
    John,

    Hello again and thanks. Appreciated.

    My wheel cylinders are very likely set up with only the two threaded holes and the angled one would be for the flexible hoses - which would make the positioning of the interconnecting pipe fairly obvious. It’s been a while since I actually last handled them.

    I seem to have managed to get the three hole bit into my head without going back for a second inspection. I was sitting at the keyboard thinking there was one for the pipe, and another for the hose - then the little voice said “what about the bleeder”? Hence the three.... I guess thinking it through one of the pair on one cylinder would have the hose and the equivalent on the other has the bleeder.

    Too easy. Always something to learn.

    Incidentally, is it better to have the bleeder on the top or bottom cylinder - seems to be some variation in thinking there?

    Cheers,

    Neil
    Hon Secretary - SLOw Inc

    1975 S3 88" - Ratel

  4. #4
    Join Date
    Jul 2012
    Location
    Brisbane
    Posts
    1,689

    Seal - part 505790

    Hello again from Sherwood.

    Still on the topic of twin leading shoe brakes and obscure parts that may or may not be missing or necessary.

    In the parts manual on the sections dealing with the front brakes on both the 4 and 6 cylinder trucks (1L 03) there is a seal (part 505790) shown that apparently fits between each of the two brake cylinders and the backing plate. No such seal appears in the sections dealing with the rear brakes on a 109" or front and rear brakes of an 88" (pre TLS front).

    Such a seal didn't come with the replacement front slave cylinders and I don't recall there being any in situ when I dis-assembled the originals.

    My question is - are these front seals actually necessary?

    Cheers,

    Neil
    Hon Secretary - SLOw Inc

    1975 S3 88" - Ratel

  5. #5
    Join Date
    Jan 1970
    Location
    Central West NSW
    Posts
    21,803
    1. If there are only two holes on the cylinder, and the hose is in one and the link pipe in the other on the top cylinder, the bleeder must be in the bottom one.

    2. I can't remember whether I found these sealing rings on the last ones I did (been a while). They will be to try and keep water out of the brakes, and in particular, to reduce the chance od water lying between the cylinder and the backing plate, where it is likely to cause corrosion.
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

  6. #6
    Join Date
    Jul 2012
    Location
    Brisbane
    Posts
    1,689
    Quote Originally Posted by JDNSW View Post
    1. If there are only two holes on the cylinder, and the hose is in one and the link pipe in the other on the top cylinder, the bleeder must be in the bottom one.

    2. I can't remember whether I found these sealing rings on the last ones I did (been a while). They will be to try and keep water out of the brakes, and in particular, to reduce the chance od water lying between the cylinder and the backing plate, where it is likely to cause corrosion.
    John,

    Hello again and thanks again for the advice. Appreciated.

    I don’t recall having seen the seals on the truck when I pulled it apart - but that was actually a fair while ago. Obvious clues like the old seals stuffed in with the bolts etc weren’t there either in this case.

    Obviously, fitting them wouldn’t hurt - so, I guess it will be a case of seeing how easy or quickly a set can be tracked down.

    Cheers,

    Neil
    Hon Secretary - SLOw Inc

    1975 S3 88" - Ratel

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!