Series 2A Brakes nightmare!!

Hi all,

I've got a real problem with the brakes on my 1969 Series 2A I just cant seem to resolve.

I MOT'd her recently and it failed because the front left and right and rear left brake are binding.

So far I've tried -

1) Adjusting the adjusters (brakes still bind even when completly off)
2) Pressure bleeding the system (for what seems like hundreds of times now)
3) Changed the front cylinders, front rubber brake lines, new springs, drums and brake shoes for new (I noticed the front right cylinder piston was sticking all the time, so hence replacing all this lot).
4) Chamfering the front and rear trailing edges of the brake shoes.
5) Replacing and adjusting the master brake cylinder (CB type)
6) Giving her a run out to see if the shoes would "bed in" at all. The result was front drums you can cook an egg on.
7) Checking all the spring postions, etc, etc..

Strangely, if I adjust the brake travel using the two nuts on the master cylinder piston rod to brake pedal, I get the following result

Adjust towards the master brake cylinder - I get no braking at all, but all the drums then turn freely.

Adjust away from the master brake cylinder - I get excellent brakes but they bind again

Can anyone suggest anything?, I'm dieing to get this sorted and get her back on the road

If your near Bracknell and could help, there's free beer in it for you!

Best regards,

Paul

I've had similar. The adjustment on the end of the master cylinder is really critical ... mine was slightly out after reassembly and the brakes would slowly bind on until the whole vehicle locked up. Nothing would then unlock them until I let a bit of pressure out of one of the unions.

I found the answer was to get the master cylinder adjustment right, then wind the adjusters on the brakes all on hard until the wheels locked, bleed the brakes to make absolutely sure there's no air in there, then wind the adjusters off until the wheels just free off. If all else is OK in your system I can't see why this shouldn't work.

Hi!, thanks for the quick reply, I'll give that a go and report back..

You must allow a small amount of free travel in the brake pedal when adjusting things. I know you have fitted a new master cyl, but if it is sucking air in (dirt in seal?) it will cause this problem.

The reason that you're getting funny things happening when adjusting the length of the actuating rod for the brake master cylinder is that there is is a little port in the master cylinder which allows fluid to flow from the brake fluid reservoir to the master cylinder and vica-versa. When you depress the brake pedal the master cylinder piston blocks this port so that the brake fluid is forced down the brake lines to the wheel cylinders and can't escape back up to the reservoir. If you adjust the actuating rod incorrectly then the port will be permanently blocked and so the brakes won't release properly.

Have you checked that all the pistons in the wheel cylinders are able to move freely?

you could have oval drums. you could try swapping the drums about ?

graham.

naked-driver said:

you could have oval drums. you could try swapping the drums about ?

graham.

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The guy has new drums!

Worf said:

The guy has new drums!

Click to expand...

if they are none genuine drums ( **** part ) like mine they will most defo be warped ?

graham.

TheSmiths88 said:

I've had similar. The adjustment on the end of the master cylinder is really critical ... mine was slightly out after reassembly and the brakes would slowly bind on until the whole vehicle locked up. Nothing would then unlock them until I let a bit of pressure out of one of the unions.

I found the answer was to get the master cylinder adjustment right, then wind the adjusters on the brakes all on hard until the wheels locked, bleed the brakes to make absolutely sure there's no air in there, then wind the adjusters off until the wheels just free off. If all else is OK in your system I can't see why this shouldn't work.

Click to expand...

Hi there. I have this exact problem on a dual system with servo on an S3. I had nice brakes for about five pedal depressions today. It's driving me up the wall.

I have a silly question, how do you go about adjusting the MBC. The Haynes manual seems less than helpful. Are you using the adjustment nuts at the top of the brake pedal, or maybe you're shimming the MBC, or perhaps there's something else I just don't know about.

Hi Guys,

Sorry about the lack of replies from me, today's been the first day I've had a chance to try the suggestions and I'm pleased to report the brakes are no longer binding!.

