Jump to content

Brake faults! I must have ruined the brake system.


Recommended Posts

Thats strange Ralph, i could have sworn there should be a seal between the master cylinder and servo. I know in the rebuild kits for the master cylinder and new one is supplied, and there was deffo one supplied with the new servo i had.

Ive just looked on microcat, and your right there certainly not anything listed. But is that because a new O ring comes supplied with the servo or master cylinder?

Link to comment
Share on other sites

Does the one way flow valve work properly ?

as for the odd pedal behaviour , it'll be hard to diagnose until you have stable vac.

If it is still there with good vac. , I'd be suspecting the front flexi-pipes

cheers

Steveb

Thanks Steve.

I've checked and replaced the one way valve off the servo.

What makes you think it could be the flexis Steve? Is there anyway I could test them?

Link to comment
Share on other sites

Thats strange Ralph, i could have sworn there should be a seal between the master cylinder and servo. I know in the rebuild kits for the master cylinder and new one is supplied, and there was deffo one supplied with the new servo i had.

Ive just looked on microcat, and your right there certainly not anything listed. But is that because a new O ring comes supplied with the servo or master cylinder?

diaphragm inside the servo is/should be sealed to the servo body, I replaced my servo a few years ago & didn't have any extra seals/gaskets to fit.

Link to comment
Share on other sites

diaphragm inside the servo is/should be sealed to the servo body, I replaced my servo a few years ago & didn't have any extra seals/gaskets to fit.

So providing the vacuum pump is working correctly, the pipe and the one way valve isn't leaking... The only thing that can leak is the servo itself? The joint at rear of the servo (pedal box side) can't leak, and neither should the joint the front side (master cylinder side).

If that's the case, it sounds like I have a faulty servo, and another issue.

Link to comment
Share on other sites

Servo should be vacuum tight, it shouldn't leak from any area.

Thanks Ralph. So the only area it can leak it's around the joint? According Google and YouTube they do duck in air on the pedal box side when the brake pedal us pressed.

Would you all agree it sounds like a faulty servo for one? And another issue with the pedal travel increasing when turning then?

Link to comment
Share on other sites

I'd try another known good servo, there is a air filter around the pedal to servo shaft under the rubber boot.

as to the pedal travel increase when turning, not sure where to look next to cure that problem.

Sorry for a stupid question Ralph. But could the one I took off be tested with just connecting the vacuum pipe with the engine running. To see how long it holds the vacuum? Or has it got to be fitted to he pedal box.

Link to comment
Share on other sites

Bent stub axle?

Thanks for the reply.

That's exactly what I thought. That's why I replaced 3 stub axles, front two have been replaced. Very much doubt it's the rear drivers side that is remaining. It would occur while driving straight if it wasn't wouldn't it?

Link to comment
Share on other sites

Sorry for a stupid question Ralph. But could the one I took off be tested with just connecting the vacuum pipe with the engine running. To see how long it holds the vacuum? Or has it got to be fitted to he pedal box.

slaving in the old servo for testing should work, can't see why it needs fiting to pedal or master cylinder for a test purpose on vacuum hold ability

Link to comment
Share on other sites

Thanks Ralph. I'll try and give that a go tomorrow then and dig the old servo out. I could even pull the pipe of dad's 300tdi and see how it works on his too.

Just a thought to rule out wheel bearing adjustment, after browsing the land rover pages tonight.

Would it be worth fitting the td5 spacer between the wheel bearings and really torquing them up tight. Just to really rule out the bearings? Or would that be a waste of time? I'm convinced it's not them though, how many times I've checked them now I've lost count. But you I spose you never know with these land rovers.

Link to comment
Share on other sites

I removed the spacer setup from my td5 axle and went back to the old system. I had very slight play in the OSF when I bought the axle, no amount of tightening would cure it. Only way to cure it was new bearings which necessitated a strip down so I opted to go back to the adjustable setup as once the bearings wear a bit you have no means of tweaking with the spacer in place.

