REAR BRAKE VALVE

52 comments

  1. imported post

    I had a small supply of new old stock valves so my cars have new ones on andI haven't had the need to take one apart.

    Not sure who to try to get one but I suppose a classic brake specialist would be a good start. Somerfords might be worth a try.

  2. imported post

    Hi

    i have taken mine apart which was stuck and cleaned it give and reassembled it and it has worked fine for the last 2 years

    although they do come up on ebay

    James

  3. imported post

    [b]Andrew1967 wrote: [/b] “Hi Ian,

    I am pretty sure that Lockheed used to do an overhaul kit so I guess they can.

    Hold on a minute…………….just checked my Lockheed reference manual and the kit number is/was SSB802.

    Hope that helps 🙂

    Andrew

    Hi Andrew,

    Doesthe kit differ between standard Mini and all three disc brake models? I know the S valve is different, not sure about the smallerdiscs on 997 and 998 Coopers.

    Regards

    Al

  4. imported post

    Hi Al,

    According to the Lockheed book (1963-76) the following applies:-

    Mk1 Mini 59-64 valve assembly 4313-746 kit SSB802

    Mk1 Mini 64-67 ' '4313-743 kitSSB802

    Mk2 Mini 67-69' '4313-749 kit SSB803 (same for Mk369 on)

    Mk1/2 Cooper/S and Mk3 S all had valve assembly 4313-743 kit SSB802

    Regards

    Andrew

  5. imported post

    Hi Andrew,

    Interesting, I'm sure I read that the 7.5' disc brake cars had a different valve but the information you have says they don't. I guess I need to see what a parts book says.

    Regards

    Al

  6. imported post

    Hi Al,

    Just double checked again and even the early 1275GT is quoted with the same part as the disc braked Coopers.

    The 61-63 997 Coopers do not have one quoted but I guess that's because they had the brake intensifier at the front.

    Let me know what info you come across.

    Andrew

  7. HI, HAS ANYONE TRIED OR HAS REBUILT OR STRIPPED THE REAR BRAKE VALVE (REAR SUBFRAME) . AS I WAS TOLD THEY STICK WHEN NOT IN USE AND CAN EFFECT THE BRAKING IS THIS TRUE AND CAN IT BE DONE THANKS IAN

  8. imported post

    Hi Ian,

    I am pretty sure that Lockheed used to do an overhaul kit so I guess they can.

    Hold on a minute…………….just checked my Lockheed reference manual and the kit number is/was SSB802.

    Hope that helps 🙂

    Andrew

  9. imported post

    The brake limiter valve is quite simple really just a plunger/piston with a rubber seal and a spring when I did mine I undone the big nut hooked the piston out cleaned it all up and used the grease that you use for caliper seals around the rubber on the piston and put it back together it works fine and has passed the MOT and has done for the last couple of years

    James

  10. imported post

    <a href='[url=http://s191.photobucket.com/albums/z307/mofojambo/?action=view&current=30012008001.jpg]http://s191.photobucket.com/albums/z307/mofojambo/?action=view&current=30012008001.jpg[/url]' target='_blank'><img src='[url=http://i191.photobucket.com/albums/z307/mofojambo/30012008001.jpg]http://i191.photobucket.com/albums/z307/mofojambo/30012008001.jpg[/url]' border='0' alt='mini brake limiter valve'></a>

  11. imported post

    Andrew1967 wrote:
    “Hi Al,

    According to the Lockheed book (1963-76) the following applies:-

    Mk1 Mini 59-64 valve assembly 4313-746 kit SSB802

    Mk1 Mini 64-67 ' ' 4313-743 kit SSB802

    Mk2 Mini 67-69 ' ' 4313-749 kit SSB803 (same for Mk3 69 on)

    Mk1/2 Cooper/S and Mk3 S all had valve assembly 4313-743 kit SSB802

    Regards

    Andrew

    Hi there,
    I've just checked all mine and all have the number 3231 233C on the outside of the casing. At least one of these is off a MK II Cooper. Any thoughts?
    Cheers, Keith

  12. imported post

    The differences between the different valves quoted for the various models is only likely to be the strength of the spring inside. Since the mini has such ashort wheelbase then the type of valve used certainly the one mounted on the rear subframe , is a shut off valve ie at a given line pressure the valve closes and then any further pedal effort the driver applies only results in a pressure increase to the fronts.

    The spring strengthcould vary according to the effective radius of the front brakes , size of caliper piston and also the size of rear wheel cylinder.

    So in terms of normal check braking the valve will probably open for 75% of brake applications , its only when you get higher decels and thus more weight transfer off the rr axle that the valve needs to work .

    So unless the valve has some crap in it its unlikely to ever wear out.

  13. imported post

    Hi Keith,

    I haven't got any boxed limiters left now so can't match up any casting numbers with part numbers.The lockheed book doesn't list casting numbers.

    regards

    Andrew

  14. imported post

    If it is only the spring which differs then presumably all have the same casting number for the body. Mine has probably suffered 40 years of exposure to the elements under the rear of a Mk2 but looks like 3231-233 followed by a stamped C.

    On the other side is cast 0829.

