Outer Limits 4x4 Board

I used to have a ;94 surf. It used a planetry pack transfer case. This meant it was small, compact and didn't drive 2 gearsets all the time. High range drvies through the gearset meaning an efficiency loss. Further there was a synchro on High range so you could upshift on the fly. There was also a synchro on the 4wd coupling.

The cruiser HF2A on the other hand uses an input and output shaft side by side with 2 sets of gears. There are no sychros on any of these gears, so going from low to high range means stopping. It's larger mostly due to packaging as far as I can tell, normalyl a planetry pack is smaller than 2 shafts. Finally, when locked up, there is no driven gears, so less power loss.

So why would a 94 surf come with a more "advanced" transfer case than a 100 series cruiser?

I know everyone's first answer will be "strength", but that's more a function of size and quantity of steel. The auto box is full of plantry packs.

Anyone with insights into Toyota's brain?

Thanx
Paul

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The HF2A does have synchro on high, so low to high shifts can be done while moving!

hdj105 wrote:The HF2A does have synchro on high, so low to high shifts can be done while moving!

Mine doesn't. Crunchy.

Paul

there is definitely a synchro on high range. you might have the wrong oil, it might be worn out, you might be trying to shift it too fast - there is a lot of rotating mass to sunchronise.

as to the 'why' of it all, as in why does the landcruiser use a constant gear drive, some of the answer is a combination of strength, weight, and vehicle mass centre . there may also be legacy reasons although the operating principles of the newer transfer cases is quite different to the old.

as to the efficiency argument, I don't think there's much in it. The older style with thrust washers on the idler shaft might have generated a bit of heat, but your transfer has all tapered roller bearings, yes there is some sliding contact on the gear teeth but the efficiency of the transfer as a whole would exceed 95% at highway speeds; the final drive is far more likely to swallow power. If you drive a landcruiser, the last thing you worry about is efficiency.

Got me interested. I'll retest when home in a few weeks.

Thx
Paul

I thought the max speed ( allowed by toyota owners manual ) advice 80km/h or lower speed to shift from 2H to 4H ..

GXL - full time 4wd.

Shift is from Overdrive in Low Range to 2nd in High Range (Auto GBox)

Overdrive tops out at about 45km/hr in Low Range.

Paul

Tapage wrote:I thought the max speed ( allowed by toyota owners manual ) advice 80km/h or lower speed to shift from 2H to 4H ..

We're talking shifting from low to high range, full time 4x4, not part time.

Regardless there shouldn't be a speed limit to shift H2 to H4 or vice versa, as long as all the wheels are going the same speed.

me3@neuralfibre.com wrote:Got me interested. I'll retest when home in a few weeks.

Thx
Paul

It may not work with the auto (more inertia, lack of definitive disconnect eg. clutch), but I regularly use it with my manual trans.

hdj105 wrote:

Tapage wrote:I thought the max speed ( allowed by toyota owners manual ) advice 80km/h or lower speed to shift from 2H to 4H ..

We're talking shifting from low to high range, full time 4x4, not part time.

Regardless there shouldn't be a speed limit to shift H2 to H4 or vice versa, as long as all the wheels are going the same speed.

Ok .. my bad .. I never own a full time Land Cruiser ( I love part time)

Tapage wrote:

hdj105 wrote:

Tapage wrote:I thought the max speed ( allowed by toyota owners manual ) advice 80km/h or lower speed to shift from 2H to 4H ..

We're talking shifting from low to high range, full time 4x4, not part time.

Regardless there shouldn't be a speed limit to shift H2 to H4 or vice versa, as long as all the wheels are going the same speed.

Ok .. my bad .. I never own a full time Land Cruiser ( I love part time)

Full time rocks on wet bitchumen, and towing. Puts the power down far far better IMO.

When I tried it last (a while ago) I shifted to N before trying to upshift range, felt crunchy, assumed no synchro on that, and stopped. I'll retest in a few weeks and post results.

Thanx
Paul