Link to comment
Share on other sites

Sorry, missed that you had changed some :)

Well, it's the only possible reason I can think of, unless you have a loose rear wheel bearing? I presume you have checked these :)

Thanks bowie. Unfortunately I've checked and changed all four hub bearings. I've thrown so much money at the brakes and axles each time left with dissapointment.

Thanks to everyone for your input, one day I will find the reasons why I have very strange faults. It's probably the reason why I have several invoices for the vehicle stating "fix poor brake efficiency" over the years

Link to comment
Share on other sites

I removed the spacer setup from my td5 axle and went back to the old system. I had very slight play in the OSF when I bought the axle, no amount of tightening would cure it. Only way to cure it was new bearings which necessitated a strip down so I opted to go back to the adjustable setup as once the bearings wear a bit you have no means of tweaking with the spacer in place.

I has similar Scott on nsf bearing. Was convinced it was the problem but nope. Thanks for clearing that up though, I won't bother with the td5 approach

Link to comment
Share on other sites

OK one last attempt, have you checked your bulkhead for cracks around the brake master?

Could be the flex of the bulkhead is changing position of master cylinder with respect to pedal, so increasing travel -only needs to be 1mm.

Clutching at straws, can you tell :P

Link to comment
Share on other sites

OK one last attempt, have you checked your bulkhead for cracks around the brake master?

Could be the flex of the bulkhead is changing position of master cylinder with respect to pedal, so increasing travel -only needs to be 1mm.

Clutching at straws, can you tell :P

Cheers Bowie. I've been clutching at straws for some time, any suggestion I very appreciated.

Where should I look exactly? Just around the pedal box mounting holes to the bulkhead? And inspect the pedal box itself?

Link to comment
Share on other sites

With a problem like this, you have to be very methodical to sort it and absolutely only change one thing at a time. So, for a start, disconnect the vacuum hose to the brake booster (and preferably plug it with a snug-fitting bolt if you plan on running your engine). While doing that, check the steering linkage isn't contacting the vacuum hose, as unlikely as that sounds! Now you are only looking at the issue you have with a soft pedal when you turn.

How about this: Jack the front of the car off the road (enough for both wheels to lose contact) by jacking and using axle stands under the axle. You want the suspension to be as it would be on the road, so don't jack off the bumper. Leave the engine off, it will only distract you. Now, put your foot on the brake and turn the wheel left to right. Does the pedal pressure change? If so, you've tracked the problem to something that moves only with the steering, most likely a rubber hose but also potentially an improperly mounted calliper. The wheels aren't turning, so it won't be a wheel bearing issue in this case.

If turning the steering doesn't provoke a change, you will need an assistant. The first test is to feel the brakes, release them, then get your assistant to rock and then spin a front wheel. Re-apply the brakes. Repeat for the other side. If one of these provokes a change in pedal feel the first time you apply the pedal, play in a wheel bearing or a warped disk is suspect. The warped disk shows up in the spin test, the wheel bearing in the rocking test.

If nothing has provoked a change in pedal feel, get the front wheels back on the ground. Now get your assistant, preferably a strong, able-bodied type or get two assistants. The idea here is to place your foot on the brake, still with no engine running, and hold that pedal. Then get the assistant(s) to rock the vehicle side to side as vigorously as they can. If this causes a change in pedal feel, there is very likely to be an issue with the suspension and hoses not being in harmony. You can check which side by getting your assistant to jack under the axle near one wheel, one corner at a time, while you hold that all important pressure on the pedal. As one wheel goes up, the other goes down. Any change is more likely to be a hose stretching under lift than one catching under compression but check for both. Obviously some care is required as the car has to be jacked a fair way and they are heavy if they fall off the jack!

I can't imagine these tests won't replicate the pedal problem. However, if they don't, you need to find a quiet bit of road, something like a carpark at night. With the vacuum hose disconnected, drive at a low speed and feel the brakes. Then, at the same speed, make a moderate turn in one direction and feel the brakes. Do the same in the other direction. If there is no effect, try going a little faster but remember that applying the brakes in a corner is a good way to roll your car so be very careful and feel your way through this with caution. If one or other turn is having an effect on pedal travel, it just means the weight of the car and duration of the turn is more effective than the feeble rocking your friends can provide! However, I feel jacking the axles a corner at a time should produce more twist on your axles. Still...

