In message , Dave Liquorice writes
Dave you are missing the point. That is exactly the problem, with constant 4 wheel drive on a suspended tow you have all the drive going through one half of the centre diff. This is what kills them. The rest of the transfer box is only to happy to turn no matter what end the power is coming from. By disconnecting the prop you can save it.
Not so! This is the difficulty alluded to in the previous message. It is not possible with the full-time 4WD used beyond the Series models to stop any part of the ground-driven part of the transfer box (which includes the inter-axle differential) from rotating. You can't disconnect the two wheels which are not on the ground.
Putting the transfer box in neutral only disconnects the transfer box from the main gearbox.
Hence the previous suggestion that in these circumstances the propshaft to the axle on the ground needs to be disconnected for a suspended tow of any significant distance.
Well that is a matter of opinion, do the doors fit any better ?
Hi All
My mot man of 28years (so he is experienced) wont put my disco on the rolling road for exactly that reason. He has a meter he puts on the floorpan and he test drives it on the road and measures inertia when braking.
Hope this helps
Paul
Yes the series 3 doors fit just fine on a Defender! Thankfully, the Defender doors are crap..
On or around Sat, 11 Jun 2005 18:00:02 +0100, Marc Draper enlightened us thusly:
still, with no load on it, I reckon it'd be OK for short distances. 's a very different story to, for exmaple, running full power through one set of wheels on a dyno.
Excepting your single axle dyno. (as opposed to MOT brake test) example the two other cases that we're considering are effectively zero torque systems where a wheel, axle or transfer box is rotating without resistance. It's not totally free of torque as accelerating the gears and friction will provide some torque. If there is little torque there is little power in the system.
As someone mentioned earlier, possibly even you yourself Austin, the killer is when the relative speed between the differential pinions and the shafts on which they run goes beyond that for which they were designed. Remember, too, that there is little lubrication at this critical interface.
If we wish, we can discuss on another occasion how differential pinion speeds can reach 'horrendous' values.
In message , Paul Tasker writes
28 years of MOT experience ! And no knowledge of how a Landrover gearbox works.That may sound a bit harsh but the internals of the disco/defender transfer box are not magic or mystical. It is all just gears, bearings and oil. And in the configuration used in the above vehicles it will not be damaged by use of a brake tester.
I personally put well over 100 landrovers a year through their MOT and all non viscous transfer boxes are pull on the brake tester. It is a much more accurate way of assessing the safety of our brakes.
Series doors are simpler than Defender doors and give more legroom and elbow room, you can get them second-hand but they're hard to find and are often in bad condition. A bad condition series door will work though, which is more than can be said for a Defender door! The window raise mechanism and the lock mechanism are weak on the Defender doors.
Here in NT Australia I've used the Govt test shed for all but one year of the 26 years that I've had my 1975 RR. For about the first 10 years they had these vehicles go through the truck bay that had 4 moveable plates that you idled up to and slammed on the brakes. The gauge was 4 column's of fluid that had to rise to a particular minimum level. Handbrake test was stall engine by trying to drive off while it was engaged. They changed and insisted that we use brake dyno, but I've never really been happy with it but had no evidence to refute their statement that they had consulted dealer/manufacturer. The only year I had it tested elsewhere, the idiot "mechanic" couldn't tell the difference between a rear brake fluid leak that he thought he saw and what turned out to be actually another leather axle oil seal failing. Fixed it myself and then went to Govt shed, not back to him. I have no problem telling the "diff" between the smell and feel of each.
As to accuracy of testing safety of brakes, I disagree. Two years ago I got mine passed while booster was faulty (actually did fail while driving there). Brakes had pressure for just a few seconds so I braked heavily, and as he looked at the right readings I lifted off quickly. Passed rego and drove straight to repair shop. If they were really serious they would make us brake a few times in quick succession to see if it remains good, but it's not up to me to re-educate them on that.
They are a real pain on some other things though, like don't all LR products leak oil and it's not necessarily a safety hazard. Comment not long ago was "You did a good job cleaning up the oil" (he had tested me a few times).
