Souster
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Posts posted by Souster
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that's good news on the servo replacement, beginning to wonder if the front flexy hoses are stretching & internally collapsing when your turning.
Thanks Ralph. Is there anyway I could pin point it do you think? I mean I've tried turning on the spot and making the issue happen, and I couldn't see any issues underneath on lock to lock. But I'm keen to isolate it if I can. Braided hoses are a pain as they can't be clamped.
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***UPDATE***
Hi all.
New servo fitted this evening. And WOW! The brakes are incredible!!
in fact that good I was a little dangerous for the first few miles on the test drive, as I was so used to pressing hard and now so little effort is needed it was locking up every time even on dry roads.
The pedal also sinks on start up every time. And the brake pedal seems to feel great so far. It's a bit inconsistent at times, mainly due to the increased travel when cornering I believe.
But overall a fantastic result so thanks to you all
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Tried removing the reservoir cap, and took it for a drive. No difference unfortunately.
New servo arriving today, should be able to fit tomorrow. I'll update with my findings and hopefully improvements in that department. Thanks everyone
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Thanks Pawl12 and western.
I had a rear hose from Dave at llama Ralph, great service from him. He's local to me.
Pawl, the brake pads are barely worn really. Although I'm still going to try what you suggested. Somehow I'm really banking on the servo causing the pedals increased travel as I have read some very weird faults from inferior servos. It's doubtful though.
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The theory is that the vacuum in the system may not be enough to pull the pistons in on its own. But the flex in the wheel brgs as you turn to full lock may be enough to push the discs against the pistons, aiding the vacuum to move them inwards.
Without the vacuum in the system the caliper piston seal friction is designed to be enough to resist "knock-back" - as long as the wheel bearing play is not excessive.
Now that's very interesting. I will try that tomorrow evening as it sounds quite promising.
Do you recommend removing the reservoir cap fully? Or slacken it and leave it on a couple of threads?
It did always make me wonder if it would have happened with old calipers and rusty pistons, so your logic sounds promising.
Thanks a lot
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where did you get the new brake flexy hoses from ? as IIRC one of our fellow members had some that had a solid liner inside instead of a tube. so no fluid could get to caliper
They were terrafirma Ralph. I regret changing to braided flexis really, as with the rubber ones it'd easier to diagnose problems.
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This might sound like a daft suggestion - but have you tried removing the brake fluid reservoir cap & checking if you have the problem still ?
I've just read most of this thread (I used to work in brake systems for a long time - so was interested) & agree with the thoughts that you have 2 problems :
1 relatively quick vacuum loss - which doesn't seem to be causing you any real braking issue as the vacuum is "topped up" by the vac pump &
2 something is causing the caliper pistons to retract more than they should - creating significant pedal travel increase to push them back to the disc.
If your reservoir cap is sealed - eg via damage, dirt or bad manufacture - the brake system is sealed & as the brake pads wear, a vacuum can be created in the system which will try to pull the caliper pistons inwards. If the caliper seal friction is low, the pistons can move quite easily & may only need a small bit of extra force from the wheel & brake disc moving with the wheel bearings as you turn.
I've actually seen vehicles where the brake pedal had to be pushed right to the floor more than once before there was braking due to this.
Releasing the cap removed the problem until the vacuum was re-created due to a lot more pad wear & increasing vacuum.
Where are you based ?
I'm processing a warranty claim on the servo, I've just had to buy a new one to be refunded the faulty one.
And thanks Pawl12. I'll certainly give it ago removing the reservoir cap,I have nothing to lose. Although I still can't get my head round why that would only work when the steering is turned?
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Thank you both.
Managed to test my dad's vacuum pump this evening, his also drops the vacuum when turned off, so it seems exactly what you said pat_pending.
I've finally proved the servo is faulty, again my apologies for it being a long winded one. It just not expected with new parts from good manufacturers, but maybe that's the world we live in now.
As for the brake pedal travel increasing when turning, I'm fantasising the new servo may also cure that. But I highly doubt it, every suggestion has now been tried.
Thank you all who posted
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Have you tried a good quality air or cordless impact gun?
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Yes the servo should hold vacuum after engine is switched off, mine does for a decent amount of time.
as yours doesn't hold hardly any vacuum, then it must have an internal leak or the body joint is not correctly sealed.
Cheers for that Ralph. Should the vacuum pump hold vacuum though? Like my mates td5 and 200tdi does. My vacuum pump just drops off when the vehicle is turned off, the other engines don't.