Solution was as suggested, reset the brake pedal height (on mine I adjusted the bolt that contacts the brake switch on the front of the brake pedal) then adjusted the MC nuts so that the MC piston could return fully. After bleeding the brakes, I've a good firm brake pedal and the brakes are great without the wheels binding!.

Adjusting the brake bolt and MC nuts allowed for maxium brake pedal travel thus solving all the brake problems!.

Easy when you think about it now, thank you for all your help guys!.

Now I just need to solve the serious electrical problem thats manifested itself, will the problems ever end?

Swidds said:

will the problems ever end?

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No - that's called "character"! If the problems ever ended, it would be called a Toyota and NOBODY wants that!!!

Rogan - are you sorted yet? Master cylinder adjustment is the two nuts you can see that are locked together, when you have undone the 6 little screws holding down the rectangular plate just by the master cylinder. Just make sure there's some float on the pushrod.

Now I just need to solve the serious electrical problem thats manifested itself, will the problems ever end?


its a rover

Hey Smiths,

Well it hasn't reoccurred yet, but I'm waiting. There seemed to be a touch of slack on the servo pushrod with the brake pedal up. I pulled the MBC and I could easily depress the pushrod 3 or 4mm with my finger. So I guess it can't be the brake pedal building up the pressure.

I cleaned all the crud off the back of the plunger, which I suppose could have had the same effect as a poorly adjusted pedal.

Additionally, the fluid reservoir was overfilled 5mm+ over the full line, I dropped the level after the last bleeding session and it hasn't returned. I cleaned out the MBC reservoir and got rid of all the scum in there, as it was badly contaminated, and then fully bled the system.

The pedal feels ok right now, but I'm not holding out much hope for the problem being solved. Currently I'm making sure I've got a spanner and a cloth with me so I can relieve the pressure if the problem recurs while I'm out.

Personally, I think there's a small clog in the MBC and the gizmo needs a rebuild. I have the valve and seal kit here, and I would have done it when I had the MBC out last time. Unfortunately I couldn't pull the reservoir off the cylinder. The Haynes said to 'lift it off', it objected strongly to the whole lifting buisness, and a perusal of the parts diagram shows an internal circlip that must be holding it on. I'm thinking it either means 'tear off with extreme prejudice', or there's something I'm missing.

I've got no idea how to get at the circlip, and I don't really want to snap the reservoir as I haven't got a replacement. Well it's more that I couldn't find a replacement at the time, and a new dual circuit MBC is silly money.

I'm hoping the whole sordid affair was caused by contamination. However, the shiny new clutch slave fitted by PO suggests some berk put DOT3 in it and all the seals are buggered.

Only time will tell I suppose.

I don't suppose anyone has a good way of getting the reservoir off the dual cyclinder MBC without snapping it do they?

After searching the forum, this post is about as close to my issue on a series III 88 with a single CV Master cylinder.

I've adjusting the settings of the MC plunger there appears to be a tiny difference between the brakes working normally and binding or having to pump the pedal twice but not binding. I've spent an hour making tiny changes on the nuts on the plunger. I'm talking about less than a quarter turn either way and getting the two extremes.

Is this the normal process to get the brakes set where it's a really sensitive setting ? Should just keep going with my nuts on the plunger or follow my gut feel that the MC is goosed to replace it or give it jolly good service.

I appreciate any sage advice.

Thanks

Grant

just had exactly thisfault on a newly aquired truck no pedal unless pumped pulled drums off found cylinders leaking replaced them plus the flexy pipes and the master cylinder still the same slight turn of the master cyl pushrod had the brakes locking on.after much head scratching i pulled the drums back off and realised the previous owner had attached the top spring across both shoes instead of the 1 side going to the back plate retainer.once this was corrected perfect brakes

Thank you.
I've only looked at the front brakes and the springs were incorrectly attached. I'll check the back ones shortly and keep y'all posted.

It worked Jock! The rear springs were also incorrectly attached. Once he springs were moved I did not need to adjust anything more. The brakes work perfectly!

Thank you

Incorrect spring position show in photo below.


Correct position shown below
It hooks onto a lug on the brake shoe, behind the snail adjuster, onto a lug you can just see in the photo

glad to help