Had a bit of a play with the diff lock this avo ......no trouble getting it in
slips in easily and the light comes on
The problem is and always has been getting it to stay in ....the slightest brush of the lever and the light goes off ( presumably so does the diff lock disengage ) . Surely it is designed to stay in place over bumpy terrain ?
i might take off the gaiter and see if there’s is room to adjust the mechanism if it looks anything like that diagram
Mine was doing it from new and despite several attempts at fixing it never worked.
On my last service I finally had it resolved. I had a new housing assembly installed under warranty. This is a known fault and there is now a service action SSM72873 out on it.
Cheers,
Jon
No, but mine was done in November last year.
Cheers,
Jon
I'm assuming not much change in the way transfer cases are engineered between models, particularly detent systems, unless you have a fangled solenoid to do the holding instead. The degree of difficulty depends on a number of factors, and I'd hate to send you on a wild goose chase if it's something else. The only time I've had trouble with lever linkages is where I've got something back to front on reassembly. Four transfer cases to date.
There are two detent balls in play. One regulates diff lock on/off, while the other regulates hi-neutral-low range selection.
I'm not an engineer so there may well be some reason why LRover do what they do.
You (well me at least) would expect a detent system to consist of a hole of uniform diameter bored through the casing, having enough clearance to allow for a ball bearing and spring, capped at one end by a grub screw and the other end by a grooved rack. If the rack were removed then you would expect the ball and spring to fall into the casing.
Don't have the measurements on hand but from memory the hi-neutral-low uses a 3/8th inch ball bearing running between three 3/8th grooves in the rack - a well matched fit. When rebuilding, the natural inclination is to fit the rack, then drop the ball and spring down the hole, and lock down with the grub screw to give a spring pressure you are happy with as judged by the hand effort required at the lever and surety of engagement.
Problem I found was that the hole was hour glassed to some extent and did not allow the ball to fully pass. The ball stuck out of the bottom of the hole just enough to catch the shoulder of a groove on the rack, giving the sense of locked engagement - however, the slightest tap on the lever results in disengagement. No amount of winding in the grub screw made any difference. In fact on disassembly the ball was jammed in the waste of the hole and had to be forced free.
I did not re-drill the hole, leaving it as it came from the factory. Instead I put the ball in place through the main cavity of the casing, below the waste in the hole, then inserted the rack - the ball now trapped in place by the rack and the waste. The spring went in through the top, enough clearance at the waste for the spring to fit through. Adjusted the grub screw pressure and all fine.
I do wonder if the waste is intentional - if your grub walks out of the hole then you only risk losing the spring - the ball remains trapped but gives maybe some feeling of 'location', but you will have to hold by hand!?
From memory the diff lock dentent shaft has two 1/4 inch grooves. You might expect a 1/4 inch ball bearing to match. Instead, in several boxes, I've found 3/8th ball bearings, same as used in the hi-neutral-low system. Because 3/8th is oversized the ball bearing sits on the shoulders of the groove, rather than in the groove. Not sure this is intentional and considered effective for purpose, or an assembly line mistake. I replace the 3/8th with a 1/4 inch.
The simplest thing for you would be check linkages first; then the grubs and spring are in place then wind them in and out until you happy with pressure required at the levers and surety of lock. If you're not getting any change in feel at the lever, and particularly if some other owner has tinkered before you, then it might be as easy as replacing a missing spring or ball. Much more work required if mismatched ball and rack groove, or ball jammed in waste.
Hi,
I've just had my 2012 defender in at the land rover dealer last week where they installed the parts for service action SSM72873 and it has made very little difference to the diff lock lever.
Before the installation of SSM72873 my diff lock lever was pretty much "spring loaded" to the middle between diff lock and no diff lock. This was the same whether in High or Low. It had never really been right since new.
Since the installation of SSM72873 the lever will stay left (diff lock) or right (no diff lock) for a max of about 30 seconds then flops back into the centre.
I do have an ashcroft centre diff installed but I don't think this should make any difference?
Who else has had service action SSM72873 installed and what are your results?
Hope to take the defender back into the land rover dealer this week.
Thanks
Kerry
After finding yesterday that my Transfer Case selector lever is able to freely rotate through the selection range with no effect on the vehicles drive or illumination of the 4X4 dash light, I’m reviving this thread as it seems the best that I can find on the site for Pumas.
My 2012 Puma has an auto transmission fitted with the LS3 6.2, and luckily is still in high range drive.
Does anyone have any other suggestions on this failure before I go delving in?
Thanks in advance and best wishes all.
Ken
My experience is with Discovery 1 transfer boxes that use old style linkage actions- engaging diff lock throws a light up on the dash, a sideways 'H' - there is no light for when you engage High-Neutral-Low. I'm not familiar with the Puma whether it has lights for both diff lock and High-Low ratio changes and whether changes are old style linkages or solenoids.
My rather long email had to do with the detent system, the system of grub screw, spring and ball bearing that holds your selected High-Neutral-Low ratio or diff lock selection in place without you having to manual hold it in place by hand.
If you haven't already, and you think it's safe to do so, move your lever into low range and hold the lever manually by hand in place, drive a short distance to see if you are actually in low range.
If you do not find yourself in low range after holding the selection lever in place by hand then you may have a broken external linkage (easy fix) or a broken (highly unlikely, check for metal in your oil) or badly worn (more likely on high mileage vehicles) selector fork inside the box.
If you do find you are in low range then linkages are fine and the detent is more than likely to be the problem.
In regard to the diff lock. You may not get a light on the dash because the bulb is blow, or the simple switching mechanism on the box is broken or its wires are loose. In some ways the light is not too important as long as you remember to move the lever to the unlocked position when back on hard surfaces. Even though you have unlocked the centre diff a sticky switch on the box sometimes leaves the light 'on' when it should be 'off' - a short drive with vibrations usually unsticks the switch and the light goes out.
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