  15. imported post

    Just checked a new 4313-746 valve in its original '60s Lockheed box and this too has the 3231 233C casting, which probably just confirms that all versions were likely to have used the same casting.

    The 1965 (1[suP]st[/suP]) edition of the Marshall & Fraser “BMC Minis� book gives some info on the valves in the “Changing the Braking System� section and list 3 valve types:

    1. A 300 psi valve fitted to early (pre mid-64) cars (no BMC part no given) – presumably the Lockheed 4313-746 valve?

    2. A 375 psi valve fitted to post mid-64 cars (BMC 21A1458) – the Lockheed 4313-743 valve?

    3. A 450 psi valve fitted to Elfs/Hornets (BMC 21A1201). Could this be the same as the later 4313-749 valve?

    Does anyone have a cross-reference for the Lockheed / BMC part numbers to clarify this?

    The following detail is provided in the book:

    “A Riley Elf/Wolsey Hornet type must be fitted, which has a limiting pressure of 375lb per sq. in. (part no. 21A1458) instead of the normal type which has a limiting pressure of 300lb per sq. in.�
    Also:
    “Mk2 Hornets prior to 590407 … and Elfs prior to 592399 …… were fitted with a rear brake pressure limiting valve operating at 450lb per sq. in. (part no. 21A1201). For best braking performance ……… these should be changed for one operating at 375lb per sq. in. (21A1458). The new valve has two grooves turned in the end of its body to distinguish it from the older type�
    And, finally:
    “Early Cooper S types can be improved by changing the rear brake pressure limiting valve to the later type as described for Elfs and Hornets. The same valves are used for both types of car. The modified valves were fitted to Austin Cooper S types from cars 551758 (RHD) and 551530 (LHD), and to Morris Cooper S types from cars 552673 (RHD) and 489070 (LHD).

    Nick

  16. imported post

    According to my Lockheed manual (for vehicles between1963-76) 4313-743 is 21A1774, 4313-746 is 21A1789 and 4313-749 is 21A2031.

    21A1775 is listed as 4313-745 which the parts book says is for a BLMC commerical but cannot see it in the appropriate section 😕

  17. imported post

    Looking at the Mini parts book, it has the following parts for the MK II….

    21A2031 for Countryman, Traveller, Van and Pickup
    21A2031 for Austin, Morris, Wolseley and Riley Saloons
    21A1775 for Cooper
    21A1774 for Cooper S

    For the Mk I, Gordon bleeding Bennett….

    2A5893, 21A1201, 21A1458 Mk I saloon
    21A1010 Mk I disabled person's vehicle
    21A1201, 21A1775, 21A1458, 21A1774 Cooper S
    2A5893, 21A1789, 21A1201, 21A1775 Cooper
    2A5893, 21A1201, 21A1775, 21A1458, 21A1774 van, pickup etc
    2A5893, 21A1789, 21A1201, 21A1775, 21A1458, 21A1774 Riley, Wolseley etc

    Given that the casting is the same number and, from looking through the parts books, mostly only the spring is different between types, is there some way to identify the type, for example, by spring pressure?

    Cheers.

  18. imported post

    i have taken my limiting valve from my mk1 67 auto with drums and stripped it.

    I am going to fit new seals did anyone find out who actually still stocks them.

    when this goes back on the braking system should be full mk1 s spec with 51/2 servo and 7.5 front discs.

    the casting numbers i can see are ??24 and 323123??

    it also has the two groves cut in where the nut goes as you can see in the picture.

    the pistion size is 0.466' at the far end.

    Am i correct in thinking is the the later type for the elfs? Would this be suitable for the setup i am hoping to use??

    should the body beplated the glodie colour of finished in black??

    thanks

  19. imported post

    radfordman wrote:
    “I have:-

     1 x 4313-743

    3 x 4313-746

    1 x 4313-749

    and 1 unknown because its box is missing.

    Nick

     

    How much for the 4313-743.Probably beswt to PM.

    Cheers, Keith

  20. imported post

    does anyone know where i can buy a rear valve repair kit.

    I have tried somerford's – no longer avalible.

    Tried a couple of other brake specialists – no responce – yet.

    thanks

    will keep my eye out for a nos one but if i cant find a good one at a good price ill rebuild this one.

  21. imported post

    [b]radfordman wrote: [/b] “I have:-

    1 x 4313-743

    3 x 4313-746

    1 x 4313-749

    and 1 unknown because its box is missing.

    Nick


    Nick,

    Do your limiters have different casting numbers on them that might be identifiers. I have a NOS one in the garage somewhere unboxed and it would be good to indentify it. 🙂

  22. imported post

    [url=http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260348339231&ssPageName=STRK:MESE:IT&ih=016]:)http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260348339231&ssPageName=STRK:MESE:IT&ih=016[/url]

  23. imported post

    Just thought I would tag on here to find out the likelyhood of mine needing attention. As I have posted previously, my car has been standing for a considerable number of years (17). I have come to the conclusion that I will buy some new rear brake pistons. Also after spending some considerable time underneath the car at the weekend fitting the exhaust and removing the fuel pump, I did wonder after looking at the limiter wether or not it too would require attention.

