Changing from low range to high range on the fly

[abaddonxi]

From this thread -
Changing from Low to High - Defender

From Camel_landy -

Changing from Low to High - Defender

No problem Lo-Hi on the move... This is the process:

1. Start off in Lo & come up through the gears until you reach 4th Lo.
2. Hopefully, you should now be on a suitable strech of road, either flat or with a slight downhill gradient.
3. Dip the clutch & drop the transfer box into Neutral and bring the clutch back up. (Double de-clutch)
4. Prepare to go into Hi (ie. get your hand in the lever ready) and as soon as you dip the clutch you need to drop it into Hi.
5. While the clutch is down, select 2nd and then bring the clutch up.

The trick is to drop it into Hi as soon as the clutch goes down as the gears are all traveling at the same speed. If you delay, you'll grind the gears...

This technique works equally as well without a heavy trailer, you'll just find that it'll be easier selecting 3rd rather than 2nd at the end.

HTH

M

And Blknight.aus' reply -
Changing from Low to High - Defender

stand by for a sledging war on this one....

yes you can do it BUT.....

get it wrong and bad things happen.

I bat for the dont do it side of the fence mainly becuase Its very easy to get wrong which you will get away with once or twice (or 30 times) but then that one time you desperately need it to go right and you get it wrong and youve had it. Ive also read of cases (seen one) where the person trying it out pooched it got nuetral, paniced and lost control of the vehicle how bad that can get depends on all the factors that are against you at the time.

I reccomend that if you can work it up to the top of the hill in low range stop at the top or a crest midway and then go again in high range.

that said... heres how to do it without a double clutch (as per the book)

get it moving in first low, grab second.
get to a nice cruisey speed for second low ( 5-8kph is usually enough)
clutch in
put the tcase in nuetral
put the main box in nuetral
put the tcase in high
put the main box in first
release the clutch
back on the noise

this will result in some clunking of the tcase and IMHO does a little damage every single time you do it BUT it does less damage than screwing a double clutch shift like Im about to describe (side note a variation of this will let you do a lo-hi in an auto)


heres how to do it by double clutching (ask someone with a IIA or earlier main gearbox to teach you this and let you practice changing into second gear to perfect this) this whole sequence takes a bit over a second to do

take off in first low and work the speed up to where your engine is well over peak torque RPMS
clutch in
select nuetral on the tcase
clutch out
let the engine revs die off to about where they would be for first gear high range at the speed the vehicle will be doing in about a seconds time
clutch in
select high on the tcase
clutch out

get it right and you do no damage
get it a little wrong in the rev matching part and it either wont go in (and grind a lot) or it will clack a little and then go in (doing about the same amount of damage as the no double clutch change described above)

BUT brain fart the sequence or ride the clutch or totally pooch the rev match and you can kill a tcase in one go.(probabley not a new one, more likely on a high K's box)

heres the short version of that and you can do this one in less than a second
get it right and like the double declutch and youve got no problems get it wrong and you dont get the option of a little clacking its straight to damage for you.

move off in first low as per the double declutch
lift off of the accelerator and then at the same time select tcase nuetral
as the engine revs drop to the speed for first gear high range push in the clutch and as soon as its on the floor select high range (this should feel like one combined movement when you get it perfect)
ease up on the clutch and down on the accelerator, catch the friction point like you would for a normal hill start and keep driving

Im not going to describe how to snap shift it...