diff windup

Spike J. As MUZBRY stated the answer is NO . All you are doing is engaging the transfer gearbox when you shift from two wheel drive into 4x4 HI or LO. As long as the front hubs are not locked, then no wind is at all possible. I often use Lo range for getting up my very steep driveway in reverse. That way I`m not working the clutch and can reverse at idle engine speed, plus accurately place my vehicle where I want it. I only lock the front hubs on muddy roads or when actually off road, but never drive your vehicle on dry bitumen roads with the front hubs engaged, as in city driving, as that's when transmission wind up can happen. That can be a costly mistake. Happy travels.

I agree. I often engage low 4WD without the hubs engaged - just using the extra gearing to help tow the van over very steep hills

John

Diff windup is happens when all 4 wheels (or more correctly 2 axles) are locked together and turn at different rates. It will only happen on hard surfaces such as a sealed road when all wheels are in driven mode.
If on a slippery surface such as sand, gravel, dust... then the wheels will slip enough to allow the transmission to relieve the stress of differences in rotation between the axles.
So having the front hubs unlocked OR running in 2WD will mean that the front wheels are not rotationally connected to the rear wheels hence no windup is possible.

I believe that even the current model Land Cruisers actually advise that you travel a certain number of kilometres each month with the hubs locked, but in 2WD to aid in lubrication etc of the diff.

On both of our work cars (Troopy) the hubs are always locked, as such if required it's just a matter of moving the TC lever to get 4WD, and we've never had an issue on bitumen.

Ant

Hi all,

Wind-up will only be an issue if the front hubs are locked AND H4 or L4 is selected through the transfer case AND you're driving on a hard, non-slip surface, such as dry bitumen. Perhaps Joe's situation where he was catching buffalo and bulls with FJ40's in H4 over rough terrain would provide enough slip to overcome any tendency for transmission wind-up - or maybe the old girls were so worn that no-one noticed anyway. :-) I'm pretty sure a really wet and slippery bitumen, or snow covered, road would be fine with everything locked up.

In reality, all a full-time 4WD vehicle is, is an free-wheeling front hub 4WD with the hubs locked and they don't suffer unduly from driving on bitumen every day - until you lock the centre diff, then it's an entirely different story.

Regards,


Charlie

Joe G2. My drivers manual states that the front hubs should never be locked and the vehicle driven in four wheel drive mode on a biutmen road.In my 50 years driving all makes and models of 4x4s, have experienced diff wind up once, and stopped immediately. Unlocked the front hubs and voila no more diff wind up. Some 4x4s advocate that you engage four wheel drive ( preferably on a gravel road ) just to lube the front diff bearings etc. If no gravel road available, and you only have bitumen, then providing you there is a long straight section ( where there are no turns ) will not harm the transmission - I know as I have done it in Perth on some freeways which are straight as an arrow .

Hi Charlie,
This discussion has brought back some old memories.
I was lucky enough to work for someone who would buy brand new FJ 40's every year when they still made them and we would strip them down to put special bar work on them, some had hydraulic bionic arms fitted. We would do the catching season in them and pull the bar work off put the roofs and doors back on then send them to a panel shop for a touch up and then trade them in on new ones with Bridge Autos the Toyota dealer in Darwin. After 1984 we had to look for good second hand ones.Those were the days.

Joe