Offroad-Express

Hi everybody, just a quick question with regards to Surf gearboxes... Does it do any damage to drive in 4W Hi whislt driving on the open rd for example? Appreciate the replies.

Hi Surf,

As long there is slippage between the road and tyres then you are sweet ie snow, ice, gravel road etc

What happens when you engage 4wd is the front wheels are then locked to the rear wheels and when you corner the rear wheels travel less distance than the front causing massive strain on the drive train on tarmac as they are locked togeather but fighting each other. If there is no slippage between the tyres and the road then either something will brake or you will get transmission windup (with damage?) where you will eventually just stop. If this happens you will have trouble disengaging 4wd and will have to jack a wheel up to 'unwind' the drive train.

Mike

Posted: Thu Sep 02, 2004 3:29 pm

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Hi Surf,

As long there is slippage between the road and tyres then you are sweet ie snow, ice, gravel road etc

What happens when you engage 4wd is the front wheels are then locked to the rear wheels and when you corner the rear wheels travel less distance than the front causing massive strain on the drive train on tarmac as they are locked togeather but fighting each other
there is no slippage between the tyres and the road then either something will brake or you will get transmission windup (with damage?) where you will eventually just stop. If this happens you will have trouble disengaging 4wd and will have to jack a wheel up to 'unwind' the drive train.[

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Doesnt this only happen when the hubs are engaged in 4wd as well. If the hubs are in free wheel then no drive is being transfered to the road wheels therefore no drive line problems
no dout I will be corrected if I'm wrong
cheers DJ

yes, but not all 4wd's have free wheeling hubs My surf is missing a set

Mike

yes, but not all 4wd's have free wheeling hubs My surf is missing a set


sorry! should have said MOST TOYOTAS have free wheeling hubs on the older models. mike do u want to buy a set of hubs???????
see I knew I would be corrected

mike do u want to buy a set of hubs???????

I could be keen DJ

No I think I will pass thanks DJ , as I like just pressing the button each time instead of getting out - turn the hubs - 4wding - then turning them again when caked in mud etc. My surf is a shiney so the less I have to get in and out the better

Mike

Your hub would be constantly engaged wouldn't they Mike, or are they auto?

They could be auto, but I couldnt see anything written on the flanges. I guess I'll find out soon enough as one of the CVS has gone so I'll find out then

Mike

I think in general if they have no switchy thing they are auto... or at least in my experience they are...

hi mike i have a set of surf cvs if you want them

I think yours are constantly engaged with a lovely plastic cover over them Mike

As previously mentioned, most definitely do not drive on the road in 4WD in a part-time 4WD vehicle. You need a fair amount of slip to avoid excessive tyre wear & transmission wind-up/damage.

Incidentally, it is very bad practice to drive with 4WD engaged & the free wheeling hubs set in the unlocked position & can do damage.

I have seen people also doing this for pulling boats up steep ramps so they can use low ratio, this is a definite no-no.

Hope this helps?
Cheers

How does driving in 4wd with the hubs unlocked do damage? The drive is being applied to the front wheels with no load but I fail to see how this is a bad thing - although driving up a steep boat ramp I would engage them anyway - I've seen photos of a 4wd being pulled back down a ramp until it dissapeared under water

Steve

I should have explained myself a bit clearer...doh!

What I should have mentioned is damage to the transfer case/gearbox. Most part-time 4WDs have a max speed when engaged in 4-Hi which varies depending on manufacturer. If you are driving on the highway with the transfer box in 4WD you may exceed the max speed, and things can overheat/get stressed, etc. Even if you don't exceed the max speed, some transfer cases on part-time 4WDs are not designed for sustained high speed running.

Also, regarding the boat ramp comment, I should have qualified that also mentioning that the torque in low range can be too great for just the rear wheels & place undue load on the axles, etc, while properly in 4-Lo (with hubs locked) the load & torque is spead across front & rear drivetrains.

I should remember to write & explain myself more clearly!!

Cheers