Help with Bedford TK please :)
 

HI, i have recently bought a bedford TK horse lorry (1977 straight six)

When i went to come back the other day from a horse show, i had almost no brakes (eeeekkkk)

The air system seems to be fine, pressure is between 6-7 and only drops if i havent used her for a few days. Handbrake also seems to be un affected, but it was a bit dicey coming home, had to crawl down the hills in 2nd gear cos brakes arent coming on until the pedal is to the floor and even then i have hardly any brakes. Tried pumping the pedal with my foot, but didnt seem to make any difference.

It passed its plating at the beginning of August so this is a very recent problem, could it be something simple?

Any advice would be more than welcome :)

It might be that the brakes need adjusting (or the linings are worn or contaminated with oil).
Maybe the servo is faulty and not operating the hydraulics.

Is it hard to adjust them? As in ... am i able to do that myself?

When i use the hand brake it is still making that hissing noise when the air is released and same when i brake, its just it doesnt seem to slow me down much!

Could they have got hot and melted as to get to the horse show the other day we had to go down a very long and winding hill ... could i have burnt my brakes out doing this... i didnt notice a smell, but the engine smells alot in the cab so maybe i wouldnt have noticed this...

I'd first check the servo and what ever you do get a pro to look the vehicle over, You don't want any mishaps while either you or your horse on-board.

Yes, you really need expert help - it's almost impossible to diagnose remotely - especially if you aren't familiar with how to adjust the brakes.

It's highly probable that you might have 'cooked' the linings descending that steep hill, but it could be a leaking wheel cylinder - which will require rectification by someone who knows what they are doing.

It might be a leaking axle hub oil seal - there's several possibilities that will need the brake drum to be removed in order to diagnose the cause.

Have you checked the fluid level i think you have air/ hydraulic brakes

Your brakes will be air over hydraulic. This means that air from the brake pedal valve will apply a hydraulic master cylinder which applies pressure to the wheel cylinders in the brake drums.
Having air pressure is essential of course, but you need a satisfactory hydraulic system for the brakes to work effectively.

It is possible to boil the brake fluid if you seriously overheat the brakes - especially if the brake fluid is 'old' (it attracts water vapour and it is the water that boils when the fluid gets hot).
This leaves 'air' in the system and the brake system needs bleeding (as a minimum) or, ideally, fresh brake fluid. It is recommended to change the brake fluid every few years (depending on the operating climate).

Alternatively it is possible to 'cook' a wheel cylinder seal if the brakes have been overheated (such as a long downhill descent under load) and subsequently the seal will leak fluid (contaminating the linings) or might 'suck in' air into the system - again requiring bleeding (as well as renewal of the faulty seal(s)!).

Used to drive a N reg TK 7.5t which had an auto lube system fitted below the gear stick and when things like gear change and brakes etc got sticky and did not work to their best a green light came on to indicate the truck needed lubrication and you manually pulled a lever to distribute the lube which had an immediate effect on how things worked it was quite an expensive extra but it worked really well I would think that if this unit was not fitted a manual top up was required but where it was I could not tell you but most likely under one of the side flaps where most top ups were done when we replaced this truck with a TL the system was built in automatically and of course this came with a tilt cab but was not half the truck of the TK as after 4 years it rotted around us and had to be replaced with a Merc

Thanks for all your replies, Its goin to the garage today for the chap to have a look at it.... I will let you know what he says :)

Having re-read your original post, I would strongly recommend that you check the indicator rod that sticks out from the 'black' unit on the sidemember (the air dual-actuator) to see whether your brakes need adjusting.
I know that you have had a mechanic look at things, but you can check yourself if the thin rod is sticking out too far (it should have a red portion) which indicates that it's time to adjust the wheelbrakes.
If the linings are too far from the drums then the hydraulics cannot push far enough (and pumping the pedal won't improve matters as it merely supplies air which pushes the hydraulics). It might be worth getting the brakes adjusted before your mechanic starts work on the servo and master cylinder.

The adjusters on each wheel are simple 'screw in' - turn until the wheel won't turn then unscrew until the wheel spins without binding. You need to jack up the axle to do this properly (and press the pedal with the engine running - or at least with air in the system - to centre the shoes when they are fully against the drum).
Once adjusted push in the thin indicator rod on the air servo and then apply the brakes - the indicator will stick out according to how much travel there is in the hydraulics.