    I guess I am reluctant to remove the unit as previous experience has proven that the fixing unions can weld themselves to the older type hydraulic piping (and the unions are showing signs of corrosion at present). Do you think it will be a good idea to strip it down and if so and I end up damaging the old pipework, is it going to cost a great deal to run new lines in? I am assuming I will need to buy a tool to splay the ends of the new copper pipework also!

    I am going to Bingley Hall at the weekend so hope to get all the stuff I require!

  24. imported post

    I've been cogitating on and off for the past few weeks and finally decided to pull out some of the regulators and see what differences there are. See photo below. The right hand unit is from a 1968 Cooper, the left one from a MK II 850 and the centre unit is the 4341-743 unit I bought from Nick (MK II Cooper S). Note the necks. Does this provide enough to identify them unambiguously?

    Cheers, Keith

  25. imported post

    I actually have NOS examples of the 3 types, so I will try to get a picture of them all to see if this can get sorted. My thought is that this will probably only cloud the issue.

    Nick

  26. imported post

    If you look inside the valves you'll find the pistons and seals are all the same,the only difference is the free length and gauge of the spring. The unit on the left is a NOS of unknown origin. The one on the right is from my '64 1071 S [with two rings around body]

    'S' spring is 35.2mm long x 1.8 dia. wire.

    NOS spring is 32.5mm x 2mm dia. wire

    The spring rate must be calibrated for each different model, depending on m/cylinder bore, servo or intensifier fitted?caliper piston size, rear w/cylinder bore and at a guess'dry' or hydrolastic springing. Unless someone has a detailed build sheet with all the different springs shown I think we'll never know. In my case I'll fit the NOS piston and seals in my original unit:)

  27. imported post

    I'm now confused… Here are the springs from my units.

    Left – 850 Mk II, 1.8mm dia wire, 34.2 mm long
    Middle – MK II Cooper, 1.8 mm dia wire, 33.6 mm long
    Right – 4313-743, 1.8 mm dia wire, 36.2 mm long

    Cheers, Keith

  28. imported post

    Just wondering how to diagnose if you have an issue with this valve, I would imagine hitting the brake pedal hard would cause the rear wheels to lock if its not functioning correctly?

    Or would it stop the rear brakes from working altogether?

    Si

  29. imported post

    radfordman wrote:
    “This is my first attempt to attach a pic. let's hope it works. These are examples of the 3 types new. ”

    It would be interesting to see the springs…..

    Mind you, you could just strip out the guts of the regulator and put slave cylinders on that are 1/16' less than the originals…. 😉

    Cheers, Keith

  30. imported post

    [b]SimonWillis wrote: [/b] “Just wondering how to diagnose if you have an issue with this valve, I would imagine hitting the brake pedal hard would cause the rear wheels to lock if its not functioning correctly?

    Or would it stop the rear brakes from working altogether?

    Si”

    When the regulator failed on my MK1, the rear wheels locked up with little provocation. The valve restricts the amount of pressure routed to the rear brakes.

  31. imported post

    [b]1071bob wrote: [/b] “If you look inside the valves you'll find the pistons and seals are all the same,the only difference is the free length and gauge of the spring. The unit on the left is a NOS of unknown origin. The one on the right is from my '64 1071 S [with two rings around body]

    'S' spring is 35.2mm long x 1.8 dia. wire.

    NOS spring is 32.5mm x 2mm dia. wire

    The spring rate must be calibrated for each different model, depending on m/cylinder bore, servo or intensifier fitted?caliper piston size, rear w/cylinder bore and at a guess'dry' or hydrolastic springing. Unless someone has a detailed build sheet with all the different springs shown I think we'll never know. In my case I'll fit the NOS piston and seals in my original unit:)

    just measure the spring in my 2 ring unit. the size is 1.8 wire x 35.2 length.

    My car as you know is a standard mini but has the same spring as bob's s.

    dont worry about the poundage bob, ill leave the spring as it is.

    Anyone got a seal kit for a brake valve?

  32. Hello everyone,

    I'm currently restoring an Authi Mini 1275 GT which has originally the 4313-743 (21A1774) valve installed.

    At the moment I only have 2ea 4313-749 (21A2031) valves available; a new one and a used one.

    I would like to upgrade one of my valves by fitting the 'right' spring (27H6620).
    So my question is if somebody:

    A) Has an old '743' unit (with the right spring) which I can obtain.

    B) Has a '743' spring which I can obtain.

    C) Can give additional information about the 27H6620 spring, so that I am able to let rebuild one.

    The lenght (35,2mm) and wire dia. (1,8mm) is o.k. for the begining. Additional information necessary would be: Inner bore dia., distance from one winding to the next (measured from centre of the wire to centre of the wire), Force necessary to compress it to half of the unloaded length. Force necessary to compress it 1/4 from the unloaded lenght.

    Hopefully somebody is able to help me.

    Best regards,
    Sven

  33. Hi Sven,

    Hope this is of help. Try this link to Minispares they have the 21A 1774 valve (not cheap), hopefully they will have a repair kit.
    Jon

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