Don't do any of the above tests with the vacuum hose connected as that has an immediate effect on pedal feel which you are trying to avoid. However, if none of the above has produced the problem, that will be your next port of call. The first thing is to remove the plug you put in your vacuum hose. Before attaching it to the booster, briefly start the engine then apply something like the convex part of a plastic spoon to the end of the hose to see how well it sucks. If you are a big, tough, New Zealander you will obviously just use your finger, knowing you won't get sucked into the engine. That will quickly tell you how much suck your pump produces. It should be quite a bit over a few seconds. If not, you have a dodgy vacuum supply - is there something causing the hose to swing on corners making this supply erratic? Long shot...

Turn the engine off. If you have had the hose connected for any reason, pump the brakes a few times to release any stored vacuum in the booster. Now reconnect the hose but don't start the engine yet. Get in the car, hold your foot firmly on the brake pedal and now start the engine. Your foot should immediately go down something like an inch as the booster supplements your foot pressure. If this doesn't happen, there is a dodgy booster (which may have a loose internal which is interfering with the vacuum supply on bends).

None of this is gospel - it's just a suggestion of how you could approach a frustrating issue. Others may be able to advise better tests. A few things are critical. If your pedal is not firm with the engine not going (pump the brakes to lose vacuum, wait a minute, then try the brakes) you have air in the system. Don't do your basic tests with any vacuum in the system or it will confuse the results. Don't test more than one thing at a time. Don't drive far or fast with the vacuum hose disconnected and certainly not in traffic! Etc etc...

Link to comment
Share on other sites

Had another quick scan through the thread and can't see it mentioned but appologies if you've already covered, just to cover all basics, have you checked the rear axle to chassis brake flexi pipe? Has this also been extended, if not it can stretch tight when cornering, possibly drawing the pistons back.

Link to comment
Share on other sites

With a problem like this, you have to be very methodical to sort it and absolutely only change one thing at a time. So, for a start, disconnect the vacuum hose to the brake booster (and preferably plug it with a snug-fitting bolt if you plan on running your engine). While doing that, check the steering linkage isn't contacting the vacuum hose, as unlikely as that sounds! Now you are only looking at the issue you have with a soft pedal when you turn.

How about this: Jack the front of the car off the road (enough for both wheels to lose contact) by jacking and using axle stands under the axle. You want the suspension to be as it would be on the road, so don't jack off the bumper. Leave the engine off, it will only distract you. Now, put your foot on the brake and turn the wheel left to right. Does the pedal pressure change? If so, you've tracked the problem to something that moves only with the steering, most likely a rubber hose but also potentially an improperly mounted calliper. The wheels aren't turning, so it won't be a wheel bearing issue in this case.

If turning the steering doesn't provoke a change, you will need an assistant. The first test is to feel the brakes, release them, then get your assistant to rock and then spin a front wheel. Re-apply the brakes. Repeat for the other side. If one of these provokes a change in pedal feel the first time you apply the pedal, play in a wheel bearing or a warped disk is suspect. The warped disk shows up in the spin test, the wheel bearing in the rocking test.

If nothing has provoked a change in pedal feel, get the front wheels back on the ground. Now get your assistant, preferably a strong, able-bodied type or get two assistants. The idea here is to place your foot on the brake, still with no engine running, and hold that pedal. Then get the assistant(s) to rock the vehicle side to side as vigorously as they can. If this causes a change in pedal feel, there is very likely to be an issue with the suspension and hoses not being in harmony. You can check which side by getting your assistant to jack under the axle near one wheel, one corner at a time, while you hold that all important pressure on the pedal. As one wheel goes up, the other goes down. Any change is more likely to be a hose stretching under lift than one catching under compression but check for both. Obviously some care is required as the car has to be jacked a fair way and they are heavy if they fall off the jack!

