Brake Problems

maestro vans · 2nd March 2007, 00:20

On one of the vans the brakes are great, minimal pedal travel to get good braking. Yet on the rest of the maestros, the pedals go down a considerable amount before the brakes work. On one I have changed the master cylinder new discs, new pads, new shoes, new rubber brake hoses, and its just the same. I can only put it down to the brake servo. I have checked the domed nut in the servo. The haynes manual recommends you dont adjust it, but could this be anything to do with it? The brakes are hard and good when the engines off, ie no servo. But when the engines running the pedal goes down a lot further, why is this?
What the general view of pedal travel from the rest of us maestro owners
Does your pedal travel a long way down before the brakes work. Are they good, and pull you up?
Any comments or suggestions welcome, as I am at a loss how to proceed now
Thanks

Maestro Vans

G Force · 2nd March 2007, 10:38

If you are saying that one van out of a large fleet of Maestros has good brakes and all the rest are the same as each other but not as keen as that one van. One possible explaination could be that the load sensing valve on the good van, has siezed in the fully laden position.

Long brake travel is usualy caused by incorrect rear brake adjustment or air in the system.

The best way to set up the rear brakes is, first and most important slacken off the hand brake adjustment before removing the rear drums. Make sure the shoes are servicable and there are no leaks from the brake cylinders, clean up as necessary and to stop the dreaded rear brake sqeak lubricate where the metal shoe rubs the backplate with copper slip. Release the self adjuster mechanism right off then lever the shoe out to make sure the self adjuster is working. Then release the self adjuster right off again. Replace the rear drums and then press the brake pedal hard three or four times, you should hear the ratchet of the self adjuster clicking. finally readjust the hand brake cable to fully on at 5 clicks normal aplication not a schwarzenegger pull.

Gary

maestro vans · 3rd March 2007, 13:41

Hi Gary,

Thanks for the reply. The rear brake cylinders have been checked, auto adjusting mechanism checked ok. Are you saying that the load sensing valve will make the braking better in the fully laden position. I know it biases the braking from approx 70/30 to 50/50 but I didnt think it would adjust the length of pedal travel. How muh travel do you get on yours out of interest. Any other ideas?

G Force · 3rd March 2007, 14:48

Quote:

Originally Posted by maestro vans

Are you saying that the load sensing valve will make the braking better in the fully laden position. ?

I would say that the brakes should feel keener if the valve was seized in the laden position and the rears can have a tendency to lock under lower speed hard braking if the van is empty. Im not thinking the pedal travel will be very different just that you may get the impression that you dont need to press the pedal as far to get the same braking force.

E_T_V · 3rd March 2007, 18:18

If you watch the load sense valve in operation you can see that it pops out a little until it touches the linkage bit where it then sits. This travel will contribute to the overall pedal feel.

Also my van has always been a pain to bleed properly, it always needs to sit for a day after the first bleed to get a really good pedal feel. Also take another look at the self adjusters as they can be fickle things (well mine are!).

wemyss · 11th March 2007, 08:41

There is a similar thread on the Montego technical help and the general consensus was that it would be the flexible hoses which are expanding under pressure.
wemyss.

Monty O · 23rd March 2007, 12:08

I had the brake callipers off to do the wheel bearing. Whilst I was re-assembling it all, I noticed that the bellows bit which the calliper mounting bolt goes into was not moving freely, so cleaned/greesed it with copper slip. The brakes felt so different I did the same to the other side, and the difference is quite noticeable, much less travel and they feel more positive to boot!

Rich · 29th March 2007, 23:10

My vans brakes are excellent, the 700 TD's are pretty feaces hot too, the latest vans brakes were rubbish, but on inspection the pads and discs were obliterated, am sure once the replacements have bedded in, they will be good too. The DLX hatch in comparison has awful brakes, but once used to them, I get in the van, and do hard stops without trying, just because I have got used to the softer ones.

It may be somthing to do with the fact the vans discs are much heaver duty, and the rear shoes and drums are much bigger?

Rich

E_T_V · 31st March 2007, 22:41

Everyone comments on how rubbish my van brakes are. They aren't rubbish but they do require a lot of effort to work them. They are sharp and work fine it just scares most people how hard you have to press them

(And yes the servo seems to be working just fine)

maestro vans · 1st April 2007, 19:05

Thanks everyone for the replies. Im gonna check that the load sensing valve hasn't seized as I am at a dead loss as to what it can be.

Maestro Vans

Peter J · 13th April 2007, 12:43

My load sensing valve appeared to be seized as the rear wheels would lock under even light braking, and adjusting it made no difference. I was quoted £180 for a new load sensing valve at Allwoods car accessory shop

So I took the old one apart, cleaned it up, put it back and it seems to work ok now

Peter J · 13th April 2007, 12:49

My van once failed the MOT on brake performance even though the brake pads were nearly new and apparently not contaminated in any way

I fitted a different brand of brake pads and it passed

so not all brands of brake pads are the same.

E_T_V · 13th April 2007, 14:16

The load sense valves are a right pain sometimes. Mine is disconnected so even if it was seized it will still pass the MOT

(Mine is a campervan so never likely to be loaded up heavily so doesn't really need one).

Pads are quite important on the van as the discs are solid ones and sometimes there can be a lot of weight to stop in a van. I tend to use Apec as they are cheap and about the same quality as OEM stuff. I know there are better pads out there but they stop me well enough until I really get the brakes hot.

Peter J · 13th April 2007, 14:35

Mine has less weight in the back than a campervan, so the rear wheels would lock under light braking (especially on a wet road) when the valve was seized. Even though it passed the MOT in this condition it was dangerous as it was difficult to control with the rear wheels locked. With the valve cleaned up and adjustment slackened off as it is now the brakes must be better balanced as when I test them it may be either a front or rear wheel that locks first.

E_T_V · 13th April 2007, 14:46

There are some instructions on a sticker in the van somewhere about how to set up the valve. The valve works on the height of the van to control the brake force to the rear wheels. I can't remember off the top of my head but the sticker tells you what the clearances should be with the vehicle unladen I think.

A seized compensator valve should fail the MOT as it is a checkable item. In general when braking in the dry the front wheels should always lock first.

Peter J · 2nd November 2007, 14:03

The tester can't have seen it was disconnected then http://www.motuk.co.uk/manual_360.htm
I have got the instructions to set the valve but it looks extremely awkward to do it accurately - taking the measurements of imaginary vertical lines, where they intersect with imaginary horizontal lines, and all in a very restricted space under the vehicle

The way I did it was to just try the brakes at different settings as I think that is more accurate than I could have got it by trying to do it by the book.

E_T_V · 2nd November 2007, 18:48

Nahh he saw it was disconnected. He even commented on it. But seeing as my van can never be loaded up heavily (due to the fact there is a double, bed, wardrobe, kitchen sink etc in there), he let it pass. Infact he has let it pass for many years like that.