The best/worst problem's I've had with the test shed were:
PhilD (sorry for long rant)
In message , PhilD writes
In the UK the brakes are tested differently
And the owner is only allowed to watch for those very reasons.
The mot tester will check for correct operation of the servo as part of the test.
The rolling road will pickup imbalance due to oil leaking onto the brake discs etc. as well as calculating the efficiency based on the weight of the vehicle.
That is the correct method according to the Vehicle Inspectorate (they now have a new name), which I discovered when a MOT test damaged my 1991 Disco.
My normal service man (LR expert) was ill so I had to use another MOT tester.
He used a single axial rolling road.
VI would not accept responsibility for the damage and would take no action against the MOT tester. Got my MP involved and he got VI to have an 'independent' investigation.
The result was that the tester needed to change his working methods, but was not held responsible for the damage to my Disco.
The damage caused the Disco to verge to the right by half a lane while towing a caravan at 55mph on the M11 at night.
If it had happened on a normal road with a vehicle coming the other way, it would have caused a head-on collision.
The MOT test is to promote safety - but we could have been killed by the error of that tester. I read sometime later in the local paper that the tester's son had died in a vehicle accident. I wonder if this father caused his son's death.
Alan
What was the damage caused as I find it difficult to believe that a damaged centre diff would "cause the Disco to verge to the right by half a lane while towing a caravan at 55mph on the M11 at night" How long after the test did this occur I suspect that this was caused by a brake imbalance which should have been noted on a single axle roller tester or other mechanical fault but the test only proves the vehicle was roadworthy on the day of the test so any faults arising after the test are not the tester responsibility which could be the reason no action was taken against him
I have tested hundreds of defenders,disco's and range rovers on a single axle roller tester and have never had a problem arise I have even done freelanders but don't anymore
In message , Alan Morris writes
Please give details of how you feel you vehicle was damaged by the test?
AS we have discussed at length the only possible way to damage it would be by applying the handbrake on the rolling road.
There is no way that damage to the centre diif you cause your vehicle to swerve into on coming traffic.
On or around Mon, 13 Jun 2005 08:11:54 +0100, Marc Draper enlightened us thusly:
Inclined to agree, there. Mind, *rear* diff, I've had one of them cause interesting effects.
In message , Austin Shackles writes
Yes Austin.
Wheel bearings, CVJ, front or rear diffs, bushes and ball joints could all cause it to swerve and none of them can be damaged by a brake tester.
My MoT tester now has a roller brake testing rig that has a "4wd" setting, which rotates the wheel not being braked in the opposite direction to the braked wheel - hence no turning of the prop shaft. I presume the test sequence doesn't include the usual "brake gently and watch the two readings rise" section. I wonder how the new Swansea-linked MoT will cope with oddities like 4wd or mechanical brake servos? As the test sequence will, AIUI, come up with vehicle-specific instructions, I wonder if someone at Swansea will have decided which vehicles can have just the Tapley meter test?
A front CVJ locked solid and the tyre got a flat spot on it.
I was not in the workshop while the test was being conducted, but I saw the large dials rotate to something like 80%. Then on the second axial, the dials only went to about 10%, and the engine revs reduced much quicker. I assumed that it had failed.
But it passed.
My service man and the VI person I spoke with at first, agreed that the tester had put a massive force on the transmission.
The first journey after the test was when the wheel locked.
The VI man told me that the tester was at fault. But after a written complaint, I their story changed.
It was suggested to me that the centre diff was on during the test.
The big question. Why did the dials on the second axial only go to such a low level. The only answer that makes sense is that the tester remembered that he was doing it wrong.
There was also a minor problem with the need to change bushes on the rear shocks, which did not need changing. Clearly the tester had no idea how to test Land Rovers.
Alan Alan.
What have engine revs got to do with it, the test is done with the vehicle in neutral?
Assuming that you mean diff lock, had that been on it would have shown itself imediately the rollers had started turning.
Or perhaps that the brakes on the rear axle aren't as effective as the rear (front= discs, rear= drums)
The rear shock bushes on a land rover are no different to any other vehicle.
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