You can adjust the wheelbrakes without jacking up the axles (for example if they are well out of adjustment) but you have to make sure that you 'back off' the adjusters so that the wheels don't bind - which will overheat the brakes - for eample if the indicator rod is along way out it's worth tuning the wheelbrake adjusters a couple of turns and checking the indicator again.

Brakes that are well out of adjustment can give the impression that the hydraulic system is faulty or that the air servo isn't working properly - exactly what your mechanic has diagnosed.

Simply fitting a new master cylinder and new seals in the air servo will not cure brakes which are well out of adjustment.

Just saying.

Footbrake adjustment.
As the master cylinder actuator is operated by air pressure from the footbrake valve, brake shoe travel is not reflected in brake pedal

movement. To provide an indication of brake shoe travel an indicator rod is incorporated in the dual actuator. The rod moves out of the

actuator housing to the same extent as the pushrod moves to operate the master , and when the red band on the indicator rod is fully exposed

the brake shoes require adjustment.
Before adjusting the brakes, check the hub bearings for slackness. If necessary, adjust the bearings.
Check also for excessive wear of the leading shoe linings. These can be examined through the inspection hole in each backplate.
To adjust, jack up each wheel in turn and proceed in the sequence given below. When adjusting the rear brakes, skotch the front wheels and

release the parking brake.
1 Charge the system to operating pressure.
2 Turn the shoe adjuster anti-clockwise until the drum is free to rotate.
3 Turn the front shoe adjuster clockwise (see fig N21) until the shoe is hard against the drum. Centralize the shoe by applying heavy pressure

to the brake pedal, then release the pedal.
4 Back off the adjuster until the shoe is just clear of the drum, ie so that the wheel rotates freely without the shoe rubbing.
5 Repeat operations 3 and 4 on the rear shoe adjuster.
Repeat for each wheel in turn.
6 Push in the indicator rod on the air actuator until it contacts the piston.

Illustration of brake adjusters:- http://i24.photobucket.com/albums/c1...n/IMGP8511.jpg

Little update
Have replaced air servo and master cylinders, brakes were better, but yesterday had brake failure again.

I can't find the indicator rod that you mentioned on the air servo, but the brakes seem to be well adjusted and there is plenty of meat left on the brakes shoes. My brake fluid levels are fine and the air pressure is around 7 on the dial.

But when I brake the pedal travels with no resistance to the floor and then I have minimal braking once my foot is on the floor.....

Any suggestions welcome :)

The indicator rod is about the diameter of a wire coat-hanger wire (from memory) and should stick-out along the axis of the air servo.
See item 23 on this illustration:- http://i24.photobucket.com/albums/c1...n/IMGP8509.jpg
Assuming that your hydraulics have been correctly bled of all air (writing the hydraulic circuit), then it is possible that there is too much travel on the brake mechanism and the wheelbrakes need adjusting.
Follow the procedure listed above.

Is this the right place to look?

Or here? Both places are black!

Another view.......

Or maybe it's here......

Basically there is the big black unit which includes the master cylinder, or next to it the other side of a chassis joist is a cylinder which is also black, but I can't see the indicator rod anywhere on either units....
Feeling blonde!

On the plus side I found where my air filter is, and after a lot of faffing about (the coach builders who put the horse bit on the back of the lorry have made it very difficult to get the filter out without totally removing the whole unit)I managed to get it off and found that it was totally black and choked up, so a new one is now on its way.

Oops, just realized the last photo is upside down....

The middle photograph is your servo/master cylinder, but it is an earlier version than my photograph, so I'm afraid that my instructions don't apply.
Sorry!

Never mind, thanks for your help anyway :)
My lorry is old... Almost as old as I am!
But she runs really well except this darn brake problem.
Looks like I will have to start saving up for a new lorry as the French here don't know what they are doing with regards to her and I am loathed to let them touch her as they don't seem to do a lot and then send me a 500E bill for the pleasure!

It's very hard to diagnose problems like this at a distance, I'm sure it would be easy back here in the U.K in any good workshop to pin point the cause very quickly. The first thing to do with any brake fault is to put the vehicle onto a brake tester to see how good the brakes are on each wheel. It might be that they are only working on one axle, or that they are all working but with very poor efficiency. Do you know if the garage you have been taking to have any way of testing the brakes on rollers and if they have did they ever give you any readings ? I think without knowing this it's all a bit working in the dark, just to change parts in the hope that it will cure the problem is very hit and miss as well as being expensive.

Thanks for your reply. In fact the point you have raised is a good one and on closer inspection of the brake shoes it appears that the back right hand shoes are a lot more worn down than on the other 3 wheels.
With this information would I be right in thinking that only one brake is working ? The others maybe seized?
Or would that just make the working one lock up?

Good logic throughout.
It would only lock up on a low-coefficient surface or when braking heavily.

Thanks for the reply.... So I am guessing I now need to jack it up, take the wheels off and give it a good clean and grease the seized parts up to see if it will free them off?

Hi again everybody, I have another question with regards to my mid 70s bedford tk.... I would like to change the oil in my gearbox, I can see where I need to let the old oil out (half inch square bolt on bottom of gearbox), but I am at a loss as to where to put the new gearbox oil in.... It's been converted to a horse box, so the engine has a solid floor on top of it, so I am crossing my fingers that I don't need to refill the oil from the top or it's a dead duck! Any ideas are welcome :) thanks in advance

Most gearboxes have a filler on the side which is positioned to give the correct level (the same applies to filling rear axles).
Filling requires either a 'syringe' or a plastic bottle with a flexible tube:- http://goldwingdocs.com/Images/HowTo...ear-Oil-13.jpg
The sort of one litre bottle that hypoid gear oil comes in (or used to) usually came with tube attached. To fill the gearbox squeeze the bottle and wait until the oil runs out of the filler hole.

Don't forget to feel around inside the drain hole after you've drained the oil to check for swarf (and loose teeth!). It's best to drain the oil when it is warm, but you might not have that luxury, in which case it's worth pouring some paraffin (or petrol if you haven't got paraffin) in the filler (after you've replaced the drain plug!) to sluice out any debris that has settled on the bottom.

That's great, thanks for the swift reply. I will get my hubby onto it to give me a hand :)

We hit a small problem.... The 1/2" bolt at the bottom of the gearbox does not want to budge! As a quick fix we topped up the gearbox oil until it ran out of the filler hole half way up, as it have to use it this Sunday for a competition.... I am worried to really force the bolt on the bottom incase it shears off!

The reason I wanted to check the level of the gearbox oil was because the gears are getting very stiff.... Although they become a lot easier after about 20 minutes of driving (?) ... So my first thought was perhaps the oil was low. Ideally I could do with getting a mechanic to give it a thorough service, but as I live in the middle of France it's proving difficult to find an HGV mechanic that has experience in an old bedford!

The oil might have 'thickened' with age, or if it was low.
Any idea how much oil you added?
As you say, getting it warm will ease the shifting problem.

Spray some penetrating oil such as WD40 around the drain plug threads and let it soak.
Repeat until you are certain that it has 'penetrated'.
Get everything warm and try to undo the drain plug - don't force it.
If it won't budge get a hot air gun and heat the area around the drain plug and try again.

If it really won't budge after the WD40 and getting it hot, then use a flexible tube through the filler/level plug to 'suck' out the old oil - use a long length of clear tubing so that you can see when the oil is coming - if you get it right it will syphon itself once you get it over the 'hump' - especially if the oil is warm.


Measure how much comes out (if you can) to get some idea how much was in there.

I believe the capacity is 6½ pints. You might not be able to get it all out but diluting it with fresh oil will help.

I do not know what oil you need - probably 80 or 90 grade and probably not EP (which tends to be for rear axles).
EP additives which contain phosphorous/sulphurous compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers.
ST90 would be my guess.

Edited to add:- you might have a plate on the side of the gearbox (rectangular with six bolts) which is where a PTO would be fitted.

Removing that would release the oil . . .
The gasket for the plate might be cork or a compressed 'paper' - though the shape is simple (and standard) and you could use dense card - anything that doesn't allow oil to seep through (and which isn't affected by oil). A motor factor (parts supplier) should be able to supply suitable material if you can't find something.

I see they want silly money for genuine gaskets! :- http://www.ebay.co.uk/itm/PTO-GASKET...p2054897.l4275

Cheaper in the States - but how much postage? http://www.ebay.co.uk/itm/M35A2-PTO-...item1c3ca28b86

Wouldn't silicone sealant or "Instant gasket" help? I once used paint as a form of gasket when I rebuilt my Granada engine.

There are many alternatives for proper gasket material (if it is a simple joint) if you get stuck - but it's a nuisance if it doesn't work and you have to rebuild again.
Exhaust system gaskets need to be special, however.

Well, yes, those and head gaskets.

I used paint as a sump gasket.

We put just over 1 litre of oil in yesterday before it was up to the fill level. I will fiddle with the drainage bolt after Sunday !