I can't imagine these tests won't replicate the pedal problem. However, if they don't, you need to find a quiet bit of road, something like a carpark at night. With the vacuum hose disconnected, drive at a low speed and feel the brakes. Then, at the same speed, make a moderate turn in one direction and feel the brakes. Do the same in the other direction. If there is no effect, try going a little faster but remember that applying the brakes in a corner is a good way to roll your car so be very careful and feel your way through this with caution. If one or other turn is having an effect on pedal travel, it just means the weight of the car and duration of the turn is more effective than the feeble rocking your friends can provide! However, I feel jacking the axles a corner at a time should produce more twist on your axles. Still...

Don't do any of the above tests with the vacuum hose connected as that has an immediate effect on pedal feel which you are trying to avoid. However, if none of the above has produced the problem, that will be your next port of call. The first thing is to remove the plug you put in your vacuum hose. Before attaching it to the booster, briefly start the engine then apply something like the convex part of a plastic spoon to the end of the hose to see how well it sucks. If you are a big, tough, New Zealander you will obviously just use your finger, knowing you won't get sucked into the engine. That will quickly tell you how much suck your pump produces. It should be quite a bit over a few seconds. If not, you have a dodgy vacuum supply - is there something causing the hose to swing on corners making this supply erratic? Long shot...

Turn the engine off. If you have had the hose connected for any reason, pump the brakes a few times to release any stored vacuum in the booster. Now reconnect the hose but don't start the engine yet. Get in the car, hold your foot firmly on the brake pedal and now start the engine. Your foot should immediately go down something like an inch as the booster supplements your foot pressure. If this doesn't happen, there is a dodgy booster (which may have a loose internal which is interfering with the vacuum supply on bends).

None of this is gospel - it's just a suggestion of how you could approach a frustrating issue. Others may be able to advise better tests. A few things are critical. If your pedal is not firm with the engine not going (pump the brakes to lose vacuum, wait a minute, then try the brakes) you have air in the system. Don't do your basic tests with any vacuum in the system or it will confuse the results. Don't test more than one thing at a time. Don't drive far or fast with the vacuum hose disconnected and certainly not in traffic! Etc etc...

Deep i really appreciate that in depth reply, thankyou very much. The weekend im going to work my way through all those checks youve suggested one by one. Thankyou to you all for your in puts and advice, eightpot ive replaced the rear flexi twice with no luck unfortunatley, i had similar thinking to you.

This week as you all know ive been inspecting the land rover, doing tests here and there to try and get to the bottom of the two problems. Well after a few of you told me to double check the servo and vacuum pump (inc pipe) i did just that on Tuesday evening. I started the land rover, and listened for any leaks around the servo and as i thought, absolutley nothing. So then i removed the pipe and valve from the servo and put my finger over the end of the sucking vacuum pump and held it there. My thoughts behind this were, if i blocked the one end and the pipe was leaking, i would feel the pump sucking further down the pipe (at a join, crack etc).... As i suspected the pipe was fine, and so was the one way valve. Refitted the pipe to the servo, checked for leaks and left it at that.

*** Something odd happened today***....

Came to use the land rover this morning... WOW the brakes were fantastic!!! Better than theyve ever been, and i couldnt fault them. I thought thats strange, they are sometimes inconsistent but not to an extent like this improvement. Drove it again this afternoon, and exactly the same, the brakes were amazing. Even the pedal sinks on start up (for the few times ive tested it) and when the engine is off, it takes 4 to 5 pedal presses to exhaust the vacuum. Locking up the wheels is so much easier, and the pedal feels more 'car like'. Braking efficiency has double by how it feels. When i got back, i thought id check the rear brakes too, and you wouldnt beleive it, perfectly polished like a good braking system should look. It almost looks like ive fitted new discs.

So why??!! Has putting my thumb over the pump for too long done me a favour? Because i certainly havent done anything else to it. And the one way valve was sealed perfectly before and after i messed. The pedal travel still increases on cornering, but when the brakes are this good, it doesnt seem to matter as much!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy