Well that was a bit hairy - swapping ends! *UPDATED* with video *AND Analysis*
Just spun my truck almost 180 turning left at traffic lights doing about 15MPH and we don't even have any snow or ice yet!
Something is wrong with it, that's for sure!
A few miles before I had engaged 4wd as I went up a muddy lane.. When I disengaged though, the truck felt 'heavy' - as though the parking break had been left partially engaged - when you took your foot off the accelerator and pushed the clutch in the vehicle slows as if you were breaking slightly..
Anyway, I had no choice but to get home and then as I turned left into the road just before my driveway and the back and front suddently changed ends.
I'll put it up on stands and take a look tomorrow. Thoughts tonight are:
1. Nothing to do with xfer box (i.e. coincidence) and 4WD unless there is some way that it could have failed to actually disengage 4wd when the lever is moved back.
2. Catastrophic wheel bearing failure? would have expected to hear that. Same for diff.
3. Failure of some part of a rea rdrum break - possible.. It certainly felt like it was being braked.. I think I could also smell a slight burning.. difficult to be sure.
4. Something interfering with one or other of the handbreak cables - quick look and I dont' think so, will investigate tomorrow.
Anyone any other ideas?
Glad you weren't anywhere near where I am. Could have made one hell of a mess (!!!??!!) Seriously though, doesn't sound good and hope you get it sorted (cheaply)
Almost certainly the 4wd was still engaged, yes may have been selected to 2wd, but with tension on the drivetrain it will not have actually disengaged. Nothing to fix!
Hmm.. but I switched in and out between S, SA and GA several times when I was first unsure of what was causing it.. I'm pretty sure I felt it engage back in S firmly.
Of course I can check easily enough tomorrow :-)
Yes, the lever may have been in S, but the gear still engaged, sometimes it will take a few turns either way to release the tension for the gear to disengage.
fcp wrote:
"A few miles before I had engaged 4wd as I went up a muddy lane.. When I disengaged though, the truck felt 'heavy' - as though the parking break had been left partially engaged - when you took your foot off the accelerator and pushed the clutch in the vehicle slows as if you were breaking slightly.".
The muddy lane may not have been soft enough to 4wd, the heavy feeling, I suspect, was transmission wind-up. The sudden release of that wound-up energy possibly was the result of the vehicle slipping, just like a wound up elastic band would.
A simple rule of off roading when it comes to using your toys in the cab, "engage when needed and disengage when not required".
4wd should have been engaged, not simply because you were on a muddy lane but when you would have lost traction. After the loose terrain was passed, the 4wd should have been disengaged. Here it is import to read the road conditions and experience will teach you that.
Hopefully, you may not have suffered any damage.
Cheers,
A few turns? how do you mean?
IIRC, the 'lockup ' problem is because font and rear have wound up tension between them I thought ? - but isn'ty that normally fixed with some forward/reverse movement (which I had done quite a bit of when getting out of the driveway).. Still that does make sense as the tendency to swap ends with 4wd engaged is well documented.
EDIT - Sorry, being dumb, I see what you mean, turning relieves windup because of outside/ inside moving at different speeds.. To clarify though - I reversed at the top of the track, turning several points to switch around for the return journey. Though now I think about it, perhaps 4WD was disengaged after that.. Hmm.
Thanks Rakesh.. Muddy lane actually was an understatement to be fair.. It was both uphill with soft mud with grass and running surface water.. It might have got there in 2WD, but I didn't want to tear up the track to do so and I had a tight corner to make at the top that would have been tricky.
Also, 4WD wasn't engaged until I was into the worst of it and it was disengaged for the return journey back down the track (long before firm ground).
That said, I take onboard what you say - I'm not hugely experienced off road for sure, though I've used 4WD in the past quite a bit on this vehicle and haven't experienced anything like this.
Hi.
Re the ways to get rid of wind up, my understanding is that it comes off more during changes in direction, so straight line may not sort it quickly, whereas turning/weaving does, but I'm no expert!
I have a feeling you had a case of 'few things coming together' which added up to a big moment. Wet, cold, bfg's and some wind up left in the drivetrain, and not least the SWB has got a very short wheelbase relative to its height and weight - we couldn't get it on a scissor lift at the garage this week as its WB was a good 50cm shorter that the carolla hatch next to it.
So hopefully nothing mechanical after all the work you've done - I nearly lost mine by deciding to turn into a garage at the last minute in the wet at about 15mph what followed was a very unexpected 'tank slapper' and yes I have all terrains on!
Glad your ok though
:-) I'm glad everyone else was OK. I can live with the truck breaking.. I can probably live with myself breaking a bit.. but if you hurt someone else (not to tempt fate of course...)... that would be a thing to regret.
You could be right though about the conditions.
Perhaps I was wrong to so quickly reject the transfer box on the basis that it was apparently disengaged.
I'll take a look tomorrow; hopefully no damage done.
One final thought, before I exceed my limited expertise, given you have a 460, as do I, I am not sure there can be any issue regarding still being in 4WD despite 2WD being selected as, unlike the 463, it' an entirely mechanical process.
No electronics holding off for 'just the right moment' etc. I am also assuming you didn't have your diff locks on, but if so that would contribute.
Ta
Simon
No, diff locks were definately disengaged.
I've re-read a number of threads on pointed3 on this subject.. I'm increasingle inclined toward the conclusion that others have suggested that 4wd did not disengage as all the other symptoms fit. I discounted it because I was sure that I felt the transfer box positively engage from one to the other, but it seems that alone (even when the lever doesn't pop-back out) isn't an indication that 4wd has actually dissngaged.
As say I am not very experienced in this area and I suppose when I have switched into and out of 4wd in the past it must have been in conditions that meant that no binding occured.
Put the truck up on stands this morning.. it was in 2DW after all, so the problem wasn't wind-up.
Rather worryingly the problem is that the rear passenger side wheel is completely locked up.
Video here:
http://www.youtube.com/watch?v=Ki6sLvT_FZ8&feature=youtu.be
http://youtu.be/EhekqoeITnc
Anyone want to place bets on what's wrong before I take it all apart? :D
It certainly explains why it suddenly swapped ends.
it can only be ,collapsed wheel bearing,brake linings becoming unbonded and jamming the hub,the brake backplate fixings failing and letting it all jam against itself with a nut or fixing stuck into the lining( ring me if you need bits i am going to hampshire later in my g and trailer )or a real wild card the diff breaking up internally (star and planetary self destruction) only jamming one side or handbrake cable getting caught up and yanked on/ or really obscure but seen it the rubber brake hose collapsing internally and holding the brake on ,but the way in which the system is piped this would lock both not just the one side -somewhere in amongst that lot is the culprit (i hope) -mike
I would prefer to wait until, after you have stripped down the drum.
OK, so the drum was locked solid. needed quite a bit of pursuasion (sledgehamer) to break the adhesion and get the drum free and off
Once off though, everything looks OK - the brakes were actually rebuilt when I changed the handbreak cables over so everything is clean and looks fine.
Drum isn't too worn, nor are linings by the loks of things - I'll put a mic on them later.
So what has happened? I have suspcions about the automatic adjuster - I'm right in thinking though that you can wind it all the way in and then the application of the brake several times should then wind it back out to the correct clearance? I wonder if the shims are wrong; though I'm not sure I have the right size feeler gague to look at that... any other way to tell?
Then again, when it was in for the MOT last when the engineer mentioned that the handbreak was underperforming on that side and so I asked him to adjust it prior to putting it through.. I wonder if he did something to it then.
Any other thoughts?
Hmm.. so one thing that doesn't look right - in the picture attached.. where exactly has the last 50mm of lining gone on the left hand shoe (circled in red). I don't have another one immediately to hand to compare (truck is hard against the wall so I can't get to the other drum)
I don't *think* it should be like that ? althought where it has broken away - if that's what it is, is irrregularly clean - it looks as though there are rivet holes that should be in use though.
Perhaps that is the reminants of what was left in the drum?
Nope, scratch that idea - found a picture in workshop manual that shows it to be the same. I guess the rivet holes are simply there because the show is used in other configurations on other vehicles.
Back to square one..
You are wrong in your assumption of winding the brakes PM me your email address.
I have just completed an article on handbrake adjustment awaiting to be posted onto the forum but this will come out on our new server
In the meantime I can send you my draft to read through, that will tell you on how to adjust the brakes shoes and proper handbrake adjustment.
Cheers,
So you think that it is the automatic adjuster that could have been at fault? Its certainly not siezed or anything.
reading a post on pointed 3 http://www.pointedthree.com/disc/forums/showthread.php?tid=14096&start=21 there seems to be something in the idea that in adjusting the handbrake (as the MOT guys did last week so that its very tight - works on just 4 clicks) when the lining is very worn can be problematic (see post 8 on).
I do have the workshop manual to hand, but would much appreciate your guide which I am sure will be much more instructive. I'll PM you.
Thanks Rakesh, great guide.
I think I'll start from scratch and re-adjust the drums and change the liners now I am at it.
The question that still puzzles me is what caused it to seize up like this in the first place.
ben , i just checked a new set of genuine perrot g wagen shoes that are in the workshop and the rivet holes with unused area are the same as you confirmed , the brake performed as if it snatched and locked itself on this is an indication possibly of the shoes leading edges being presented at an unusual angle -hence the grab -check that all the assemblies for auto/manual adjustment /retaining clips and springs are correct and not transposed ,it is very easily done (the new /alternative shoes is a good idea) if you are brave do a side to side swap and see if you nearly crash in the other direction! (joking)
put it all together and give the brakes a good old I.T.U. and see what gives ,if they have been relined recently i wonder if the compound/friction material is too soft ? hence its potential behaviour for grabbing /or if the brake was dragging and creating excess heat then making a grab likely?? atb mike
Hi Mike,
The linings actually haven't been changed recently and still have a bit of wear left. I think the thing to do is to strip them back down and re-build, though this forecast weather will make that tricky this week!
Reading around a bit on the subject of grab and drum brakes I came across a paragraph from wikipedia on the subject of drum brakes continuing to actuate even when external force is no longer applied:
"Drum brakes can be grabby if the drum surface gets light rust or if the brake is cold and damp, giving the pad material greater friction. Grabbing can be so severe that the tires skid and continue to skid even when the pedal is released. Grab is the opposite of fade: when the pad friction goes up, the self-assisting nature of the brakes causes application force to go up. If the pad friction and self-amplification are high enough, the brake stay engaged due to self-application, even when the external application force is released." http://en.wikipedia.org/wiki/Drum_brake
I know that contamination on the linings can also cause this - that's why I think a complete rebuild is probably the way to go (switch to braided hoses and flush the whole system I think).
yes that sounds a good call ,i used to drive a little old 7.5 ton ford d series horse lorry and the brakes were murder for grabbing when cold -really snatchy -once some heat got into the drums and linings -all was well -we did a full reline on the front axle where the problem lay and hey presto no more trouble -must of been a poor compound as the drums were not skimmed and were found not to be oval- the self locking is a well known and nasty it can be caused by the chamfer on the leading edges being too small or the taper of the lining being incompatible with the diameter of the drum /can be made worse after a drum skim /check max wear allowance spec?-mike
Looking at the lining again tonight they are actualling very unevenly worn too. Top to bottom and left and right shoes all have differing amounts of wear. Unfortunately I think its one of those situations where there's no sense in mucking around and so both the old linings and drums need to get swapped.
There are somethngs you can live with being less that reliable/ consistent.. Brakes aren't one of them !
Its really annoying because it was only just back on the road. However noone was hurt, the truck wasn't damaged and, in the end my honour was found to be intact vis-a-vis 4wd selection and wind-up!
Thanks again everyone for input - I'll document the change (Rakesh, I'll forward on any photos) and report back.
Glad you found the culprit!
Yes, it was an interesting experience and just shows how easily the SWB can get out of shape - its a big lump of steel to not be in control!
New linings and drums ordered anyway.
yes they can be tail happy ,the lwb 460 can be a bit naughty also .when you put the 606 in with the myna pump and holset hx35 you will have a 2 ton tvr ..
With more reliability than a TVR I hope :-)
It's a good point though - .. I can just imagine the boost kicks in when wet and all of a sudden you're making love to a hedge :D
I've never considered it until now because the vehichle has never felt anything but very planted.
And for the purpose I had in mind (overland rally next year) the 606/ Myna seems a good bet, but...
So maybe some 463 axels and transfer box, hmmm...
LOL
the w463 can skid in ice too despite full time 4x4, can be interesting, glad you have found the culprit and rather easier than the alternative
yes the torque surge is huge and i can make my lwb go a bit 'tokyo drift' in the wet rather easily... 330nm std my one 350 ish and 2 wd and a wet slippy junction ,when tony b and i drove to meet up with spider at andover we got crossed up in the wet powering out onto the sliproad for the a303 . basically it could bite you if you do not catch it, as they are heavy old buzzards and the weight really starts working against you like an early porsche 911 (spin like a hammer on a shiny floor)
ben, maybe you should think about the rear disc conversion i am doing as it will be better for your motorsport application??
it's ok ,all good fun - jacky ickx did ok on the paris dakar with his drumbraked 460 so...
:D LOL, yes and he won it!
With 2 spares in the back and 4wd on sand, mine won't be quite so tail light in the desert anyway I hope, Roll cage is definitely going in though!
Despite my misgivings and earlier critique of why anyone should want to spend E2.5K+ on the ORC rear disc conversion, I must admit that having seen your post on the sprinter disc conversion you are doing, I was actually quite tempted (especially when I thought about the alternative pain of spending £230 on a new set of linings and drums).
I went ahead with them anyway this morning because I need the vehicle back on the road this week, but I might just have another think about the rear disc option when I finally take her off he road in May to start the prep work for the race.
I had something very similiar happen after my rear shoes were re-lined. Mechanic put the push rod back in the wrong way round and this caused the shoes to 'over adjust' and jam against the drum. only happens once the auto-adjuster has operated for a while. Just a thought.
Chris
I spent the weekend re-building the rear brakes having ordered new drums and liners and having had both sides apart and looked at it in a bit more detail, I think your experience is exactly what has happened in this instance too. When I actually got the other drum off (both needed a good thump with a sledgehammer to free), it was much more obvious where the lining had jammed at the top in the way you describe.
To explain: The adjustment of the new handbrake cables (which was done for me as a quick favour by the MOT mechanic to get it through) seems to have been done without taking account of the need for a corresponding adjustment to the auto-adjusters on the drum, which had the effect of 'kicking out' the tops of the shoes, leading to the front on both sides eventually 'digging in' and jamming against the forward rotation of the drum (had the adjusters been manually rolled forward then the gap between drum and liner would have remained consistent).
Anyway, new liners and drums went on today (thanks Rakesh - your guide proved very helpful) and took very little adjustment to get spot on with the 0.5mm gap correct out of the box and almost no adjustment needed to the handbrake. Performance is excellent - way better that they have ever been and definitely worth doing.
A few observations from this today:
1. Despite what the workshop manual says, with new liners and drums, I needed to have the adjusters wound all but 1/2 turn back in for them to fit. Other people have posted this as their experience too it seems. Some discussion that the newer liners are slightly bigger that the original stock liners were.
2. The shiny new drums will rust in an instant (like seconds when exposed to moisture!). I'm trying POR20 VHT oven-cured aluminium paint with them, we'll see how they last, but for now looks good.
3. When slackening the handbrake cables (especially if new) you need to slacken them A LOT.
Way more than you think you need to in fact.
If the shoes are seated full in at the top, you won't get the drums on and it probably because you still need to take slack out of the handbrake cables. I found that once I had taken enough out to get the drums on (which left the shoes fully seated), the 0.5mm gap that's required liner to shoe was correct as it was 'out of the box'. The handbrake cables then needed no more than a couple of turns to set within the required 3 clicks
4. The auto-adjusters only adjust the front shoes when braking going forward. To adjust the rear shoes you need to brake heavily a few times in reverse (industrial estate car park in the snow was good for testing it all out this evening :-) )
5. Squashing your fingers between the wheel and the hub as the rim drops off the hub while you are trying to line it up to do the wheel bolts up in the dark while its -2 and snowing hurts - a lot. Swearing helps some I found, but really no substitute for actually being able to see what you are doing :-)
More pictures and commentary here www.flickr.com/photos/benstoneham/sets/72157632567204667/
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Yes that would have been interesting!
Whatever it is, I'm sure it will be sortable easily enough.. I'm fortunate enough to be able to do most work myself so labour is cheap :-)
It was an unexpected event though.. very fortunate that noone was behind me really. It was good lesson in how quickly, once traction is lost, a SWB vehicle with high CG and little mass at the rear (no seats or anything in the back) can get out of shape.. I've spun a few cars over the years (not on the road for the most part!) and this was a whole lot quicker that I'd have expected. The Mud Terrain tires probably don't help either (great in mud, poor on wet, cold tarmac)
On reflection I suppose I could have chosen not to have driven the vehicle back after it started to feel strange.. but to be frank it the sensation of drag was quite subtle and - not enough to think it very serious.
Anyway, alls well that ends well. Noone huts, truck OK, lessons learned and we'll find out actually what went wrong tomorrow :-)