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Hi All. Sorry to bring this one back up, but ive been doing some testing, and getting closer to the one problem, or maybe both.
Firstly, i purchased a vacuum gauge and tested the vacuum the pump produced at tickover (apologies if this isnt the correct teminology to follow):
-my 300tdi: 24 inches mercury with a warm engine, 23 with a cold engine (seems odd that this differs between days? Beleive it could be temperature though?)
-A friends 200tdi: 24 inches mercury with a cold engine-A 2002 td5 defender: 25 inches mercury cold engine
-My dads 300tdi: Very low reading of about 18 inches mercury
One thing i did notice, was the 200tdi and td5 engine held the vacuum on the gauge as soon as the engine was switched off and remained at that pressure for a while, where as my 300tdi loses the vacuum. Im yet to try my dads as i forgot, but his pump is seeming worn compared to my new one.
Next test i did was on my servo with a mityvac which produces a vacuum, using the connection into the servo acting like a vacuum pump. I tried producing a vacuum on my servo, and had absolutly no luck at all, couldnt get the mityvac to budge off zero. I then tried my friends 200tdi and td5 defender, and managed to get almost maximum vacuum reading on the gauge despite it being hard. I removed my vacuum pipe from pump to servo and pressure tested it, no leaks or issues at all.So its clear i have a servo leak so that will be replaced (hopefully under warranty). My question i have is, should my vacuum pump hold pressure as soon as the engine is switched off? like the 200tdi and td5... or doesnt it matter when the one way valve is working correctly in the servo?
Thankyou all and sorry its been long winded. -
Even a genuine part can be faulty....
Does seem like you are narrowing it down though
Got anyone with a second hand one (even your own old one?) to swap in and test?
Could even go electric.... Boydie has done this very successfully.
Cheers Bowie. My dad has virtually the same vehicle as me,so I was thinking of getting a vacuum gauge and comparing the readings to mine. A friend has a 200tdi and td5 defender too,so I can get some figures of what it should be.
I know for certain that the one I removed wasn't providing as much vacuum as this one. But that pump I removed was also inconsistent, sometimes brakes very just about ok, sometimes it felt like new servo assistance at all. Henc
e me replacing it
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have you changed the vac pump at any point? they do pack in as the diaphram can wear/split. it is cam/plunger driven from the engine
I changed it about 3/4 months for a bearmach part, it did have a sticker on it called briturk though. Which didn't give me much confidence. Cheers Pete
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lots if you google vacuum testing gauge ------------- https://www.google.co.uk/webhp?sourceid=chrome-instant&rlz=1C1ASUC_enGB582GB582&ion=1&espv=2&ie=UTF-8#q=vacuum+testing+gauge&tbm=shop
Cheers Ralph. I'll look into that. If the good brakes aren't sustained. I will invest in one of those and find out if the vacuum pump in intermittent. Despite being new! It was only a "briturk" branded bearmach pump
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You must have disturbed whatever it was that was not right. Whtever you took off, I'd look at it all very carefully in a good light, with a loup or magnifying glass if need be - you don't want a sudden reversion to how it was
All i did was pull the vacuum pipe off the servo, nothing more. All i can think of is possibly caused seals or pistons ( I have no idea) to seal better in the vacuum pump, and its providing more vacuum/suction. I couldnt have disturbed anything else.
Is there a gauge of some sort i can test the vacuum pressure?
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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!
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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
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?
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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
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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
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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.
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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?
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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.
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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?
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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.
Brake faults! I must have ruined the brake system.
in Defender Forum (1983 - 2016)
Posted
Hi All
Hope you all had a good Christmas!
Today, I decided to remove the drivers side front caliper, while still connected. Put two old pads between existing pads (to act as a disc) tie the caliper out the way. And take it for a small drive on private land.
I planned to do this both sides, and whichever caliper removed didn't show the pedal sinking on cornering was the problematic corner.
Anyway, it didn't seem like a very good test. As I was too wary of the security of the caliper. However, the pedal did seemed to me more spongy. I'm wondering of that was due to the bends in the flexi pipe being more severe.
Anyway, while the wheels we're off. I thought sod it, I might as well tighten the bearings as tight as possible before they bind too much. And see if the same happens... and it did!
So it's 100% not a hub bearing issue now. There was no play before I adjusted them, but I thought I'd give it ago incase.
Is the only thing it can be now is the brake flexis? I'm very very reluctant to replace more parts and have to bleed brakes again with what I've already done.
If it is the flexis, does anyone know who custom makes them in the rubber variety instead of stainless?
Thank you